Forests buffer the climate‐induced decline of body mass in a mountain herbivore

Abstract

Climate change is known to affect key life‐history traits, such as body mass, reproduction, and survival in many species. Animal populations inhabiting mountain habitats are adapted to extreme seasonal environmental conditions but are also expected to be especially vulnerable to climate change. Studies on mountain ungulates typically focus on populations or sections of populations living above the tree line, whereas populations inhabiting forested habitats are largely understudied. Here, we investigate whether forested areas can mitigate the impact of climatic change on life‐history traits by evaluating the interactive effects of temperature and habitat characteristics on body mass variation in the Alpine chamois Rupicapra rupicapra rupicapra. We examined data of 20,573 yearling chamois collected from 1993 to 2019 in 28 mountain ranges in the Austrian Eastern Alps, characterized by different proportion of forest cover. Our results show that the temporal decline of chamois body mass is less pronounced in areas with greater proportion of forest cover. For chamois living in forest habitats only, no significant temporal change in body mass was detected. Variation in body mass was affected by the interaction between density and snow cover, as well as by the interaction between spring temperatures and forest cover, supporting the role of forests as thermal buffer against the effects of increasing temperatures on life‐history traits in a mountain ungulate. In turn, this study suggests a buffering effect of forests against climate change impacts. Assessments of the consequences of climate change on the life‐history traits and population dynamics of mountain‐dwelling species should thus consider the plasticity of the species with respect to the use and availability of different habitat types.

Reflections of ecological differences? Stress responses of sympatric Alpine chamois and red deer to weather, forage quality, and human disturbance

“…However, this possibility should not be excluded based on our results, as our sampling locations were located well below the timber line. Since daily temperature extremes are dampened in the forest compared with open areas, neither species may have been exposed to challenging thermal conditions at their upper limits in the relative shade of the forest even during July or August (see also Reiner et al, 2021 ). However, both chamois and red deer showed a physiological stress response to drought conditions during summer, and this result was consistent across all summer models, regardless of whether only site 1 or all 3 sites were included for red deer.…”

Habitat and climate shape growth patterns in a mountain ungulate

“…The Alpine chamois is the most abundant mountain ungulate of the European Alps (Corlatti et al, 2011 ) and inhabits alpine areas above the tree line as well as subalpine and montane forests ( cf . Reiner et al, 2021 ). Male chamois have a longer period of body growth (Garel et al, 2009 ) and show greater intra‐annual variations in mass than females due to higher mass loss during the rut (Mason et al, 2011 ).…”

“…Recent studies suggest that key life‐history traits, such as survival and reproductive effort, vary substantially between chamois populations (Bleu et al, 2015 ; Mason et al, 2011 ). Chamois are morphologically and physiologically adapted to environmental conditions at high altitudes, i.e., cold winters with high precipitation in the form of snow (Ascenzi et al, 1993 ); therefore, spatial and temporal variations in body mass in context with increasing temperatures may occur (Ciach & Pęksa, 2018 ; Reiner et al, 2021 ; Rughetti & Festa‐Bianchet, 2012 ; Willisch et al, 2013 ). Changes in environmental conditions may affect patterns of mass and mass growth differently in habitats with different characteristics.…”

“…Changes in environmental conditions may affect patterns of mass and mass growth differently in habitats with different characteristics. For example, Reiner et al ( 2021 ) showed that, in chamois, the effects of increasing spring and summer temperatures on yearling body mass are mitigated in forested areas, which suggests a temperature‐buffering effect of forests. These habitat‐specific differences in body mass are likely related to differences in foraging opportunities and thermoregulatory costs (Bubenik, 1984 ).…”

“…Here we investigate large‐scale variations in the patterns of body mass and growth of Alpine chamois in relation to increasing spring and summer temperatures and habitat variations (i.e., proportion of forest cover), while controlling for the effects of sex, age, and population density across 31 (sub)populations in the Central European Alps. We take advantage of an exceptionally large dataset ( n = 178,175) of chamois harvested over 27 consecutive years between 1993 and 2019 in mountain ranges with different proportions of forest cover (Reiner et al, 2021 ). Specifically, we hypothesize (i) a slower growth in mass and higher adult mass in mountain ranges with less predictable environmental conditions (i.e., alpine areas with lower forest cover) and (ii) larger differences in body mass patterns in relation to variations in spring and summer temperatures in mountain ranges with lower forest cover compared to mountain ranges with higher forest cover (Cook et al, 1998 ; Reiner et al, 2021 ).…”