Biology subjects

Haerdtle, W.

Publications and source records attributed to Haerdtle, W..

6 recordsLinked to original sources

bioRxiv2026

Functional niche attributes shape species interaction roles in ecological networks

Identifying how species interact in ecological networks is key to understanding species' contributions to ecosystem functioning, but can be difficult to establish in species-rich communities. Functional niches, which capture broader ecological strategies, are often easier to assess and could help approximate species' interaction roles. We tested this by integrating species interaction and leaf functional trait data of tree species and leaf-associated interaction types from a large-scale forest biodiversity experiment. We found that identity, variability, and similarities of functional niches shaped corresponding aspects of interaction roles. Interestingly, however, this association inversed in the case of functional niche variability, which decreased instead of increased the variability of species interactions. This suggests a potential trade-off between processes that determine variability in functional and interaction space. Furthermore, effects were not constrained within aspects, with similarities of interactions being particularly responsive to most tested niche aspects, indicating that interaction-based competition among plants is particularly sensitive to functional niche differences. Moreover, many effects of functional niches depended on tree species biomass and tree species richness, highlighting the importance of the larger ecological context for determining species interaction roles. Together, our findings show that species' interaction roles, while clearly altered by, are not simply a consequence of functional niches. Instead, interaction roles integrate multiple aspects of functional niches depending on species performances and community composition and can therefore be crucial for anticipating ecosystem change.

ecology↗

bioRxiv2026

Multitrophic interaction networks mediate biodiversity effects on ecosystem multifunctionality

Biodiversity loss threatens the multifunctionality of ecosystems on which human well-being ultimately depends. Changes in multitrophic species interactions may be key to explaining the ecological consequences of biodiversity loss, but research explicitly linking species interactions and ecosystem multifunctionality remains rare. To assess interaction-mediated biodiversity effects and underlying mechanisms, characterizing the structure of species interaction networks is invaluable. Using comprehensive species interaction and ecosystem functioning data from a large-scale tree biodiversity experiment, we find consistent effects of the structure of species interaction networks on ecosystem multifunctionality across multiple types of antagonistic and mutualistic interactions. While positive effects of network size align with expected positive effects of multitrophic species diversity, positive effects of niche overlap among interacting species and negative effects of highly connected species (i.e. high linkage density) reveal additional, interaction-mediated drivers of multifunctionality. Specifically, the effects of niche overlap suggest benefits of functionally similar species, and the effects of linkage density underscore the importance of specialized interactions in promoting ecosystem multifunctionality. These findings emphasize that to effectively safeguard ecosystem service provisioning, ecosystem management and biodiversity conservation not only need to account for biodiversity changes at multiple trophic levels, but also explicitly for how species interact among each other.

ecology↗

bioRxiv2025

Enhancing structural heterogeneity in managed forest landscapes promotes gamma but not beta diversity in understorey plant communities

O_LIAlthough habitat heterogeneity is known to enhance local species diversity, the effects of management-driven structural heterogeneity on understorey plant communities across spatial scales remain poorly understood, despite their crucial role for forest biodiversity and ecosystem functioning. C_LIO_LITo analyse how forest understorey plant communities respond to an enhancement of structural heterogeneity in managed forests, we established 11 experimental sites consisting of two paired forest landscapes, an untreated homogenous control and a treatment district (ESBC). In treatment districts, structural heterogeneity was enhanced through different combinations of local patch-scale manipulations of light and deadwood features, leading to greater between-patch heterogeneity at the landscape scale. We performed a meta-analysis across these 11 sites using a Hill-Chao number and sample coverage standardisation framework. C_LIO_LIGamma diversity increased across taxonomic, functional and phylogenetic facets in structurally heterogeneous forests (ESBC districts) via higher alpha diversity. This effect was positively associated with heterogeneity in light availability between forest patches, but not with their mean light availability. In contrast, we found no support that species turnover among patches (i.e., beta diversity) significantly contributes on average to the observed increase in gamma diversity. However, both the direction and magnitude of beta diversity responses varied substantially among landscapes. C_LIO_LIOn average, structurally heterogeneous forests supported higher species richness for both open and closed forest habitat species. C_LIO_LISynthesis and applications: Our findings highlight the benefits of enhancing structural heterogeneity for understorey plant diversity in managed forest landscapes. Specifically, management strategies that create a spatial mosaic of interventions, such as combining single-tree removal with group felling, can increase the variety of light niches among forest patches, thereby supporting the conservation of a wide range of understorey plant species, including forest specialists. C_LI

ecology↗

bioRxiv2024

Biomass allocation of trees in response to mono- and heterospecific neighbourhoods

Carbon sequestration by trees is crucial to mitigate the effects of the current climate crisis. The extent to trees sequester and allocate carbon to above- or belowground structures in turn is mediated by neighbouring species. Although many studies have demonstrated positive effects of diverse neighbourhoods on a trees productivity, little is known about biomass allocation responses to mono-vs. heterospecific neighbourhoods. In the present study we quantified above- and belowground biomass production and root-to-shoot ratios (RSR) of trees grown in mono- and heterospecific neighbourhoods. To this end we analysed growth of mono- and heterospecific tree species pairs (TSPs) established in a greenhouse and a field experiment. In the greenhouse experiment response variables were measured after one year of growth after sapling harvest. In the field experiment, conducted in the context of a forest biodiversity experiment in subtropical China, we analysed biomass density and RSR over three years using terrestrial laser scanner and minirhizotrons. RSR of trees in heterospecific TSPs were significantly higher than in monospecific TSPs. In the greenhouse experiment, this was related to a stronger below-than aboveground overyielding in heterospecific TSPs. In the field experiment, trees in heterospecific TSPs showed a stronger increase in aboveground investments over time than in monospecific TSPs, indicating that positive diversity effects became stronger for aboveground structures with progressing tree development. Our findings are consistent with the optimal biomass partitioning theory and highlight the importance of tree-tree interactions on biomass allocation. Higher RSR in mixtures further suggest a higher resistance or resilience of tree saplings against environmental stressors related to climate change (drought, heat waves).

ecology↗

bioRxiv2022

ReSurveyGermany: Vegetation-plot time-series over the past hundred years in Germany

Vegetation-plot resurvey data are a main source of information on terrestrial biodiversity change, with records reaching back more than one century. Although more and more data from re-sampled plots have been published, there is not yet a comprehensive open-access dataset available for analysis. Here, we compiled and harmonised vegetation-plot resurvey data from Germany covering almost 100 years. We show the distribution of the plot data in space, time and across habitat types of the European Nature Information System (EUNIS). In addition, we include metadata on geographic location, plot size and vegetation structure. The data allow calculating temporal biodiversity change at the community scale and reach back further into the past than most comparable data yet available. They also enable tracking changes in the incidence and distribution of individual species across Germany. In summary, the data come at a level of detail that holds promise for broadening our understanding of the mechanisms and drivers behind plant diversity change over the last century.

ecology↗

bioRxiv2017

Strong positive biodiversity-productivity relationships in a subtropical forest experiment

Forest ecosystems contribute substantially to global terrestrial primary productivity and climate regulation, but, in contrast to grasslands, experimental evidence for a positive biodiversity-productivity relationship in highly diverse forests is still lacking1. Here, we provide such evidence from a large forest biodiversity experiment with a novel design2 in subtropical China. Productivity (stand-level tree basal area, aboveground volume and carbon and their annual increment) increased linearly with the logarithm of tree species richness. Additive partitioning3 showed that increasing positive complementarity effects combined with weakening negative selection effects caused a strengthening of the relationship over time. In 2-species mixed stands, complementary effects increased with functional distance and selection effects with vertical crown dissimilarity between species. Understorey shrubs reduced stand-level tree productivity, but this effect of competition was attenuated by shrub species richness, indicating that a diverse understorey may facilitate overall ecosystem functioning. Identical biodiversity-productivity relationships were found in plots of different size, suggesting that extrapolation to larger scales is possible. Our results highlight the potential of multi-species afforestation strategies to simultaneously contribute to mitigation of climate change and biodiversity restoration.

ecology↗