Effects of abandonment on plant diversity in semi‐natural grasslands along soil and climate gradients

• Published in: Journal of vegetation science Vol. 28; no. 4; pp. 838 - 847
• Main Authors: Wehn, Sølvi, Taugourdeau, Simon, Johansen, Line, Hovstad, Knut Anders, Tanentzap, Andrew
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.07.2017
• Subjects: Abandonment; Abundance; Biodiversity; boreal; Calcareous soils; Climate; Climate models; Collinearity; Dry matter; Ecosystems; Flowers & plants; Fodder; functional diversity; functional traits; Grasslands; Grazing; Land use; Leaf area; Leaves; Leda; pH effects; Plant diversity; Plant extracts; plant species richness; Plants (botany); Resilience; Seeds; semi‐natural grasslands; Single-nucleotide polymorphism; soil; Soil analysis; Soil fertility; Soil moisture; Soils; Species diversity; Species richness; taxonomic diversity; Taxonomy
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/jvs.12543

Questions What are the effects of abandonment on plant diversity in semi‐natural grasslands? Do the effects of abandonment on taxonomic and functional diversity vary along environmental gradients of climate and soil? Location West and mid‐Norway. Methods Plant composition was surveyed in 110 subplots of 4 m2 in 14 sites across grazed and abandoned semi‐natural grasslands. Climate data were extracted and soil composition analysed. To reduce the number of explanatory variables and deal with collinearity, we performed PCA. Data on the plant species vegetative height (H), leaf dry matter content (LDMC), specific leaf area (SLA), seed mass (SM) and number of seeds per plant (SNP) for 175 species were extracted from the LEDA database. Measures of plant diversity (species richness, CWM of functional traits and functional diversity (evenness and range)) were calculated for each subplot. To estimate the effects of abandonment on plant diversity and examine how these effects are moderated by gradients in soil and climate, we fitted mixed models to the data including site as a random effect. Results Species richness in the subplots was lower in abandoned semi‐natural grasslands, especially on more calcareous soils. CWM H, LDMC and SM were higher in abandoned semi‐natural grasslands. CWM LDMC was only higher in the driest subplots. The ranges in H, SLA and SM, as well as evenness in LDMC were also higher in abandoned semi‐natural grasslands,but the range in LDMC was lower. Conclusions It is important to assess both taxonomic and functional diversity to understand ecosystem processes. The species pool in ecosystems influenced by a long history of intermediate grazing includes a high proportion of low stature, grazing‐tolerant plant species. Abandonment of extensive land‐use practices will cause a decline in taxonomic diversity (plant species richness) in such systems due to increased abundance of plants with high stature that outcompete the lower, grazing‐tolerant plants. This process is predominant especially if moisture, soil fertility and pH are at intermediate levels. Changes in species communities due to abandonment will also influence ecosystem functioning, such as nutrient turnover and fodder production resilience. We found that sheep grazing show positive effect on plant richness and affects functional identity and diversity in Norway. The differences between grazed and abandoned semi‐natural grasslands vary along environmental gradients; richness along the soil fertility gradient and functional diversity along the precipitation gradient. We conclude that to understand ecosystem processes both taxonomic and functional aspects have to be assessed.