Academic literature on the topic 'Fern nutrient availability'

When habitats are heterogeneous regarding key abiotic factors, and individual organisms have no control over the environment in which they develop, labile sex expression can allow individuals to adjust their sex based on local environmental conditions, resulting in increased individual fitness. Sexual lability is found extensively in homosporous ferns, where sex expression is often regulated via the pheromone antheridiogen. Nutrient availability may provide additional signals for sex determination in fern gametophytes, particularly if nutrient demands required for sexual development differ by sex. The model fern Ceratopteris richardii Brongn. has a well-characterized antheridiogen response and short time to sexual maturity. Although tests for nutrient effects on sex determination have been conducted in this fern, tests for differences in nutrient demands by sex have not. Elemental analysis demonstrated that 14-day-old ameristic male and meristic female or hermaphrodite gametophytes of C. richardii differ significantly in their relative carbon and nitrogen masses, resulting in significantly dissimilar C:N ratios between the sexes. Average gametophyte dry mass in ameristic males was approximately half that of meristic plants of the same age, and contained less N than meristic gametophytes in both relative and absolute terms. Those characteristic differences in elemental composition imply that variation in nutrient availability could potentially influence sex expression in C. richardii gametophyte populations, rather than regulation of sex determination by the antheridiogen system alone.

Macroecological patterns of leaf traits can be used to assess adaptive responses of plants to environmental stress. Here we present the first such study on a large number of fern species (403) along gradients of elevation (temperature) and humidity. To assess how the representation of traits such as degree of lamina dissection, leaf length, leaf mass per area (LMA), trichome density, venation density, stomatal density, and of adaptive strategies such as poikilohydry vary at the community and species levels in response to changes in humidity and temperature in the Bolivian Andes, we (1) compared whole pteridophyte communities at 14 sites, and (2) analysed intraspecific variation of the morphological traits of 17 fern species along an elevational gradient at 1700–3400 m in humid forest. Among the fern communities of the 14 sites, leaf length decreased with elevation and aridity, LMA increased with elevation, and trichome density and venation density increased with aridity. The study of intraspecific variation among 17 species showed an increase of stomatal density with elevation in six of 11 species (filmy ferns lacked stomata), an increase of specific weight in 15 species, a decrease of trichome density in seven of 10 species (other species lacked hairs), and a decrease of venation density in seven of 10 cases. Some of these trends can be interpreted adaptively: leaf thickness appears to increase in situations with low nutrient availability rather than with low water availability, whereas a dense cover of scales or hairs serves as a protection against insolation or as a vehicle for the absorption of water in poikilohydric species. In arid areas, trichome density increased with elevation, while it decreased with elevation in cloudy and humid regions. For most traits, variation was more pronounced at the community than at the species level, except for stomatal density, which varied much more strongly within than between species. Several of these morphological and anatomical characters can be used to infer palaeoclimatic conditions based on fossil pteridophyte floras.

The Big Five mass-extinction events are characterized by dramatic changes in primary producers. Initial disturbance to primary producers is usually followed by a succession of pioneers that represent qualitative and quantitative changes in standing crops of land plants and/or phytoplankton. On land, a transient collapse of arborescent (tree-bearing) vegetation and the rapid spread of a pioneer vegetation dominated by ferns and fern allies characterizes the Permian/Triassic (P/T), Triassic/Jurassic (T/J), and Cretaceous/Paleogene (K/Pg) mass-extinction events. The availability of low-quality food, such as herbaceous low-growing plants, likely played a role in triggering secondary extinctions of herbivores (reptiles, insects). Furthermore, malformation of acritarchs, pollen, and spores during the end-Ordovician, end-Devonian, P/T and T/J extinctions also suggests primary producers were of lesser quality. More importantly, changes in vegetation drove important increases in weathering and erosion leading to elevated nutrient transfer from the continents to the oceans. In the marine realm, the end-Ordovician, end-Devonian, end-Permian, and end-Triassic extinction events are all followed by periods of high primary production, which is reflected in the widespread deposition of black shales. Due to their small size, low nutritional quality, and possible toxicity, the abundance of picoplankton, such as prasinophytes, acritarchs, as well as bacterioplankton (cyanobacteria and green sulfur bacteria) may have been additional factors in delaying ecosystem recovery.

A 27-ha field study was set up in 1994 within the Petawawa Research Forest near Chalk River, Ontario with input and support from local research scientists, forest managers and forest technicians. The study was designed to examine the effects of partial cutting, site preparation and underplanting in natural eastern white pine (Pinus strobus L.) stands. A complete randomized block experimental design was followed with four replicates. Three thinning (control, one-crown and two-crown spacing) and four site preparation (control, scarification, brush control using herbicide, and both scarification and brush control using herbicide) treatments were applied. Natural regeneration and planted seedling survival and growth, soil nutrient availability and other environmental factors are being monitored and recorded. Early results have contributed to the development of a new provincial silvicultural guide and a prototype expert decision support system for white pine management. Research activities are evaluated and coordinated with field practices each year through the development of formal collaborative agreements, meetings, joint workshops and field tours. On-site staff is helping to collect field data and provide fire protection. The site has served as a field demonstration area for people interested in white pine ecosystem management. The study is described within the FERN network of sites on the Internet. Key words: eastern white pine, Pinus strobus, natural regeneration, understory planting, multidisciplinary field research, forest research sites

Long term environmental changes, induced both by natural and anthropogenic causes, cannot be assessed by looking solely at historical records of temperature, rainfall, water quality, etc. Frequently, such records are nonexistent. Where they do exist, they are often too short to be of much use. However, sediments contain a stratigraphic record of environmental change that allows comparison of the historic period influenced largely by humans, with prehistoric time when climate was the major determinant of environmental conditions.The stratigraphic record contains various fossilized organic materials which reflect environmental conditions at the time of the their deposition. Most abundant are pollen and spores of aquatic and terrestrial plants. Correspondence between pollen assemblages and vegetation has been found in all parts of the world. Therefore stratigraphic changes in pollen taxa reveal much information regarding the vegetational history of a region. Knowledge of the ecological requirements of various taxa can then be used to infer past climatic conditions. For example, dominance of Juglans (walnut) pollen indicates wet conditions while abundance of Pteridium (bracken fern) spores is an indicator of fire, suggesting drier conditions. Pollen can also be used to trace human disturbance to the environment. Sharp increases in the pollen of Ambrosia (ragweed) in sediment cores indicate large scale land clearance by man.Seeds preserved in sediments provide another measure of temporal vegetational change. Generally, seeds are not dispersed far from the parent plant; hence they provide a more local record of vegetation than pollen. A decrease in seeds of aquatic plants and increase in seeds of higher ground taxa when accompanied by increased sedimentation rates is an indicator of infilling of an aquatic environment. If unaccompanied by increased sedimentation, the change more likely represents lowering of sea level. Disappearance of seeds of taxa sensitive to turbidity and eutrophication provide another long term record of human disturbance.Distributions of diatoms are affected by temperature, salinity, oxygen, light availability and nutrient levels in the water. Therefore changes in diatom species preserved in the sediments can be used as indicators of climate, turbidity, anoxia and eutrophication in aquatic ecosystems.Many inorganic substances preserved in sediments also provide a long term record of changes in the environment. Nitrogen and phosphorus can be measured in cores and used as a surrogate record of water quality in lakes and estuaries. Sharp increases in sedimentary accumulation of metals record wastewater discharge and fuel emissions, related to human activity.

Abstract. Reactive nitrogen (N) increase in the biosphere has been a noteworthy aspect of global change, producing considerable ecological effects on the functioning and dynamics of the terrestrial ecosystems. A number of observational studies have explored responses of plants to experimentally simulated N enrichment in boreal and temperate forests. Here we investigate how the dominant trees and different understory plants respond to experimental N enrichment in a subtropical forest in China. We conducted a 3.4-year N fertilization experiment in an old-aged subtropical evergreen broad-leaved forest in eastern China with three treatment levels applied to nine 20 m × 20 m plots and replicated in three blocks. We divided the plants into trees, saplings, shrubs (including tree seedlings), and ground-cover plants (ferns) according to the growth forms, and then measured the absolute and relative basal area increments of trees and saplings and the aboveground biomass of understory shrubs and ferns. We further grouped individuals of the dominant tree species, Castanopsis eyrei, into three size classes to investigate their respective growth responses to the N fertilization. Our results showed that the plot-averaged absolute and relative growth rates of basal area and aboveground biomass of trees were not affected by N fertilization. Across the individuals of C. eyrei, the small trees with a DBH (diameter at breast height) of 5–10 cm declined by 66.4 and 59.5 %, respectively, in N50 (50 kg N ha−1 yr−1) and N100 fertilized plots (100 kg N ha−1 yr−1), while the growth of median and large trees with a DBH of > 10 cm did not significantly change with the N fertilization. The growth rate of small trees, saplings, and the aboveground biomass of understory shrubs and ground-cover ferns decreased significantly in the N-fertilized plots. Our findings suggested that N might not be a limiting nutrient in this mature subtropical forest, and that the limitation of other nutrients in the forest ecosystem might be aggravated by the enhanced N availability, potentially resulting in an adverse effect on the development of natural subtropical forest.

In South Korea, most metal mines were abandoned and caused contamination for more than 30 years. Even the soil is highly contaminated with trace elements, plants still grow in the area and can affect the contamination. Phytolith is amorphous silica in the plant body. Phytolith is resistant to decomposition, and the stabilization of carbon, nutrients, and toxic substances accumulated in the phytolith is being studied. In this study, the Gilgok gold mine, which is contaminated with arsenic was selected as the research site. We selected Phragmites japonica and Thelypteris palustris as targets for the analysis of arsenic accumulation in plants and phytolith. Plants accumulate more phytolith at the riverside. The higher water content of soil increased the Arsenic (As) concentration in the frond of the T. palustris. Soil available silicon (Si) did not affect phytolith accumulation but increased As accumulation in the plant and phytolith. The research result showed that P. japonica and T. palustris have the ability to accumulate As in phytolith and the accumulation can be changed with soil characteristics and plant species. This As accumulation in phytolith can affect plant tolerance in contaminated areas and change the As availability in the soil. The result of the research can be used as a database to build a sustainable environment.

Abstract. Coexisting plant species in a karst ecosystem may use diverse strategies of trade off between carbon gain and water loss to adopt to the low soil nutrient and low water availability conditions. An understanding of the impact of CO2 diffusion and maximum carboxylase activity of Rubisco (Vcmax) on the light-saturated net photosynthesis (A) and intrinsic water use efficiency (iWUE) can provide insight into physiological strategies of the water–carbon regulation of coexisting plant species used in adaptation to karst environments at the leaf scale. We selected 63 dominant species (across 6 life forms) in a subtropical karst primary forest in southwestern China, measured their CO2 response curves, and calculated the corresponding stomatal conductance to CO2 (gs), mesophyll conductance to CO2 (gm), and Vcmax. The results showed that gs and gm varied about 7.6- and 34.5-fold, respectively, and that gs was positively related to gm. The contribution of gm to the leaf CO2 gradient was similar to that of gs. gs ∕ A, gm ∕ A and gt ∕ A was negatively related to Vcmax ∕ A. The relative limitations of gs (ls), gm (lm), and Vcmax (lb) to A for the whole group (combined six life forms) were significantly different from each other (P < 0.05). lm was the largest (0.38 ± 0.12), followed by lb (0.34 ± 0.14), and ls (0.28 ± 0.07). No significant difference was found between ls, lm, and lb for trees and tree/shrubs, while lm was the largest, followed by lb and ls for shrubs, grasses, vines and ferns (P < 0.05). iWUE varied about 3-fold (from 29.52 to 88.92 µmol CO2 mol−1 H2O) across all species, and was significantly correlated with gs, Vcmax, gm ∕ gs, and Vcmax ∕ gs. These results indicated that karst plants maintained relatively high A and low iWUE through the covariation of gs, gm, and Vcmax as an adaptation to a karst environment.

Water fern Azolla microphylla symbioses with Anabaena azollae which is able to fix N2. Fern growth is strongly influenced by the availability of macro nutrients such as phosphate. The aim of this study was to determine the effect of concentration of phosphate fertilizers and different water levels on the growth and nitrogen uptake of Azolla microphylla. Research was conducted by using randomized block design with three replications. The treatment were water level which consists of 0 cm, 2 cm, 4 cm, and 6 cm, and the concentration of phosphates (P) which is composed of without and with 15 ppm, 30 ppm and 45 ppm. The results showed that the water level are interdependent with the phosphates concentration to influence Azolla’s covered area at 7-21 days after planting, wet weight, total dry weight, and total nitrogen uptake of Azolla microphylla. The water level 2 cm at a concentration of 30 ppm of phosphate fertilizers is the best treatment combination to increase Azolla’s covered area at 7-21 HST, wet weight, total dry weight, and total nitrogen uptake of Azolla microphylla.

Este trabajo está enfocado en la relación entre la productividad y la riqueza de especies de helechos terrestres, y en la disponibilidad de nutrientes a través de un gradiente altitudinal en Ecuador. El trabajo de campo fue realizado durante tres años entre 2009 y 2011, el cual fue llevado a cabo en 8 niveles altitudinales entre 500m y 4000m en la Cordillera Oriental de los Andes ecuatorianos. Diversidad, biomasa, productividad y caracteres funcionales de las hojas de los helechos terrestres fueron estudiados en tres cuadrantes permanentes de 400m2 por cada elevación. Se reportaron un total de 91 especies de helechos terrestres en 32 géneros y 18 familias. A través del gradiente altitudinal, el pico más alto de riqueza de especies se registró en elevaciones medias y la riqueza de especies estuvo débilmente relacionada a medidas de productividad del ecosistema y más fuerte relacionado a la productividad de los hehechos terrestres, lo cual podría estar determinado por un incremento en el número de individuos de helechos y por la disponibilidad de nichos. Sin embargo, en cada nivel altitudinal la relación entre la riqueza de especies de helechos y la productividad de helechos fue negativa, lo cual principalmente se debe a la competencia interespecífica; es decir, en ambas escalas espaciales de este estudio, la diversidad de helechos parece estar limitada por el número de nichos disponibles y la competencia para ocupar estos nichos. Al comparar los caracteres funcionales de las hojas de helechos y árboles a través del gradiente altitudinal se observó similaridades entre ellos. Sin embargo, se encontró una diferencia en el área específica de las hojas entre helechos y árboles, lo cual refleja los diferentes niveles de luz de ambas formas de vida. Respecto los cambios altitudinales en biomasa y productividad de helechos y árboles se encontró una notable diferencia entre estas dos formas de vida, lo cual apoya la hipótesis de que ambos grupos de plantas están creciendo limitados por diferentes factores.