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Journal articles on the topic 'Tress gradient hypothesis'

Author: Grafiati

Published: 7 July 2024

Last updated: 19 July 2025

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1

Keith, Arthur R., Joseph K. Bailey, and Thomas G. Whitham. "Assisted migration experiments along a distance/elevation gradient show limits to supporting home site communities." PLOS Climate 2, no. 5 (2023): e0000137. http://dx.doi.org/10.1371/journal.pclm.0000137.

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We addressed the hypothesis that intraspecific genetic variation in plant traits from different sites along a distance/elevation gradient would influence the communities they support when grown at a new site. Answers to this hypothesis are important when considering the community consequences of assisted migration under climate change; i.e., if you build it will they come?. We surveyed arthropod communities occurring on the foundation riparian tree species Populus angustifolia along a distance/elevation gradient and in a common garden where trees from along the gradient were planted 20–22 year

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Paoli, Gary David. "Divergent leaf traits among congeneric tropical trees with contrasting habitat associations on Borneo." Journal of Tropical Ecology 22, no. 4 (2006): 397–408. http://dx.doi.org/10.1017/s0266467406003208.

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A prediction of the hypothesis that niche processes control plant species distributions across edaphic gradients is that pairwise comparisons of related species on contrasting soils should show consistent patterns of trait divergence. This hypothesis was tested in lowland Bornean rain forest by combining measurements of leaf traits, soil nutrients and the distribution of tree species in the Dipterocarpaceae across a nutrient gradient. Nine species were studied, comprising four related pairs in Shorea (phylogenetic independent contrasts; PICs) and one habitat generalist (Dipterocarpus sublamell

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Lyu, Lixin, Susanne Suvanto, Pekka Nöjd, Helena M. Henttonen, Harri Mäkinen, and Qi-Bin Zhang. "Tree growth and its climate signal along latitudinal and altitudinal gradients: comparison of tree rings between Finland and the Tibetan Plateau." Biogeosciences 14, no. 12 (2017): 3083–95. http://dx.doi.org/10.5194/bg-14-3083-2017.

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Abstract. Latitudinal and altitudinal gradients can be utilized to forecast the impact of climate change on forests. To improve the understanding of how these gradients impact forest dynamics, we tested two hypotheses: (1) the change of the tree growth–climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. To address this, we utilized tree-ring data from a latitudinal gradient in Finland and from two altitudinal gradients on the Tibetan Plateau. W

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Xie, Yajun, Zhaozhao Tan, Xuesheng Xu, Yonghong Xie, and Shengsheng Xiao. "Potential Hypotheses Predicting the Patterns of Major Nutrients in Leaves on a Global Scale." Forests 16, no. 1 (2025): 80. https://doi.org/10.3390/f16010080.

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Climatic force might sharpen the latitudinal gradients of foliar nutrients directly (the Temperature–Plant Physiological hypothesis) or indirectly (either through soil nutrient, the Soil Substrate Age hypothesis, or plant functional type (e.g., herbs and trees) composition, the Species Composition hypothesis). However, the validities, effectiveness, and key drivers of these hypotheses have not been further examined globally. Here, we tested these hypotheses by synthesizing data from 2344 observations of leaf N, leaf P, and leaf K in terrestrial plants. The results indicated that leaves enriche

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He, Jianing, Caiwen Ning, Wentao Zhang, Ümüt Halik, and Zehao Shen. "The Effect of Elevation on the Population Structure, Spatial Patterning and Intraspecific Interactions of Picea schrenkiana in the Eastern Tianshan Mountains: A Test of the Stress Gradient Hypothesis." Forests 14, no. 10 (2023): 2092. http://dx.doi.org/10.3390/f14102092.

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Changes in age structure, spatial distribution and intraspecific interactions across environmental gradients often reflect adaptations of plant populations to their environment. Our study explored the growth status of the Picea schrenkiana population on the north slope of the eastern Tianshan Mountains and tested the stress gradient hypothesis (SGH) against changes in the age structure and spatial pattern of P. schrenkiana populations along the environmental gradient. We sampled the forests at eight elevational locations, comprising a total of 24 plots of 30 × 30 m area from 1800 to 2500 m a.s

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Jiang, Zihan, Qiuyu Liu, Wei Xu, and Changhui Peng. "The Importance of Energy Theory in Shaping Elevational Species Richness Patterns in Plants." Biology 11, no. 6 (2022): 819. http://dx.doi.org/10.3390/biology11060819.

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Many hypotheses have been proposed to explain elevational species richness patterns; however, evaluating their importance remains a challenge, as mountains that are nested within different biogeographic regions have different environmental attributes. Here, we conducted a comparative study for trees, shrubs, herbs, and ferns along the same elevational gradient for 22 mountains worldwide, examining the performance of hypotheses of energy, tolerance, climatic variability, and spatial area to explain the elevational species richness patterns for each plant group. Results show that for trees and s

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Mitchell, Robert J., L. Katherine Kirkman, Stephen D. Pecot, Carlos A. Wilson, Brian J. Palik, and Lindsay R. Boring. "Patterns and controls of ecosystem function in longleaf pine - wiregrass savannas. I. Aboveground net primary productivity." Canadian Journal of Forest Research 29, no. 6 (1999): 743–51. http://dx.doi.org/10.1139/x99-051.

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Longleaf pine - wiregrass (Pinus palustris Mill. - Aristida stricta Michx.) woodlands occupy sites ranging from deep, xeric sandhills to the edge of wetlands in the southeastern United States. Aboveground net primary productivity (ANPP) of the overstory and understory were determined for three replicate sites of three site types (xeric, intermediate, and wet-mesic) that span a wide environmental gradient. In addition, soil moisture (at 30 and 90 cm) and N mineralization (in situ buried bag incubations) were measured through an annual cycle. Longleaf pine - wiregrass ecosystems varied by nearly

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Araujo, Felipe de Carvalho, Carolina Njaime Mendes, Gabriela Gomes Pires, Gisele Cristina de Oliveira Menino, Marco Aurelio Leite Fontes, and Rubens Manoel Dos Santos. "Adaptive strategy of tree communities on an environmental harshness hinterland inselberg in Minas Gerais, Brazil." Australian Journal of Botany 65, no. 5 (2017): 463. http://dx.doi.org/10.1071/bt16252.

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Trees and other plants growing in stressful environments can display adaptive strategies such as sprouting, which is considered to be a functional trait for the persistence niche. For example, inselbergs are rocky outcrops that impose limitations on many plant forms through selective pressure to adapt to these environments. The present research tested the hypotheses that environmental harshness enhances sprouting, and that multi-stemmed trees have different persistence dynamics compared with single-stemmed trees. We sampled vegetation in 2006 and 2011 across a soil depth gradient in three area

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Lamit, L. J., T. Wojtowicz, Z. Kovacs, et al. "Hybridization among foundation tree species influences the structure of associated understory plant communities." Botany 89, no. 3 (2011): 165–74. http://dx.doi.org/10.1139/b11-006.

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Understanding how genetic identity influences community structure is a major focus in evolutionary ecology, yet few studies examine interactions among organisms in the same trophic level within this context. In a common garden containing trees from a hybrid system (Populus fremontii S. Wats. × Populus angustifolia James), we tested the hypothesis that the structure of establishing understory plant communities is influenced by genetic differences among trees and explored foliar condensed tannins (CTs) and photosynthetically active radiation (PAR) as mechanisms. Several findings support our hypo

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Roncal, Julissa. "Habitat differentiation of sympatric Geonoma macrostachys (Arecaceae) varieties in Peruvian lowland forests." Journal of Tropical Ecology 22, no. 4 (2006): 483–86. http://dx.doi.org/10.1017/s0266467406003270.

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Among the hypotheses invoked to explain high species richness in tropical forests, the niche differentiation hypothesis has received observational and experimental support (Ashton 1969, Chesson 2000, Clark et al. 1999, Souza & Martins 2004, Svenning 2001, Terborgh & Mathews 1999). Habitat specialization with regard to edaphic factors and topography has been observed in several plant groups including trees, lianas, shrubs, ferns and palms (Clark et al. 1999, Ibarra-Manriquez & Martinez-Ramos 2002, Svenning 1999, Tuomisto & Ruokolainen 1993). Treefall gaps and light gradients hav

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Khudadad. "A Middle Devonian vernal pool ecosystem provides a snapshot of the earliest forests." PLOS ONE 16, no. 9 (2021): e0255565. http://dx.doi.org/10.1371/journal.pone.0255565.

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The dichotomy of the earliest ecosystems into deltaic and floodplain forests was a long-standing view in paleobotany. The morphological traits such as nonbranching rootlets, bifurcating rhizomes, and bulbous bases of the primitive trees such as Eospermatopteris and lycopsids were considered adaptations to the lowland deltaic environments. In contrast, the traits of Archaeopteris trees such as wood, hierarchical branching networks of roots, and true leaves are an adaptation to the upland floodplain environments. The discovery of the Town of Cairo Highway Department (TCHD) fossil site in Upstate

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Ntirugulirwa, Bonaventure, Etienne Zibera, Nkuba Epaphrodite, et al. "Thermophilisation of Afromontane forest stands demonstrated in an elevation gradient experiment." Biogeosciences 20, no. 24 (2023): 5125–49. http://dx.doi.org/10.5194/bg-20-5125-2023.

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Abstract. The response of tropical trees and tree communities to climate change is crucial for the carbon storage and biodiversity of the terrestrial biosphere. Trees in tropical montane rain forests (TMFs) are considered particularly vulnerable to climate change, but this hypothesis remains poorly evaluated due to data scarcity. To reduce the knowledge gap in the response of TMF trees to warming, we established a field experiment along a 1300–2400 m elevation gradient as a proxy for warming in Rwanda. Seedling-size trees of 20 species native to montane forests in eastern and central Africa we

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Soria-Carrasco, Víctor, and Jose Castresana. "Diversification rates and the latitudinal gradient of diversity in mammals." Proceedings of the Royal Society B: Biological Sciences 279, no. 1745 (2012): 4148–55. http://dx.doi.org/10.1098/rspb.2012.1393.

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The latitudinal gradient of species richness has frequently been attributed to higher diversification rates of tropical groups. In order to test this hypothesis for mammals, we used a set of 232 genera taken from a mammalian supertree and, additionally, we reconstructed dated Bayesian phylogenetic trees of 100 genera. For each genus, diversification rate was estimated taking incomplete species sampling into account and latitude was assigned considering the heterogeneity in species distribution ranges. For both datasets, we found that the average diversification rate was similar among all latit

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Coleborn, Katie, Gabriel C. Rau, Mark O. Cuthbert, Andy Baker, and Owen Navarre. "Solar-forced diurnal regulation of cave drip rates via phreatophyte evapotranspiration." Hydrology and Earth System Sciences 20, no. 11 (2016): 4439–55. http://dx.doi.org/10.5194/hess-20-4439-2016.

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Abstract. We present results of a detailed study of drip rate variations at 12 drip discharge sites in Glory Hole Cave, New South Wales, Australia. Our novel time series analysis, using the wavelet synchrosqueezed transform, reveals pronounced oscillations at daily and sub-daily frequencies occurring in 8 out of the 12 monitored sites. These oscillations were not spatially or temporally homogenous, with different drip sites exhibiting such behaviour at different times of year in different parts of the cave. We test several hypotheses for the cause of the oscillations, including variations in p

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Almeida, Renan N. D., Michael Greenberg, Cedoljub Bundalovic-Torma, et al. "Predictive modeling of Pseudomonas syringae virulence on bean using gradient boosted decision trees." PLOS Pathogens 18, no. 7 (2022): e1010716. http://dx.doi.org/10.1371/journal.ppat.1010716.

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Pseudomonas syringae is a genetically diverse bacterial species complex responsible for numerous agronomically important crop diseases. Individual P. syringae isolates are assigned pathovar designations based on their host of isolation and the associated disease symptoms, and these pathovar designations are often assumed to reflect host specificity although this assumption has rarely been rigorously tested. Here we developed a rapid seed infection assay to measure the virulence of 121 diverse P. syringae isolates on common bean (Phaseolus vulgaris). This collection includes P. syringae phylogr

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Tejeda Landero, Victor Manuel, Lázaro Rafael Sánchez-Velásquez, Héctor Viveros-Viveros, Armando Aparicio-Rentería, and Rafael Flores-Peredo. "Seed bank formation and removal of Pinus hartwegii (Pinaceae) seeds along an altitudinal gradient in the Cofre de Perote National Park, Veracruz, Mexico." Botanical Sciences 97, no. 4 (2019): 623–29. http://dx.doi.org/10.17129/botsci.2204.

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Background: Seed banks, an important element in the natural regeneration of plant communities, are regulated mostly by granivores along an altitudinal gradient. Question/Hypothesis: Pinus hartwegii forms transient and probably persistent seed banks along an altitudinal gradient. Seed removal will vary according to the removing agents, the altitude and the season. Species under study/Data description/Mathematical model: The formation of seed banks and the removal of Pinus hartwegii (Pinaceae) seeds along an altitudinal gradient were evaluated in different seasons using a linear mode

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Abanikanta, Bhadra, Kumar Pattanayak Sanjaya, and Kumar Dhal Nabin. "Mid-domain effect: A hypothesis testing in the Gandhamardan natural forest of Bargarh and Balangir districts, Odisha, India." Biolife 4, no. 2 (2022): 308–26. https://doi.org/10.5281/zenodo.7317833.

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<strong>ABSTRACT</strong> Tree community is the structural and functional basis of forest ecosystems. Forest ecosystem on hills is influenced by elevation due to variation in temperature, aspect and topographic features. Can the understanding of tree species occurrence guided by altitude help in finding the distributional pattern in different elevational bands? Gandhamardan hills belong to Eastern Ghats in Bargarh and Balangir districts of Odisha, India (20°53<strong>'</strong>29.7<strong>''</strong>N, 82°49<strong>'</strong>57.8<strong>''</strong>E). One hundre

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Farina, Vittorio, Riccardo Lo Bianco, and Paolo Inglese. "Vertical Distribution of Crop Load and Fruit Quality within Vase- and Y-shaped Canopies of `Elegant Lady' Peach." HortScience 40, no. 3 (2005): 587–91. http://dx.doi.org/10.21273/hortsci.40.3.587.

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Canopy shape and depth may influence crop uniformity of peach trees at harvest. To test this hypothesis we examined yield distribution and fruit quality changes at different canopy levels of peach trees trained to delayed vase (DV) and perpendicular Y (Y). Trees of both training forms were divided vertically into six or seven 50-cm-deep layers and fruit was harvested at commercial ripening from each layer separately. Regardless of training form, number of fruit and yield per layer were highest in the central part of the canopy, but more evenly distributed among canopy layers in Y trees. In DV

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Rodríguez-Quintero, W., and Ernesto Gianoli. "Abundance and diversity of lianas in a Neotropical dry forest: the influence of soil moisture." Plant Ecology and Evolution 149, no. (3) (2016): 329–34. https://doi.org/10.5091/plecevo.2016.1233.

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<b>Background and aims</b> – Based on data across tropical forests, a leading hypothesis posits that lianas are better competitors than trees under water shortage. Evaluating this hypothesis at a local scale may provide insights into its generality. We tested whether the abundance of lianas –relative to trees– decreases with soil moisture in a Neotropical dry forest. We also evaluated the influence of water availability on liana diversity.<b>Methods</b> – Lianas (≥ 1 cm diameter) and trees (≥ 1.5 m height) were counted and identified, and soil moisture was measured, in twenty 10 × 10 m plots a

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Seo, Sung Won. "Market Timing and Seasoned Equity Offering." Institute of Management and Economy Research 15, no. 1 (2024): 145–57. http://dx.doi.org/10.32599/apjb.15.1.202403.145.

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Purpose - In this study, we propose an empirical model for predicting seasoned equity offering (SEO here after) using machine learning methods. Design/methodology/approach - The models utilize the random forest method based on decision trees that considers non-linear relationships, as well as the gradient boosting tree model. SEOs incur significant direct and indirect costs. Therefore, CEOs’ decisions of seasoned equity issuances are made only when the benefits outweigh the costs, which leads to a non-linear relationship between SEOs and a determinant of them. Particularly, a variable related

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Edenius, Lars, Kjell Danell, and Hans Nyquist. "Effects of simulated moose browsing on growth, mortality, and fecundity in Scots pine: relations to plant productivity." Canadian Journal of Forest Research 25, no. 4 (1995): 529–35. http://dx.doi.org/10.1139/x95-060.

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Current theory on plant–animal interactions predicts that the outcome of herbivory on plant performance will be dependent on plant productivity. Thus, slow-growing plants should be less able to compensate for biomass losses than fast-growing plants, and therefore be more susceptible to herbivory if attacked. We simulated winter browsing by moose (Alcesalces (L.)) on Scots pine (Pinussylvestris L.) along a gradient of plant productivity and addressed the following questions: (1) Does herbivory affect growth independently of plant productivity? (2) Is herbivory a more important mortality factor

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Haverd, V., B. Smith, M. Raupach, et al. "Coupling carbon allocation with leaf and root phenology predicts tree–grass partitioning along a savanna rainfall gradient." Biogeosciences 13, no. 3 (2016): 761–79. http://dx.doi.org/10.5194/bg-13-761-2016.

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Abstract. The relative complexity of the mechanisms underlying savanna ecosystem dynamics, in comparison to other biomes such as temperate and tropical forests, challenges the representation of such dynamics in ecosystem and Earth system models. A realistic representation of processes governing carbon allocation and phenology for the two defining elements of savanna vegetation (namely trees and grasses) may be a key to understanding variations in tree–grass partitioning in time and space across the savanna biome worldwide. Here we present a new approach for modelling coupled phenology and carb

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Haverd, V., B. Smith, M. Raupach, et al. "Coupling carbon allocation with leaf and root phenology predicts tree-grass partitioning along a savanna rainfall gradient." Biogeosciences Discussions 12, no. 19 (2015): 16313–57. http://dx.doi.org/10.5194/bgd-12-16313-2015.

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Abstract. The relative complexity of the mechanisms underlying savanna ecosystem dynamics, in comparison to other biomes such as temperate and tropical forests, challenges the representation of such dynamics in ecosystem and Earth system models. A realistic representation of processes governing carbon allocation and phenology for the two defining elements of savanna vegetation (namely trees and grasses) may be a key to understanding variations in tree/grass partitioning in time and space across the savanna biome worldwide. Here we present a new approach for modelling coupled phenology and carb

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Loppi, Stefano, Stergios Arg Pirintsos, and Vincenzo De Dominicis. "ANALYSIS OF THE DISTRIBUTION OF EPIPHYTIC LICHENS ON QUERCUS PUBESCENS ALONG AN ALTITUDINAL GRADIENT IN A MEDITERRANEAN AREA (TUSCANY, CENTRAL ITALY)." Israel Journal of Plant Sciences 45, no. 1 (1997): 53–58. http://dx.doi.org/10.1080/07929978.1997.10676670.

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The distribution of epiphytic lichens on Quercus pubescens in Tuscany, central Italy, was studied by means of multivariate techniques along an altitudinal gradient from 0 to 900 m. Great differences in community structure were found and the altitude of 500 m was identified as an ecotone. Epiphytic lichen vegetation on trees below the ecotone varied significantly in relation to bark pH. Climatic parameters (temperature and rainfall) were probably related to altitude. Dust was probably responsible for the rise in bark pH. The distribution of lichen species in the sampling belts fitted the core-s

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Nakanyala, Jesaya, and Martin Hipondoka. "Root structure of shrub encroaching plants in the African savannas: insights from Terminalia sericea (Burch. ex DC) across a climate gradient in the Kalahari Basin." European Journal of Ecology 6, no. 1 (2020): 17–26. http://dx.doi.org/10.17161/eurojecol.v6i1.13779.

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The mechanisms under which shrubs outcompete grasses to cause shrub encroachment in the African savannas a contentious issue. The popular model, Walter’s two-layer hypothesis is still inconclusive. It suggests that trees and shrubs in the savannas develop deeper roots to avoid competition with grasses. This study was designed to test this hypothesis by investigating the root system of T. sericea, one of the common encroaching species in the Kalahari Basin. Using direct excavation methods, 39 shrubs were randomly excavated across the Kalahari Basin. Results revealed contrasting rooting strategi

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Liu, Juan, Xiangwei He, Jingya Sun, and Yuchao Ma. "A Degeneration Gradient of Poplar Trees Contributes to the Taxonomic, Functional, and Resistome Diversity of Bacterial Communities in Rhizosphere Soils." International Journal of Molecular Sciences 22, no. 7 (2021): 3438. http://dx.doi.org/10.3390/ijms22073438.

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Bacterial communities associated with roots influence the health and nutrition of the host plant. However, the microbiome discrepancy are not well understood under different healthy conditions. Here, we tested the hypothesis that rhizosphere soil microbial diversity and function varies along a degeneration gradient of poplar, with a focus on plant growth promoting bacteria (PGPB) and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG (antibiotics resistance genes) annotation revealed that available potassium (AK) was

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Shamim, Ahmed, and Pretzsch Hans. "TLidar-based crown shape indicates tree ring pattern in Norway spruce (Picea abies (L.) H. Karst) trees across competition gradients. A modeling and methodological approach." Ecological indicators 2023, no. 148 (2023): 110116. https://doi.org/10.5281/zenodo.7716499.

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Tree crowns and growth rings are physiologically and functionally connected through supporting and resource sharing. Management interventions may strongly influence tree growth by altering this linkage. However, conventional approaches have limited ability to characterize crown shape precisely, thus hindering our understanding of the relationship between crown shape and tree ring patterns. We, thus, aimed to test three hypotheses: (HI) Crown shape (regularity vs. irregularity) and ring patterns (regularity or irregularity) are significantly correlated and (HII) vary across density gradients; i

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Angelou, Nikolas, Jakob Mann, and Ebba Dellwik. "Wind lidars reveal turbulence transport mechanism in the wake of a tree." Atmospheric Chemistry and Physics 22, no. 4 (2022): 2255–68. http://dx.doi.org/10.5194/acp-22-2255-2022.

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Abstract. Solitary trees are natural land surface elements found in almost all climates, yet their influence on the surrounding airflow is poorly known. Here we use state-of-the-art, laser-based, remote sensing instruments to study the turbulent wind field in the near-wake region of a mature, open-grown oak tree. Our measurements provide for the first time a full picture of the mixing layer of high turbulence that surrounds the mean wind speed deficit. In this layer, we investigate the validity of a two-dimensional vectorial relation derived from the eddy-viscosity hypothesis, a hypothesis com

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Du, W. G., L. Shou, and J. Y. Shen. "Habitat selection in two sympatric Chinese skinks, Eumeces elegans and Sphenomorphus indicus: do thermal preferences matter?" Canadian Journal of Zoology 84, no. 9 (2006): 1300–1306. http://dx.doi.org/10.1139/z06-116.

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We studied the habitat selection and thermal biology of two sympatric Chinese skinks ( Eumeces elegans Boulenger, 1887 and Sphenomorphus indicus (Schmidt, 1928)) to test the effect of thermal preference on habitat partitioning. We measured thermal and structural attributes of the microhabitats occupied by these two skink species, as well as their field body temperatures and activity patterns. We then quantified the preferred body temperatures of these species in a thermal gradient. Compared with S. indicus, E. elegans occupied microhabitats with fewer trees, more rocks, and higher ambient temp

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Werner, Florian A., and Jürgen Homeier. "Diverging Elevational Patterns of Tree vs. Epiphyte Species Density, Beta Diversity, and Biomass in a Tropical Dry Forest." Plants 13, no. 18 (2024): 2555. http://dx.doi.org/10.3390/plants13182555.

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There is evidence to suggest that vascular epiphytes experience low competition for resources (light, water, and nutrients) compared to terrestrial plants. We tested the hypothesis that low resource competition may lead to higher nestedness among vascular epiphyte assemblages compared to trees. We studied the species composition and biomass of epiphytes and trees along an elevation gradient in a tropical dry forest in SW Ecuador. Both life-forms were inventoried on 25 plots of 400 m2 across five elevation levels (550–1250 m). Tree species density and total species richness increased with eleva

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Vamshi Kumar, C. "Predicting Heart Diseases Using Machine Learning and Different Data Classification Techniques." INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 09, no. 06 (2025): 1–9. https://doi.org/10.55041/ijsrem49766.

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Abstract - The goal of this study is to advance early detection of heart disease through a data-oriented strategy that employs machine-learning algorithms and various data classification techniques. There is a greater awareness globally around managing cardiovascular disease as we strive to achieve accurate and precise diagnosis within the parameters of time in clinical practice. In this study we explore a number of supervised learning methods such as Logistic Regression, Decision Trees, Random Forest, Support Vector Machines (SVM), K-Nearest Neighbors (KNN), and Gradient Boosting for predicti

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Kirchner, Michelle, Lucie Ciccone, Clyde Sorenson, and Elsa Youngsteadt. "Urbanization strengthens vertical stratification of ant nutrient preferences in a temperate forest ecosystem." PLOS ONE 20, no. 3 (2025): e0320380. https://doi.org/10.1371/journal.pone.0320380.

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Resource and nutrient availability varies spatially and influences animal foraging patterns. Under the compensation hypothesis, animals should preferentially forage for the most limiting nutrient in the environment. Animal nutrient preferences have been well studied in the tropics, where terrestrial and arboreal fauna are clearly differentiated and limited by different nutrients. In temperate forests, vertical stratification of the fauna may be less pronounced and its role in foraging ecology is poorly understood. Here, we examine nutrient preference patterns over a vertical gradient in temper

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Kitamura, Keiko, Kentaro Uchiyama, Saneyoshi Ueno, Wataru Ishizuka, Ikutaro Tsuyama, and Susumu Goto. "Geographical Gradients of Genetic Diversity and Differentiation among the Southernmost Marginal Populations of Abies sachalinensis Revealed by EST-SSR Polymorphism." Forests 11, no. 2 (2020): 233. http://dx.doi.org/10.3390/f11020233.

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Research Highlights: We detected the longitudinal gradients of genetic diversity parameters, such as the number of alleles, effective number of alleles, heterozygosity, and inbreeding coefficient, and found that these might be attributable to climatic conditions, such as temperature and snow depth. Background and Objectives: Genetic diversity among local populations of a plant species at its distributional margin has long been of interest in ecological genetics. Populations at the distribution center grow well in favorable conditions, but those at the range margins are exposed to unfavorable e

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Heymans, Lyse, Jean-Yves Meyer, Claudine Ah-Peng, et al. "Do Native and Alien Species Differ in Their Ecological Strategies? A Test with Woody Plants in Tropical Rainforests on Réunion Island (Mascarene Archipelago, Indian Ocean)." Plants 12, no. 23 (2023): 3990. http://dx.doi.org/10.3390/plants12233990.

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Understanding the mechanisms of biological invasions (e.g., competitive exclusion) is a key conservation challenge, especially on islands. Many mechanisms have been tested by comparing the characteristics of native and alien species, but few studies have considered ecological strategies. Here we aim at comparing the competitive ability, stress tolerance, and ruderalism (CSR) of native and alien trees in the tropical rainforests of Réunion Island. A total of sixteen 100 m2 plots (eight ‘near-trail’ and eight ‘off-trail’, at less disturbed sites) were established over a 2100 m elevational gradie

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Walter, Christopher A., Mark B. Burnham, Mary Beth Adams, Brenden E. McNeil, Lindsay N. Deel, and William T. Peterjohn. "Nitrogen Availability Decreases the Severity of Snow Storm Damage in a Temperate Forest." Forest Science 66, no. 1 (2019): 58–65. http://dx.doi.org/10.1093/forsci/fxz064.

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Abstract Storms are among the greatest natural disturbances in temperate forests, and increased nitrogen (N) availability is thought to increase storm damage. However, the extent to which N availability increases damage from snowfall is less clear. To test how N availability might affect the susceptibility of trees to snow damage in a temperate forest, we took advantage of an opportunistic storm and surveyed damage in fertilized and unfertilized stands, and across a native N availability gradient. In response to a severe, early season snow storm—a consequence of Superstorm Sandy—the percentage

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Fernandez, R. Thomas, and James A. Flore. "Intermittent CaCl2 Sprays during Rain to Prevent Sweet Cherry Cracking." HortScience 30, no. 4 (1995): 793F—793. http://dx.doi.org/10.21273/hortsci.30.4.793f.

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Fruit of sweet cherry (Prunus avium L.) crack during or after rain due, in part, to absorption of water through the fruit surface driven by the water potential gradient. In 1972, J. Vittrup-Christensen suggested that overhead misting of calcium salts during precipitation may be an effective way to prevent cherry cracking by reducing the water potential gradient. We tested this hypothesis by designing a computer-controlled irrigation system to intermittently spray a 10% CaCl2 solution on trees during rain events. Spray emitters were placed in the middle and at the top of the canopy. The program

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Fernandez, R. Thomas, and James A. Flore. "Intermittent CaCl2 Sprays during Rain to Prevent Sweet Cherry Cracking." HortScience 30, no. 4 (1995): 793F—793. http://dx.doi.org/10.21273/hortsci.30.4.793.

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Fruit of sweet cherry (Prunus avium L.) crack during or after rain due, in part, to absorption of water through the fruit surface driven by the water potential gradient. In 1972, J. Vittrup-Christensen suggested that overhead misting of calcium salts during precipitation may be an effective way to prevent cherry cracking by reducing the water potential gradient. We tested this hypothesis by designing a computer-controlled irrigation system to intermittently spray a 10% CaCl2 solution on trees during rain events. Spray emitters were placed in the middle and at the top of the canopy. The program

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Rodionov, Andrei, Sara L. Bauke, Christian von Sperber, et al. "Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems." Biogeochemistry 150, no. 3 (2020): 313–28. http://dx.doi.org/10.1007/s10533-020-00700-8.

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Abstract Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient in total P stocks. We analyzed the oxygen isotopic composition of HCl-extractable phosphate (δ18OP) and identified differences in P speciation with increasing soil depth using X-ray absorp

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Skelton, Robert P., Leander D. L. Anderegg, Jessica Diaz, et al. "Evolutionary relationships between drought-related traits and climate shape large hydraulic safety margins in western North American oaks." Proceedings of the National Academy of Sciences 118, no. 10 (2021): e2008987118. http://dx.doi.org/10.1073/pnas.2008987118.

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Quantitative knowledge of xylem physical tolerance limits to dehydration is essential to understanding plant drought tolerance but is lacking in many long-vessel angiosperms. We examine the hypothesis that a fundamental association between sustained xylem water transport and downstream tissue function should select for xylem that avoids embolism in long-vessel trees by quantifying xylem capacity to withstand air entry of western North American oaks (Quercus spp.). Optical visualization showed that 50% of embolism occurs at water potentials below −2.7 MPa in all 19 species, and −6.6 MPa in the

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Escoto-Rodríguez, Martín, José M. Facelli, and Jennifer R. Watling. "Do wide crowns in arid woodland trees reflect hydraulic limitation and reduction of self-shading?" Functional Plant Biology 41, no. 12 (2014): 1221. http://dx.doi.org/10.1071/fp14022.

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In arid regions many tree species develop broad crowns. A number of hypotheses involve trade-offs between growth in height and horizontal spreading, but there is no explanation for the switch from vertical to horizontal growth during development. Using Acacia papyrocarpa Benth as a model, we measured tree height and crown shape across different sites and topographic positions. We also measured δ13C of phyllodes from crown tops and lateral spreading branches. Trees were significantly taller at the base of a hill, where water availability is typically greater, than on the adjacent steep hillslop

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Hunter, John T. "Changes in Allometric Attributes and Biomass of Forests and Woodlands across an Altitudinal and Rainfall Gradient: What Are the Implications of Increasing Seasonality due to Anthropogenic Climate Change?" International Journal of Ecology 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/208975.

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Canonical correspondence analysis and linear regressions were used to relate height, diameter, and dispersion measurements of 36,380 stems from 197 species recorded in 2,341 plots against both climatic and landscape variables. Above ground biomass increased in wetter and cooler locations that ameliorate the seasonal rainfall deficits. Taller and greater diameter trees with lower wood densities occur at higher altitudes. Differences between locations are based on a change in the composition of species rather than a change in the allometric properties within a species. The results support the hy

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Payette, Serge, Ann Delwalde, Claude Morneau, and Claude Lavole. "Patterns of tree stem decline along a snow-drift gradient at treeline: a case study using stem analysis." Canadian Journal of Botany 74, no. 11 (1996): 1671–83. http://dx.doi.org/10.1139/b96-203.

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Current hypotheses on conifer tree stem degradation at treeline indicate the influence of frost desiccation caused by dehydration of wind-exposed needles above the snowpack because of frozen soil or wind abrasion. Here, we examine, in an exploratory study, the potential of detailed stem analysis to identify other causal factors at a subarctic treeline site using black spruce (Picea mariana (Mill.) BSP.) trees distributed along a wind-exposure gradient and showing various degrees of stem damage, from the normal, conical growth form to the mat growth form. Temporal patterns of stem development r

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Momolli, Dione Richer, Marcos Vinicius Winckler Caldeira, Gabriel Soares Lopes Gomes, et al. "Stem Longitudinal Gradient for Basic Density, Carbon, Nitrogen, and CN Ratio in Khaya spp.: Improved Correlation Using Diameter Instead of Commercial Height." Forests 15, no. 11 (2024): 1923. http://dx.doi.org/10.3390/f15111923.

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The basic wood density influences the carbon stock, playing a crucial role in climate-changing global mitigation through carbon sequestration. Understanding wood carbon release depends on the Nitrogen assessment and CN ratio. Therefore, our research aimed to: (i) Compare basic density, organic carbon, nitrogen, and C/N ratio among the Khaya grandifoliola, K. ivorensis, and K. senegalensis; (2) Analyze the gradient along positions and diameter of the commercial stem; (3) Recommend the most representative sampling position for each species based on the diameter. The experimental area is located

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Briggs, Emma, Marc de Kamps, Willie Hamilton, Owen Johnson, Ciarán D. McInerney, and Richard D. Neal. "Machine Learning for Risk Prediction of Oesophago-Gastric Cancer in Primary Care: Comparison with Existing Risk-Assessment Tools." Cancers 14, no. 20 (2022): 5023. http://dx.doi.org/10.3390/cancers14205023.

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Oesophago-gastric cancer is difficult to diagnose in the early stages given its typical non-specific initial manifestation. We hypothesise that machine learning can improve upon the diagnostic performance of current primary care risk-assessment tools by using advanced analytical techniques to exploit the wealth of evidence available in the electronic health record. We used a primary care electronic health record dataset derived from the UK General Practice Research Database (7471 cases; 32,877 controls) and developed five probabilistic machine learning classifiers: Support Vector Machine, Rand

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De Troyer, André. "Impact of diaphragmatic contraction on the stiffness of the canine mediastinum." Journal of Applied Physiology 105, no. 3 (2008): 887–93. http://dx.doi.org/10.1152/japplphysiol.00198.2008.

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To assess the coupling between a particular hemidiaphragm and the individual lungs, the left and right phrenic nerves were separately stimulated in anesthetized dogs, and the mean changes in pleural pressure over the two lungs were evaluated by measuring the changes in airway opening pressure (ΔPao) in the two bronchial trees. Stimulation induced a fall in Pao in both lungs. However, ΔPao in the contralateral lung was only 65% of that in the ipsilateral lung. Thus, although the canine ventral mediastinum is a delicate structure, it sustained a significant pressure gradient. The hypothesis was

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Beier, Colin M., Scott E. Sink, Paul E. Hennon, David V. D’Amore, and Glenn P. Juday. "Twentieth-century warming and the dendroclimatology of declining yellow-cedar forests in southeastern Alaska." Canadian Journal of Forest Research 38, no. 6 (2008): 1319–34. http://dx.doi.org/10.1139/x07-240.

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Decline of yellow-cedar ( Chamaecyparis nootkatensis ((D. Don) Spach) has occurred on 200 000 ha of temperate rainforests across southeastern Alaska. Because declining forests appeared soon after the Little Ice Age and are limited mostly to low elevations (whereas higher elevation forests remain healthy), recent studies have hypothesized a climatic mechanism involving early dehardening, reduced snowpack, and freezing injury. This hypothesis assumes that a specific suite of microclimatic conditions occurs during late winter and declining cedar populations across the region have responded simila

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Groner, Elli, and Avshalom Babad. "Demonstration in Ramon LTER site of the compensation hypothesis providing an alternative scenario to desertification." ARPHA Conference Abstracts 8 (May 28, 2025): e149155. https://doi.org/10.3897/aca.8.e149155.

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Climate changes bring a new era in which hot dry areas become even hotter and drier. This leads to state shifts and specifically desertification processes. Desertification includes the state shifts from non-desert to deserts and within deserts reduction of primary productivity. Studying shifts in ecosystem states and desertification requires long term ecosystem research and monitoring (LTERM). This can take decades and because temporal variability of precipitation in deserts is very high, it is difficult to distinguish between noise and trends. Space for time substitution is a tool aiding LTER

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Yurko, Ronald, Max G’Sell, Kathryn Roeder, and Bernie Devlin. "A selective inference approach for false discovery rate control using multiomics covariates yields insights into disease risk." Proceedings of the National Academy of Sciences 117, no. 26 (2020): 15028–35. http://dx.doi.org/10.1073/pnas.1918862117.

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To correct for a large number of hypothesis tests, most researchers rely on simple multiple testing corrections. Yet, new methodologies of selective inference could potentially improve power while retaining statistical guarantees, especially those that enable exploration of test statistics using auxiliary information (covariates) to weight hypothesis tests for association. We explore one such method, adaptiveP-value thresholding (AdaPT), in the framework of genome-wide association studies (GWAS) and gene expression/coexpression studies, with particular emphasis on schizophrenia (SCZ). Selected

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Baker, T. R., O. L. Phillips, W. F. Laurance, et al. "Do species traits determine patterns of wood production in Amazonian forests?" Biogeosciences 6, no. 2 (2009): 297–307. http://dx.doi.org/10.5194/bg-6-297-2009.

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Abstract. Understanding the relationships between plant traits and ecosystem properties at large spatial scales is important for predicting how compositional change will affect carbon cycling in tropical forests. In this study, we examine the relationships between species wood density, maximum height and above-ground, coarse wood production of trees ≥10 cm diameter (CWP) for 60 Amazonian forest plots. Average species maximum height and wood density are lower in Western than Eastern Amazonia and are negatively correlated with CWP. To test the hypothesis that variation in these traits causes the

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Sitienei, Miriam, Ayubu Anapapa, and Argwings Otieno. "Application of XGBoost Regression in Maize Yield Prediction." Asian Journal of Probability and Statistics 24, no. 1 (2023): 1–9. http://dx.doi.org/10.9734/ajpas/2023/v24i1513.

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Artificial Intelligence (AI) is the human-like intelligence imbued in machines so that they can perform tasks that normally require human intelligence. Machine learning is an AI technique which carries on the concepts of predictive analytics with one important distinction: the AI system can make assumptions, test hypotheses, and learn independently. XGBoost, Extreme gradient boosting, is a popular machine-learning library for regression tasks. It implements the gradient-boosting decision tree algorithm, which combines several feeble decision trees to produce a robust predictive model. In Boost

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