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175 results for “tree structure”

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dryad36/100

Non-structural carbohydrates predict survival in saplings of temperate trees under carbon stress

1. Non-structural carbohydrates (NSCs) mediate plant survival when the plant's carbon (C) balance is negative, suggesting that NSCs could predict plant survival under C stress. To examine this possibility, we exposed saplings of six temperate tree species to diverse levels of C stress created by the combination of two light conditions (full light availability and deep shade) and two defoliation levels (severe defoliation and non-defoliation). We then measured survival, biomass, and total NSCs and soluble sugar (SSs) concentrations in different organs of both dead and live saplings. 2. We estimated mean NSCs and SSs contents and concentrations per sapling and fitted logistic generalized mixed-effects models to determine if NSCs and SSs predict survival. Using inverse prediction modelling, we also determined whether there is a common NSCs and SS threshold across species at the time of sapling's death. 3. Defoliation and shade reduced the mean sapling's NSCs and SSs contents, indicating C stress. Mean sapling NSCs and SSs contents and concentrations predicted survival and the robustness of the models improved with the inclusion of species. At death, saplings of the exotic deciduous tree species Acer pseudoplatanus exhibited significantly lower mean NSCs and SSs contents than saplings of the evergreen conifer species Podocarpus nubigenus and lower stem NSCs and SSs concentrations than the broadleaf evergreen species Drimys winteri. 4. The energetic role that NSCs and SSs play in plants under C stress was evidenced by the capacity of these compounds to predict sapling survival under C stress. No common threshold of NSCs and SSs contents or concentrations for sapling survival amongst species was found, indicating that the level of these compounds may not be good proxies for interspecific comparisons of tolerance to C stress. Presumably, there are species-specific limits for the mobilization and use of NSCs and SSs in metabolism. 5. Our results anticipate that the inclusion of NSCs and SSs in modelling will improve predictions regarding tree responses to ongoing climate change. Nonetheless, a better understanding of the many roles that carbohydrates play in plant survival under C stress is required to scale predictions up to the community level.

opencc-zeroAug 2022View details →

zenodo36/100

Data_Changes in Tree Diversity, Structure and Functional Trait Identity Drive Biomass Increase along Elevational Gradients in Subtropical Forests of Southern China

In this article "Changes in Tree Diversity, Structure and Functional Trait Identity Drive Biomass Increase along Elevational Gradients in Subtropical Forests of Southern China", these files contain community inventory data collected at our three study sites.

opencc-by-4.0Jul 2022View details →

zenodo36/100

Datasets to quantify the impact of lianas on 3D tree structure and biomass

This dataset consists of terrestrial laser scanning (TLS) point clouds and their corresponding quantitative structure models (QSMs) of 182 trees. There are two point clouds for each tree, one containing only the wood points and the other containing the leaf points of the tree. The QSMs of the trees are in .mat format and the detailed readME file to read the QSMs can be found here: https://github.com/InverseTampere/TreeQSM.

opencc-by-4.0Aug 2022View details →

dryad36/100

Data from: Linking environmental stability with genetic diversity and population structure in two Atlantic Forest palm trees

Spatial patterns of biodiversity in the Atlantic Forest of Brazil are well characterized. However, there is no consensus on the biological processes underlying these patterns, and multiple competing hypotheses have been proposed, several of which center on climatic stability. Here, we ask if Late Quaternary climatic stability predicts contemporary population structure and genomic-level diversity in two palm species: Syagrus botryophora and S. pseudococos (Arecaceae) We first use species occurrence data to model the distribution of suitable environments in 62 time-slice climate projections over the last 120 thousand years, and summarize stability over that period. We then use >25,000 RADseq-generated SNPs to i) describe the spatial patterns of genomic variation in both species, ii) test how well genomic variation is explained by isolation by distance and by the environmental resistance imposed by historical instability (isolation by resistance) and iii) test for a correlation between genetic diversity and historical stability. The contemporary range of S. botryophora has been relatively stable over the last 30 thousand years and there are two isolated regions of high stability for S. pseudococos. The genomic data recovers a clear pattern of isolation by distance in S. botryophora and two structured populations in S. pseudococos. Consequently, the contribution of isolation by resistance to overall genetic structure is much higher in S. pseudococos. Genetic diversity is not significantly correlated with historical stability in either species. Based on the concordance between historical stability and genetic structure, Late Quaternary climate stability may have maintained population connectivity within S. botryophora and promoted intraspecific divergence in S. pseudococos. Conversely, historical stability does not seem to be driving spatial patterns of genetic diversity. This study supports the primary role of climatic stability in determining spatial population structure, but not genetic diversity, in the Atlantic Forest.

opencc-zeroSep 2022View details →

dryad36/100

Data from: Increased intake of tree forage by moose is associated with intake of crops rich in non-structural carbohydrates

Animals representing a wide range of taxonomic groups are known to select specific food combinations to achieve a nutritionally balanced diet. The nutrient balancing hypothesis suggests that, when given the opportunity, animals select foods to achieve a particular target nutrient balance, and that balancing occurs between meals and between days. For wild ruminants who inhabit landscapes dominated by human land use, nutritionally imbalanced diets can result from ingesting agricultural crops rich in starch and sugar (non-structural carbohydrates, NC), which can be provided to them by people as supplementary feeds. Here, we test the nutrient balancing hypothesis by assessing potential effects that the ingestion of such crops by Alces alces (moose) may have on forage intake. We predicted that moose compensate for an imbalanced intake of excess NC by selecting tree forage with macro-nutritional content better suited for their rumen microbiome during wintertime. We applied DNA metabarcoding to identify plants in faecal and rumen content from the same moose during winter in Sweden. We found that the concentration of NC-rich crops in faeces predicted the presence of Picea abies (Norway spruce) in rumen samples. The finding is consistent with the prediction that moose use tree forage as a nutritionally complementary resource to balance their intake of NC-rich foods, and that they ingested P. abies in particular (normally a forage rarely eaten by moose) because it was the most readily available tree. Our finding sheds new light on the foraging behaviour of a model species in herbivore ecology, and on how habitat alterations by humans may change the behaviour of wildlife.

opencc-zeroMay 2024View details →

dryad36/100

Effects of long-term fixed fire regimes on African savanna vegetation biomass, vertical structure and tree stem density

<ol> <li>Fire plays an integral role in shaping the vegetation structure of savanna ecosystems. However, effects of fire regime characteristics, such as frequency and season of burn, on savanna vegetation structure, biomass and tree abundance across landscape types are largely unknown. </li> <li>We used high-resolution airborne Light Detection and Ranging (LiDAR) to investigate the long-term effects of fire manipulation on savanna vegetation in Kruger National Park, South Africa. We analysed the effects of fire exclusion and experimental burns every 1, 2, 3, 4 and 6 years and during different seasons on aboveground biomass (AGB), tree stem densities and vegetation vertical height profiles across a rainfall gradient and on contrasting geologies. </li> <li>Across savanna types, and especially in drier savannas, fire season was more influential for constraining AGB than was fire frequency. Plots experiencing fires during the late- and mid-dry season had 44.50% and 43.60%, respectively, lower AGB relative to unburnt plots than wet-season fires. However, in mesic savannas, fire frequency interacted with fire season to influence AGB: plots subjected to high frequency, dry season fires had 55.35% lower AGB than unburnt plots, whereas plots burnt in the wet season at lower frequencies had lower AGB (24.40% lower than unburnt plots) than plots subjected to high frequency, wet-season fires (13.74% lower AGB than unburnt plots). </li> <li>Fire regimes had variable effects on tree densities, and effects varied with savanna type. Woody vertical vegetation profiles showed the largest differences in response to dry season fires, with the greatest divergence in vegetation height classes < 5m. </li> <li>Synthesis and applications. Understanding the influence of fire regimes on vegetation structure has important implications for the management of savanna heterogeneity, and for predicting trajectories of change in savanna vegetation as fire regimes vary with climate change. We show that the magnitude of the effect of fire on woody vegetation structure varies with savanna context. Our results suggest that heterogeneous vegetation structure can be achieved by applying fires in the dry season in mesic savannas, whereas in dry savannas, variation in fire regimes is less consequential for constraining biomass accumulation and altering vegetation structure. </li> </ol>

opencc-zeroMay 2023View details →

dryad36/100

Microevolutionary processes in a foundation tree inform macrosystem patterns of community biodiversity and structure

Despite an increased focus on multiscale relationships and interdisciplinary integration, few macroecological studies consider the contribution of genetic-based processes to landscape-scale patterns. We tested the hypothesis that tree genetics, climate, and geography jointly drive continental-scale patterns of community structure, using genome-wide SNP data from a broadly distributed foundation tree species (<a>Populus fremontii</a> S. Watson) and two dependent communities (leaf-modifying arthropods and fungal endophytes) spanning southwestern North America. Four key findings emerged: (1) Tree genetic structure was a significant predictor for both communities; however, the strength of influence was both scale- and community-dependent. (2) Tree genetics was the primary driver for endophytes, explaining 17% of variation in continental-scale community structure, whereas (3) climate was the strongest predictor of arthropod structure (24%). (4) Power to detect tree genotype<a>—</a>community phenotype associations changed with scale of genetic organization, increasing from individuals to populations to ecotypes, emphasizing the need to consider nonstationarity (i.e., changes in the effects of factors on ecological processes across scales) when inferring macrosystem properties. Our findings highlight the role of foundation tree species as drivers of macroscale community structure and provide macrosystems ecology with a theoretical framework for linking fine- and intermediate-scale genetic processes to landscape-scale patterns. Management of genetic diversity harbored within foundation species is a critical consideration for conserving and sustaining regional biodiversity.

opencc-zeroJun 2023View details →

dryad36/100

Avian species functional diversity and habitat use the role of forest structural attributes and tree diversity in the Midlands Mistbelt forests of KwaZulu-Natal, South Africa

Forest transformation has major impacts on biodiversity and ecosystem functioning. Identifying the influence of forest habitat structure and composition on avian functional communities is important for conserving and managing forest systems. This study investigated the effect of forest structure and composition characteristics on bird species community structure, habitat use, and functional diversity in 14 Mistbelt forest patches of the Midlands of KwaZulu-Natal in South Africa. We surveyed bird communities using point counts. We quantified bird functional diversity for each forest patch using three diversity indices: functional richness, functional evenness, and functional divergence. We further assessed species-specific responses by focusing on three avian forest specialists, orange ground-thrush Geokichla gurneyi, forest canary Crithagra scotops, and Cape parrot Poicephalus robustus. We found that bird community and forest-specialist species responses to forest structure and tree species diversity differed. Also, forest structural complexity, canopy cover, and tree species richness were the main forest characteristics better at explaining microhabitat influence on bird functional diversity. Forest patches with relatively high structural complexity and tree species richness had higher functional richness. Different structural characteristics influenced habitat use by the three forest specialists. Tree species diversity influenced C. scotops and G. gurneyi positively, while P. robustus responded negatively to forest patches with high tree species richness. Our study showed that site-scale forest structure and composition characteristics are important for bird species richness and functional richness. Forest patches with high tree species diversity and structural complexity should be maintained to conserve forest specialists, bird species richness, and functional richness.

opencc-zeroAug 2023View details →

dryad36/100