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Bruelheide H.,Martin Luther University of Halle Wittenberg | Bohnke M.,Martin Luther University of Halle Wittenberg | Both S.,Martin Luther University of Halle Wittenberg | Fang T.,Gutianshan National Nature Reserve | And 38 more authors.
Ecological Monographs | Year: 2011

Subtropical broad-leaved forests in southeastern China support a high diversity of woody plants. Using a comparative study design with 30×30 m plots (n1/427) from five successional stages (<20, <40, <60, <80,≤80 yr), we investigated how the gradient in species composition reflects underlying processes of community assembly. In particular, we tested whether species richness of adult trees and shrubs decreased or increased and assessed to which degree this pattern was caused by negative density dependence or continuous immigration over time. Furthermore, we tested whether rare species were increasingly enriched and the species composition of adult trees and shrubs became more similar to species composition of seedlings during the course of succession. We counted the individuals of all adult species and shrubs >1 m in height in each plot and counted all woody recruits (bank of all seedlings ≤1 m in height) in each central 10×10 m quadrant of each plot. In addition, we measured a number of environmental variables (elevation, slope, aspect, soil moisture, pH, C, N, and C/N ratio) and biotic structural variables (height and cover of layers). Adult species richness varied from 25 to 69 species per plot, and in total 148 woody species from 46 families were recorded. There was a clear successional gradient in species composition as revealed by nonmetric multidimensional scaling (NMDS), but only a poor differentiation of different successional stages with respect to particular species. Adult richness per 100 individuals (rarefaction method) increased with successional stage. None of the measured abiotic variables were significantly correlated with adult species richness. We found no evidence that rare species were responsible for the increasing adult species richness, as richness of rare species among both adults and recruits was independent of the successional stage. Furthermore, the similarity between established adults and recruits did not increase with successional stage. There was a constant number of recruit species and also of exclusive recruit species, i.e., those that had not been present as adult individuals, across all successional stages, suggesting a continuous random immigration over time. © 2011 by the Ecological Society of America.

Gutianshan National Nature Reserve in Zheijiang, is located west of Shanghai in China. Credit: Helge Bruelheide, MLU/iDiv Many of the previous studies on global species diversity are inaccurate. These are the conclusions of an international research group, led by Martin Luther University Halle-Wittenberg (MLU) in collaboration with the German Centre for Integrative Biodiversity Research Halle - Jena - Leipzig (iDiv), which carried out a long-term study on biodiversity in the subtropical forests of China. The study shows that there might be an under- or overestimation of global biodiversity by up to 50 per cent when the survey is based on only a few taxa. The study's findings were published in the journal "Nature Communications". The international research group "BEF-China" received funding from the German Research Foundation (DFG) for a period of eight years. Its aim was to determine the diversity of the species present in an ecosystem. "This presents a massive challenge, particularly for tropical and subtropical forest ecosystems that have a rich variety of species," says Professor Helge Bruelheide from the Institute of Biology at MLU who led the research group. Even though the global diversity of plant species is well known, there are only a few studies that have attempted to record the variety of animal species - from the bugs found under bark to web-building spiders - as well as the plant species found in these forests. The tiny living creatures - such as the fungi and bacteria in the soil that are useful and harmful to plants - have often been disregarded. "All of these species are what makes up global biodiversity," Bruelheide explains. This is why many of the studies investigating the scale of this biodiversity have only been speculation. The international research team now has sound estimates in China about the number of species belonging to 43 different major taxa. These estimates are based on individual test plots as well as on an entire nature reserve. "A key feature of our project region is that it reflects the current situation of the earth's forests better than the tropical lowland rainforests which have been the main focus of many studies up until now," says Dr Andreas Schuldt from Leuphana University Lüneburg, the lead author of the study. "Forty-seven per cent of the humid tropical and subtropical forests occur in mountainous regions, a situation that is very similar to our project region. We can now assume that, in regions with different altitudes, slopes and solar orientation, species numbers increase at a different rate according to area than in lowland rain forests." The majority of rainforest research has focused on the more accessible lowland rainforests. This new study underscores the necessity of carrying out more intensive investigations in the mountainous rainforests, says Schuldt. Another new feature of this study is the way it combines traditional ways of determining species with modern methods of DNA analysis. This allows scientists to determine the number of bacteria and fungi taxa found in soil. This important contribution was made by Dr Tesfaye Wubet and Professor François Buscot from the Helmholtz Centre for Environmental Research (UFZ) in Halle. The team took a complete inventory of 27 sample plots in the Gutianshan National Nature Reserve in Zhejiang province west of Shanghai. The scientists were able to record in excess of 77,000 individuals from more than 1,000 plant and animal species, and 6,000 microorganism taxa. Geobotanist Helge Bruelheide adds: "This work is an example of why long-term research is so essential. Studies such as this cannot be achieved within the usual funding period of three years. They require years of repeated investigations on numerous sample plots." The numbers show that, according to the researchers' projections, one ha of subtropical forest can capture around 38 per cent of all species while 10 ha can capture 76 per cent of the species. "This reveals the limited informational value of sample plots with very selective distribution globally," says Bruelheide. The larger the area and the number of woody plants, i.e. trees and shrubs, the less precisely one can predict the overall diversity of other taxa. Methods of spatial statistics were integrated into the study to lay the foundations for more precise future predictions about the number of species found in large areas, such as entire continents, based on environmental conditions. Explore further: Fungi, often seen as pests, play a crucial role policing biodiversity in rainforests More information: Andreas Schuldt et al. Multitrophic diversity in a biodiverse forest is highly nonlinear across spatial scales, Nature Communications (2015). DOI: 10.1038/ncomms10169

Both S.,Martin Luther University of Halle Wittenberg | Fang T.,Gutianshan National Nature Reserve | Bohnke M.,Martin Luther University of Halle Wittenberg | Bruelheide H.,Martin Luther University of Halle Wittenberg | And 5 more authors.
Journal of Vegetation Science | Year: 2011

Question: Knowledge of the interaction between understorey herb and overstorey tree layer diversity is mostly restricted to temperate forests. How do tree layer diversity and environmental variables affect herb layer attributes in subtropical forests and do these relationships change in the course of succession? Do abundance and diversity of woody saplings within the herb layer shift during succession? Location: Subtropical broad-leaved forests in southeast China (29°8′18″-29°17′29″N, 118°2′14″118°11′12″E). Methods: A full inventory of the herb layer including all plants below 1-m height was done in 27 plots (10 × 10m) from five successional stages (<20, <40, <60, <80 and ≥80 yr). We quantified the contribution of different life forms (herbaceous, woody and climber species) to herb layer diversity and productivity and analysed effects of environmental variables and tree layer diversity on these attributes. Results: Herb layer composition followed a successional gradient, as revealed by non-metric multidimensional scaling (NMDS), but diversity was not correlated to the successional gradient. There was no correlation of diversity across layers. Herb layer productivity was neither affected by tree layer diversity nor by herb layer diversity. Although abundance of woody species in the herb layer decreased significantly during succession, woody species contributed extraordinarily to herb layer species diversity in all successional stages. All environmental factors considered had little impact on herb layer attributes. Conclusions: The subtropical forest investigated displays an immense richness of woody species in the herb layer while herbaceous species are less prominent. Species composition of the herb layer shows a clear successional pattern, however, the presence or absence of certain species appears to be random. © 2011 International Association for Vegetation Science.

Yang X.,Martin Luther University of Halle Wittenberg | Yang X.,CAS Kunming Institute of Botany | Bauhus J.,Albert Ludwigs University of Freiburg | Both S.,Martin Luther University of Halle Wittenberg | And 13 more authors.
European Journal of Forest Research | Year: 2013

Experimental forest plantations to study biodiversity-ecosystem functioning (BEF) relationships have recently been established in different regions of the world, but subtropical biomes have not been covered so far. Here, we report about the initial survivorship of 26 tree species in the first such experiment in subtropical China. In the context of the joint Sino-German-Swiss Research Unit "BEF-China," 271 experimental forest plots were established using 24 naturally occurring tree species and two native commercial conifers. Based on the survival inventories carried out in November 2009 and June 2010, the overall survival rate was 87 % after the first 14 months. Generalized mixed-effects models showed that survival rates of seedlings were significantly affected by species richness, the species' leaf habit (deciduous or evergreen), species identity, planting date, and altitude. In the first survey, seedling establishment success decreased with increasing richness levels, a tendency that disappeared in the second survey after replanting. Though evergreen species performed less well than deciduous species with establishment rates of 84 versus 93 % in the second survey, their planting success exceeded the general expectation for subtropical broad-leaved evergreen species. These results have important implications for establishing mixed-species plantations for diversity conservation and improvement of ecosystem functioning in the Chinese subtropics and elsewhere. Additional costs associated with mixed-species plantations as compared to conventional plantations also demonstrate the potential of upscaling BEF experiments to large-scale afforestation projects. © 2013 Springer-Verlag Berlin Heidelberg.

Nadrowski K.,University of Leipzig | Pietsch K.,University of Leipzig | Baruffol M.,University of Zürich | Both S.,Martin Luther University of Halle Wittenberg | And 16 more authors.
PLoS ONE | Year: 2014

Future climates are likely to include extreme events, which in turn have great impacts on ecological systems. In this study, we investigated possible effects that could mitigate stem breakage caused by a rare and extreme ice storm in a Chinese subtropical forest across a gradient of forest diversity. We used Bayesian modeling to correct stem breakage for tree size and variance components analysis to quantify the influence of taxon, leaf and wood functional traits, and stand level properties on the probability of stem breakage. We show that the taxon explained four times more variance in individual stem breakage than did stand level properties; trees with higher specific leaf area (SLA) were less susceptible to breakage. However, a large part of the variation at the taxon scale remained unexplained, implying that unmeasured or undefined traits could be used to predict damage caused by ice storms. When aggregated at the plot level, functional diversity and wood density increased after the ice storm. We suggest that for the adaption of forest management to climate change, much can still be learned from looking at functional traits at the taxon level. © 2014 Nadrowski et al.

Bohnke M.,Martin Luther University of Halle Wittenberg | Kreissig N.,Martin Luther University of Halle Wittenberg | Krober W.,Martin Luther University of Halle Wittenberg | Fang T.,Gutianshan National Nature Reserve | Bruelheide H.,Martin Luther University of Halle Wittenberg
Trees - Structure and Function | Year: 2012

Concerning forest communities, not much is known about the relationship between wood traits and environmental conditions. Using a succession series, we analyzed which wood anatomical traits were correlated with successional stage and asked which traits and which environmental factors were particularly important for the trait-environment relationship. An extensive dataset of 11 groups of wood traits was generated for 93 woody species that occurred in 27 permanent plots in a secondary subtropical secondary broadleaved forest in Zhejiang Province (SE-China) and subjected to Fourth Corner Analyses, using different permutation models. We encountered a strong relationship of wood porosity, visibility of growth rings and vessel arrangement to the successional gradient. Compared to biotic community characteristics such as density of plants, abiotic environmental variables such as soil characteristics, aspect and inclination of the plots showed only marginal correlations to wood anatomical traits. Furthermore, the link between environment and species composition of the forest communities was found to be more important in explaining the trait-environment relationship than between the communities and species wood traits. In addition, our results support the idea that most of the species in the subtropical forest might be functionally equivalent. © 2011 Springer-Verlag.

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