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Journal articles on the topic 'Seedling stands'
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1
Groninger, J. W., J. R. Seiler, S. M. Zedaker, and P. C. Berrang. "Photosynthetic response of loblolly pine and sweetgum seedling stands to elevated carbon dioxide, water stress, and nitrogen level." Canadian Journal of Forest Research 26, no. 1 (1996): 95–102. http://dx.doi.org/10.1139/x26-010.
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Seedling stands of loblolly pine (Pinustaeda L.) and sweetgum (Liquidambarstyraciflua L.) were grown in monoculture or mixed stands for two growing cycles in controlled-environment chambers. Treatments consisted of ambient (408 ppm) and elevated (806 ppm) CO2, concentrations, water-stressed and well-watered conditions, and low (20 kg N/ha) and high (215 kg N/ha) nitrogen application rates. Photosynthesis rates were measured under ambient and elevated cuvette CO2 concentrations for both whole stands and individual seedlings from these stands. Significant interactions between CO2 and water suggested that elevated CO2 concentration compensated for low water availability in individually measured loblolly pine and in whole seedling stands regardless of stand type. Expressing photosynthesis on a soil area versus a leaf-mass basis influenced the photosynthetic rankings of the three stand types relative to one another. Net photosynthetic rates per unit leaf mass were 390 and 880% higher in individually measured seedlings than in whole monoculture stands for loblolly pine and sweetgum, respectively. Lower photosynthetic contributions from lower canopy leaves in whole seedling stands compared with the upper canopy leaves used in individual-seedling measurements were thought to be responsible for lower photosynthetic rates in seedling stands. These results suggest that photosynthetic response is influenced by canopy dynamics that are unaccounted for by individual-seedling measurements of photosynthesis. Differences in photosynthetic response between loblolly pine and sweetgum stands and individuals are thought to be largely due to species-specific differences in canopy light extinction characteristics.
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Tuskan, G. A., K. E. Francis, S. L. Russ, W. H. Romme, and M. G. Turner. "RAPD markers reveal diversity within and among clonal and seedling stands of aspen in Yellowstone National Park, U.S.A." Canadian Journal of Forest Research 26, no. 12 (1996): 2088–98. http://dx.doi.org/10.1139/x26-237.
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Fire in 1988 created a situation that allowed a rare aspen seedling recruitment event to occur within Yellowstone National Park. Through the use of (i) 194 randomly amplified polymorphic DNA (RAPD) markers from 14 select primers, (ii) measures of population diversity, and (iii) neighbor-joining analysis it was determined that the postfire aspen seedling population contains greater diversity within each of the four sampled stands than that found within all of the 10 sampled mature aspen stands that pre-existed the fire. Unlike previous studies, a large portion of the molecular variation in both the seedling and mature populations was partitioned among stands. Furthermore, variation was unexpectedly detected among ramets within each mature stand. The mature stands appear to be clonally derived, yet individual ramets within stands varied slightly and incrementally in their RAPD profile. These data suggest that somatic mutations may be occurring and accumulating in clonal aspen stands. A proposed scenario of stand establishment and development involving the accumulation of somatic mutations and elimination of genetically related seedlings arising from a rare founder event provides the theoretical basis for the observed differences among and within seedling and mature stands of aspen in Yellowstone National Park.
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Schultheis, Jonathan R., Daniel J. Cantliffe, Herbert H. Bryan, and Peter J. Stoffella. "Improvement of Plant Establishment in Bell Pepper with a Gel Mix Planting Medium." Journal of the American Society for Horticultural Science 113, no. 4 (1988): 546–52. http://dx.doi.org/10.21273/jashs.113.4.546.
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Abstract Germinated pepper (Capsicum annuum L.) seeds were combined with plug-mix, or plug-mix and Liquagel or Laponite 445 gel at various concentrations and volumes of solution to determine their effects on plant stands and seedling growth. Treatments with pregerminated seed led to earlier, more uniform seedling emergence and larger seedlings than those with non-pregerminated seeds. Final plant stands were similar for both treatments. Plant stands and seedling growth were greater and more uniform with Liqua-gel gel mix formulations than Laponite. Seeds in planting mixes with high concentrations of Laponite (2.0% by volume) and large volumes of gel solution (1.75 liter per liter of plug-mix) in dry and moist soils emerged slower and resulted in lower and less uniform stands than the plug-mix treatments. The optimum gel mix medium for plant establishment (rate and total emergence, stand uniformity, and early seedling growth) consisted of 1.0 liter of plug-mix per 1.25 liters of gel solution at a Liqua-gel concentration of 1.0%.
4
Fried, Jeremy S., John C. Tappeiner II, and David E. Hibbs. "Bigleaf maple seedling establishment and early growth in Douglas-fir forests." Canadian Journal of Forest Research 18, no. 10 (1988): 1226–33. http://dx.doi.org/10.1139/x88-189.
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Survival, age and height distributions, and stocking of bigleaf maple (Acermacrophyllum Pursh) seedlings were studied in 1- to 250-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands in western Oregon to identify the stages in stand development in which bigleaf maple is most likely to establish successfully from seed. Maple seedling emergence averaged 30–40% where seeds were planted and protected from rodents but was typically <2% for unprotected seeds. Seedling survival after 2 years was highly dependent on canopy density, measured by percent sky. Average 1st-year survival of seedlings originating from planted, protected seeds was highest in clearcuts (1–2 years old, 36% survival, 56% sky) and pole-size stands (41–80 years old, 30% survival, 17% sky) with sparse understories and canopies. It was lowest in young stands with dense canopies (20–40 years old, 4% survival, 8% sky) and old stands (81–250 years old, 14% survival, 13% sky) with dense understories. Naturally regenerated populations of bigleaf maple seedlings, which occurred in aggregations (0.005–0.04 ha in area), were most abundant (up to 10 000/ha) in pole-size Douglas-fir stands. Although seedling size distributions within stands had a strongly inverse J shaped form, size distributions within aggregations appeared more normal (bell-shaped). Seedling age rarely exceeded 15 years. Seedlings grew slowly in the understory, often reaching only 25 cm in height after 8–10 years, and were intensively browsed by deer. Naturally regenerated seedlings were virtually absent from clearcuts, probably because of dense competing vegetation and lack of seed caused by poor dispersal and seed predation. The "window" for the most successful establishment of bigleaf maple seedlings appears to begin after canopy thinning and end before forbs and shrubs invade.
5
Kim, Choonsig, Terry L. Sharik, Martin F. Jurgensen, David S. Buckley, and Richard E. Dickson. "Effects of nitrogen availability on northern red oak seedling growth in oak and pine stands in northern Lower Michigan." Canadian Journal of Forest Research 26, no. 6 (1996): 1103–11. http://dx.doi.org/10.1139/x26-122.
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The nitrogen (N) status and dry weight increment of northern red oak (Quercusrubra L.) seedlings in relation to N availability were examined at various levels of canopy cover and understory removal treatments under field conditions in red oak and red pine (Pinusresinosa Ait.) stands. Net N mineralization rates over two growing seasons following canopy cover treatments were determined by the in situ buried bag technique. Canopy removal increased N mineralization in both oak and pine stands. Net N mineralization rates were ≈1.2–2.2 times higher in the clearcut and the other partial canopy cover treatments than in the uncut stands. Net N mineralization in the same canopy cover treatments was ≈2–3 times higher in red oak stands than in red pine stands. However, red oak seedlings from the same canopy cover treatments in both stand types had similar dry weight, N concentrations, N content, and N-use efficiency despite differences in soil N availability. The only exception was ≈2 times greater seedling dry weight and N content in the red oak clearcuts compared with the red pine clearcuts. The similarity in seedling performance within partial canopy removal or uncut stands may have been due to limiting factors other than N in the red oak stands. Red oak seedlings from litter removal treatments within the clearcuts had significantly higher N-use efficiency than those from the herb and shrub removal treatments. These results suggest that (i) canopy manipulation increases soil N availability; (ii) increases in dry weight and N uptake by red oak seedlings when forest canopies are completely removed are due, in part, to increased available soil N; (iii) red oak seedling response to soil N availability resulting from no or only partial canopy removal may be the same in different stand types (e.g., red oak vs. red pine) because factors other than N, such as light, are limiting.
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Valverde-Barrantes, OJ, JA Hogan, and OJ Rocha. "EFFECTS OF CANOPY OPENNESS ON SEEDLING SURVIVAL AND GROWTH AFTER SELECTIVE LOGGING IN A MONODOMINANT LOWLAND SWAMP FOREST IN COSTA RICA." JOURNAL OF TROPICAL FOREST SCIENCE 34, no. 1 (2022): 34–47. http://dx.doi.org/10.26525/jtfs2022.34.1.34.
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The mechanism proposed to explain tree monodominance in tropical forests is that the dominant species forms a dense canopy and produces shade-tolerant seedlings, which together favor selfreplacement. Under this hypothesis, seedlings of monodominant species should have limited ability to respond to drastic increases in understory light, like those resulting from logging. Therefore, monodominant species should lose their seedling dominance after logging-induced canopy opening. To test this hypothesis, the current study measured seedling survival and growth of the monodominant species, Prioria copaifera, and its main competitor, Pentaclethra macroloba, in two forest stands that differ in logging history and in an unlogged stand in southeastern Costa Rica. Although, growth rates and survival of previously established seedlings were similar for both species across the three stands, seedling survival and growth decreased as light increased, with the effect being more pronounced for Prioria than for Pentaclethra. The study also investigated the ability of Prioria to respond to changing light environments by transplanting seedlings into logging-induced canopy gaps. Contrary to prediction, Prioria seedlings survived and grew better in gap centers than in gap edges or under a closed canopy. This result contrasts with established seedlings that cannot acclimate to changes in light conditions. Therefore, we conclude that continued Prioria dominance in selectively logged forests depends more on seedling production after canopy disturbance than on the established seedling present before disturbances.
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Park, Byung Bae, Youngtak Ko, Jonathan O. Hernandez, Ser-Oddamba Byambadorj, and Si Ho Han. "Growth of Deciduous and Evergreen Species in Two Contrasting Temperate Forest Stands in Korea: An Intersite Experiment." Plants 11, no. 7 (2022): 841. http://dx.doi.org/10.3390/plants11070841.
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Poor seedling establishment and growth can be a result of the limitation of light and soil resources in the forest understory. Here, we investigate the interacting effects of stand and soil characteristics on the seedling growth of deciduous species (Fraxinus rhynchophylla and Zelkova serrata) and evergreen species (Pinus koraiensis) through a 3-year intersite experiment in two contrasting forest stands. Seedlings were grown in both oak and pine stands using two different soil types, i.e., gray-brown forest soil (GB) and red-yellow forest soil (RY). Soil physicochemical properties, light intensity, tree-seedling height, root-collar diameter (RCD), and biomass growth were analyzed between two stands and/or soil types. Light availability was generally more abundant in the pine stand (mean: 1074.08 lx or 20.25%) than the oak stand (mean: 424.33 lx or 9.20%) throughout the year. The height and RCD growth of fast-growing and deciduous F. rhynchophylla and Z. serrata were higher in the pine than in the oak stand, particularly in GB soil. The growth of the slow-growing and evergreen P. koraiensis was not affected by the forest stand, except for its higher root growth in the oak stand and RY soil. Therefore, abundant light availability can enhance the growth and seedling establishment of F. rhynchophylla and Z. serrata in the pine-stand understory. Contrarily, P. koraiensis may be planted in the understory regardless of light condition, but with a slower growth rate.
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Bank, S. K., P. Rao, R. S. Tripathi, and H. N. Pandey. "Dynamics of tree seedling populations in a humid subtropical forest of northeast India as related to disturbance." Canadian Journal of Forest Research 26, no. 4 (1996): 584–89. http://dx.doi.org/10.1139/x26-067.
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Recruitment and survival of four important broad-leaved tree species, viz Quercusdealbata L., Quercusgriffithii Hk., Rhododendronarboreum Sm., and Schimakhasiana Dyer., were studied over 2 years in the undisturbed, mildly disturbed and highly disturbed forest stands of a subtropical humid forest of Meghalaya, northeast India. Recruitment of S. khasiana seedlings was maximum in the highly disturbed stand, while Q. dealbata seedlings were abundant in the undisturbed and mildly disturbed stands. Seedlings of Q. dealbata, Q. griffithii, and R. arboreum were equally successful in all the stands, while S. khasiana seedlings showed better survival in the highly disturbed stand than in the mildly disturbed and undisturbed stands. Six microenvironmental factors, viz photosynthetically active radiation, relative humidity, air temperature, soil temperature, soil moisture, and thickness of litter on the forest floor, were correlated with the age-specific mortality rate of seedlings. In Q. dealbata, Q. griffithii, and S. khasiana, mortality rate was significantly affected by microenvironmental factors, while in R. arboreum mortality was not correlated with any of the microenvironmental factors. On the basis of seedling recruitment and survival pattern, it was concluded that Q. dealbata, Q. griffithii, and R. arboreum were successful in both disturbed and undisturbed forest stands, while S. khasiana seedlings showed better survival and establishment in the disturbed stands.
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Kneeshaw, Daniel D., and Yves Bergeron. "Ecological factors affecting the abondance of advance regeneration in Quebec's southwestern boreal forest." Canadian Journal of Forest Research 26, no. 5 (1996): 888–98. http://dx.doi.org/10.1139/x26-097.
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Boreal forest disturbance regimes have changed during the past century, in turn changing regeneration and stand dynamics of these forests. This is occurring at the same time that the forest industry is emphasizing operations that take advantage of pre-established natural regeneration. This study has therefore investigated the effect of various ecological factors on the abundance of Abiesbalsamea (L.) Mill., Piceaglauca (Moench) Voss, Piceamariana (Mill.) BSP, Thujaoccidentalis L., Betulapapyrifera Marsh., and Populustremuloides Michx. natural regeneration in some boreal stands in the Abitibi region of Quebec. Abiotic ecological site classification variables were found to be poorly correlated with seedling densities for most species. Parent trees, as a seed source, and stand type, for its influence on the quality of the seedbed, were strongly correlated with abundant conifer regeneration. As expected, time since fire was positively correlated with seedling abundance for late successional species, whereas it was not related to the abundance of early successional species. Post-fire disturbances, such as those due to spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks, accounted for the variations in seedling densities observed with respect to stand age. The presence of budworm-caused gaps was positively correlated with regeneration abundance, whereas shrub competition, which was greatest in large gaps, was negatively correlated with advance regeneration density. Forest management based on abundance of pre-established regeneration should focus mainly on mixed stands because seedling density is very low in hardwood stands and because of the strong competition found in large gaps of resinous forests. The low number of seedlings observed, especially in coniferous stands, may limit the effectiveness of operations that take advantage of advance regeneration. The large variability observed among site and stand types limits their operational use in predicting seedling densities.
10
Zhou, Minyi, Terry L. Sharik, Martin F. Jurgensen, Dana L. Richter, Margaret R. Gale, and Thomas D. Drummer. "Regeneration of Northern Red Oak in Relation to Ectomycorrhizae in Oak and Pine Stands after Overstory and Understory Manipulations." Northern Journal of Applied Forestry 15, no. 4 (1998): 182–90. http://dx.doi.org/10.1093/njaf/15.4.182.
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Abstract Growth of northern red oak (Quercus rubra L.) seedlings in relation to colonization by indigenous ectomycorrhizal (ECM) fungi was studied in oak and pine stands in northern Lower Michigan that were subjected to overstory and understory manipulations. Two stand types (oak and pine), three blocks of each stand type, four canopy cover treatments (clearcut, 25% cover (50% cover in the first year), 75% cover and uncut), and two understory treatments (shrub removal and untreated control) were involved in the experiment. Northern red oak acorns from a common seed source were sown in May 1991 to simulate natural regeneration. Seedling growth and its relation to percent ECM were evaluated for the first two growing seasons. A significantly larger root-collar diameter of northern red oak seedlings was found in pine stands than in oak stands for the first growing season (P < 0.001). However, this difference could not be explained by overall ECM colonization. Seedling growth and ECM colonization were not affected by the shrub removal treatment during the first two growing seasons. In contrast, northern red oak seedling size and weight were strongly influenced by the overstory treatment, with lower levels of canopy cover resulting in larger seedlings. Seedlings had the greatest percent ECM in the partial cover treatment (25-50%) and the lowest percent ECM in the clearcut. After accounting for the effects of canopy cover, the relationship between total biomass of northern red oak seedlings and percent ECM was positively correlated (P = 0.001) during the first growing season and negatively correlated (P = 0.038) during the second growing season. A positive relationship between root/shoot ratio and percent ECM also existed in the first year (P = 0.003) in both oak and pine stands, but only in the oak stands in the second year (P = 0.039). These results indicate that ECM promoted more root development than shoot development, particularly underpartial canopy cover (25%-50%) treatments, where the greatest percent ECM and largest root/shoot ratio were found. Moreover, our results suggest that these partial canopy cover treatments provide a favorable balance between ECM abundance and northern red oak seedling development in both oak and pine stands on intermediate quality sites, and may lead to northern red oak regeneration success on such sites. North. J. Appl. For. 15(4):182-190.
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Blyth, Colette, Matthew J. Christmas, Doug C. Bickerton, et al. "Increased Genetic Diversity via Gene Flow Provides Hope for Acacia whibleyana, an Endangered Wattle Facing Extinction." Diversity 12, no. 8 (2020): 299. http://dx.doi.org/10.3390/d12080299.
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In this paper we apply a conservation genomics approach to make evidence-based management recommendations for Acacia whibleyana, an endangered shrub endemic to Eyre Peninsula, South Australia. We used population genomic analysis to assess genetic connectivity, diversity, and historical inbreeding across all known stands of the species sampling remnant stands, revegetated stands of unknown origin, and a post-fire seedling cohort. Our results indicate a degree of historical connectivity across the landscape, but habitat loss and/or pollinator community disruption are potential causes of strong genetic structure across the remnant stands. Remnant stands had low genetic diversity and showed evidence of historical inbreeding, but only low levels of intra-stand relatedness indicating that risks of contemporary inbreeding are low. Analysis of a post-fire first generation cohort of seedlings showed they likely resulted from intra-stand matings, resulting in reduced genetic diversity compared to the parents. However, admixed seedlings in this cohort showed an increase in heterozygosity relative to likely sources and the non-admixed seedlings of the same stand. Assisted inter-stand gene flow may prove an effective management strategy to boost heterozygosity and corresponding increases in adapting capacity in this endangered species.
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Baker, James B., and Michael G. Shelton. "Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands—IV. Natural and Planted Seedling/Sapling Stands." Southern Journal of Applied Forestry 22, no. 1 (1998): 53–59. http://dx.doi.org/10.1093/sjaf/22.1.53.
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Abstract A 3- to 6-yr-old naturally regenerated even-aged loblolly pine (Pinus taeda L.) stand and a 5-yr-old loblolly pine plantation on good sites (SILob = 85 to 90 ft at 50 yr) were cut to density levels of 50, 90, 180, 270, and 360 seedlings and/or saplings/ac. Two pine release treatments (none and individual tree release with a herbicide) were applied to the natural stand, but were not imposed in the plantation because site preparation treatments were applied before planting. At 2, 5, and 10 yr after installation, plots were inventoried to determine: (1) the lowest threshold of seedling/sapling density that was feasible to manage, (2) the time required for poorly stocked seedling/sapling stands to reach an acceptable stocking level, and (3) whether release treatments would improve survival and growth of understocked, natural seedling/sapling stands. Results indicated that loblolly pine plantations on good sites having at least 180 trees/ac (30% stocking) reached an acceptable stocking level of 60% by age 10 and produced up to 1,500 ft³/ac (19 cd/ac) of merchantable volume by age 15. By this age, trees in plantations with 270 and 360 trees/ac displayed good form, but at densities of 180, 90, and 50 trees/ac the trees still retained large branches nearly to the ground. Natural stands having at least 180 trees/ac that were released from overtopping by hardwood at age 5 reached 60% stocking by age 15 but produced only 627 ft³/ac (8 cd/ac) of merchantable volume. When pines in the natural stand were not released, only plots with 360 trees/ac reached an acceptable 60% stocking level by age 15 but only produced 539 ft³/ac (7 cd/ac) of merchantable volume. The observed differences in recovery rates in the understocked pine stands principally reflected the levels of competing hardwoods. Results suggest that understocked, natural stands or plantations of pine seedlings/saplings with fewer than 180 trees/ac (less than 30% stocking), at age 5, should probably be liquidated and a new stand established unless the landowner is willing to sacrifice significant reductions in early volume production. South. J. Appl. For. 22(1)53-59.
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Nyland, Ralph D. "Origin of Small Understory Beech in New York Northern Hardwood Stands." Northern Journal of Applied Forestry 25, no. 3 (2008): 161–63. http://dx.doi.org/10.1093/njaf/25.3.161.
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Abstract I sampled understory beech with heights that were 4 ft tall or less to determine their origin in 22 northern hardwood stands in New York. The proportion of seedling-origin beech ranged from 5 to 75% across sites. However, in 20 stands, the majority of beech (58–91%) with heights of 2–4 ft tall had a root sucker origin. Coupled with other information from published sources, findings suggest four possibilities about beech regeneration: (1) seed production and/or early seedling survival may have a clonal linkage, with some genotypes producing little viable seed, or with few seedlings surviving after germination; (2) a prevalence of root suckers among the taller understory beech suggests their higher potential for long-term survival and development and limited shifts in the genetic makeup of that species within a stand; (3) at some level of stocking, taller understory beech root suckers may interfere with survival and development of seedling regeneration; and (4) because the taller understory beech has a root sucker origin at most sites, root suckers may just develop more rapidly than seedlings.
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Silva, Paulo S. D., Inara R. Leal, Rainer Wirth, Felipe P. L. Melo, and Marcelo Tabarelli. "Leaf-cutting ants alter seedling assemblages across second-growth stands of Brazilian Atlantic forest." Journal of Tropical Ecology 28, no. 4 (2012): 361–68. http://dx.doi.org/10.1017/s0266467412000259.
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Abstract:Secondary forests promote an increased abundance of leaf-cutting ants (LCA) but the consequences on forest dynamics have been poorly addressed. Here we examine seedling assemblage attributes, seed germination and seedling survival across foraging zones of Atta cephalotes colonies inhabiting 15 second-growth patches (25–47 y old) of Atlantic forest. Seeds and seedlings were monitored within foraging zones and control sites over 1 y, including spots around ant nests. Overall, 1862 seedlings from 108 plant species were recorded. Seedling density decreased by 53% in foraging-zone plots (3.31 ± 0.23 seedlings m−2) when compared with control plots (7.02 ± 0.44 seedlings m−2) and a similar decrease was observed for species richness. Ant-induced alterations in the seedling assemblage were further indicated by segregation between foraging-zone and control plots (NMDS), habitat effects on species similarity (ANOSIM), and indicator tree species associated with control plots. While seed germination and seedling survivorship were uncorrelated to either nest distance or age of second-growth stands (with the exception of Tapirira guianensis), defoliation by LCAs was a significant cause of seedling mortality. Our results suggest that LCAs interfere with successional trajectories of Atlantic forest as foraging zones filter seedling establishment, supporting less-dense, impoverished and convergent seedling assemblages.
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De Noronha, Maísa, Rock Ouimet, Martin Barrette, Alain Leduc, and Yves Bergeron. "Influence of Leaf Litter and Humus Composition on the Development of Black Spruce Seedlings: A Greenhouse Experimentation." Forests 13, no. 11 (2022): 1832. http://dx.doi.org/10.3390/f13111832.
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In boreal forests in Canada, broadleaf stands are characterized by generally well-drained soils and a humus-rich layer. In contrast, spruce-moss stands are often characterized by more poorly drained soils and acidic humus layer. However, presence of these two forest types in various degrees of mixture in stands can be beneficial to spruce seedlings productivity. It was hypothesized that leaf litter and humus from pure spruces-moss stands, pure broadleaf stands, and mixed stand may influence Black spruce (Picea mariana (Mill.) BSP) seedling growth and development differently. A greenhouse experiment was carried out to evaluate the effect of different leaf litter and different humus on spruces seedlings. Our results suggest better development for seedlings grown in humus from mixed stands and pure broadleaf stands compared to humus from pure B. spruce or standard forest nursery substrate. Furthermore, leaf litter from broadleaf trees species, such as species Speckle alder (Alnus rugosa (Du Roi) R.T. Clausen), T. aspen (Populus tremuloides Michx), Willows (Salix spp.) and Paper birch (Betula papyrifera Marsh.), has shown distinct results in the growth and development of B. spruce seedlings in greenhouse. Furthermore, promotion of mixed stand can increase B. spruce productivity by improving the physicochemical composition of the forest floor.
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Lilieholm, R. J., L. S. Davis, R. C. Heald, and S. P. Holmen. "Effects of Single Tree Selection Harvests on Stand Structure, Species Composition, and Understory Tree Growth in a Sierra Mixed Conifer Forest." Western Journal of Applied Forestry 5, no. 2 (1990): 43–47. http://dx.doi.org/10.1093/wjaf/5.2.43.
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Abstract After 20-28 years of single tree selection harvests in initially irregular even-aged stands, stand structure is approaching a target uneven-aged diameter distribution. Seedling stocking in managed stands is nearly three times greater than that of unmanaged stands. Although shade-tolerant species comprise the bulk of most size classes in both managed and unmanaged stands, selection harvests have resulted in adequate quantities of seedlings from all five conifer species, including pines. In managed stands, current small-tree stocking and rates of growth appear adequate to sustain single tree selection harvests over much of a 90-year growth simulation. Simulated peak growth rates of uneven-aged stands compare favorably with actual and anticipated yields from the forest's uneven- and even-aged stands. West. J. Appl. For. 5(2):43-47, April 1990.
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BRÉVAULT, T., H. GUIBERT, and K. NAUDIN. "PRELIMINARY STUDIES OF PEST CONSTRAINTS TO COTTON SEEDLINGS IN A DIRECT SEEDING MULCH-BASED SYSTEM IN CAMEROON." Experimental Agriculture 45, no. 1 (2009): 25–33. http://dx.doi.org/10.1017/s0014479708006972.
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SUMMARYThe present study evaluated the pest constraints of an innovative crop management system in Cameroon involving conservation tillage and direct seeding mulch-based strategies. We hypothesized that the presence of mulch (i) would support a higher density of phytophagous arthropods particularly millipedes as well as pathogenic fungi that cause severe damage to cotton seedlings and (ii) would reduce early aphid infestations. The impact of two cover-crop mulchesCalopogonium mucunoidesandBrachiaria ruziziensison the vigour of seedling cotton stands and arthropod damage was assessed in two independent field experiments conducted in 2001 and 2002 respectively. In both experiments the presence of mulch negatively affected cotton seedling stand by 13–14% compared to non-mulched plots and the proportion of damaged seedlings was higher in mulched than in non-mulched plots supporting the hypothesis that mulch favoured soil pest damage. In both experiments insecticidal seed dressing increased the seedling stand and the number of dead millipedes collected and fungicide had little or no effect on seedling stand and vigour. It was however observed in 2002 that the fungicide seed dressing had a positive effect on seedling stand in non-mulched plots but not in mulched plots suggesting that fungi may have been naturally inhibited byB. ruziziensismulch. The dynamics of aphid colonization was not influenced by the presence of mulch. In 2001 taller seedlings were found in mulched than non-mulched plots probably due to greater water and nutrient availability inC. mucunoides-mulched plots than in non-mulched plots.
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Hobbs, RJ, and L. Atkins. "Fire-Related Dynamics of a Banksia Woodland in South-Western Western Australia." Australian Journal of Botany 38, no. 1 (1990): 97. http://dx.doi.org/10.1071/bt9900097.
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We studied the post-fire vegetation development of a low open woodland dominated by Banksia attenuata and B. menziesii near Perth, Western Australia. Two similar stands burned in autumn and spring displayed different regeneration patterns, with seedling regeneration occurring only in the autumn burn area. Vegetative regrowth was more rapid and post-fire species numbers were higher in the spring burn area. Introduced annuals increased significantly in the autumn fire area. Longer-term vegetation development was studied in a series of stands ranging in age since last fire from 1 to >44 years. Species richness was greatest in the 5-year-old stand, and many shrub species were most abundant 2-5 years after fire. Non-native annuals were found only in stands less than 5 years old since last fire. Dominance by the shrub Eremaea pauciflora increased with stand age, although shrub structure and total biomass did not vary greatly except in the oldest stand studied. The proportion of total shrub biomass accounted for by leaves declined with stand age. Both the two major Banksia species had mixed size structures with seedlings present in all stands, indicating that neither is dependent on fire for recruitment. The results indicate that while autumn burns promote seedling regeneration they may also increase invasion by non-natives, and spring burning may be preferable in these Banksia woodlands. Burning rotations longer than those required for fuel reduction purposes are necessary to maximise conservation values.
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Harrington, Timothy B. "Five-year growth responses of Douglas-fir, western hemlock, and western redcedar seedlings to manipulated levels of overstory and understory competition." Canadian Journal of Forest Research 36, no. 10 (2006): 2439–53. http://dx.doi.org/10.1139/x06-139.
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Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn ex D. Don) seedlings were planted in March 2001 within three clearcut-harvested, shelterwood, or thinned stands of mature Douglas-fir near Olympia, Washington. From 2002 to 2005, areas of vegetation control of 0, 4.5, or 9 m2 were maintained with herbicides around a total 162 seedlings per species. Photosynthetically active radiation (PAR) was 34%, 62%, and 100% of full sunlight in thinned stands, shelterwoods, and clearcuts, respectively. Effects of overstory level and vegetation control on seedling growth and resource availability generally were additive. Seedling stem volume index in clearcuts averaged four to eight times that observed in thinned stands, and with vegetation control, it averaged two to four times that observed without it. In thinned stands, relative growth rate of seedling stem volume index had a positive linear relationship with PAR (R2 = 0.38). Foliar nitrogen content of Douglas-fir explained 71% of the variation in relative growth rate. Factors explaining the most variation in foliar nitrogen content differed between thinned stands (PAR, R2 = 0.34) and clearcuts or shelterwoods (midday water potential, R2 = 0.63), suggesting that light and root competition, respectively, were the primary growth-limiting factors for these overstory levels.
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Urrea, K., J. C. Rupe, and C. S. Rothrock. "Effect of Fungicide Seed Treatments, Cultivars, and Soils on Soybean Stand Establishment." Plant Disease 97, no. 6 (2013): 807–12. http://dx.doi.org/10.1094/pdis-08-12-0772-re.
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Seedling diseases are one of the major production problems for soybean. The primary control of soybean seedling diseases is by fungicide seed treatments but comparisons of seed treatments are difficult because stand responses are often erratic in the field. The objective of this study was to determine the efficacy of soybean fungicide seed treatments in naturally infested soils under controlled environments at three temperatures. Seed of three soybean cultivars were treated with six fungicide treatments or not treated and planted in two soil types collected from two fields in April, May, and June 2008 and 2009. Tests were conducted in growth chambers at 21°C (April planting), 25°C (May planting), or 28°C (June planting). Stands were determined when at least 25% of the seedlings reached the V4 growth stage. Seed treatments improved stands at all three temperatures, in both soils, and in both years. In general, the broad-spectrum fungicides trifloxystrobin + metalaxyl and mefenoxam + fludioxonil + azoxystrobin resulted in the highest stands. The selective fungicide treatments metalaxyl and pentachloronitrobenzene + carboxin were effective at all three temperatures, implying that Pythium spp. and Rhizoctonia solani, respectively, were involved in seedling disease and active over a range of temperatures. The efficacy of fungicides was not consistently associated with the cultivars used in this study.
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Grassbaugh, Elaine M., Mark A. Bennett, and Andrew F. Evans. "656 Improving Seedling Establishment of Medicinal Herbs." HortScience 34, no. 3 (1999): 561B—561. http://dx.doi.org/10.21273/hortsci.34.3.561b.
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Successful crop production and optimum yields, regardless of the species, can be accomplished only when maximum stand establishment is achieved. Stand reduction after planting typically results in reduced yields and lower crop quality. Several classes of factors (environmental, edaphic, biotic) contribute to successful stand establishment in crop production and should be considered in growing medicinal plants. Environmental factors (e.g., temperature and moisture extremes) as well as pathogens and insect pests that attack seeds and seedlings may contribute to reduced stands. Soil related factors such as pH, nutrient availability, and crusting may also restrict seedling growth. Understanding the requirements for optimum seed germination and the environmental conditions into which the seed is sown is essential for uniform crop establishment. Vigor tests can aid growers in determining the optimum temperature range for seed germination. Many cultural practices may also influence soil related factors and contribute to successful stand establishment in the field. Seed vigor tests (SSAA, thermogradient results) along with seed treatments and enhancements can assess seed vigor, improve germination and lead to more reliable stands of medicinal species.
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Coyle, David R., William J. Mattson, Alexander L. Friend, and Kenneth F. Raffa. "Effects of an invasive herbivore at the single plant scale do not extend to population-scale seedling dynamics." Canadian Journal of Forest Research 44, no. 1 (2014): 8–16. http://dx.doi.org/10.1139/cjfr-2013-0307.
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A complex of nine invasive weevils has established in the northern hardwood forests of the Great Lakes Region. These weevils have become the numerically dominant arthropod fauna in the lower vegetation strata of this ecosystem. Effects of these folivorous adults and rhizophagous larvae on seedling survival and density are unknown. We measured the impact of adult weevil defoliation on individual sugar maple (Acer saccharum Marshall) seedlings, the numerically dominant flora in these stands. Over 14 500 seedlings were measured to examine the effects of larval abundance, adult abundance, and adult defoliation on seedling dynamics during 2005–2009. Heavy defoliation led to individual sugar maple seedling mortality. However, at the stand level there was no measureable net effect of invasive weevils against the high natural background rates of seedling mortality. Seedling growth and biomass were reduced by high adult or larval populations, which were associated with heavy leaf and root herbivory, but not by moderate adult or larval populations. We conclude that high levels of redundancy and compensatory processes in this environment allow sugar maple seedling populations to tolerate high levels of weevil damage, although additional stresses could reduce this resilience.
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Parent, Sylvain, Marie-Josée Simard, Hubert Morin, and Christian Messier. "Establishment and dynamics of the balsam fir seedling bank in old forests of northeastern Quebec." Canadian Journal of Forest Research 33, no. 4 (2003): 597–603. http://dx.doi.org/10.1139/x02-194.
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This study examines balsam fir (Abies balsamea (L.) Mill.) recruitment in old fir stands. Studying the regeneration of these stands is essential to understand the regeneration dynamic of the species in the absence of stand-destroying disturbances. The objectives were (1) to obtain substrateseedling associations for different age-classes and according to the presence or absence of adventitious roots; (2) to evaluate the contribution of the seed rain to seedling recruitment; (3) to re-examine age structures using the most appropriate method that minimizes estimation errors due to the presence of adventitious roots. A total of 90 quadrats (1 m2) were established along transects. In each quadrat, subtrates were characterized (type and topography) and their area was estimated. All balsam fir seedlings (<50 cm tall) present in the quadrats were located, harvested whole (root and shoot), and described (age, height, presence of adventitious roots, etc). Fir seedlings were strongly associated with woody mounds covered with thin mats of mixed mosses and Pleurozium shreberi (Bird.) Mitt. but negatively associated with flat topography particularly dominated by Hylocomium splendens (Hedw.) B.S.G. The presence of adventitious root is related to seedling age more than substrate type or topography. The age structure is in agreement with seed production and disturbance regime.
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Lunt, Ian D., Heidi C. Zimmer, and David C. Cheal. "The tortoise and the hare? Post-fire regeneration in mixed Eucalyptus - Callitris forest." Australian Journal of Botany 59, no. 6 (2011): 575. http://dx.doi.org/10.1071/bt11151.
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Seedling regeneration after a high intensity wildfire was assessed in a mixed forest dominated by Eucalyptus species and Callitris endlicheri (Parl.) F.M. Bailey. Patterns were compared against the ‘slow seedling’ or ‘tortoise-and-hare’ theory of competitive interactions between gymnosperms and angiosperms. Browsing effects were documented using fenced plots, and seedling density, mortality and height were assessed over 6 years, from 2004–10. Consistent with expectations, Eucalyptus seedlings grew faster than Callitris seedlings in most situations. Callitris seedlings grew faster and produced seed cones sooner in plots with fewer Eucalyptus seedlings compared with plots with dense Eucalyptus seedlings. The local growth rates of Callitris seedlings were not associated with long-term site suitability for Callitris, as many plots with diminutive Callitris seedlings and dense Eucalyptus seedlings were dominated by Callitris trees before the 2003 fire. Contrary to expectations, few Callitris seedlings died during the 6-year period, so competition during the regeneration phase did not regulate co-existence. Strong drought tolerance and the ability to persist in dense, unthinned stands may enable Callitris to persist beneath dense Eucalyptus regeneration. Nevertheless, Callitris seedlings growing with dense Eucalyptus seedlings have a longer primary juvenile period than seedlings in sites with fewer seedling or adult eucalypts, which places these stands at greater risk of mortality in future fires and greater risk of browsing in the meantime.
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Routa, Johanna, Yrjö Nuutinen, and Antti Asikainen. "Productivity in Mechanizing Early Tending in Spruce Seedling Stands." Croatian journal of forest engineering 41, no. 1 (2019): 1–11. http://dx.doi.org/10.5552/crojfe.2020.619.
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According to National Forest Inventory data, there is an urgent need for tending seedling stands of at least 700,000 ha and a need for 1 million ha in the next few years in Finland. The motivation for forest owners to conduct pre-commercial silvicultural operations is low due to the associated high costs. Especially the costs of tending and clearing operations after the regeneration of the stand have been increasing. In addition, the availability of labor is a restricting factor due to the high seasonality of silvicultural works. In the 2000s, several solutions for the mechanization of tending have been proposed. These are based on the use of harvester or a forwarder as a base machine. Typically, light weight base machines are favored to reduce the hourly cost of operations and the impacts on the remaining seedlings. There have been challenges with the high speed of the cutting device, which increases the risk of damages to the head and the ignition of forest fires when the circular saw or chain hits stones, for example. In addition, the chain can become dislocated due to bending forces caused by stumps. Cutlink has presented a low RPM solution based on rotating cone-shaped shears that cut 50–100 cm wide corridors between and around seedlings. In this study, the productivity of mechanized tending with Cutlink´s device compared to manual tending was evaluated in spruce seedling stands in central Finland. The productivity, fuel consumption and quality of the seedling stand after the operation were measured. In early tending, the productivity of motor manual tending was notably better than when using the Cutlink device. Crucial factors for the competitiveness of a mechanized alternative include the annual working hours and finding suitable working areas for the machine. Additional work for the device and base machine can also be found in the clearing of forest road sides.
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Parent, Sylvain, and Jean-Claude Ruel. "Chronologie de la croissance chez des semis de sapin baumier (Abies balsamea (L.) Mill.) après une coupe à blanc avec protection de la régénération." Forestry Chronicle 78, no. 6 (2002): 876–85. http://dx.doi.org/10.5558/tfc78876-6.
Full textAbstract:
The method of harvesting with protection of the advanced regeneration consists of a complete removal of the main canopy to release a seedling bank established under the overstory shade. After harvesting, seedlings acclimated to understory conditions could suffer from moisture stress, especially the small, juvenile seedlings (less than six years). The objective of the study is to determine the capacity of understory-acclimated balsam fir seedlings to respond positively and immediately to release. The response to release was studied in two seedling populations belonging to two distinct climatic regions of Quebec, the Western and the Eastern sections of the balsam fir-white birch ecological domain. Results show that the response patterns were similar in both populations. Response to release occurred in two steps. One year after harvesting, basal ring width was on the average five times larger than prior to harvesting (p > 0.001). Height growth only became significantly higher the second year after release (p < 0.001). On average, juveniles showed higher height growth rates (height growth/height) than older seedlings. This rate was negatively correlated to seedling height at harvesting (r = -0,68, p < 0.001). Our study clearly shows that balsam fir seedlings can respond immediately and positively to large openings. The strong response of juvenile seedlings to release indicates that these can contribute significantly to the future stand. The geographic and climatic differences between the two stands under study suggest that these observations apply to a wide range of balsam fir stands. Key words: advance growth, balsam fir, release
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Wright, Robert A., Ross W. Wein, and Bruce P. Dancik. "Population Differentiation in Seedling Root Size Between Adjacent Stands of Jack Pine." Forest Science 38, no. 4 (1992): 777–85. http://dx.doi.org/10.1093/forestscience/38.4.777.
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Abstract Seeds from adjacent wet-site and dry-site jack pine stands were planted in a common growth chamber, and seedlings were grown with and without drought. Population differentiation in root and shoot growth traits was assessed 14 and 35 days after seedling emergence. Seedlings originating from the wet site had significantly more tertiary roots than those originating from the dry site. Differences between wet- and dry-site populations in secondary root length and shoot biomass disappeared when adjusted for the effects of higher mean seed weight in the dry-site population. The strength of correlations between seedling size parameters and seed weight varied with seedling age and exposure to drought. Droughty conditions inhibited secondary and tertiary but not primary root growth. For. Sci: 38(4):777-785.
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Ristau, Todd E., and Stephen B. Horsley. "When Is Pin Cherry (Prunus pensylvanica L.) a Problem in Allegheny Hardwoods?" Northern Journal of Applied Forestry 23, no. 3 (2006): 204–10. http://dx.doi.org/10.1093/njaf/23.3.204.
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Abstract Pin cherry (Prunus pensylvanica L.) has important effects on early stand development when it occurs at high densities. We used data describing the first 15 years of stand development in eight clearcuts and used plots that had at least 25 black cherry or 100 desirable seedlings at age 3, as well as different levels of pin cherry stocking. Our findings identified seven pin cherry >5 ft tall at age 3 on 6-ft-radius plots as the threshold for negative effects on stocking of seedling-origin trees of desirable species at age 15. We incorporated these finding into the regeneration followup chart used as part of the Silviculture of Allegheny Hardwoods (SILVAH) decision support framework. Of eight stands used in this study, four had a pin cherry interference problem, and four did not. By age 15, there were one-third as many desirable seedling-origin stems, mostly black cherry (Prunus serotina Ehrh.), in stands with pin cherry above the critical threshold density. We suggest some silvicultural options for addressing the problem.
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Spence, C. Eiry, and David A. MacLean. "Regeneration and stand development following a spruce budworm outbreak, spruce budworm inspired harvest, and salvage harvest." Canadian Journal of Forest Research 42, no. 10 (2012): 1759–70. http://dx.doi.org/10.1139/x2012-121.
Full textAbstract:
Spruce budworm ( Choristoneura fumiferana (Clemens)) (SBW) outbreaks are a major disturbance that influence stand dynamics and succession in balsam fir ( Abies balsamea (L.) Mill.) dominated forests of eastern Canada. We used stand and regeneration data collected from five plots in each of one immature and five mature stands before, during, and 30 years following the last major SBW outbreak in the Cape Breton Highlands to examine the role of stand and regeneration characteristics in shaping future stand development. Comparisons were also made between regeneration in four SBW outbreak stands versus two SBW salvage stands, with and without a subsequent precommercial thinning, and with 25 plots that underwent SBW emulation harvest. In mature unharvested balsam fir stands, species composition 30 years following the SBW outbreak was closely related to predisturbance species composition, and in immature fir stands, hardwood composition increased from 0% to 4%–27%. Species composition in harvested stands varied depending on whether intolerant hardwoods had been precommercially thinned, where thinned stands had 30% less hardwood 30 years postdisturbance than unthinned stands. Seedling density decreased by 17%–85% from 1979 to 1989 in all SBW outbreak stands, but average seedling height increased by 17%–500% as live canopy cover decreased from an average of 50% to 4%. Results suggest that advanced regeneration should be protected during harvest of balsam fir dominated stands, post-outbreak precommercial thinning will increase tree growth, and live tree retention can help develop late-seral structural characteristics in second-growth stands.
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Singh, Vikaspal, Dhanpal Singh Chauhan, and Sabyasachi Dasgupta. "Effect of stand structure and aspect on the regeneration of banj oak (Quercus leucotrichophora A. Camus) forest along disturbance in Garhwal Himalaya, Uttarakhand, India." Forestry Studies 68, no. 1 (2018): 33–39. http://dx.doi.org/10.2478/fsmu-2018-0003.
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Abstract A study was conducted in an oak forest, to find out the relationship of stand structure, aspect and regeneration of species. Among all disturbance stands the density of banj oak Quercus leucotrichophora A. Camus individuals was peaked at 40–50 cm and 50–60 cm diameter at breast height (DBH) classes and low tree density was observed with the increasing DBH classes. North aspect showed higher density for most of girth classes as compared to south facing aspect. Among all the stands, low seedling density was recorded in undisturbed stand at south facing aspect as compared to the moderately and highly disturbed stands. The tree density of Q. leucotrichophora was higher in the undisturbed stand followed by moderately disturbed and highly disturbed stand. But in case of seedling density the higher density were observed at undisturbed and highly disturbed stand in both of the aspects.
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Preisser, Evan L., Mailea R. Miller-Pierce, Jacqueline Vansant, and David A. Orwig. "Eastern hemlock (Tsuga canadensis) regeneration in the presence of hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa)." Canadian Journal of Forest Research 41, no. 12 (2011): 2433–39. http://dx.doi.org/10.1139/x11-155.
Full textAbstract:
The hemlock woolly adelgid (Adelges tsugae Annand) is an invasive hemipteran that poses a major threat to eastern hemlock (Tsuga canadensis (L.) Carrière) forests in the United States. We conducted three surveys over a five-year period that assessed the density of hemlock woolly adelgid (HWA) and a second invasive pest, the elongate hemlock scale (EHS; Fiorinia externa Ferris), overstory hemlock mortality, and hemlock regeneration in ~140 hemlock stands (mean size, 44 ha; range, 7–305 ha) within a 7500 km2 north–south transect of southern New England (USA). In each stand, we rated HWA and EHS density on 50 hemlock trees using a 0–3 scale (0, none; 1, 1–10 organisms/m branch; 2, 11–100 organisms/m branch; 3, >100 organisms/m branch). Data on the presence or absence of regeneration were taken in 2005; in 2007 and 2009, we quantitatively assessed regeneration by counting the number of hemlock seedlings in three 16 m2 plots per stand. In 2005, 81% of sampled stands had HWA, 72% had EHS, and 66% had hemlock regeneration. In 2007, 86% of sampled stands had HWA, 79% had EHS, and 46% had hemlock regeneration. In 2009, 91% of stands had HWA, 87% had EHS, and 37% had hemlock regeneration. The proportion of stands with hemlock regeneration declined 46% between 2005 and 2009, and hemlock seedling density declined 71% between 2007 and 2009. A best-fit model selection algorithm found that this decrease was inversely correlated with stand-level adelgid density. There was no correlation between the change in seedling density and stand-level density of the elongate hemlock scale. The apparent decline in regeneration suggests that the ecosystem-level changes currently occurring in southern New England may be difficult to reverse.
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Hewitt, Rebecca E., Donald Lee Taylor, Teresa N. Hollingsworth, Christopher B. Anderson, and Guillermo Martínez Pastur. "Variable retention harvesting influences belowground plant-fungal interactions of Nothofagus pumilio seedlings in forests of southern Patagonia." PeerJ 6 (July 6, 2018): e5008. http://dx.doi.org/10.7717/peerj.5008.
Full textAbstract:
Background The post-harvest recovery and sustained productivity of Nothofagus pumilio forests in Tierra del Fuego may be affected by the abundance and composition of ectomycorrhizal fungi (EMF). Timber harvesting alters EMF community structure in many managed forests, but the impacts of harvesting can vary with the management strategy. The implementation of variable retention (VR) management can maintain, increase, or decrease the diversity of many species, but the effects of VR on EMF in the forests of southern Patagonia have not been studied, nor has the role of EMF in the regeneration process of these forests. Methods We evaluated the effects of VR management on the EMF community associated with N. pumilio seedlings. We quantified the abundance, composition, and diversity of EMF across aggregate (AR) and dispersed (DR) retention sites within VR managed areas, and compared them to primary forest (PF) unmanaged stands. EMF assemblage and taxonomic identities were determined by ITS-rDNA sequencing of individual root tips sampled from 280 seedlings across three landscape replicates. To better understand seedling performance, we tested the relationships between EMF colonization, EMF taxonomic composition, seedling biomass, and VR treatment. Results The majority of EMF taxa were Basidiomycota belonging to the families Cortinariaceae (n = 29), Inocybaceae (n = 16), and Thelephoraceae (n = 8), which was in agreement with other studies of EMF diversity in Nothofagus forests. EMF richness and colonization was reduced in DR compared to AR and PF. Furthermore, EMF community composition was similar between AR and PF, but differed from the composition in DR. EMF community composition was correlated with seedling biomass and soil moisture. The presence of Peziza depressa was associated with higher seedling biomass and greater soil moisture, while Inocybe fibrillosibrunnea and Cortinarius amoenus were associated with reduced seedling biomass and lower soil moisture. Seedling biomass was more strongly related to retention type than EMF colonization, richness, or composition. Discussion Our results demonstrate reduced EMF attributes and altered composition in VR treatments relative to PF stands, with stronger impacts in DR compared to AR. This suggests that VR has the potential to improve the conservation status of managed stands by supporting native EMF in AR. Our results also demonstrate the complex linkages between retention treatments, fungal community composition, and tree growth at individual and stand scales.
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Tappeiner II, John C., and Paul B. Alaback. "Early establishment and vegetative growth of understory species in the western hemlock – Sitka spruce forests of southeast Alaska." Canadian Journal of Botany 67, no. 2 (1989): 318–26. http://dx.doi.org/10.1139/b89-046.
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To determine how Vaccinium alaskaense, Cornus canadensis, Coptis asplenifolia, Tiarella trifoliata, and Rubus pedatus invade and maintain themselves in conifer forests, we conducted experiments on seed germination and seedling survival and examined clonal development in old-growth, young-growth, and 4- to 6-year-old stands. Seed of all species germinated well in laboratory and field tests (average 23 – 90%), but low germination rates of C. canadensis and T. trifoliata under actual field conditions may retard their invasion of young stands. Survival of all species at 3 and 4 years was lower in the young stand (40 years) than in the old stand (250 + years) and may be related to incident solar radiation. Regressions of the percentage of survival on percentage of transmitted solar radiation were significant (P ≤ 0.05) for all species except C. canadensis. Seed predation and type of seedbed (moss, logs, duff) had little effect on germination and survival rates. Average annual rhizome or stolon growth was slower in the young stand (1 – 3 cm) than in the old stand (1 – 34 cm). In the clearcut, clones had dense foliage because of shorter internodes and more leaves per node and annual rhizome and stolon growth averaged 77 – 160 cm. Both seedling establishment among clones and continual clonal expansion maintain species in old stands, while invasion in young stands is primarily by seedling establishment.
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Quaranta, Luca, Piera Di Marzio, Romeo Di Pietro, Fabrizio Ferretti, Umberto Di Salvatore, and Paola Fortini. "Analysis of the functional traits of Quercus cerris L. seedlings in the Molise region (southern Italy)." Plant Sociology 59, no. 1 (2022): 11–24. http://dx.doi.org/10.3897/pls2022591/02.
Full textAbstract:
This study deals with the analysis of seedling fitness in three Quercus cerris wood stands, namely Selva di Castiglione (SC), Bosco della Ficora (BF) and Bosco di San Leo (BSL), developed in different lithological and physiographic conditions and subjected to different forestry practices. A phytosociological study was carried out for analysing the coenological features of the forest stands and to classify these latter from a syntaxonomic point of view. The Pignatti-Ellenberg index (PEi) was calculated on the matrix composed of the phytosociological relevés in order to highlight possible ecological differences or gradients among stands. The phenotypic parameters considered were the stem and root length and the leaf area, whereas the plant functional traits (PFTs) were specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (Lth) and chlorophyll content (CHL). The results showed that seedlings coming from different sampling sites exhibited similar values in all the phenotypic parameters. Instead, statistically significant differences were observed in the PFTs. The results suggested that the different adaptation strategies implemented by the seedlings are to be related to the physical environment of the sampling sites and to the different forest structures. The Selva di Castiglione forest stand (SC) exhibited better growth conditions for seedlings testified by higher values of SLA and CHL and lower values of LDMC and Lth. These were interpreted as greater investment in carbon production aimed at rapid development and renewal of the seedling rather than carbon storage aimed at ensuring leaf longevity.
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Quaranta, Luca, Marzio Piera Di, Pietro Romeo Di, Fabrizio Ferretti, Salvatore Umberto Di, and Paola Fortini. "Analysis of the functional traits of Quercus cerris L. seedlings in the Molise region (southern Italy)." Plant Sociology 59 (May 16, 2022): 11–24. https://doi.org/10.3897/pls2022591/02.
Full textAbstract:
This study deals with the analysis of seedling fitness in three Quercus cerris wood stands, namely Selva di Castiglione (SC), Bosco della Ficora (BF) and Bosco di San Leo (BSL), developed in different lithological and physiographic conditions and subjected to different forestry practices. A phytosociological study was carried out for analysing the coenological features of the forest stands and to classify these latter from a syntaxonomic point of view. The Pignatti-Ellenberg index (PEi) was calculated on the matrix composed of the phytosociological relevés in order to highlight possible ecological differences or gradients among stands. The phenotypic parameters considered were the stem and root length and the leaf area, whereas the plant functional traits (PFTs) were specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (Lth) and chlorophyll content (CHL). The results showed that seedlings coming from different sampling sites exhibited similar values in all the phenotypic parameters. Instead, statistically significant differences were observed in the PFTs. The results suggested that the different adaptation strategies implemented by the seedlings are to be related to the physical environment of the sampling sites and to the different forest structures. The Selva di Castiglione forest stand (SC) exhibited better growth conditions for seedlings testified by higher values of SLA and CHL and lower values of LDMC and Lth. These were interpreted as greater investment in carbon production aimed at rapid development and renewal of the seedling rather than carbon storage aimed at ensuring leaf longevity.
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Jones, R. K. "Seedling Blight Development and Control in Spring Wheat Damaged by Fusarium graminearum Group 2." Plant Disease 83, no. 11 (1999): 1013–18. http://dx.doi.org/10.1094/pdis.1999.83.11.1013.
Full textAbstract:
Aspects of seedborne infection in Fusarium-damaged and undamaged seed lots of hard red spring wheat were studied. In a 22°C environment, seedling blight developed from plantings of Fusarium-damaged seed that were characterized by both reduction and delay in emergence and postemergence seedling death. After 28 days, stand counts from the Fusarium-damaged seed lot averaged 46%, compared with 98% from the undamaged seed lot. However, the mean dry weight of surviving seedlings from the Fusarium-damaged lot was not statistically different from that of seedlings from the undamaged seed lot. Surface-sterilization reduced recovery of Fusarium graminearum group 2 from the damaged lot by 7% and increased germination by 32%, suggesting that seed are both infected and contaminated with viable propagules of the fungus. In field experiments, seed treatment with maneb- or thiabendazole-containing fungicide combinations significantly reduced seedling blight and improved stands derived from the Fusarium-damaged seed lot. Triazole fungicides, including difenoconazole, fenbuconazole, and tetraconazole, were less effective. Triazole fungicides and carboxin-containing fungicide combinations controlled loose smut in these trials, while maneb seed treatments did not. In four field tests, seedling blight incidence in plantings of Fusarium-damaged seed increased as soil temperatures during emergence increased. The distribution of blighted seedlings was random and not clustered. Seedling blight did not develop in field plantings of the undamaged seed lot.
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Clinton, P. W., R. B. Allen, and M. R. Davis. "Nitrogen storage and availability during stand development in a New Zealand Nothofagus forest." Canadian Journal of Forest Research 32, no. 2 (2002): 344–52. http://dx.doi.org/10.1139/x01-188.
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Stemwood production, N pools, and N availability were determined in even-aged (10, 25, 120, and >150-year-old) stands of a monospecific mountain beech (Nothofagus solandri var. cliffortioides (Hook. f.) Poole) forest in New Zealand recovering from catastrophic canopy disturbance brought about by windthrow. Nitrogen was redistributed among stemwood biomass, coarse woody debris (CWD), the forest floor, and mineral soil following disturbance. The quantity of N in stemwood biomass increased from less than 1 kg/ha in seedling stands (10 years old) to ca. 500 kg/ha in pole stands (120 years old), but decreased in mature stands (>150 years old). In contrast, the quantity of N stored in CWD declined rapidly with stand development. Although the mass of N stored in the forest floor was greatest in the pole stands and least in the mature stands, N availability in the forest floor did not vary greatly with stand development. The mass of N in the mineral soil (0100 mm depth) was also similar for all stands. Foliar N concentrations, net N mineralization, and mineralizable N in the mineral soil (0100 mm depth) showed similar patterns with stage of stand development, and indicated that N availability was greater in sapling (25 years old) and mature stands than in seedling and pole stands. We conclude that declining productivity in older stands is associated more with reductions in cation availability, especially calcium, than N availability.
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Cantonwine, E. G., C. C. Holbrook, A. K. Culbreath, R. S. Tubbs, and M. A. Boudreau. "Genetic and Seed Treatment Effects in Organic Peanut." Peanut Science 38, no. 2 (2011): 115–21. http://dx.doi.org/10.3146/ps11-5.1.
Full textAbstract:
ABSTRACT Stand establishment has been a challenge for organic peanut production in the Southeastern United States. Field experiments were conducted in 2007 and 2009 in research plots certified for organic production to evaluate the potential of genotype selection, shelling procedure, and seed treatment with Bacillus subtilis to improve stand establishment and seedling emergence rates, reduce incidence of Aspergillus crown rot, and increase seedling biomass. Seed of 15 peanut genotypes were mechanically shelled or hand-shelled, and treated with B. subtilis or untreated prior to planting in early June. Percent stand was estimated for each plot 17–21 days after planting (DAP), and percent seedlings affected by Aspergillus crown rot and plant biomass were estimated 21–24 DAP. Seed treatment significantly affected stand establishment for three genotypes each year, Georgia-01R both years, C-99R and Tifguard in 2007, and C34-24-69 and C724-19-25 in 2009. In all of these cases, the hand-shelled plots had significantly greater stands than the mechanically shelled plots for untreated and/or B. subtilis treated seed. B. subtilis treatment improved stands for two of the mechanically shelled treatments that significantly responded to hand shelling. Despite low incidence, there was a significant reduction of crown rot in the hand-shelled plots compared to the mechanically shelled plots across years and genotypes. The cultivar Georganic, which has been planted to organic peanut systems in Georgia in recent years, was among the genotypes with the lowest seedling establishment rates and biomass. Based on these results, it is recommended that sorting thresholds for damaged seed be higher for seed destined for organic production, and that breeding efforts that include assessments of factors involved in seedling establishment and growth be prioritized.
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Tappeiner, John C., and John C. Zasada. "Establishment of salmonberry, salal, vine maple, and bigleaf maple seedlings in the coastal forests of Oregon." Canadian Journal of Forest Research 23, no. 9 (1993): 1775–80. http://dx.doi.org/10.1139/x93-224.
Full textAbstract:
To identify seedling regeneration niches for four coastal Oregon shrub and hardwood species (salmonberry (Rubusspectabilis Pursh), salal (Gaultheriashallon Pursh), vine maple (Acercircinatum Pursh), and bigleaf maple (Acermacrophyllum Pursh)) we studied the seed predation, emergence, survival, and growth of these species on disturbed and undisturbed soil in thinned, unthinned, and clear-cut conifer stands on two sites in the Oregon Coast Ranges. For all species, seedling emergence and survival were greater in thinned stands than in clearcuts or unthinned stands. In addition, emergence of salmonberry and salal was greater on mineral soil than on soil in which the organic layers were intact. After four years, height of salmonberry was greatest in the clearcuts, where it averaged 23 cm. Bigleaf maple and vine maple, which were heavily browsed in the clearcuts, reached their greatest height in the thinned stands, averaging 16 and 15 cm, respectively. Salal seedlings survived only in thinned stands and grew slowly, reaching a height of only 4–5 cm in 4 years. Seedling emergence and predation both were related to seed size. On both disturbed and undisturbed soil, vine and bigleaf maple, the species with the largest seeds, had the highest rates of emergence but also the highest rates of seed predation among the four species.
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Wanner, James L., and Robert O. Tinnin. "Some effects of infection by Arceuthobiumamericanum on the population dynamics of Pinuscontorta in Oregon." Canadian Journal of Forest Research 19, no. 6 (1989): 736–42. http://dx.doi.org/10.1139/x89-113.
Full textAbstract:
We examined a stand of Pinuscontorta var. murrayana (Grev. and Balf.) Engelm. having trees ranging in level of infection by Arceuthobiumamericanum Nutt. ex Engelm. from none to heavy (dwarf mistletoe rating 0–6). The following varied inversely with the level of infection in one of two years of sampling: cone production, cone length, seed mass, and radial growth at breast height. The following not measured more than once, but also varied inversely with the level of infection: pollen production, stem volume, survival of trees older than 45 years, and soil pH. Varying directly with the level of infection were 1st-year seedling density, survival of 1-year-old-seedlings, survival of 26- to 45-year-old trees, soil organic matter, abundance of litter, and soil calcium. We found that total basal area was similar in all study plots, regardless of the level of infection. These data are consistent with suggestions of reduced carbohydrate reserves within the trees as a result of infection, improved conditions for seedling survival in heavily infected stands, and freed resources in heavily infected stands (due to death of mature trees), leading to an increased population density of seedlings and saplings. We suggest that in the stand we studied, the parasite promotes an environment (through modification of the host) that favors regeneration of the host and thereby of itself.
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Anderson, JE, and WH Romme. "Initial Floristics in Lodgepole Pine (Pinus contorta) Forests Following the 1988 Yellowstone Fires." International Journal of Wildland Fire 1, no. 2 (1991): 119. http://dx.doi.org/10.1071/wf9910119.
Full textAbstract:
The Yellowstone fires of 1988 produced a mosaic of Pinus contorta stands subjected to fire of varying severities. In August, 1989, we inventoried density of vascular plants in paired plots at seven burned stands. One plot was in a severe canopy bum; the paired plot was in an adjacent area that burned at moderate severity. Density of vascular plants was consistently higher in moderate than in severe burn plots. At all sites, floristic composition largely reflected the species present before the fire. Two-thirds of the individuals present in the first postfire season were from vegetative regrowth of plants that survived the fire; of the remaining third, most were P. contorta seedlings. Fire severity had a strong influence on seedling density; at all sites, P. contorta seedling density was higher in the plot classified as a moderate bum. P. contorta seedling density was not related to that of potential competitors. Within sites, the key variable explaining differences between moderate and severe plots is probably loss of seeds consumed or killed by severe canopy fires; differences among sites are likely a consequence of availability of seeds at the time of the fire, a function of the proportion of serotinous trees in the stand.
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Weber, Adrian, J. P. (Hamish) Kimmins, Benjamin Gilbert, Yueh-Hsin Lo, and Juan A. Blanco. "Multiple-pathway succession in coastal Tsuga heterophylla, Thuja plicata, and Abies amabilis forests on northeastern Vancouver Island, British Columbia." Canadian Journal of Forest Research 44, no. 10 (2014): 1145–55. http://dx.doi.org/10.1139/cjfr-2014-0060.
Full textAbstract:
Sustainable forest practices are often designed to mimic natural disturbance and successional processes, yet succession is poorly understood in many ecosystems. On northeastern Vancouver Island, the “disturbance hypothesis” is a widely assumed succession model asserting that shade-tolerant western redcedar (Thuja plicata Donn ex D. Don) and the ericaceous shrub salal (Gaultheria shallon Pursh) invade and colonize highly productive western hemlock (Tsuga heterophylla (Raf.) Sarg.) – Pacific silver fir (Abies amabilis Douglas ex J. Forbes) stands (HA) on zonal sites in the absence of stand-replacing wind disturbance. This leads to the development of low-productivity, low-density, uneven-aged, open-crowned redcedar–hemlock–salal stands (CH). In conflict with this model, old, apparently stable HA stands lacking redcedar can be found on such sites as well. We sought evidence for the predicted transition to CH stands by examining stand composition, crown closure, tree size class frequency distributions, salal cover, and redcedar establishment on young HA (∼90 years old), old HA (>160 years), and CH (>160 years) stands. When adjacent to a redcedar stand, young HA stands had fewer redcedar seedlings but more redcedar adult trees than old HA stands. However, redcedar abundance did not differ between young and old HA stands at distances further than 10 m from adjacent redcedar stands. This could indicate that redcedar recruits into HA stands at stand establishment and that redcedar seedling establishment is low under the thick canopy of young HA stands. The chronosequence data also suggest that both old HA and CH stands are self-replacing stand types in these forests, contrary to the disturbance hypothesis. We develop a new, multipathway model for this ecosystem that is based on the chronosequence data and life-history traits of the focal tree species and suggest that disturbance plays a role opposite to the equilibrium model.
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Pasanen, Hannes, Virve Rehu, Kaisa Junninen, and Jari Kouki. "Prescribed burning of canopy gaps facilitates tree seedling establishment in restoration of pine-dominated boreal forests." Canadian Journal of Forest Research 45, no. 9 (2015): 1225–31. http://dx.doi.org/10.1139/cjfr-2014-0460.
Full textAbstract:
Because many currently protected forests are former timber production areas, restoration activities are often used to re-establish their natural structures. In this experimental study, we monitored the establishment of tree seedlings in previously managed but currently protected Scots pine (Pinus sylvestris L.) dominated stands in boreal forests 5 years after restoration measures. The study included eight study areas (115 sample plots) in southern Finland. We compared seedling abundance between five study groups: untreated control forest, unburned canopy gap, burned full-canopy forest, burned canopy gap, and thinned and burned forest. Density of tree seedlings was highest in burned canopy gaps (mean 25.4 seedlings/100 m2 compared with 6.0 seedlings/100 m2 in control sites). In particular, birch (Betula spp.) and Scots pine were significantly more abundant within burned canopy gaps than in unburned gaps. We conclude that opening within-stand canopy gaps, especially in combination with prescribed burning, can be useful in forest restoration as the gaps diversify age-class structure and tree species composition of single-cohort pine stands.
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Kellomäki, Seppo, and Hannu Väisänen. "Model computations on the impact of changing climate on natural regeneration of Scots pine in Finland." Canadian Journal of Forest Research 25, no. 6 (1995): 929–42. http://dx.doi.org/10.1139/x95-102.
Full textAbstract:
Based on model computations, the regeneration of Scots pine (Pinussylvestris L.) in southern (60°N) and northern (66°N) Finland was studied in relation to an elevating temperature. The temperature elevation increased flowering and the subsequent seed crop, particularly in northern Finland, with a decrease in the frequency of zero crops. In southern Finland, the number of seedlings produced by each seed crop increased when applying wide spacing, but decreased when applying narrow spacing of parent trees. This was due to a decrease in soil moisture induced by the increasing evaporative demand and transpiration of the parent trees. In northern Finland, temperature elevation substantially increased the success of regeneration in terms of seedlings produced by each seed crop regardless of the spacing of parent trees. In terms of the density of seedling stands and the height and diameter growth of seedlings, the establishment of a seedling stand within a given period of time was substantially improved under the improved temperature conditions in both southern and northern Finland.
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Brose, Patrick H. "A comparison of the effects of different shelterwood harvest methods on the survival and growth of acorn-origin oak seedlings." Canadian Journal of Forest Research 41, no. 12 (2011): 2359–74. http://dx.doi.org/10.1139/x11-143.
Full textAbstract:
Timely development of newly germinated oak (Quercus spp.) seedlings into competitive-sized regeneration is an essential part of the oak regeneration process. The amount of sunlight reaching the forest floor partly governs this development, and foresters often use the shelterwood system to expose oak seedlings to varying degrees of insolation. To further understand the seedling development–sunlight–shelterwood relationships, I conducted a multiyear study at five locations in Pennsylvania. Each location had four stands either uncut or recently treated with one of three shelterwood harvest methods (preparatory cut, first removal cut, or final removal cut) resulting in four different levels of sunlight reaching the forest floor. In each stand, four 32 m2 plots were prepared, and each was planted with 400 acorns of black (Quercus velutina Lam.), chestnut (Quercus montana Willd.), northern red (Quercus rubra L.), or white oak (Quercus alba L.) and protected from wildlife. Germination success was universally high and for the next 8 years, I monitored seedling survival and measured seedling growth. The final and first removal cut treatments had higher seedling survival than the preparatory cut and uncut treatments. Oak seedling growth was positively related to sunlight availability; seedlings in the final removal cut grew the most, followed in descending order by those in the first removal cut, preparatory cut, and uncut treatments. These findings provide insight into the subtleties of regenerating oak forests with the shelterwood system.
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McWilliams, William H., Susan L. Stout, Todd W. Bowersox, and Larry H. McCormick. "Adequacy of Advance Tree-Seedling Regeneration in Pennsylvania's Forests." Northern Journal of Applied Forestry 12, no. 4 (1995): 187–91. http://dx.doi.org/10.1093/njaf/12.4.187.
Full textAbstract:
Abstract Measurement of tree seedlings and herbaceous vegetation from 499 sample locations across Pennsylvania revealed that advance tree-seedling regeneration is inadequate for new stand establishment across most of the State. The samples were located in stands from 40% to 75% stocked to focus on stands with ample light and growing space for establishment of abundant advance regeneration. A range of regeneration adequacy criteria was applied to the measurements. Using the least stringent criterion, a low density of stems of any tree species, resulted in 40% of the sample locations being adequately stocked. Applying the most stringent criterion, a high density of stems of desirable species, resulted in only 4% of the sample locations being adequately stocked. With the exception of forest-type group, no significant relationship was found between the adequacy of regeneration and other variables tested at the broad level of geographic scale of this study. Levels of fern and grass sufficient to hamper tree-seedling development were found at 54% of the sample locations. Fern species that propagate primarily by spreading rhizomes accounted for 70% of the total fern sample. North. J. Appl. For. 12(4):187-191.
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McLaren, Brian E., and Robert A. Janke. "Seedbed and canopy cover effects on balsam fir seedling establishment in Isle Royale National Park." Canadian Journal of Forest Research 26, no. 5 (1996): 782–93. http://dx.doi.org/10.1139/x26-088.
Full textAbstract:
While balsam fir (Abiesbalsamea (L.) Mill.) dominated forests are vanishing from the southwest end of Isle Royale National Park, Michigan, renewal of fir stands is occurring on the northeast end. We speculate that the difference is related both to severe browsing by moose (Alcesalces L.), and to the frequency of disturbances like fire and windthrow. A survey of 24 stands and in situ experimentation on Isle Royale show that balsam fir seedling survival is optimal under 40–79% canopy cover. Late-season and overwinter mortality in 1-year-old seedlings is highest under >80% canopy cover, while germination is lowest under <40% cover. We also rank germination substrates by "preference ratios," and by comparing the overwinter survival of young fir seedlings on five natural media. We find best performance on hypnaceous moss, variable survival success on rotten wood, and highest mortality on broadleaf litter. However, ample seedling densities occur on the southwest end of the island, and the failure of fir to reach the overstory in this area is apparently not related to poor seedling establishment.
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Robert, Emilie, Suzanne Brais, Brian D. Harvey, and David Greene. "Seedling establishment and survival on decaying logs in boreal mixedwood stands following a mast year1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems." Canadian Journal of Forest Research 42, no. 8 (2012): 1446–55. http://dx.doi.org/10.1139/x2012-085.
Full textAbstract:
In the boreal forest, establishment of tree regeneration is tightly linked to both mast years and the availability of adequate germination beds for seedlings. We took advantage of a mast year (2006) in the eastern boreal mixedwood to compare seedling establishment in 2007 and seedling survival 2 and 4 years later on sections of fallen logs and equivalent areas of adjacent forest floor. Several factors that could explain establishment of seedlings on logs were measured, including wood resistance, density, moisture content, and C/N ratio. Our results show that small-seeded species, such as white birch ( Betula papyrifera Marsh.) and white spruce ( Picea glauca (Moench) Voss), establish preferentially on logs whereas balsam fir ( Abies balsamea (L.) Mill.), a relatively large-seeded species, establishes more often on the forest floor. Using logistic regressions, we confirmed that the probability of seedling establishment on logs declines with wood resistance, while the survival probability is inversely proportional to stand deciduous basal area. Survival rate was similar for seedlings established on the forest floor and on logs. However, none of the white birch seedlings established on the forest floor in 2007 were alive by 2011. Even following an exceptional mast year, log occurrence in eastern mixedwood stands would not suffice to obtain adequate white spruce stocking levels.
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Khan, Afsheen. "Seedling diversity and spatial distribution of some conifers and associated tree species in highly disturbed Western Himalayan regions in Pakistan." Journal of Forest Science 67, No. 4 (2021): 175–84. http://dx.doi.org/10.17221/138/2020-jfs.
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This article encompasses the impacts of disturbance, regeneration potential of conifers and the dynamics of tree species seedlings along the spatial scale in Murree forest. The seedling status preferably of conifers along with associated broadleaved dominant tree species is determined by a quantitative evaluation of diversity functions. An empirical approach is applied to predicting the future of seedlings under stress as well as the current hypothetical appearance of seedlings in the forest. The need of analysing diversity of this forest is due to highly disturbed conditions there, and this paper is designed to know the recent trends of species diversity in the area. Species diversity and species abundance at a seedling level are estimated by using standard formulas of diversity measurements. Thirty stands are used for the evaluation of seedling abundance in highly disturbed conditions with the examination of diversity in the area. Seedling density is too low in the forest whereas diversity is also in poor condition. Seedlings from four conifers with three broadleaved species in different stands indicated the low density of future trees. The mean density·ha<sup>–1</sup> of pine seedlings is consecutively low in Pinus wallichiana (16 ± 2), Pinus roxburghii (11 ± 3), Cedrus deodara (9 ± 3), Abies pindrow (8 ± 3). The correlation coefficient is as low as 0.76, 0.66 and 0.61 in Pinus roxburghii, Cedrus deodara and Abies pindrow, respectively, while Pinus wallichiana showed a significant correlation, i.e. P &gt; 0.5. Hence, this study claims that the survival of the forest is threatened as seedling density and diversity are too low. This forest needs serious attention towards preventing and conserving pines and other associated species seedlings for the existence of this forest in future.
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Lorentz, Kimberly A., and Patrick J. Minogue. "Potential Invasiveness for Eucalyptus Species in Florida." Invasive Plant Science and Management 8, no. 1 (2015): 90–97. http://dx.doi.org/10.1614/ipsm-d-14-00030.1.
Full textAbstract:
AbstractTo assess the potential invasiveness of common eucalyptus species planted for pulpwood, mulch wood or bioenergy crops, field surveys of eucalyptus seedling recruitment were conducted in north and central Florida locations within seed bearing eucalyptus stands and in the proximate plant communities where seed dispersal may occur. Plant communities included non-grazed pasture, intensively site-prepared forestland, abandoned forest road and upland mixed pine- hardwood forest. No eucalyptus seedlings were found in any of the 310 1-m2 survey plots across the two locations. Second, seed addition studies were conducted to determine the relative potential for seedling emergence and survival among Eucalyptus amplifolia, E. camaldulensis and E. grandis added into plots at two seed densities, under disturbed and nondisturbed conditions, in the understory of the eucalyptus stands and in each of the aforementioned proximate plant communities. Overall, the probability of emergence of added seed was very low (P = 0.0 to 0.0032), and seed density effects were not significant. Emergence was significantly greater in disturbed conditions compared to nondisturbed conditions for seedlings originating from natural seed rain from the eucalyptus canopy in central Florida. The amount of time that seedlings survived was greater for E. camaldulensis compared to the other species but no seedlings survived more than 13 wk. These data indicate that under specific favorable conditions, eucalyptus seedlings may establish within or proximate to planted stands, but the overall level of invasiveness demonstrated by E. amplifolia and E. grandis is low for north or central Florida. The demonstrated role of disturbance in facilitating eucalyptus seedling recruitment suggests that a stable perennial plant community (native grasses) should be established instead of bare soil buffer zones to mitigate spread.