Changing Spring Phenology Dates in the Three-Rivers Headwater Region of the Tibetan Plateau during 1960–2013

The variation of the vegetation growing season in the Three-Rivers Headwater Region of the Tibetan Plateau has recently become a controversial topic. One issue is that the estimated local trend in the start of the vegetation growing season(SOS)based on remote sensing data is easily affected by outliers because this data series is short. In this study, we determine that the spring minimum temperature is the most influential factor for SOS. The significant negative linear relationship between the two variables in the region is evaluated using Moderate Resolution Imaging Spectroradiometer–Normalized Difference Vegetation Index data for 2000–13. We then reconstruct the SOS time series based on the temperature data for 1960–2013.The regional mean SOS shows an advancing trend of 1.42 d(10 yr)during 1960–2013, with the SOS occurring on the 160th and 151st days in 1960 and 2013, respectively. The advancing trend enhances to 6.04 d(10 yr)during the past 14 years. The spatiotemporal variations of the reconstructed SOS data are similar to those deduced from remote sensing data during the past 14 years. The latter exhibit an even larger regional mean trend of SOS [7.98 d(10 yr)] during 2000–13. The Arctic Oscillation is found to have significantly influenced the changing SOS, especially for the eastern part of the region,during 2000–13.

Grassland degradation in the ＂Three-River Headwaters＂ region, Qinghai Province

Supported by MSS images in the mid and late 1970s,TM images in the early 1990s and TM/ETM images in 2004,grassland degradation in the＂Three-River Headwaters＂region （TRH region）was interpreted through analysis on RS images in two time series,then the spatial and temporal characteristics of grassland degradation in the TRH region were analyzed since the 1970s.The results showed that grassland degradation in the TRH region was a continuous change process which had large affected area and long time scale,and rapidly strengthen phenomenon did not exist in the 1990s as a whole.Grassland degradation pattern in the TRH region took shape initially in the mid and late 1970s.Since the 1970s,this degradation process has taken place continuously,obviously characterizing different rules in different regions.In humid and semi-humid meadow region,grassland firstly fragmentized, then vegetation coverage decreased continuously,and finally＂black-soil-patch＂degraded grassland was formed.But in semi-arid and arid steppe region,the vegetation coverage decreased continuously,and finally desertification was formed.Because grassland degradation had obviously regional differences in the TRH region,it could be regionalized into 7 zones, and each zone had different characteristics in type,grade,scale and time process of grassland degradation.

A method for determining vegetation growth process using remote sensing data: A case study in the Three-River Headwaters Region, China

Accurate measurements of the associated vegetation phenological dynamics are crucial for understanding the relationship between climate change and terrestrial ecosystems. However, at present, most vegetation phenological calculations are based on a single algorithm or method. Because of the spatial, temporal, and ecological complexity of the vegetation growth processes, a single algorithm or method for monitoring all these processes has been indicated to be elusive. Therefore, in this study, from the perspective of plant growth characteristics, we established a method to remotely determine the start of the growth season(SOG) and the end of the growth season(EOG), in which the maximum relative change rate of the normalized difference vegetation index(NDVI) corresponds to the SOG, and the next minimum absolute change rate of the NDVI corresponds to the EOG. Taking the Three-River Headwaters Region in 2000–2013 as an example, we ascertained the spatiotemporal and vertical characteristics of its vegetation phenological changes. Then, in contrast to the actual air temperature data, observed data and other related studies, we found that the SOG and EOG calculated by the proposed method is closer to the time corresponding to the air temperature, and the trends of the SOG and EOG calculated by the proposed method are in good agreement with other relevant studies. Meantime, the error of the SOG between the calculated and observed in this study is smaller than that in other studies.

Climate change and its driving effect on the runoff in the ＂Three-River Headwaters＂ region

Based on the precipitation and temperature data of the 12 meteorological stations in the ＂Three-River Headwaters＂ region and the observed runoff data of Zhimenda in the headwater sub-region of the Yangtze River, Tangnaihai in the headwater sub-region of the Yellow River and Changdu in the headwater sub-region of the Lancang River during the period 1965-2004, this paper analyses the trends of precipitation, temperature, runoff depth and carries out significance tests by means of Mann-KendalI-Sneyers sequential trend test. Mak- kink model is applied to calculate the potential evaporation. The runoff model driven by pre- cipitation and potential evaporation is developed and the influence on runoff by climate change is simulated under different scenarios. Results show that during the period 1965-2004 the temperature of the ＂Three-River Headwaters＂ region is increasing, the runoff of the three hydrological stations is decreasing and both of them had abrupt changes in 1994, while no significant trend changes happen to the precipitation. The runoff model suggests that the precipitation has a positive effect on the runoff depth, while the potential evaporation plays a negative role. The influence of the potential evaporation on the runoff depth of the Lancang River is found to be the significant in the three rivers; and that of the Yellow River is the least. The result of the scenarios analysis indicates that although the precipitation and the potential evaporation have positive and negative effects on runoff relatively, fluctuated characteristics of individual effect on the runoff depth in specific situations are represented.

Livestock-carrying capacity and overgrazing status of alpine grassland in the Three-River Headwaters region, China

The Three-River Headwaters region in China is an ecological barrier providing en- vironmental protection and regional sustainable development for the mid-stream and down- stream areas, which also plays an important role in animal husbandry in China. This study estimated the grassland yield in the Three-River Headwaters region based on MODIS NPP data, and calculated the proper livestock-carrying capacity of the grassland. We analyzed the overgrazing number and its spatial distribution characteristics through data comparison be- tween actual and proper livestock-carrying capacity. The results showed the following： （1） total grassland yield （hay） in the Three-River Headwaters region was 10.96 million tons in 2010 with an average grassland yield of 465.70 kg/hm2 （the spatial distribution presents a decreasing trend from the east and southeast to the west and northwest in turn）; （2） the proper livestock-carrying capacity in the Three-River Headwaters region is 12.19 million sheep units （hereafter described as ＂SU＂）, and the average stocking capacity is 51.27 SU [the proper carrying capacity is above 100 SU/km2 in the eastern counties, 60 SU/km2 in the cen- tral counties （except Madoi County）, and 30 SU/km2 in the western counties]; and （3） total overgrazing number was 6.52 million SU in the Three-River Headwaters region in 2010, with an average overgrazing ratio of 67.88% and an average overgrazing number of 27.43 SU/km2 A higher overgrazing ratio occurred in Tongde, Xinghai, Yushu, Henan and Z^kog. There was no overgrazing in Zhiduo, Tanggula Township and Darlag, Qumerleb and Madoi. The re- mainder of the counties had varying degrees of overgrazing.

基于EOF分析的三江源区植被覆盖变化时空分布特征

基于遥感图像1999—2010年SPOT-VEGETATION NDVI数据,利用经验正交函数(EOF)分析方法,研究了近12a来三江源区植被变化的时空分布特征。结果显示近12a来源区植被覆盖呈整体增加趋势:(1)第一特征向量(方差贡献率为45.62%)及对应时间系数表明源区植被覆盖逐渐增加,且增速加快;(2)第二特征向量(方差贡献率为9.77%)及对应时间系数表明东南部和中部植被变化情况以退化为主,而东北部和西南部植被变化情况以增加为主。

Response of runoff in the headwater region of the Yellow River to climate change and its sensitivity analysis

Response of the runoff in the headwater region of the Yellow River to climate change and its sensibility are analyzed based on the measured data at the four hydrological stations and ten weather stations during the period 1959-2008. The result indicates that change of temperature in the region has an obvious corresponding relationship with global warming and the changes of annual average temperature in each subregion in the region have been presenting a fluctuant and rising state in the past 50 years. However the change of precipitation is more intricate than the change of temperature in the region because of the influences of the different geographical positions and environments in various areas, and the change of annual precipitation in the main runoff-producing area has been presenting a fluctuant and decreasing state in the past 50 years. And there is a remarkable nonlinear correlativity between runoff and precipitation and temperature in the region. The runoff in the region has been decreasing continuously since 1990 because the precipitation in the main run-off-producing area obviously decreases and the annual average temperature continuously rises. As a whole, the runoff in each subregion of the headwater region of the Yellow River is quite sensitive to precipitation change, while the runoff in the subregion above Jimai is more sensitive to temperature change than that in the others in the region, correspondingly.

Temperature variation and abrupt change analysis in the Three-River Headwaters Region during 1961-2010

In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. （1） There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. （2） The tendency rate of annual average temperature in the THRHR was 0.36℃ 10a^-1, while the tendency rates in the Yellow River Headwater Region （YERHR）, Lancangjiang River Headwater Region （LARHR） and Yangtze River Headwater Region （YARHR） were 0.37℃ 10a^-1, 0.37℃ 10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. （3） The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average temperatures were mainly in the late 1990s, while the abrupt changes of autumn and winter average temperatures appeared primarily in the early 1990s and the early 21st century respectively. （4） With the global warming, the diversities of altitude and underlying surface in different parts of the Tibetan Plateau were possibly the main reasons for the high increasing rate of temperature in the THRHR.

Differential changes in precipitation and runoff discharge during 1958–2017 in the headwater region of Yellow River of China

Maintenance of steady streamflow is a critical attribute of the continental river systems for safeguarding downstream ecosystems and agricultural production.Global climate change imposes a potential risk to water supply from the headwater by changing the magnitude and frequency of precipitation and evapotranspiration in the region.To determine if and to what extent the recent climate changes affected streamflow in major river systems,we examined the pattern of temporal variations in precipitation,temperature,evapotranspiration and changes in runoff discharge during 1958–2017 in the headwater region of the Yellow River in northeastern Tibetan Plateau.We identified 1989 as the turning point for a statistically significant 14% reduction in streamflow discharge(P < 0.05) for the period 1989–2017 compared with 1958–1988,approximately coinciding with changes in the monthly distribution but not the interannual variations of precipitation,and detected a mismatch between precipitation and runoff after 2000.Both annual precipitation and runoff discharge displayed fourand eight-year cyclic patterns of changes for the period 1958–1988,and a six-year cyclic pattern of changes for the period 1989–2017,with two intensified two-year cyclic patterns in the changes of precipitation and a three-year cyclic pattern in the change of runoff further detected for the later period.Our results indicate that the temporal changes in runoff are not strictly consistent with the temporal variations of precipitation in the headwater region of Yellow River during the period 1958–2017.In particular,a full recovery in annual precipitation was not reflected in a full recovery in runoff toward the end of the study period.While a review of literature yielded no apparent evidence of raised evapotranspiration in the region due to recent warming,we draw attention to increased local retention of rainwater as a possible explanation of differential changes in precipitation and runoff.

Effects of Grassland Restoration Approaches in Different Major Function-oriented Zones of the Headwater Region of the Yellow River in China

Given the high alpine grassland coverage and intensive animal grazing activity, the ecosystem and livelihood of the herders are extremely vulnerable in the headwater region of the Yellow River. A series of programs have been implemented by the Chinese government to restore degraded grasslands in this region, and major function-oriented zones(MFOZs) applied in 2014, have divided the region into three zones, i.e., the development prioritized, restricted, and prohibited zones, based on environmental carrying capacity, as well as the utilization intensity of grassland. This study identified various restoration approaches adopted in different MFOZs, and assessed the effects of the approaches in order to determine the most effective approaches. We collected 195 questionnaires from herders to analyze the effects of the various restoration approaches, and additional remote sensing and statistical data were also used for the analysis. Four distinct differences in the ecological and socioeconomic characteristics were found in three MFOZs.(1) Five technologies were applied in the study areas.(2) The grassland recovery rate was higher in development prioritized zones than in restricted and prohibited zones during 2000 and 2016, and especially high and very high coverage grasslands increased in the areas where crop-forage cultivation and grass seeding dominated in the prioritized zones.(3) The net income of households in the development prioritized zone was the best of all three zones.(4) The degree of awareness and willingness of herders to restore grassland was more positive in development prioritized zones than in restricted zones, where more herders adopted approaches with a combination of enclosure + deratization + crop-forage cultivation + warm shed. Based on these findings, it is recommended that decision-makers need to increase their efforts to narrow the gap of willingness and behavior between herders and other stakeholders, such as researchers and grassland administrators, in order to ensure grassland sustainability in the MFOZs. It is also beneficial to understand the effects of restoration on the ecological carrying capacities in different zones depending on the different development goals.

Spatio-temporal variation of precipitation in the Three-River Headwater Region from 1961 to 2010

Based on a monthly dataset of precipitation time series （1961-2010） from 12 me- teorological stations across the Three-River Headwater Region （THRHR） of Qinghai Province China, the spatio-temporal variation and abrupt change analysis of precipitation were exam- ined by using moving average, linear regression, spline interpolation, the Mann-Kendall test and so on. Major conclusions were as follows. （1） The long-term annual and seasonal pre- cipitation in the study area indicated an increasing trend with some oscillations during 1961-2010; however, the summer precipitation in the Lantsang （Lancang） River Headwater Region （LARHR）, and the autumn precipitation in the Yangtze River Headwater Region （YERHR） of the THRHR decreased in the same period. （2） The amount of annual precipita- tion in the THRHR and its three sub-headwater regions was greater in the 1980s and 2000s. The springs were fairly wet after the 1970s, while the summers were relatively wet in the 1960s, 1980s and 2000s. In addition, the amount of precipitation in the autumn was greater in the 1970s and 1980s, but it was relatively less for the winter precipitation, except in the 1990s （3） The normal values of spring, summer, winter and annual precipitation in the THRHR and its three sub-headwater regions all increased, but the normal value of summer precipitation in the LARHR had a negative trend and the normal value of winter precipitation declined in general. （4） The spring and winter precipitation increased in most of the THRHR. The summer autumn and annual precipitation increased mainly in the marginal area of the west and north and decreased in the regions of Yushu, Zaduo, Jiuzhi and Banma. （5） The spring and winter precipitation in the THRHR and its three sub-headwater regions showed an abrupt change, except for the spring precipitation in the YARHR. The abrupt changes of spring precipitation were mainly in the late 1980s and early 1990s, while the abrupt changes of winter precipita- tion were primary in the mid- to late 1970s. This research would be helpful for further under- standing the trends and periodicity of precipitation and for watershed-based water resource management in the THRHR.

A systematic review of research studies on the estimation of net primary productivity in the Three-River Headwater Region, China

The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity（NPP） is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we（1） summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;（2） discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and（3） assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.

三江源区鱼类多样性调查及保护对策

了解三江源区鱼类多样性及其资源现状,为三江源区生态系统保护和流域管理提供科学依据。2022年8月开展了长江源、黄河源、澜沧江源鱼类调查,分析了3个水系鱼类组成与分布,探讨了鱼类多样性特征,研究了三江源地区鱼类群落的空间格局。结果表明:三江源区共调查到鱼类18种,其中长江源9种,黄河源8种,澜沧江源6种;根据相对重要性指数,长江源优势种3种,依次为细尾高原鳅(Triplophysa stenura)、小头高原鱼(Herzensteinin microcephalus)、裸腹叶须鱼(Ptychobarbus dipogon),黄河源优势种2种,包括麻尔柯高原鳅(T.markehenensis)和黄河裸裂尻鱼(Schizopygopsis pylzovi),澜沧江源优势种4种,依次为前腹裸裂尻鱼(S.anteroventris)、裸腹叶须鱼、东方高原鳅(T.orientalis)和细尾高原鳅;三江源区鱼类多样性相对较低,其中澜沧江源最高,长江源次之,黄河源最低。对鱼类种类组成进行聚类分析,结果表明长江源和澜沧江源相近,黄河源则与长江源、澜沧江源差距较大。为切实保护好三江源区鱼类资源,建议加强本底调查,开展关键栖息地生态环境监测和保护,构建三江源区水生生物资源数据库,关注气候变化对水生态环境的影响,预防和控制外来鱼类入侵。

三江源区草地水土保持与防风固沙功能临界植被覆盖度时空变化分析

三江源区是中国重要的生态安全屏障,其水土保持与防风固沙功能对中国及其周边地区生态安全具有重大意义。水土保持与防风固沙功能临界植被覆盖度是三江源草地生态保护与恢复的关键指标,但其变化尚不明确。本研究利用修正通用土壤流失方程(RUSLE)和修正通用土壤风蚀方程(RWEQ)模拟了1979—2018年三江源区草地水土保持与防风固沙功能临界植被覆盖度并分析了其时空变化。结果表明:(1)近40年来,三江源区草地水土保持功能临界植被覆盖度东南高、西北低,多年平均值为12.21%±1.42%,年增长率为0.30%(P<0.01)。(2)防风固沙功能临界植被覆盖度西北高、东南低,多年平均值为39.84%±11.94%,有不显著增长趋势。(3)水土保持及防风固沙功能临界植被覆盖度西北高、东南低,多年平均值为45.38%±10.04%,年增长率为0.32%(P<0.05),变化范围为11.73%~58.56%。三江源区西北部水土保持及防风固沙功能临界植被覆盖度大于50%,西南大部分区域不超过40%。(4)水土保持及防风固沙功能临界植被覆盖度在长江源区和黄河源区东北部呈下降趋势,其中黄河源东北部下降趋势显著(P<0.01),在黄河源区南部和澜沧江源区呈显著上升趋势(P<0.01)。本研究结果可为三江源生态环境保护以及高寒草地多目标管理提供科学依据与数据支撑。

近60年三江源地区降水集中度和季节性降水特征变化分析

三江源作为“中华水塔”,是中国重要的淡水之源和生态系统屏障。降水集中度、季节降水量、降水频率和降水强度的演变是气候变暖背景下水循环的关键过程,对植被生长和水资源管理具有重要意义。本研究利用中国气象局1961-2020年的CN05.1日降水格点数据,计算了三江源的降水集中度指数(Precipitation Concentration Index,PCI),厘清了三江源降水集中度和降水年内分配的演变规律,研究了季节降水量、降水频率和降水强度的气候态、年际变化、长期趋势以及距平变化。研究结果表明:(1)三江源地区降水集中指数PCI为17.5,降水具有一定集中性;整个区域PCI由东南向西北递增,降水集中度增大;近60年三江源地区PCI以-1.71%·(10a)^(-1)的变化率减小,降水的年内分配趋于均匀;生长季降水分配的减少将影响该地区农业生产和生态系统的维持。(2)近60年不同季节降水量和降水强度整体呈现显著增加趋势,夏季降水频率减少,其他季节降水频率增加;春夏秋三个季节降水强度的增加主导了降水量的增加,冬季降水频率的增加主导了降水量的增加。冬春季增湿高于夏秋季,春季降水量和降水强度的增长率为8.09%·(10a)-1和6.94%·(10a)^(-1),冬季降雪量和降雪频率的增长率为7.27%·(10a)^(-1)和4.4%·(10a)^(-1);长江源区部分地区的旱涝分布趋于极端化,生态系统的脆弱性加剧。(3)近60年三江源区域平均的降水量、降水频率和降水强度以每年1.36 mm、0.024%和0.0056 mm·d^(-1)的数值增加;降水量、降水频率和降水强度累积距平整体呈现负距平,突变年份分别为2003年、1989年和2003年;雨季降水频率减小,降水强度增加,旱季降水频率和降水强度均增加,这种变化在近10年尤为剧烈。本研究可以为该地区土壤侵蚀、农业生产、水资源管理以及气候变化相关研究提供参考。

三江源地区春季流量与积雪的年际变化关系

基于三江源区站点流量资料、中国区域格点降水气温资料及遥感积雪资料,分析了长江、黄河和澜沧江源区春季流量的年际变化及其与降水、积雪、气温的关系。结果表明,1980~2020年三江源地区春季流量年际变化显著,其中5月流量的年际变率最大;三江源地区春季流量受春季雪深影响最大,其中4月、5月流量受雪深、积雪覆盖率、前期累积降水的影响显著,且流量与雪深的正相关性最强,5月流量与雪深相关系数可达0.7以上。进一步分析表明,高原积雪对流量的影响随源区不同流域、春季不同月份呈现一定的差异,其中黄河源区4月、5月流量受4月雪深影响最明显,澜沧江源区4月、5月流量与2~5月的雪深均存在较好关系,而长江源区5月流量则主要与4~5月雪深显著正相关。源区积雪对春季流量的影响也存在一定的海拔依赖性,其中低海拔区域积雪对流量的影响更多体现在春季前期,而黄河源区阿尼玛卿山、长江源区巴颜喀拉山脉及唐古拉山脉等高海拔区域的积雪对流量的影响可以持续到5月。气温作为春季融雪径流的关键因子,主要是通过影响源区前期积雪量、融雪产流过程,进而影响春季流量的异常。本研究结果在深入认识青藏高原气候变化对三江源地区春季流量的影响及过程等方面具有重要意义。

基于贝叶斯模型平均的2003–2015年青海三江源地区地表蒸散发数据集

蒸散发(Evapotranspiration,ET)是陆地水、碳和能量交换的重要组成部分。基于不同模型和不同遥感数据估算的ET,存在不同程度的不确定性。贝叶斯模型平均(Bayesian model averaging,BMA)提供了降低不确定性的一种途径。本研究采用中国三江源地区水热通量观测数据,以ARTS、PT-JPL、MOD16和SSEBop遥感蒸散发产品为基础,进行了BMA集成研究,生成了三江源地区2003–2015年250 m空间分辨率的年均地表蒸散发数据集。通过验证各输入模型和BMA集成模型结果,发现基于BMA的ET与通量观测数据相关性达0.94,能够解释观测数据季节变化的89%,优于单个模型的性能。说明BMA模型集成能够整合不同模型内在优势,降低结果估算的不确定性,从而获得更可靠的估算结果。本数据集可为三江源区域水热变化研究和生态系统调节功能评估提供更精确的数据支持。

三江源区高寒草原退化对不同生长期土壤真菌群落的影响

土壤真菌群落在草地生态系统物质循环过程中扮演着重要角色,但草地退化对不同生长期土壤真菌群落的影响尚不清楚。本研究以三江源高寒草原为研究对象,通过野外调查和高通量测序技术,探究草原退化对植物不同生长期土壤真菌群落特征的影响及其驱动因素。结果表明,三江源区高寒草原不同生长期土壤真菌群落优势菌门均为子囊菌门和担子菌门,草原退化显著降低了优势菌门的相对丰度;在不同生长期土壤真菌群落多样性存在显著差异(P<0.05),表现为生长季初期较低,末期则较高;草原退化对土壤真菌群落多样性影响不显著(P>0.05),但显著改变了不同生长期内土壤真菌群落结构(P<0.05);相比于原生草原,退化草原土壤真菌群落结构与植物群落特征表现出更强的相关关系,植物群落生物量和土壤有机质含量是显著影响退化草原土壤真菌群落结构的主要因子(P<0.05)。研究结果表明,草原退化改变了土壤真菌群落结构,增强了土壤真菌群落的资源限制。因此,针对植被群落的修复将有利于退化高寒草原土壤真菌群落的恢复。

三江源区蒸散发时空变化特征及影响因素分析

为研究2001~2020年三江源区蒸散发的时空变化特征以及影响因素,基于MOD16A2数据和气象数据,采用Slope趋势分析、MK显著性检验和偏相关分析,分析了三江源区蒸散发的年际变化、空间分布、趋势变化和对气候的响应。结果表明:2001~2020年三江源区多年平均蒸散发为401.28 mm,平均以0.9821 mm/a的速率缓慢增加。三江源区蒸散发空间变化范围为46.51~575.59 mm,呈现东部高、西部低的特征;2001~2020年三江源区蒸散发主要呈现上升的趋势,主要分布在三江源区的东北部地区;气温升高对蒸散发增加起到了显著的促进作用。研究成果可为三江源区水资源管理、生态环境保护以及气候变化适应等方面提供参考。

三江源区高寒草地生态恢复措施及效果评价

基于文献计量法整理了2005—2020年三江源区生态保护、恢复和建设的文献,梳理了三江源区主要生态保护、恢复和建设措施,提出恢复与建设效果评价指标体系,运用Meta分析评估不同恢复措施在高寒退化草地生态系统恢复中的效果.结果表明:高寒轻度退化草地最适合的技术措施是短期、中期围栏封育和N、P添加,不适合长期禁牧和大量施肥.中度退化草地最适合的技术措施是休牧、追加N、P或大量氮肥,不适合施有机肥或低氮肥.重度退化草地最适合的技术措施是休牧,不适合采用短期围栏封育和低氮量施肥.