TY - JOUR

T1 - Tree diversity alters the structure of a tri-trophic network in a biodiversity experiment

AU - Staab, Michael

AU - Blüthgen, Nico

AU - Klein, Alexandra Maria

N1 - We thank Thomas Thieme for Aphididae species identification. Werner Holzinger confirmed the Auchenor-rhyncha morphospecies classification and Wolfgang Dorow the identity of the taxonomically ambiguous Polyrhachis dives. Jan Peters helped with parts of the fieldwork. Andreas Schuldt critically commented an earlier version of the manuscript. Helge Bruelheide, Bernhard Schmid, Sabine Both, Keping Ma, Xiaojuan Liu, and the entire coordination team of the BEF China project are gratefully acknowledged for their support. This study was funded by the German Science Foundation (DFG FOR 891/2, KL 1849/6-1

PY - 2015/7/1

Y1 - 2015/7/1

N2 - Species and processes in ecosystems are part of multi-trophic interaction networks. Plants represent the lowest trophic level in terrestrial ecosystems, and experiments have shown a stabilizing effect of plant diversity on higher trophic levels. Such evidence has been mainly collected in experimental grasslands. Forests are structurally more complex than grasslands and support the majority of the global biodiversity, but studies on multi-trophic interaction networks are missing in experimental tree diversity gradients. In a forest diversity experiment in southeast China, we examined how tree diversity affects the structure of trophobiotic networks. Trophobioses are tri-trophic interactions between plants, sap-sucking Hemiptera and honeydew-collecting ants that can be subdivided into a largely mutualistic Hemiptera-ant and an antagonistic plant-Hemiptera network. We inspected almost 7000 trees in 146 plots ranging from monocultures to 16 tree species mixtures and found 194 trophobioses consisting of 15 tree, 33 Hemiptera and 18 ant species. We found that tree diversity increased the proportion of trees harboring trophobioses. Consistent with the prediction that mutualistic and antagonistic networks respond differently to changing environments, we found that the generality index of the mutualistic Hemiptera-ant but not the antagonistic plant-Hemiptera network increased with tree diversity. High generality, maintained by high tree diversity, might correspond to higher functional stability. Hence, our results indicate that tree diversity could increase via bottom-up processes the robustness of ant-Hemiptera associations against changing environmental conditions. In turn, the plant-Hemiptera network was highly complementary, suggesting that host-specific Hemiptera species may be vulnerable to co-extinction if their host plants disappear. Based on our results, we provide possible future research directions to further disentangle the bottom-up effect of tree diversity on the structure of trophobiotic networks.

AB - Species and processes in ecosystems are part of multi-trophic interaction networks. Plants represent the lowest trophic level in terrestrial ecosystems, and experiments have shown a stabilizing effect of plant diversity on higher trophic levels. Such evidence has been mainly collected in experimental grasslands. Forests are structurally more complex than grasslands and support the majority of the global biodiversity, but studies on multi-trophic interaction networks are missing in experimental tree diversity gradients. In a forest diversity experiment in southeast China, we examined how tree diversity affects the structure of trophobiotic networks. Trophobioses are tri-trophic interactions between plants, sap-sucking Hemiptera and honeydew-collecting ants that can be subdivided into a largely mutualistic Hemiptera-ant and an antagonistic plant-Hemiptera network. We inspected almost 7000 trees in 146 plots ranging from monocultures to 16 tree species mixtures and found 194 trophobioses consisting of 15 tree, 33 Hemiptera and 18 ant species. We found that tree diversity increased the proportion of trees harboring trophobioses. Consistent with the prediction that mutualistic and antagonistic networks respond differently to changing environments, we found that the generality index of the mutualistic Hemiptera-ant but not the antagonistic plant-Hemiptera network increased with tree diversity. High generality, maintained by high tree diversity, might correspond to higher functional stability. Hence, our results indicate that tree diversity could increase via bottom-up processes the robustness of ant-Hemiptera associations against changing environmental conditions. In turn, the plant-Hemiptera network was highly complementary, suggesting that host-specific Hemiptera species may be vulnerable to co-extinction if their host plants disappear. Based on our results, we provide possible future research directions to further disentangle the bottom-up effect of tree diversity on the structure of trophobiotic networks.

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=84928415661&partnerID=8YFLogxK

U2 - 10.1111/oik.01723

DO - 10.1111/oik.01723

M3 - Other (editorial matter etc.)

AN - SCOPUS:84928415661

VL - 124

SP - 827

EP - 834

JO - Oikos

JF - Oikos

SN - 0030-1299

IS - 7

ER -