Abstract
Leymus chinensis (Trin.) is the dominant vegetation type in eastern Eurasian temperate grasslands but is decreasing due to the combined pressure of reduced precipitation and overgrazing. This study evaluated the separate and combined effects of precipitation and defoliation on net primary productivity (NPP) and composition of a L. chinensis steppe to promote the sustainable development of temperate grasslands through improved management practices. The effects of three precipitation gradients (precipitation unchanged, reduced by 50%, and increased by 50%) and two clipping intensities (clipping once or twice per year) were examined on NPP and composition of the L. chinensis community using a 7-year in situ controlled trial at the Guyuan State Key Monitoring and Research Station of Grassland Ecosystem in China. The results showed that: (1) a 50% reduction in natural precipitation significantly decreased NPP; a 50% increase in precipitation did not significantly increase NPP, but it decreased the importance value of L. chinensis because more water promoted the growth of competing species. (2) Clipping twice per year increased NPP, but the increase was from the dry matter of other species (DMO) component, and not from the dry matter of L. chinensis. (3) The standardized coefficients of a regression model (β) for DMO, NPP, and the importance value of L. chinensis were 0.685, 0.532, and −0.608 for precipitation, and 0.369, 0.419, and −0.276 for clipping mode, respectively. This study demonstrated that variation in precipitationis the key driver of NPP and composition of a L. chinensis steppe under the precipitation range and clipping intensities evaluated. This improved understanding of the effects of precipitation and clipping on NPP and composition will allow for improved, sustainable management of L. chinensis temperate grassland steppes.
Highlights
Temperate grassland is an important vegetation type in arid and semiarid regions around the world
This study demonstrated that variation in precipitationis the key driver of net primary productivity (NPP) and composition of a L. chinensis steppe under the precipitation range and clipping intensities evaluated
Bai et al found that precipitation on the L. chinensis steppe during January to July was a significant variable in simplified multiple regression analyses [24]
Summary
Temperate grassland is an important vegetation type in arid and semiarid regions around the world. Grasslands dominated by L. chinensis are widely distributed and it is the dominant vegetation type in eastern Eurasian temperate grasslands This grassland type occupies an area of 3 × 105 ha in Inner Mongolia, and it plays a key role in providing livestock forage, wildlife habitat, and environmental security to the nation [16,17]. Baoyin et al reported that a quadratic function was a better predictor of NPP than linear or logarithmic equations [25] Both quantity and timing of precipitation play a key role in the productivity and species richness of annual and perennial species in temperate grassland ecosystems [22,26]
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