Advancing plant phenology causes an increasing trophic mismatch in an income breeder across a wide elevational range

Maik Rehnus,Kurt Bollmann,Marta Peláez

doi:10.1002/ecs2.3144

Abstract

AbstractTo avoid trophic mismatches, large herbivores should reschedule the breeding timing to keep in synchrony with the recent advance of plant phenology caused by climate change. To do so, individuals must track resources along two main non‐exclusive axes: time (rescheduling the breeding timing) and space (i.e., shifting their range). While the vast majority of studies have focused on the study of specific populations inhabiting small and homogeneous environments, little is known about the response of species across large regions with highly heterogeneous topographies. Here, we studied roe deer (Capreolus capreolus), an income breeder that has demonstrated a lack of phenotypic plasticity on birth timing in a densely forested lowland area, and evaluated its ability to track resources along a wide elevational gradient (288–2366 m a.s.l.). We used data from 8986 parturition events collected in Switzerland during the period 1971–2015. We hypothesize that the mismatch between roe deer parturition dates and peak resource availability will increase over the study period. In addition, we expect this mismatch to be larger in low areas compared to higher elevation areas. Contrary to previous studies, we did find a consistent, but small, trend toward more advance parturition dates through time across all elevations. However, this rate of advance was less than that of the plant phenology indicators, resulting in an increasing mismatch at all elevations. Parturition dates changed on average at a rate between 7.5 times slower than the growing season start and 5 times slower than the flowering start. Thus, at the lowest elevations, parturition timing has already fallen outside the optimal time window for high‐quality forage, while at high elevations, parturitions are still synchronized with the peak availability of quality forage. Our study emphasizes the need for large‐scale study designs along climatic gradients to help understand the complex relationships that shape adaptation across environments. This would allow for better understanding of how populations will respond to the new environmental conditions imposed by climate change.

Highlights

Rising temperatures as a consequence of climate change have led to an overall spring phenology advancement for many organisms across the Northern Hemisphere (Menzel 2003, Cleland et al 2007, Roberts et al 2015)
Temporal changes in parturition date A slight trend toward more advanced parturition dates through time was found at different scales and elevational intervals
We found a consistent advance toward earlier parturition dates across all scales and most elevational ranges that could be associated with a response to climate change

Summary

Introduction

Rising temperatures as a consequence of climate change have led to an overall spring phenology advancement for many organisms across the Northern Hemisphere (Menzel 2003, Cleland et al 2007, Roberts et al 2015). Phenological mismatches may occur if a different magnitude of response disrupts previously synchronous trophic interactions (Visser et al 1998, Koh et al 2004). Demography and population viability (Brook et al 2009, Bronson 2009, Miller-Rushing et al 2010, Usui et al 2017). For plant consumers, such as large herbivores, breeding timing is the period of peak energy demand for females which should match the optimal time in terms of resource availability (Post et al 2003, H€am€al€ainen et al 2017). A mismatch can reduce annual reproductive success (Clutton-Brock et al 1987, Plard et al 2014, Paoli et al 2018) and future reproductive performance of both females and newborns (Clutton-Brock et al 1983, Festa-Bianchet et al 2000)

Methods

Results

Conclusion