Multifaceted fine-grain niche modelling: Two mountain plants in one relic location

Abstract

Fine-grain species niche modelling in topographically diverse areas poses a serious challenge. Nonetheless, it is important for studying factors enabling species’ survival in a changing climate and understanding current species distribution. Niches of two mountain species: Cotoneaster integerrimus Medik and Valeriana tripteris L., were analyzed in a specific area of limestone hill Góra Zborów, which can be treated as a model of topographically differentiated area located outside mountains. The area constitutes a regional center of biodiversity and is protected as a nature reserve. C. integerrimus and V. tripteris are considered to have relic localities there. The aim of the study was a multifaceted fine-grain comparison of Cotoneaster integerrimus and Valeriana tripteris niches: 1) according to variables derived from high-resolution topographical model of the study area; 2) according to direct site characteristics; 3) according to species coexisting with the analyzed taxa.During the field studies, the data regarding abiotic conditions and plant cover were gathered from sites of the selected species. To better characterize these sites against the surrounding environment, a topographical model of the entire Góra Zborów was also used. Niche modelling was conducted by multivariate analysis in environmental space, with the usage of PCA and DCA ordinations. Also step regression models were used to identify the predominant co-occurring plant species. The results of different computational methods suitable for different kinds of variables were compared.The results of all analyses remained consistent with the field observations. ‘Heat load’ combined with ‘Aspect’, and ‘Wetness’ combined with ‘Slope’ variables accurately explained the environmental differentiation of the area derived from topography characteristics. The overlap of the species’ niches was significant; however, the niches were not identical. C. integerrimus could grow in more insolated habitats characterized by higher cover of ground vascular flora, in which case significant positive relations with several herb taxa co-occurrence were identified. V. tripteris preferred the presence of barren rocks, higher cover of bryophytes, and trees and shrubs that shaded the locality.Niche overlap analysis conducted with differentiated methods underlined the importance of the variable selection for the analysis result, and the value and complementarity of different computational methods. The presented analysis can also be regarded as an attempt at a demonstration of the area conservation value by the study concerning only two chosen species. The study confirmed the importance of Góra Zborów Nature Reserve as the possible refugial area during climate changes.