TY - JOUR

T1 - Long-term drought triggers severe declines in carabid beetles in a temperate forest

AU - Weiss, Fabio

AU - von Wehrden, Henrik

AU - Linde, Andreas

N1 - Funding Information: – Fabio Weiss was funded through the Biosphere Reserves Institute and the Innovation and Career Center ‘ProBio‐LaB' by the Ministry of Science, Research and Culture of the federal state of Brandenburg (MWFK). Publisher Copyright: © 2024 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos.

PY - 2024/4

Y1 - 2024/4

N2 - Evidence for widespread declines in arthropods is growing and climate change is one of the suspected drivers. Recent droughts in Europe were unprecedented in the previous centuries and we are only beginning to understand the impacts on ecosystems. We analysed a 24-year dataset of carabid beetles from a temperate forest area in northeast Germany and investigated linear and non-linear trends in carabid abundance, biomass, diversity and species traits. We were especially interested if and how these were linked to droughts at different temporal scales using the standardized precipitation evapotranspiration index (SPEI). We found significant linear declines in abundance and biomass with annual rates of −3.1% (0.95 CI [−5.3, −1]) and –4.9% (0.95 CI [−9.4, −1.6]), respectively. Non-linear trends were closely related to the SPEI when considering the climatic water balance of the previous six years and showed severe declines between 2015 and 2022 (−71% abundance, 0.95 CI [−84, −61] / −89% biomass, 0.95 CI [−97, −59]). However, there remained a significant annual background-decline of −2.1% (0.95 CI [−5.7, −0.2]) and −3.1% (0.95 CI [−6.5, −0.1]), respectively, which occurred independently of drought. We observed negative trends in standardized carabid diversity metrics and a shift in species assemblage that were less directly linked to droughts. Declining and drought-sensitive species tended to be larger predators with low dispersal abilities. This study is among the very first to investigate the impacts of the current unprecedented drought on forest insects in central Europe. Our findings add to the concerning amount of evidence for widespread declines in arthropods while pointing towards weather anomalies and climate change as one important driver.

AB - Evidence for widespread declines in arthropods is growing and climate change is one of the suspected drivers. Recent droughts in Europe were unprecedented in the previous centuries and we are only beginning to understand the impacts on ecosystems. We analysed a 24-year dataset of carabid beetles from a temperate forest area in northeast Germany and investigated linear and non-linear trends in carabid abundance, biomass, diversity and species traits. We were especially interested if and how these were linked to droughts at different temporal scales using the standardized precipitation evapotranspiration index (SPEI). We found significant linear declines in abundance and biomass with annual rates of −3.1% (0.95 CI [−5.3, −1]) and –4.9% (0.95 CI [−9.4, −1.6]), respectively. Non-linear trends were closely related to the SPEI when considering the climatic water balance of the previous six years and showed severe declines between 2015 and 2022 (−71% abundance, 0.95 CI [−84, −61] / −89% biomass, 0.95 CI [−97, −59]). However, there remained a significant annual background-decline of −2.1% (0.95 CI [−5.7, −0.2]) and −3.1% (0.95 CI [−6.5, −0.1]), respectively, which occurred independently of drought. We observed negative trends in standardized carabid diversity metrics and a shift in species assemblage that were less directly linked to droughts. Declining and drought-sensitive species tended to be larger predators with low dispersal abilities. This study is among the very first to investigate the impacts of the current unprecedented drought on forest insects in central Europe. Our findings add to the concerning amount of evidence for widespread declines in arthropods while pointing towards weather anomalies and climate change as one important driver.

KW - biodiversity

KW - climate change

KW - drought legacy

KW - ground beetles

KW - insect decline

KW - standardized precipitation evapotranspiration index (SPEI)

KW - Biology

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=85182722972&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/b62f8f6a-941b-3d36-955d-11e42b8818a3/

U2 - 10.1111/ecog.07020

DO - 10.1111/ecog.07020

M3 - Journal articles

AN - SCOPUS:85182722972

VL - 2024

JO - Ecography

JF - Ecography

SN - 0906-7590

IS - 4

M1 - e07020

ER -