Dispersal ability, trophic position and body size mediate species turnover processes: Insights from a multi‐taxa and multi‐scale approach

Aim: Despite increasing interest in β-diversity, that is the spatial and temporal turno-ver of species, the mechanisms underlying species turnover at different spatial scales are not fully understood, although they likely differ among different functional groups. We investigated the relative importance of dispersal limitations and the en-vironmental filtering caused by vegetation for local, multi-taxa forest communities differing in their dispersal ability, trophic position and body size.Location: Temperate forests in five regions across Germany.Methods: In the inter-region analysis, the independent and shared effects of the re-gional spatial structure (regional species pool), landscape spatial structure (dispersal limitation) and environmental factors on species turnover were quantified with a 1-ha grain across 11 functional groups in up to 495 plots by variation partitioning. In the intra-region analysis, the relative importance of three environmental factors related to vegetation (herb and tree layer composition and forest physiognomy) and spatial structure for species turnover was determined.Results: In the inter-region analysis, over half of the explained variation in community composition (23% of the total explained 35%) was explained by the shared effects of several factors, indicative of spatially structured environmental filtering. Among the independent effects, environmental factors were the strongest on average over 11 groups, but the importance of landscape spatial structure increased for less disper-sive functional groups. In the intra-region analysis, the independent effect of plant species composition had a stronger influence on species turnover than forest physi-ognomy, but the relative importance of the latter increased with increasing trophic position and body size.Main conclusions: Our study revealed that the mechanisms structuring assemblage composition are associated with the traits of functional groups. Hence, conserva-tion frameworks targeting biodiversity of multiple groups should cover both envi-ronmental and biogeographical gradients. Within regions, forest management can enhance β-diversity particularly by diversifying tree species composition and forest physiognomy

Potential of Airborne LiDAR Derived Vegetation Structure for the Prediction of Animal Species Richness at Mount Kilimanjaro

The monitoring of species and functional diversity is of increasing relevance for the development of strategies for the conservation and management of biodiversity. Therefore, reliable estimates of the performance of monitoring techniques across taxa become important. Using a unique dataset, this study investigates the potential of airborne LiDAR-derived variables characterizing vegetation structure as predictors for animal species richness at the southern slopes of Mount Kilimanjaro. To disentangle the structural LiDAR information from co-factors related to elevational vegetation zones, LiDAR-based models were compared to the predictive power of elevation models. 17 taxa and 4 feeding guilds were modeled and the standardized study design allowed for a comparison across the assemblages. Results show that most taxa (14) and feeding guilds (3) can be predicted best by elevation with normalized RMSE values but only for three of those taxa and two of those feeding guilds the difference to other models is significant. Generally, modeling performances between different models vary only slightly for each assemblage. For the remaining, structural information at most showed little additional contribution to the performance. In summary, LiDAR observations can be used for animal species prediction. However, the effort and cost of aerial surveys are not always in proportion with the prediction quality, especially when the species distribution follows zonal patterns, and elevation information yields similar results

Arthropod decline in grasslands and forests is associated with landscape-level drivers

Weisser, Wolfgang W/0000-0002-2757-8959; Penone, Caterina/0000-0002-8170-6659; Schall, Peter/0000-0003-4808-818X; Bauhus, Jurgen/0000-0002-9673-4986WOS: 000493807800042PubMed: 31666721Recent reports of local extinctions of arthropod species(1), and of massive declines in arthropod biomass(2), point to land-use intensification as a major driver of decreasing biodiversity. However, to our knowledge, there are no multisite time series of arthropod occurrences across gradients of land-use intensity with which to confirm causal relationships. Moreover, it remains unclear which land-use types and arthropod groups are affected, and whether the observed declines in biomass and diversity are linked to one another. Here we analyse data from more than 1 million individual arthropods (about 2,700 species), from standardized inventories taken between 2008 and 2017 at 150 grassland and 140 forest sites in 3 regions of Germany. Overall gamma diversity in grasslands and forests decreased over time, indicating loss of species across sites and regions. In annually sampled grasslands, biomass, abundance and number of species declined by 67%, 78% and 34%, respectively. The decline was consistent across trophic levels and mainly affected rare species; its magnitude was independent of local land-use intensity. However, sites embedded in landscapes with a higher cover of agricultural land showed a stronger temporal decline. In 30 forest sites with annual inventories, biomass and species number-but not abundance-decreased by 41% and 36%, respectively. This was supported by analyses of all forest sites sampled in three-year intervals. The decline affected rare and abundant species, and trends differed across trophic levels. Our results show that there are widespread declines in arthropod biomass, abundance and the number of species across trophic levels. Arthropod declines in forests demonstrate that loss is not restricted to open habitats. Our results suggest that major drivers of arthropod decline act at larger spatial scales, and are (at least for grasslands) associated with agriculture at the landscape level. This implies that policies need to address the landscape scale to mitigate the negative effects of land-use practices.DFGGerman Research Foundation (DFG)We thank T. Lewinsohn, S. Meyer and V. Wolters for their comments and suggestions for the analyses; M. Lutz, J. Bartezko, P. Freynhagen, I. Gallenberger, M. Turke, M. Lange, T. Kahl, E. Pasalic, E. Sperr, K. Kremer and all student helpers for conducting arthropod sampling in the field and laboratory; R. Achtziger, E. Anton, T. Blick, B. Buche, M.-A. Fritze, R. Heckmann, A. Kastner, F. Kohler, G. Kohler, T. Kolkebeck, C. Morkel, F. Schmolke, T. Wagner and O. Wiche for arthropod species identification; C. Seilwinder and R. Honecker for GIS work; the managers of the three Exploratories (K. Wells, S. Renner, K. Reichel-Jung, S. Gockel, K. Wiesner, K. Lorenzen, A. Hemp and M. Gorke) for their work in maintaining the site and project infrastructure; C. Fischer and S. Pfeiffer for giving support through the central office; A, Ostrowski, M. Owonibi and J. Nieschulze for managing the central database; and D. Hessenmoller, I. Schoning, F. Buscot and the late E. Kalko for their role in setting up the Biodiversity Exploratories project. The work has been funded by the DFG Priority Program 1374 'Infrastructure-Biodiversity-Exploratories'. Field work permits were issued by the responsible state environmental offices of Baden-Wurttemberg, Thuringen and Brandenburg

Processed climate station data for the southern slopes of Kilimanjaro, Tanzania

This dataset consists of processed (gap filled) climate station data. The data is obtained from the web interface of TubeDB which is an easy to operate software system for archiving, quality control, query and processing time series data in an efficient manner. Further details of Tube DB can be found in this article : Wöllauer S, Zeuss D, Hänsel F, Nauss T (2021) TubeDB: An on-demand processing database system for climate station data. Computers & Geosciences [https://doi.org/10.1016/j.cageo.2020.104641]

Heterogeneity–diversity relationships differ between and within trophic levels in temperate forests

The habitat heterogeneity hypothesis predicts that biodiversity increases with increasing habitat heterogeneity due to greater niche dimensionality. However, recent studies have reported that richness can decrease with high heterogeneity due to stochastic extinctions, creating trade-offs between area and heterogeneity. This suggests that greater complexity in heterogeneity–diversity relationships (HDRs) may exist, with potential for group-specific responses to different facets of heterogeneity that may only be partitioned out by a simultaneous test of HDRs of several species groups and several facets of heterogeneity. Here, we systematically decompose habitat heterogeneity into six major facets on ~500 temperate forest plots across Germany and quantify biodiversity of 12 different species groups, including bats, birds, arthropods, fungi, lichens and plants, representing 2,600 species. Heterogeneity in horizontal and vertical forest structure underpinned most HDRs, followed by plant diversity, deadwood and topographic heterogeneity, but the relative importance varied even within the same trophic level. Among substantial HDRs, 53% increased monotonically, consistent with the classical habitat heterogeneity hypothesis but 21% were hump-shaped, 25% had a monotonically decreasing slope and 1% showed no clear pattern. Overall, we found no evidence of a single generalizable mechanism determining HDR patterns

Does plant diversity affect the water balance of established grassland systems?

Evidence from experimental grasslands indicated that plant biodiversity modifies the water cycle but it is unclear if this is also true for established land-use systems. Therefore, we investigated how evapotranspiration (ETa), downward flux (DF), and upward flux (UF) in soil are related with land use and plant diversity in agriculturally managed grassland. In three Central European regions (“Biodiversity Exploratories”), we studied 29 grassland plots (50m x 50m; 9-11 plots per region) covering the land-use classes pasture, mown pasture, and meadow in at least triplicate per region. From 2010 to 2015, we measured soil moisture, meteorological conditions, plant species richness, cover and number of species in the functional groups of grasses, herbs, and legumes, aboveground biomass and root biomass on each plot. Annual ETa, DF, and UF were calculated for two soil layers with a soil water balance model and statistically analyzed for land-use and biodiversity effects with analysis of variance. Water fluxes were not significantly affected by land-use class. UF did not vary between plots with different species richness and plant functional group composition. DF from topsoil increased with increasing number of grass species. ETa from topsoil decreased with increasing species richness and with the number of herb or legume species, while ETa from subsoil increased. Our results demonstrate that plant diversity influences the soil depth partitioning of water use, but the complex drivers of this relationship in agriculturally managed grassland still need to be disentangled

Arthropod decline in grasslands and forests is associated with landscape-level drivers

Recent reports of local extinctions of arthropod species1, and of massive declines in arthropod biomass2, point to land-use intensification as a major driver of decreasing biodiversity. However, to our knowledge, there are no multisite time series of arthropod occurrences across gradients of land-use intensity with which to confirm causal relationships. Moreover, it remains unclear which land-use types and arthropod groups are affected, and whether the observed declines in biomass and diversity are linked to one another. Here we analyse data from more than 1 million individual arthropods (about 2,700 species), from standardized inventories taken between 2008 and 2017 at 150 grassland and 140 forest sites in 3 regions of Germany. Overall gamma diversity in grasslands and forests decreased over time, indicating loss of species across sites and regions. In annually sampled grasslands, biomass, abundance and number of species declined by 67%, 78% and 34%, respectively. The decline was consistent across trophic levels and mainly affected rare species; its magnitude was independent of local land-use intensity. However, sites embedded in landscapes with a higher cover of agricultural land showed a stronger temporal decline. In 30 forest sites with annual inventories, biomass and species number—but not abundance—decreased by 41% and 36%, respectively. This was supported by analyses of all forest sites sampled in three-year intervals. The decline affected rare and abundant species, and trends differed across trophic levels. Our results show that there are widespread declines in arthropod biomass, abundance and the number of species across trophic levels. Arthropod declines in forests demonstrate that loss is not restricted to open habitats. Our results suggest that major drivers of arthropod decline act at larger spatial scales, and are (at least for grasslands) associated with agriculture at the landscape level. This implies that policies need to address the landscape scale to mitigate the negative effects of land-use practices