Spatio-temporal Pattern of Net Primary Productivity in Hengduan Mountains area, China： Impacts of Climate Change and Human Activities

Net primary productivity(NPP), a metric used to define and identify changes in plant communities, is greatly affected by climate change, human activities and other factors. Here, we used the Carnegie-Ames-Stanford Approach(CASA) model to estimate the NPP of plant communities in Hengduan Mountains area of China, and to explore the relationship between NPP and altitude in this region. We examined the mechanisms underlying vegetation growth responses to climate change and quantitatively assessed the effects of ecological protection measures by partitioning the contributions of climate change and human activities to NPP changes. The results demonstrated that: 1) the average total and annual NPP values over the years were 209.15 Tg C and 468.06 g C/(m2·yr), respectively. Their trend increasingly fluctuated, with spatial distribution strongly linked to altitude(i.e., lower and higher NPP in high altitude and low altitude areas, respectively) and 2400 m represented the marginal altitude for vegetation differentiation; 2) areas where climate was the main factor affecting NPP accounted for 18.2% of the total research area, whereas human activities were the primary factor influencing NPP in 81.8% of the total research area, which indicated that human activity was the main force driving changes in NPP. Areas where climatic factors(i.e., temperature and precipitation) were the main driving factors occupied 13.6%(temperature) and 6.0%(precipitation) of the total research area, respectively. Therefore, the effect of temperature on NPP changes was stronger than that of precipitation; and 3) the majority of NPP residuals from 2001 to 2014 were positive, with human activities playing an active role in determining regional vegetation growth, possibly due to the return of farmland back to forest and natural forest protection. However, this positive trend is decreasing. This clearly shows the periodical nature of ecological projects and a lack of long-term effectiveness.

Quantitative Assessment of the Relative Contributions of Climate and Human Factors to Net Primary Productivity in the Ili River Basin of China and Kazakhstan

It is necessary to quantitatively study the relationship between climate and human factors on net primary productivity(NPP)inorder to understand the driving mechanism of NPP and prevent desertification.This study investigated the spatial and temporal differentiation features of actual net primary productivity(ANPP)in the Ili River Basin,a transboundary river between China and Kazakhstan,as well as the proportional contributions of climate and human causes to ANPP variation.Additionally,we analyzed the pixel-scale relationship between ANPP and significant climatic parameters.ANPP in the Ili River Basin increased from 2001 to 2020 and was lower in the northeast and higher in the southwest;furthermore,it was distributed in a ring around the Tianshan Mountains.In the vegetation improvement zone,human activities were the dominant driving force,whereas in the degraded zone,climate change was the primary major driving force.The correlation coefficients of ANPP with precipitation and temperature were 0.322 and 0.098,respectively.In most areas,there was a positive relationship between vegetation change,temperature and precipitation.During 2001 to 2020,the basin’s climatic change trend was warm and humid,which promoted vegetation growth.One of the driving factors in the vegetation improvement area was moderate grazing by livestock.

Monitoring the impact of climate change and human activities on grassland vegetation dynamics in the northeastern Qinghai-Tibet Plateau of China during 2000–2015

Climate change and human activities can influence vegetation net primary productivity(NPP), a key component of natural ecosystems. The Qinghai-Tibet Plateau of China, in spite of its significant natural and cultural values, is one of the most susceptible regions to climate change and human disturbances in the world. To assess the impact of climate change and human activities on vegetation dynamics in the grassland ecosystems of the northeastern Qinghai-Tibet Plateau, we applied a time-series trend analysis to normalized difference vegetation index(NDVI) datasets from 2000 to 2015 and compared these spatiotemporal variations with trends in climatic variables over the same time period. The constrained ordination approach(redundancy analysis) was used to determine which climatic variables or human-related factors mostly influenced the variation of NDVI. Furthermore, in order to determine whether current conservation measures and programs are effective in ecological protection and reconstruction, we divided the northeastern Qinghai-Tibet Plateau into two parts: the Three-River Headwater conservation area(TRH zone) in the south and the non-conservation area(NTRH zone) in the north. The results indicated an overall(73.32%) increasing trend of vegetation NPP in grasslands throughout the study area. During the period 2000–2015, NDVI in the TRH and NTRH zones increased at the rates of 0.0015/a and 0.0020/a, respectively. Specifically, precipitation accounted for 9.2% of the total variation in NDVI, while temperature accounted for 13.4%. In addition, variation in vegetation NPP of grasslands responded not only to long-and short-term changes in climate, as conceptualized in non-equilibrium theory, but also to the impact of human activities and their associated perturbations. The redundancy analysis successfully separated the relative contributions of climate change and human activities, of which village population and agricultural gross domestic product were the two most important contributors to the NDVI changes, explaining 17.8% and 17.1% of the total variation of NDVI(with the total contribution >30.0%), respectively. The total contribution percentages of climate change and human activities to the NDVI variation were 27.5% and 34.9%, respectively, in the northeastern Qinghai-Tibet Plateau. Finally, our study shows that the grassland restoration in the study area was enhanced by protection measures and programs in the TRH zone, which explained 7.6% of the total variation in NDVI.

Desertification dynamic and the relative roles of climate change and human activities in desertification in the Heihe River Basin based on NPP

Relative roles of climate change and human activities in desertification are the hotspot of research on desertification dynamic and its driving mechanism.To overcome the shortcomings of existing studies,this paper selected net primary productivity （NPP） as an indicator to analyze desertification dynamic and its impact factors.In addition,the change trends of actual NPP,potential NPP and HNPP （human appropriation of NPP,the difference between potential NPP and actual NPP） were used to analyze the desertification dynamic and calculate the relative roles of climate change,human activities and a combination of the two factors in desertification.In this study,the Moderate Resolution Imaging Spectroradiometer （MODIS）-Normalised Difference Vegetation Index （NDVI） and meteorological data were utilized to drive the Carnegie-Ames-Stanford Approach （CASA） model to calculate the actual NPP from 2001 to 2010 in the Heihe River Basin.Potential NPP was estimated using the Thornthwaite Memorial model.Results showed that 61％ of the whole basin area underwent land degradation,of which 90.5％ was caused by human activities,8.6％ by climate change,and 0.9％ by a combination of the two factors.On the contrary,1.5％ of desertification reversion area was caused by human activities and 90.7％ by climate change,the rest 7.8％ by a combination of the two factors.Moreover,it was demonstrated that 95.9％ of the total actual NPP decrease was induced by human activities,while 69.3％ of the total actual NPP increase was caused by climate change.The results revealed that climate change dominated desertification reversion,while human activities dominated desertification expansion.Moreover,the relative roles of both climate change and human activities in desertification possessed great spatial heterogeneity.Additionally,ecological protection policies should be enhanced in the Heihe River Basin to prevent desertification expansion under the condition of climate change.

气候变化和人类活动对云南省植被净初级生产力的影响

深入理解气候变化和人类活动对植被变化的驱动机制对于生态保护和可持续发展有重要的科学意义。本研究基于MOD17A3/NPP产品数据,采用线性趋势分析、Mann-Kendall显著性分析、Hurst指数和二阶偏相关分析,探讨云南省2001-2021年植被NPP的时空分布特征和未来持续性以及植被NPP与气候条件的关系。采用偏导趋势残差法分离和量化气候变化和人类活动对植被NPP的影响。结果发现,空间上,2001-2021年云南植被NPP年均值南高北低。不同植被类型NPP值(单位:gC∙m^(-2))从大到小依次为:林地(1106.7 gC∙m^(-2))、灌木(964.4 gC∙m^(-2))、农田(946.6 gC∙m^(-2))和草地(878.8 gC∙m^(-2))。植被NPP随海拔上升先增后降。(2)在研究时段内,植被NPP年均值为1020.8±30.7 gC∙m^(-2),最小值和最大值分别出现在2010年(950.0)和2019年(1062.1)。植被NPP呈显著增加趋势,增加率为2.1 gC∙m^(-2)∙a^(-1)(p<0.05),增加和显著增加的面积分别占研究区总面积70.0%和26.3%。不同植被类型NPP的增加率(单位:gC∙m^(-2)∙a^(-1))从大到小依次为:草地(4.1 gC∙m^(-2)∙a^(-1))、农田(3.5 gC∙m^(-2)∙a^(-1))、灌木(2.8 gC∙m^(-2)∙a^(-1))和林地(1.3 gC∙m^(-2)∙a^(-1))。Hurst指数均值为0.60,植被NPP未来变化趋势持续增加和由减少转为增加的面积占总面积的55.5%和9.3%,表明大部分地区植被NPP未来仍将持续增加。(3)2001-2021年云南省平均气温显著增加,降水和太阳辐射波动减少。大部分地区植被NPP与气温、降水和太阳辐射正相关,气温对植被NPP的影响大于降水和太阳辐射。(4)气候变化和人类活动对云南植被NPP变化的相对贡献率分别为27.1%和72.9%,正贡献的面积分别占研究区总面积的59.4%和64.6%,相对贡献率>60%的面积占比分别为12.7%和73.4%。大部分地区人类活动对植被NPP的影响大于气候变化。云南植被改善主要受气候变化和人类活动的共同作用的影响,植被退化则主要受人类活动主导和两者共同作用的影响,生态保护、恢复工程对云南植被改善有着显著的促进作用。

1982—2020年乌兰县植被NPP时空动态特征及驱动力量化分析

气候变化和人类活动对植被NPP(net primary productivity,净初级生产力)的驱动作用是全球气候变化背景下的研究热点,并且在不同的时空尺度上尚不能达成共识。中国西北寒旱牧区植被生态系统脆弱,对气候变化和人类活动的响应十分敏感,该研究以青海省乌兰县作为代表性研究区,采用GIMMS-NDVI and MOD-NDVI数据融合构建了长时序归一化植被指数(normalized difference vegetation index,NDVI)数据集,并结合CASA(carnegie-ames-stanford approach)模型获取了研究区1982—2020年植被生长季NPP,利用Sen+MK趋势分析方法探究了研究区植被生长季NPP的时空演变特征,同时采用构建的ADE+Sen量化归因方法对多种气候要素和人类活动的驱动作用进行了定量分析。结果表明,研究区植被生长季NPP多年均值为(205.9±11.5)g/(m^(2)·a)(以C计),年际变化无显著趋势,不同植被类型的生长季NPP年际波动过程与全域生长季NPP基本一致。在空间上,植被生长季NPP自西向东逐渐增加,年际变化趋势具有明显的空间异质性,且整体以退化为主,平均变化率为-0.151 g/(m^(2)·a2),其中表现出严重退化和轻度退化的面积占比分别达到了31.7%和29.5%。气候变化主导的植被面积占比达85.2%,其贡献值的绝对平均值为1.025 g/(m^(2)·a2),约是人类活动贡献值绝对平均值的2倍,太阳辐射、降水量、平均气温和平均风速均是影响植被生长季NPP动态的主要气候因素。该研究表明研究区植被整体表现为退化状态,气候变化是导致该现象的主导驱动因素。研究结果可为中国西北寒旱牧区植被生态系统的可持续利用和保护提供参考。

高寒生态系统脆弱性及其对气候变化和人类活动的响应

了解陆地生态系统的脆弱性和基本机制是适应和减轻全球气候变化影响的决策基础。生态系统的脆弱性可以通过生产力对气候变化的敏感性和适应性进行量化。采用1982—2018年青海省境内基于遥感的现实净初级生产力(NPP_(R))和气候驱动的潜在净初级生产力(NPP_(C)),量化了高寒生态系统的敏感性(Sensitivity)、适应性(Adaptability)和脆弱性(Vulnerability)。然后探讨了生态系统脆弱性的时空变化,并分别从人类活动和气候变化的影响方面分析了其基本机制。结果表明:(1)基于NPP_(R)和NPP_(C)的生态系统脆弱性在空间上呈现出中度脆弱的模式,脆弱性从东南向西北由不脆弱依次递增到极度脆弱等级。(2)耕地的脆弱性较低,基于NPP_(R)和NPP_(C)的指数分别为-1.31和-0.93,这是由于其适应水平较高而敏感性较低;森林次之,指数为-1.18(NPP_(R))和-1.06(NPP_(C));草原的指数为-0.17(NPP_(R))和-0.17(NPP_(C));而荒漠的脆弱性较高,指数为0.77(NPP_(R))和0.78(NPP_(C)),这是由于其敏感性较高,适应性较低。(3)基于NPP_(R)的高寒草地的脆弱性有两个温度阈值(-2.2±0.8)℃和(5.5±0.8)℃,一个降水阈值(387±45.6)mm,两个干旱指数阈值为(14.2±20.2)和(78.2±20.2)。而基于NPP_(C)的脆弱性也发现了同样的阈值,并且数值相似。阈值表明最佳气候条件下,生态系统将具有较高的适应性和较低的敏感性,即较低的脆弱性。但如果气温较低或较高,或者降水较低,生态系统的脆弱性将会更高。(4)人类活动对东部地区生态系统的脆弱性产生了强烈的影响,但就整个青海省的生态系统而言,这些影响在区域平均水平上较小。这项研究表明,在高寒脆弱的生态系统中,气候条件决定了脆弱性在空间上的分布情况,这应该被视为生态保护决策的理论基础。此外,本研究发现的阈值将为生态系统生态学提供一个案例研究,并应在世界各地的脆弱生态系统中广泛探索。

草地植被生产力模拟及其影响因素

准确估算草地生态系统的净初级生产力是研究全球陆地碳氮循环的重要问题之一。本研究探讨了人类活动和气候变化对草地植被生产力的影响及其作用机制,回顾了用于估算植被生产力的模型方法:统计模型、光能利用率模型、生态系统过程模型的发展和进步及其应用现状。在总结不同估算植被生产力模型研究进展的基础上,探讨模型应用于草地生态系统研究时存在的优势和局限性,为今后有关草地植被生产力的研究中可以根据不同研究对象的特点选择更为合适的研究方法提供一定的借鉴。

云南省净初级生产力时空变化及其影响因素分析

净初级生产力(net primary production,NPP)是衡量生态系统碳循环的重要指标。文章基于MOD17A3HGF数据和气象数据,利用Theil-Sen Median趋势分析、重心模型和相关性分析等方法对云南省2011—2020年NPP时空变化特征和影响因素进行研究,并定量区分人类活动和气候变化对植被的影响。结果表明:2011—2020年云南省NPP在空间上呈自西向东、自南向北逐渐下降的分布特征,平均值为1025.22 gC·m^(-2)·a^(-1);高波动区主要分布在迪庆藏族自治州和怒江傈僳族自治州;NPP与气温显著相关区域主要分布在滇东地区,与降水显著相关区域主要分布在滇中和滇东北地区;影响研究区植被恢复的因子顺序为:气候变化>气候变化与人类活动共同作用>人类活动;影响研究区植被退化的因子顺序为:人类活动>气候变化与人类活动共同作用>气候变化。

Environmental factors affecting regional differences and decadal variations in the buried flux of marine organic carbon in eastern shelf sea areas of China

To characterize environmental factors controlling decadal-scale variations in the buried flux of marine organic carbon(BFC_(m))in the eastern shelf sea areas of China(ECSS),four well preserved sediment cores collected from the central Yellow Sea mud(CYSM)area,the Yellow Sea Coastal Current(YSCC)area and the Changjiang River Estuary(CRE)were investigated in this study.In the CYSM,variations in BFC_(m) were found to be dependent on variations in primary productivity and to exhibit a cyclical trend possibly related to fluctuations in the Pacific Decadal Oscillation(PDO)and the East Asian winter monsoon index(EAWM).In the YSCC,BFC_(m) likewise depends on primary productivity.Prior to the 1950s,variations in BFC_(m) were similar to that of the EAWM.After the 1950s,BFC_(m) increased rapidly and exhibited maximum values in the surface layer,consistent with an increase in primary productivity caused by the input of terrestrial nutrients associated with China’s economic development.In the CRE,variations in BFC_(m) were affected by several competing factors making it difficult to identify clear relationships between variations in BFC_(m) and primary productivity.In contrast,long-term variability in BFC_(m) is more similar to changes in the Changjiang River sediment load.Thus,it is speculated that the construction of dams along the Changjiang River may be the main cause of variations in BFC_(m) in this area.Given the disproportionate effects of human activities on marine environments and decadal variations in BFC_(m) in the ECSS,careful attention should be paid to regional differences in organic carbon preservation and environmental changes lest estimates of these values be made imprecise or inaccurate.

祁连山国家公园植被时空变化及其对人类活动的响应

祁连山国家公园地处青藏、蒙新、黄土三大高原交汇地带的祁连山北麓,作为国家公园体制试点之一,是我国重要的生态功能区、水源涵养地和生物多样性保护优先区域,其生态功能不可忽视。以祁连山国家公园2000—2019年归一化植被指数(NDVI)和净初级生产力(NPP)数据为基础,结合气温、降水、土地利用、矿产开采和旅游发展数据,利用泰尔-森趋势分析(Theil-Sen趋势分析)、曼-肯德尔检验(Mann-Kendall显著性检验)、土地转移概率矩阵和多元残差分析方法,分析该区域的植被时空分布特征、变化趋势特征及其对气候变化和人类活动的响应。结果表明:(1)2000—2019年祁连山国家公园内NDVI和NPP在空间上呈现出东南高西北低,由东南向西北递减的格局。时间上呈现上升趋势,上升速率分别为0.0053/a和0.0014/a;(2)祁连山国家公园内NPP提高、降低和稳定区域分别占总面积的87.29%、0.40%和12.30%。降低区域零星分布于整个国家公园,其中在走廊南山和冷龙岭交汇处,靠近甘青两省交界边缘分布最为集中。提高区域分布广泛,尤其以国家公园东部最为明显;(3)祁连山国家公园NDVI与气温呈现显著正相关区域约占40.18%,与降水呈现正相关区域约占25.70%,气温上升、降水增多促进了国家公园植被生长,适宜的水热组合对植被生长更有利;(4)人类活动对植被变化的影响具有两面性:约有28.91%矿业、旅游和水电站在整改、规范之后植被生长状况仍较差,生态环境没有明显恢复;退耕还林还草工程、生态林建设工程成效显著,近3年林地、草地面积增多。(5)祁连山国家公园大部分植被覆盖变化是由气候变化和人类活动共同导致。

气候变化和人类活动对祁连山国家公园植被净初级生产力的定量影响

祁连山国家公园作为西北地区重要的生态安全屏障和水源涵养地,研究其植被变化对西北地区的生态安全具有重要意义。基于2000—2019年祁连山国家公园的MOD17A3遥感数据,利用一元线性回归、偏相关分析、多元线性回归和残差分析等方法,分析了祁连山国家公园植被净初级生产力(NPP)的时空态势及其与降水、气温和人类活动的相关性,在此基础上量化气候变化和人类活动对植被NPP的影响。结果表明:(1)2000—2019年祁连山国家公园植被NPP整体呈波动上升趋势,且空间上呈东高西低的分布格局,其多年平均值为113.14 g C m^(-2)a^(-1),年均增长量达1.41 g C m^(-2)a^(-1);(2)植被NPP与降水、气温均呈正相关,其中降水对植被NPP影响更为显著;(3)人类活动区植被NPP总体呈增加趋势,与2016年相比,2019年人类活动区植被NPP增加的面积占87%,植被NPP降低的面积占13%;(4)在植被恢复区,气候变化和人类活动对植被恢复分别解释了92%和8%;在植被退化区,气候变化和人类活动对植被退化分别解释了29%和71%。研究结果可为祁连山国家公园生态环境保护与管理提供科学的决策依据。

气候因素和人类活动对砒砂岩区植被净初级生产力的影响

砒砂岩区是黄土高原水土流失最严重的地区之一,其植被生长状况对该区控制土壤侵蚀和维护生态平衡起着重要作用。本文基于CASA模型和Rclimdex 1.0分别计算了2001—2021年砒砂岩区植被净初级生产力NPP和18个极端气候指数,采用趋势分析、相关分析、随机森林重要性排序、残差分析等研究了砒砂岩区NPP时空变化及其对气候因素的响应特征,并量化了气候因素和人类活动对砒砂岩区NPP的相对贡献。结果表明:(1)2001—2021年砒砂岩区NPP变化呈显著增加趋势,但未来82.5%的区域NPP将由增加趋势变为减少趋势。(2)年际尺度上,砒砂岩区NPP与年均气温、年总降水量、极端强降水指数主要呈正相关,与冷夜日数TN10P、气温日较差DTR呈负相关。季节尺度上,春季均温以及暖夜日数增加有利于NPP增加,且存在滞后影响。夏季暖昼日数增加不利于植被生长,且NPP对夏季暖昼日数存在3个月的滞后响应。夏季极端强降水有利于NPP增加,而夏季干旱不利于植被生长,且NPP对持续干燥日数CDD存在3个月的滞后响应。(3)气候因素和人类活动共同促进了砒砂岩区NPP增加,裸露区和覆沙区气候贡献占主导地位,气候因素相对贡献为62.13%和60.06%,覆土区以人类活动贡献为主导,人类活动贡献率为60.40%。

黄河流域草地净初级生产力时空动态及其驱动机制

黄河流域是生态系统的敏感区,流域草地生态系统在气候变化和人类活动驱动下发生了显著变化。基于多源遥感影像和气象站点资料等,采用改进后的CASA模型估算2001—2018年黄河流域草地净初级生产力(NPP),评估定量反演结果精度,分析研究时段内流域草地净初级生产力时空动态,探讨气候要素和人类活动对流域草地净初级生产力的影响。结果表明:1)基于改进的CASA模型能够高精度模拟黄河流域草地NPP。2)2001—2018年黄河流域草地NPP呈增加趋势,且在2013年发生突变。2001—2013年气候和人类活动均促进流域草地NPP增加,而2013年后人类活动抑制流域草地NPP增加的作用明显增强,抑制区域面积较前一阶段增加34.89%。整体上,人类活动对草地NPP的影响强度低于气候要素影响强度。3)耕地和建设用地面积的变化,是驱动实际净初级生产力动态的重要人类活动要素。耕地和建设用地面积的增加与草地面积减少、实际净初级生产力增加速率的降低紧密相关。伴随经济发展,应坚持实施退耕还林还草政策,并加强对草地生态保护的监督。

青藏高原不同季节植被NPP空间分异的定量归因

对人类活动量化中考虑区域生态条件的差异,基于季节尺度,利用潜在NPP与实际NPP计算HAII,选取植被类型、高程、坡度等7个自然因子与HAII进行空间分异探测分析,以更细的季节尺度揭示多因子的影响规律。结果表明:在描述青藏高原人类活动对植被NPP的空间分异影响方面,HAII的解释力与显著性均优于人类活动值,其解释力最高为0.714。在多因子影响植被NPP空间分异方面,自然与人为因子均表现出明显季节差异,夏季人类活动解释力最高,春、秋季减弱,冬季则主要受自然因子影响。其中,坡度、温度、法向直射辐射量与散射辐射量在春、秋、冬季表现出单一的驱动影响,植被生存条件较好的夏季,因子出现明显拐点,降水因子的限制阈值随季节变化。因子交互作用中,人类活动、降水、气温及植被类型4个因子之间产生的交互作用是影响青藏高原NPP的主要驱动力。综合人类活动及多个自然因子,在青藏高原植被生态工程建设中,需主要考虑人类活动、降水、气温及植被类型4个因子,各季节主导因子不同。在干旱少雨地区,人类活动应被重点考虑。研究结果可为不同植被生境条件下的区域提供生态系统管理的参考依据。

中国植被NPP变化及其影响因素分析

为了厘清2001—2020年植被净初级生产力(net primary production,NPP)变化及其影响因素的具体作用机制,通过趋势分析研究中国植被NPP时空变化趋势,通过残差分析定量分析人类活动对植被生长变化过程中的作用,基于土地利用变化、气象、社会经济活动等数据建立结构方程模型,分析气候以及具体的人类活动对植被NPP变化的影响。结果表明:植被NPP变化及影响因素具有阶段性和区域性;植被NPP在20年间整体呈上升趋势,人类活动起到促进作用;从行政分区上看,北方等区域在前10年具有较快的增长趋势,南方等区域在后10年具有较快的增长趋势;20年间,影响植被NPP变化的驱动因子主要为气候和人为改变土地利用,在后10年则主要为人为改变土地利用的影响,气候因子影响能力降低。该研究揭示了中国植被NPP变化趋势及其影响因素的具体作用机制,对理解中国生态环境变化具有重要意义,可为制定相应的环境保护和生态恢复政策提供科学依据。

近30年来江苏海岸带NPP和LST的时空变化及影响因素

近30年来,复杂的气候变化与剧烈的人类活动造成江苏省海岸带生态演变剧烈,且呈现显著的空间异质性。植被净初级生产力(NPP)和地表温度(LST)是生态系统的2个关键参数,通过将1990−2020年Landsat遥感影像与CASA计算模型和相关性分析等方法结合,分析了江苏海岸带NPP和LST的时空变化及影响因素,结果表明:①由于人类对沿海滩涂资源的利用以及养殖业的发展等,江苏海岸带范围随岸线不断变化,岸线逐步向海推进,且南部向海推进范围大于北部。②近30年来,江苏海岸带NPP和LST呈现出显著的时空异质性特征。时间上1990、2000、2010、2020年代的NPP月均值分别为102.88、88.23、156.62、98.90 g C·m^(−2),呈现下降-上升-下降趋势,而LST月均值分别为32.6、31.7、28.3、37.6℃,呈现先下降后上升的趋势。空间上,NPP与LST在江苏海岸带南北分布呈现出一定差异性。③地表覆盖类型是影响江苏海岸带NPP和LST时空异质性的主要因素。林地的NPP最高,养殖池塘NPP最低;人工建筑的LST值最高,湿地、水域与养殖池塘的LST值相对较低。此外,随着气温升高,NPP和LST有逐渐上升的趋势,而植被覆盖度的升高则导致NPP上升和LST下降。

Impacts of land conversion and management measures on net primary productivity in semi-arid grassland

Ecological restoration measures implemented in China have profoundly impacted vegetation NPP.This study aimed to estimate the effects of the land conversion and management measures on the grassland ecosystem in semi-arid regions.Land use data were employed from 2000 to 2015 to compare land conversion and coverage changes in Xilingol grassland.Then,the contributions of land conversion and management policies were quantified by assessing the difference between actual NPP and climate-induced NPP changes.The results indicated that the grassland area had a net loss of 534.42 km^(2),and the net area of increased vegetation coverage was 74,683.05 km^(2).Furthermore,the total NPP increased by 8,010.73 Gg C·yr^(−1)(1 Gg=10^(9)g),of which the human activities,including grazing management measures(+6,809.40 Gg C·yr^(−1))and land conversion(45.72 Gg C·yr^(−1))contributed to 85.58%of the increase in NPP.Transformation from desert and farmland dominated grassland expansion and NPP increase,while urbanization and desertification caused large grassland reduction and NPP loss.The grazing management increased vegetation NPP in most regions except for some regions in the desert steppe and the farming-pastoral zone.Related policies should be further adjusted to strengthen the management of the desert steppe and farming-pastoral regions.

基于全球净初级生产力的能源足迹计算方法

净初级生产力是当前生态足迹改进研究的重要突破口。针对传统能源足迹存在着忽略多数土地的碳吸收贡献、碳吸收能力界定不清等不足,提出了基于全球平均净初级生产力的能源足迹计算方法。结果表明:单位质量能源的生态足迹空间构成中,前3位依次为海洋、林地和草地,分别占28.32%、27.25%、21.77%。单位空间占用面积的能源热值由高至低依次为电力、气态、液态和固态能源,分别达2.11×106—9.76×107、108—116、88—99、68—72 GJ/hm2。对各类能源生态影响的判断均较传统方法乐观,这是综合考虑全球各类土地和水体碳吸收贡献的结果。基于全球净初级生产力的能源足迹反映了能源消费的空间占用平均水平,有助于提高评价结果的真实性与准确性。

净初级生产力的人类占用:一种衡量区域可持续发展的新方法

可持续发展的生态评估是当前国际生态经济学与可持续发展研究的前沿问题之一,净初级生产力的人类占用从生态系统初级生产力的角度可以定量评估一个国家或地区发展的生态持续性程度,是近年来国际上一种重要的生物物理量衡量方法。论文简要介绍了净初级生产力人类占用的基本理论与核算方法,分析了该方法应用于区域可持续发展生态评估的基本原理。综合国外相关研究的最新进展,研究认为,定量表征区域可持续发展的生态上限是净初级生产力人类占用方法的最大优点,而该方法应用于区域可持续发展生态评估的不足之处则主要表现在关键参数的不确定性、可持续性的评价阈值、研究数据的缺乏和生物量进出口问题等4方面。