Maintenance of forest ecosystem multifunctionality and the provision of ecosystem services requires high biodiversity in all forest layers, including the understorey. Understorey species have specific needs regarding site conditions, which are influenced by the overstorey in a species-specific way. Changes in the overstorey composition and diversity may therefore affect understorey diversity and productivity. However, former studies examining these relations yielded inconsistent results. We quantified the overstorey-understorey diversity and productivity relations at different spatial scales, relating the observed patterns to resource heterogeneity and niche creation in mixed stands as potentially driving mechanisms. We performed vegetation surveys in 209 plots of 30 m x 30 m in six European forest regions. In each region, the plots covered a gradient of “target” tree species richness (SR) from monocultures to five-species mixed stands. Within each plot, we assessed species identity and cover in three 5 m x 5 m quadrats, and clipped the aboveground biomass in one frame of 0.5 m x 0.5 m per quadrat. We examined the understorey compositional variation between and within regions, the influence of taxonomic diversity and functional dispersion in the overstorey on understorey diversity and productivity. Apart from interregional differences in understorey composition, we found lower compositional differentiation between quadrats in higher target tree SR levels, as these share more tree species and probably have more similar environmental conditions. Functional dispersion between target tree species positively influenced quadrat-level understorey biomass, but taxonomic nor functional target tree species diversity affected understorey SR and diversity on the quadratlevel. This contrasts with the forest-level results of several regions where the presence of two-species mixed stands clearly increased the understorey SR compared to monocultures only, indicating the creation of novel niches that are colonized by new understorey species. Adding higher target tree SR levels did not further increase forest-level understorey SR. The influence of understorey biomass on quadrat-level understorey SR was best approached by a quadratic relation although most of the variation remained unexplained. The overstorey-understorey diversity relation should be evaluated at multiple spatial scales, especially at the forest-level, instead of only at the individual stand level.

Effects of tree species richness on understorey vegetation diversity and productivity in European forests / Coppi, Andrea; Carrari, Elisa. - ELETTRONICO. - (2015), pp. 126-126. (Intervento presentato al convegno Sostenere il pianeta, boschi per la vita Ricerca e innovazione per la tutela e la valorizzazione delle risorse forestali tenutosi a Firenze nel 15-18 Settembre 2015).

Effects of tree species richness on understorey vegetation diversity and productivity in European forests

COPPI, ANDREA;CARRARI, ELISA
2015

Abstract

Maintenance of forest ecosystem multifunctionality and the provision of ecosystem services requires high biodiversity in all forest layers, including the understorey. Understorey species have specific needs regarding site conditions, which are influenced by the overstorey in a species-specific way. Changes in the overstorey composition and diversity may therefore affect understorey diversity and productivity. However, former studies examining these relations yielded inconsistent results. We quantified the overstorey-understorey diversity and productivity relations at different spatial scales, relating the observed patterns to resource heterogeneity and niche creation in mixed stands as potentially driving mechanisms. We performed vegetation surveys in 209 plots of 30 m x 30 m in six European forest regions. In each region, the plots covered a gradient of “target” tree species richness (SR) from monocultures to five-species mixed stands. Within each plot, we assessed species identity and cover in three 5 m x 5 m quadrats, and clipped the aboveground biomass in one frame of 0.5 m x 0.5 m per quadrat. We examined the understorey compositional variation between and within regions, the influence of taxonomic diversity and functional dispersion in the overstorey on understorey diversity and productivity. Apart from interregional differences in understorey composition, we found lower compositional differentiation between quadrats in higher target tree SR levels, as these share more tree species and probably have more similar environmental conditions. Functional dispersion between target tree species positively influenced quadrat-level understorey biomass, but taxonomic nor functional target tree species diversity affected understorey SR and diversity on the quadratlevel. This contrasts with the forest-level results of several regions where the presence of two-species mixed stands clearly increased the understorey SR compared to monocultures only, indicating the creation of novel niches that are colonized by new understorey species. Adding higher target tree SR levels did not further increase forest-level understorey SR. The influence of understorey biomass on quadrat-level understorey SR was best approached by a quadratic relation although most of the variation remained unexplained. The overstorey-understorey diversity relation should be evaluated at multiple spatial scales, especially at the forest-level, instead of only at the individual stand level.
2015
Sostenere il pianeta, boschi per la vita Ricerca e innovazione per la tutela e la valorizzazione delle risorse forestali
Sostenere il pianeta, boschi per la vita Ricerca e innovazione per la tutela e la valorizzazione delle risorse forestali
Firenze
Coppi, Andrea; Carrari, Elisa
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1050675
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