Temperate deciduous forest biome occupies a large area in temperate western Eurasia. The vast territory it occupies suggests a common origin as it formed a continuous and much broader area during the late Tertiary. The Pleistocene climatic oscillations caused successive reductions and expansions with differential impact on floristic extinctions in the different parts of this biome. This could be reflected in the diversity of vascular plants in the separate subregions of the total area and in their biogeographic relationships. We try to understand the main drivers of the diversity patterns of the three different elements of the forest community: trees, shrubs and forest-floor plants. Nine subregions have been selected for the survey encompassing the area and variability of western Eurasian temperate deciduous forests, and 1,000 vegetation plots were selected within each of them from the EVA database, making a total of 9,000 plots. The dataset was homogenized and standardized, and the species were classified into the following life forms: For ligneous species, trees, shrubs or dwarf-srubs, either perennial or deciduous, and conifers or non-conifers. For herbs, hemicryptophytes, geophytes or therophytes. Lianas and epiphytes were also considered as well as ferns. For the analyses, the plant communities were deconstructed into three layers: tree, shrub and floor. Generalized linear mixed models (GLMM) were used to analyse the influence of current climate, historical climate and topography on species richness by accounting for regional effects. Redundancy analysis (RDA) with variance partitioning was used to describe the variation in life forms along abiotic gradients. The three forest layers were analysed jointly and separately in order to find out whether their variation patterns were similar or different. The Balkans, Alps and Carpathians appeared to be the richest in plant species, whereas the British Isles and the Hyrcanian region were the poorest. Annual temperature range and annual mean temperature were the best predictors of species richness for the whole dataset and for the shrub layer. The tree layer richness was mainly explained by the annual temperature range and elevation. The current climate was the main predictor of the composition of the whole community, the tree layer and the floor layer, while the shrub layer was also influenced by historical climate. Our overview of the diversity of temperate deciduous forests in western Eurasia demonstrates different patterns and drivers across life-forms and forest layers. The diversity of trees is mainly linked to current climatic conditions, while the shrub layer is also driven by postglacial-glacial climatic stability, suggesting a different origin from forest trees.

The temperate deciduous forests of western Eurasia: plant diversity, biogeographic relationships and climatic drivers

Marcenò Corrado;
2022

Abstract

Temperate deciduous forest biome occupies a large area in temperate western Eurasia. The vast territory it occupies suggests a common origin as it formed a continuous and much broader area during the late Tertiary. The Pleistocene climatic oscillations caused successive reductions and expansions with differential impact on floristic extinctions in the different parts of this biome. This could be reflected in the diversity of vascular plants in the separate subregions of the total area and in their biogeographic relationships. We try to understand the main drivers of the diversity patterns of the three different elements of the forest community: trees, shrubs and forest-floor plants. Nine subregions have been selected for the survey encompassing the area and variability of western Eurasian temperate deciduous forests, and 1,000 vegetation plots were selected within each of them from the EVA database, making a total of 9,000 plots. The dataset was homogenized and standardized, and the species were classified into the following life forms: For ligneous species, trees, shrubs or dwarf-srubs, either perennial or deciduous, and conifers or non-conifers. For herbs, hemicryptophytes, geophytes or therophytes. Lianas and epiphytes were also considered as well as ferns. For the analyses, the plant communities were deconstructed into three layers: tree, shrub and floor. Generalized linear mixed models (GLMM) were used to analyse the influence of current climate, historical climate and topography on species richness by accounting for regional effects. Redundancy analysis (RDA) with variance partitioning was used to describe the variation in life forms along abiotic gradients. The three forest layers were analysed jointly and separately in order to find out whether their variation patterns were similar or different. The Balkans, Alps and Carpathians appeared to be the richest in plant species, whereas the British Isles and the Hyrcanian region were the poorest. Annual temperature range and annual mean temperature were the best predictors of species richness for the whole dataset and for the shrub layer. The tree layer richness was mainly explained by the annual temperature range and elevation. The current climate was the main predictor of the composition of the whole community, the tree layer and the floor layer, while the shrub layer was also influenced by historical climate. Our overview of the diversity of temperate deciduous forests in western Eurasia demonstrates different patterns and drivers across life-forms and forest layers. The diversity of trees is mainly linked to current climatic conditions, while the shrub layer is also driven by postglacial-glacial climatic stability, suggesting a different origin from forest trees.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1517826
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