Effects Of Different Grassland Management Patterns On Soil Nutrients And Stoichiometry

After the implementation of the grassland contracted,two grassland management patters were generated on the Qinghai-Tibetan Plateau,namely single-household management pattern?SMP,neighboring households are separated by fences?and multi-household management pattern?MMP,two or more households share grassland with each other?due to the restriction of water and the psychological dependence of herdsmen.In fact,MMP was an imitation of the traditional nomadic way,which had been prevalent in pastoral areas of the Qinghai-Tibet Plateau at present.However,a series of problems arising from this kind of grassland management?including whether to solve the problems caused by fencing,whether to create new problems,and how to affect animal husbandry production,herdsmen's income and grassland quality?need to be further studied.To this end,by comparing SMP and MMP,it can not only provide a scientific basis for the rational management of grassland in China,but also provide some suggestions for accelerating the development of animal husbandry in pastoral areas.Due to the lack of small-scale ground observation data and the regional differences in the plateau area,and some scholars have indicated that the future focus of the two grassland management patterns should be on soil quality.So,in this study,the soil nutrients and their stoichiometric characteristics under two management patterns?24 SMP and 20 MMP,all of which were winter grasslands?were studied by field investigation and sampling in Nagqu,Tibet.The specific results were as follows:?1?Except to pH and available phosphorus,the SOC,STN,STP and Hydrolyzable Nitrogen of MMP scenario were significantly higher than SMP scenario by 14.4%,12.8%,9.3%and 16.2%.The values of MMP scenario were 84.31 g·kg^-1,6.87 g·kg^-1,0.59 g·kg^-11 and 0.43 g·kg^-1,respectively.The values of SMP scenario were 73.67 g·kg^-1,6.09 g·kg^-1,0.54 g·kg^-1and 0.37 g·kg^-1,respectively.In the vertical direction,except for the soil pH increased significantly with the increase of soil depth,the other nutrient contents decreased significantly with the increase of soil depth,and it had surface aggregation.?2?Except for the 15-30 cm soil layer,the STN:STP of MMP scenario were higher than SMP scenario by 11.5%,and there were no differences in the stoichiometric of the soil between MMP scenario and SMP scenario.In the vertical direction,regardless of management,the SOC:STP and STN:STP at 0-15 cm soil depth were significantly higher than those at 15-30 cm both in SMP and MMP,and SOC:STN in 15-30 cm depth of SMP scenario were significantly higher than soil depth at 0-15 cm.Although MMP scenario also had this trend,the differences were not significant.?3?pH were positively correlated with available phosphorus and SOC:STN?P<0.01?,and negatively correlated with STN:STP?P<0.05?;SOC were positively correlated with nutrient indices and stoichiometric characteristics;STN were positively correlated with other indicators except for a significant negative correlation with SOC:STN;STP were positively correlated with hydrolyzed nitrogen,available phosphorus and STN:STP,and negatively correlated with nagetively correlated with SOC:STN;Hydrolyzed nitrogen were significantly positively correlated with other indicators,except for irrelevant to SOC:STN;Available phosphorus were significantly positively correlated with SOC:STP and STN:STP;SOC:STN was significantly positively correlated with SOC:STP,and negative correlation with STN:STP;SOC:STP was significantly positively correlated with STN:STP.The correlation coefficient between soil SOC and STN was the highest?0.81?.Except for the significant linear correlation between SOC and STN,there were nonlinear coupling relationships between other nutrient indices and their stoichiometric characteristics.In addition to available phosphorus,SOC,STN,STP,pH and hydrolyzed nitrogen had effective influences to SOC:STN;SOC:STP were closely related to SOC,STN,STP and hydrolyzed nitrogen;STN:STP were significantly affected by STN,STP and hydrolyzed nitrogen.In summary,compared with SMP scenario,the soil quality under MMP scenario were better and more conducived to protect grassland.Therefore,the government should strengthen the guidance and training of MMP,construct a more large-scale and complete production system.Secondly,it should protect the existing MMP as much as possible or expand the grassland contractual management rights,implement incentives,and actively encourage more SMP to merge into MMP.Herdsmen should keep the original nomadic elements,such as seasonal transfer,as far as possible according to the local grassland conditions and the development conditions of animal husbandry.In addition,it can not be used to evaluate soil quality in Nagqu area of Tibet by soil stoichiometric characteristics alone.It needs to be combined with soil nutrient status.