Thermal niche predictors of alpine plant species

Abstract

Within the context of species distribution models, scrutiny arises from the choice of meaningful environmental predictors. Thermal conditions are not the sole driver, but are the most widely acknowledged abiotic driver of plant life within alpine ecosystems. We linked long-term measurements of direct, plant-relevant, near-surface temperatures to plant species frequency. Across 47 sites located along environmental gradients within the Scandinavian mountain chain, the thermal preferences of 26 focal species of vascular plants, lichens, and bryophytes were explored. Based on partial least-squares regression, we applied a relative importance analysis to derive inductively the thermal variables that were best related to a species' frequency. To discover potential seasonal variability of thermal controls, analyses were both differentiated according to meteorological season and integrated across the entire year. The pronounced interspecies and temporal variability of thermal constraints revealed the thermal niches were much more nuanced and variable than they have commonly been represented. This finding challenges us to present, interrogate, and interpret data representing these thermal niches, which seems to be required in order to move beyond purely probabilistic and correlative descriptions of species' range limits. Thus, this information will help improve predictions of species distributions in complex arctic-alpine landscapes.

Differences in Mobility and Dispersal Capacity Determine Body Size Clines in Two Common Alpine-Tundra Arthropods

“…Elevation and position were recorded using differential GPS. At each site, we recorded the frequency of vascular plants in four plots of 1 m 2 , each with 25 subplots of 20 × 20 cm size (see Löffler and Pape [39] for a more detailed description).…”

Multidimensionality in the thermal niches of dung beetles could limit species’ responses to temperature changes

“…Deriving thermal niches from occurrence data typically provides a partial description of the whole potential response of the species (Sánchez-Fernández et al 2012, Saupe et al 2018). However, occurrence-based thermal niches may nevertheless be characterized by different attributes such as the optimum temperature and niche breadth (Gouveia et al 2014, Löffler & Pape 2020, Fig. 2).…”

Contrasting growth response of evergreen and deciduous arctic‐alpine shrub species to climate variability

“…Both B. nana and E. hermaphroditum are able to mitigate the effects of extreme negative temperatures, but only E. hermaphroditum shows a strong positive response to those conditions, benefiting from prolonged snow-free periods. This suggests that in contrast to deciduous species, E. hermaphroditum is able to continue photosynthetic activity and remain energetically effective in synthesizing carbohydrates during at least parts of the winter months (Gimeno et al 2012, Wyka and Oleksyn 2014, L€ offler and Pape 2020. While nutrition uptake and soil moisture access are extremely limited during those times, high global radiation can lead to additional photosynthetic opportunities (K€ orner 2015, Saccone et al 2017).…”

“…The ridge positions used for sampling were stratified-randomly chosen to cover the elevational gradient, following the framework of our long-term alpine ecosystem research project (LTAER; e.g., L€ offler and Finch 2005, Hein et al 2014, Frindte et al 2019, Beckers et al 2020. They were placed at elevational levels from the tree line upwards, shifted by approximately 100 height-meters between regions to account for the depression of the elevational zonation toward the west (L€ offler et al 2006(L€ offler et al , L€ offler and Pape 2020(L€ offler et al , L€ offler et al, 2021. In accordance with the elevationally constrained range of the studied two species, we chose ten specimens from the oceanic region (700-1300 m a.s.l.)…”

“…Our aim in applying this statistical approach was solely to use variable selection methods to assess the relative importance of certain micro-environmental conditions in promoting or hindering growth, and to define a subset of relevant conditions. Primarily intended for multidisciplinary problems (Wold 1980), PLSR has found application in ecological studies during the past decade (Carrascal et al 2009, Frindte et al 2019, L€ offler and Pape 2020. Main advantages include that it works without distributional assumptions (Wold 1980, Dijkstra 1983, Vinzi et al 2010) and deals efficiently with unreliability and heteroscedasticity issues (Martens andNaes 1989, Frindte et al 2019).…”