Dynamics and controls of ecosystem multiserviceability across the Qingzang Plateau

Ecosystem multiserviceability(EMS),a comprehensive and significant ecological indicator,reflects the capacity of ecosystems to offer multiple services concurrently.Intensified climate change and human activity are continu-ously altering ecosystem functions,services,and EMSs.However,numerous studies have only focused on one or a few ecosystem services,rarely taking into account spatial-temporal distribution and drivers of EMS on behalf of different agencies.We calculated EMS including pastoralist(PA),environmental protection agency(EPA),bio-diversity conservation agency(BCA),and climate change mitigation agency(CCMA)using grassland production,habitat quality,water conservation,and carbon sequestration.Then,the effects of geographical features,climate factors,and human activities on spatial-temporal patterns of EMS were explored.The result indicated that EMS showed a decreasing tendency from the southeast to northwest on the Qingzang Plateau(QZP).Meanwhile,there were no obvious fluctuations in four simulated scenarios(PA,EPA,BCA and CCMA)among different vegetation types during 2000 to 2015.Notably,EMS of all simulated scenarios decreased in the alpine steppe ecosystem,but negligible changes were found in other ecosystems from 2015 to 2020.Moreover,the relative importance of precipitation in annual mean value(from 2000 to 2020)of PA,EPA,BCA and CCMA were 0.13,0.11,0.30 and 0.19,respectively.Overall,precipitation played the dominant role on the dynamics of EMS,followed by elevation and human footprint.Our findings highlighted that understanding the patterns and drivers of EMS could provide a reference for the regional management and maintenance of ecosystem stability on QZP.

Cattle manure biochar and earthworm interactively affected CO_(2)and N_(2)O emissions in agricultural and forest soils:Observation of a distinct difference

The application of manure-derived biochar offers an alternative to avoid the direct application of manure to soil causing greenhouse gas emission.Soil fauna,especially earthworms,can markedly stimulate carbon dioxide(CO_(2))and nitrous oxide(N_(2)O)emissions from soil.This study therefore investigated the effect of cattle manure biochar(added at rates of 0,2%,or 10%,coded as BC0,BC2 and BC10,respectively)application,with or without earthworm Aporrectodea turgida,on emissions of CO_(2) and N_(2)O and changes of physic-chemical properties of agricultural and forest soils in a laboratory incubation experiment.The BC10 treatment significantly enhanced cumulative CO_(2) emissions by 27.9%relative to the untreated control in the agricultural soil.On the contrary,the BC2 and BC10 treatments significantly reduced cumulative CO_(2) emissions by 16.3%–61.1%and N_(2)O emissions by 92.9%–95.1%compared to the untreated control in the forest soil.The addition of earthworm alone significantly enhanced the cumulative CO_(2) and N_(2)O fluxes in agricultural and forest soils.Cumulative CO_(2) and N_(2)O fluxes were significantly increased when BC2 and BC10 were applied with earthworm in the agricultural soil,but were significantly reduced when BC10 was applied with earthworm in the forest soil.Our study demonstrated that biochar application interacted with earthworm to affect CO_(2) and N_(2)O emissions,which were also dependent on the soil type involved.Our study suggests that manure biochar application rate and use of earthworm need to be carefully studied for specific soil types to maximize the climate change mitigation potential of such management practices.

Toward a sustainable grassland ecosystem worldwide

Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of humans.Currently,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal resolutions.In global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland conditions.To master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the globe.As presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial heterogeneity.The decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.

重新认知青藏高原围栏禁牧的作用

围栏禁牧是中国政府为恢复青藏高原等地退化草地而采取的一项重要政策.然而,关于围栏对高寒草地生态系统功能和服务及其对牧民生计的影响,人们的认识还很有限.本研究荟萃分析和基于问卷的调查显示,围栏禁牧时间长达4年和8年的时间里可以有效地促进高寒草甸以及草原的地上植被生长,更长时间的围栏并没有带来任何生态和经济效益.研究还发现,围栏限制了野生动物的活动范围,增加了非围栏地区的放牧压力,降低了牧民的满意度,且给地区和国家政府带来了巨大的财政成本.因此,建议在适当的情况下,应鼓励传统的游牧方式来利用草地,在严重退化的草地上应采用短期围栏(4~8年),在重要的野生动物栖息地应避免使用围栏,特别是受保护的大型哺乳动物分布的区域.研究结果可为青藏高原草地可持续管理提供一定的参考.

Mass loss and nutrient dynamics during litter decomposition in response to warming and nitrogen addition in a desert steppe

Plant litter decomposition has been studied extensively in the context of both warming and increased atmospheric nitrogen deposition. However, the temporal patterns of mass loss and nutrient release in response to warming and nitrogen addition remain unclear. A 2-year decomposition experiment aimed to examine the effects of warming and nitrogen addition on decomposition rate, and nitrogen and phosphorus dynamics. The effects of warming and nitrogen addition on decomposition of litter of Stipa breviflora, a dominant species in a desert steppe of northern China, were studied. Warming and nitrogen addition significantly enhanced litter mass loss by 10% and 16%, respectively, and moreover promoted nitrogen and phosphorus release from the litter in the first year of decomposition, followed by an immobilization period. The interactive effects of warming and nitrogen addition on mass loss, nitrogen and phosphorus concentrations of litter were also found during the decomposition. This study indicates that warming and nitrogen addition increased litter mass loss through altering litter quality. These findings highlight that interactions between climate change and other global change factors could be highly important in driving decomposition responses.

植物功能群在调控气候和土壤因子对蒙古高原草原群落物种丰富度和生物量影响中的作用

植物功能群组成主要受环境因素驱动,同时植物功能群组成也是影响草地生物多样性和生产力的主要因素之一。因此,理解植物功能群在调控环境因素对生态系统功能和生物多样性影响中可能发挥的作用至关重要。通过对蒙古高原草原65个样点的植物生物量和物种丰富度的调查,将157种多年生草本植物分为两种植物功能群(即禾草和杂类草)。通过随机森林模型和普通最小二乘回归,确定与植物功能群物种丰富度和地上生物量显著相关的环境因素(即干燥度、土壤总氮和pH),并利用结构方程模型探讨筛选出的环境因素与群落物种丰富度和生物量间的关系,以及植物功能群在驱动这种关系中发挥的作用。干燥度与禾草、杂类草以及整个群落的地上生物量和物种丰富度均呈显著的单峰关系。所有的物种丰富度和生物量指标均与土壤总氮和pH值显著相关。禾草在维持蒙古高原草原生态系统群落生物量中起着关键作用,并受气候因素的直接影响。而杂类草物种丰富度决定了群落总丰富度,并受到土壤因素直接的调控。因此,群落组成在调控环境因素对群落生物量和植物多样性的影响中起着关键作用。