Hypothesis‐driven species distribution models for tree species in the Bavarian Alps

Abstract

Question: What are the main drivers for tree species distribution in the Bavarian Alps? What are the species-specific habitat requirements? Are predictions in accordance with expert knowledge?Location: Bavarian Alps (Southern Germany).Methods: To describe tree species-environment relationships, we established species distribution models for the 14 most common tree species of the region. We combined tree species occurrence data from forest inventories and a vegetation database with environmental data from a digital elevation model, climate maps and soil maps. For modelling, we used generalized additive models (GAM) combined with techniques to account for spatial autocorrelation and uneven coverage of environmental gradients. We developed parsimonious models to judge whether statistical models correspond to models based on expert knowledge.Results: Conceptual models were generally in accordance with expectations.Variables based on average temperatures were the most important predictors in most models. Proxies for soil properties such as water and nutrient availability were statistically significant and generally plausible, but appeared largely redundant for model performance. Altitudinal limits of tree species were generally well represented by models. Most species responded differently to summer and January temperatures, indicating that temperature variables are proxies not only for energy balance, but also for frost damage and drought. Although model building benefits considerably from collation with expert knowledge, there are limitations.Conclusions: Meaningful species distribution models can be obtained from noisy data sets covering only a small fraction of species ranges. Models calibrated with such data sets benefit from hypothesis-driven model building rather than strict data-driven model building. Hence, misleading explanations and predictions can be avoided and uncertainties identified. Nevertheless, projections based on climate scenarios can be substantially improved only with models calibrated on a wider data set. Ideally, environmental gradients should cover the whole niche space of a species, or at least include regions with analogous climate.

Prediction of Dominant Forest Tree Species Using QuickBird and Environmental Data

“…Also, our results agreed with many other studies with regards to the importance of temperature [23,25] and rainfall [23,28,37], in modelling the distribution of tree group species.…”

“…The results which predicted the spatial distribution of tree species using the climatic variables group showed that all three variables-temperature, evapo-transpiration and rainfall-were significant parameters in modelling the distribution of tree species, and agreed with the results of [25,33]. Also, our results agreed with many other studies with regards to the importance of temperature [23,25] and rainfall [23,28,37], in modelling the distribution of tree group species.…”

“…The physical, chemical, and biological properties of soil affected the distribution and establishment of plants. Previous studies [25,83,84] emphasized the importance of soil characteristics in species distribution.…”

Range Wide Phylogeography of Dactylopius coccus (Hemiptera: Dactylopiidae)

“…See, e.g., Austin and Smith (1987), Austin (2002), Mellert et al, (2011). The early applications of species modeling tended to focus on explanation ).…”

Floristic Change at the Drought Limit of European Beech (Fagus sylvatica L.) to Downy Oak (Quercus pubescens) Forest in the Temperate Climate of Central Europe

“…But at local to landscape scales, disturbances, species interactions and direct physiologically effective parameters control the occurrence of plant species and plant communities. Variables influencing vegetation distribution can be broadly related to moisture, energy, nutrient availability and geomorphodynamics (Mellert et al, 2011). To study drought or aridity-induced vegetation limits, moisture supply is the main factor to be considered.…”