Abstract
Fertilization, especially with nitrogen (N), increases aboveground primary productivity (APP), but reduces plant species richness at some level. Silicon (Si) fertilization alone, or with addition of N or phosphorus (P), has multiple direct and indirect beneficial effects on plant growth and development, both for individuals and the whole community. This study aimed to examine the effects of Si, N, P, NSi and PSi combinations on APP and species richness of the community and of four functional groups in an alpine meadow. The results showed that plots fertilized with Si in combination with either N or P had higher APP than when fertilized with N or P alone. Addition of N or P increased APP, and the higher APP occurred when the highest level of N was added, indicating co-limitation of N and P, with N being most limiting. Silicon fertilization alone or with addition of N increased the APP of grasses and forbs. Nitrogen addition decreased the community species richness; Si with addition of N alleviated the loss of species richness of the whole community and the forbs group. For the four functional groups, N or P addition increased the species richness of grasses and decreased that of forbs. Our findings highlight the importance of Si in improving APP and alleviating N fertilization-induced biodiversity loss in grasslands, and will help improve our ability to predict community composition and biomass dynamics in alpine meadow ecosystems subject to changing nutrient availability.
Highlights
Climatic conditions such as temperature and moisture limit plant productivity and nutrient cycling in cold regions, especially in alpine meadow, which leads to a strong nitrogen (N)- and phosphorus (P)-limitation in plant growth (Tamm 1991; Nadelhoffer et al 1992)
The study was conducted in the Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University, which is located in Maqu, on the eastern Tibetan
Our present study showed that Si addition alone significantly increased the aboveground primary productivity (APP) of the whole community and the functional groups of grasses, sedges and forbs in an alpine meadow in 2013
Summary
Climatic conditions such as temperature and moisture limit plant productivity and nutrient cycling in cold regions, especially in alpine meadow, which leads to a strong nitrogen (N)- and phosphorus (P)-limitation in plant growth (Tamm 1991; Nadelhoffer et al 1992). Plant communities are especially sensitive to N or P addition, and changes in the plant community structure are often mediated through increased productivity following addition of N or P (Clark et al 2007). Considerable evidence indicates that change in N and P availability can dramatically alter local species composition, plant community structure and biological diversity (Gough et al 1994; Stevens et al 2004). Biological diversity plays an important role in the functioning and sustainability of ecosystems (Tilman et al 1996).
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