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Université de l’agriculture de Chine (2015)

The Inner Mongolia Grassland Productivity and Biodiversity Response to Grazing and Precipitation

Jyoti Bhandari

Titre : The Inner Mongolia Grassland Productivity and Biodiversity Response to Grazing and Precipitation

Auteur : Jyoti Bhandari

Grade : Doctoral Dissertation 2015

Université : Université de l’agriculture de Chine

Résumé
Understanding the effects of grazing disturbance, climatic variables and biodiversity on plant production is important for grassland management and conservation. Therefore in our present study, we aim to analyze the effect of grazing, biodiversity and climatic variables on plant production in semi-arid grassland of Inner Mongolia. We found that there were significant differences in above ground dry matter between grazed and ungrazed sites in typical steppe and meadow steppe grasslands. Livestock grazed sites resulted in a decrease of above ground dry matter compared to the ungrazed sites. We found a significant positive relationship between growing season precipitation and above ground dry matter in these semi-arid grasslands. Rain use efficiency (RUE) is an important indicator for identifying the response of plant production to variation in precipitation patterns, especially in semiarid ecosystem grasslands in Inner Mongolia. Our results showed that RUE based on above ground dry matter (RUEADM) was lowest in the wettest year (2012) and highest in the year following the driest year (2008). There was no significant correlation between RUEADM and rain use efficiency based on total dry matter (RUETDM) in typical and desert steppe. RUETDM was strongly correlated with both annual precipitation (AP) and growing season precipitation (GSP) compared to RUEADM·RUEADM, therefore, cannot be used in place of RUETDM·RUEADM increased with species richness. The relationship between RUEADM and species richness was significantly correlated in meadow steppe, typical steppe and desert steppe. The ratio of above ground dry matter of C3and C4plant was differed significantly with three major site types. Above ground dry matter was the highest in sites dominated by C4plants. At sites dominated by C3and at C3and C4mixed sites a significant positive linear relationship between above ground dry matter with both species richness index and Simpson’s diversity index was recorded. However, in sites dominated by C4plants, above ground dry matter is not significantly related to species richness and diversity. The results suggest that the sites dominated by C3plants and the C3and C4mixed sites are important for diversity conservation in semi-arid grassland of Inner Mongolia. Legumes are important part of natural grassland which plays a significant role in ecological sustainability of grassland ecosystem. At least two legume species occurred in68.8%of the sites studied. It was dominated by annual legumes genera such as Astragalus, Medicago and Caragana. The3-year average annual above ground dry matter was5.97g m-2which accounted for5.02%of total above ground dry matter of community. Both the legume above ground dry matter and its percentage of the total were low in Inner Mongolia. It is concluded that in semi-arid grassland of Inner Mongolia low precipitation combined with high temperatures during the growing season, strongly affecting establishment and growth of annual legumes. In general our study concluded that overgrazing by domestic livestock and limited precipitation are the main cause of grassland degradation, and sustainable grazing management strategies would aid in the conservation of these ecosystems.

Mots clés : grassland production; diversity; grazing; precipitation; above ground dry matter;

Présentation (CNKI)

Page publiée le 14 février 2017, mise à jour le 18 septembre 2017