Evaluation of the water conservation function in the Ili River Delta of Central Asia based on the InVEST model

The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.

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.

Spatial Variability of Soil Carbon to Nitrogen Ratio and Its Driving Factors in Ili River Valley,Xinjiang,Northwest China

Soil carbon to nitrogen(C/N) ratio is one of the most important variables reflecting soil quality and ecological function,and an indicator for assessing carbon and nitrogen nutrition balance of soils.Its variation reflects the carbon and nitrogen cycling of soils.In order to explore the spatial variability of soil C/N ratio and its controlling factors of the Ili River valley in Xinjiang Uygur Autonomous Region,Northwest China,the traditional statistical methods,including correlation analysis,geostatistic alanalys and multiple regression analysis were used.The statistical results showed that the soil C/N ratio varied from 7.00 to 23.11,with a mean value of 10.92,and the coefficient of variation was 31.3%.Correlation analysis showed that longitude,altitude,precipitation,soil water,organic carbon,and total nitrogen were positively correlated with the soil C/N ratio(P < 0.01),whereas negative correlations were found between the soil C/N ratio and latitude,temperature,soil bulk density and soil p H.Ordinary Cokriging interpolation showed that r and ME were 0.73 and 0.57,respectively,indicating that the prediction accuracy was high.The spatial autocorrelation of the soil C/N ratio was 6.4 km,and the nugget effect of the soil C/N ratio was 10% with a patchy distribution,in which the area with high value(12.00–20.41) accounted for 22.6% of the total area.Land uses changed the soil C/N ratio with the order of cultivated land > grass land > forest land > garden.Multiple regression analysis showed that geographical and climatic factors,and soil physical and chemical properties could independently explain 26.8%and 55.4% of the spatial features of soil C/N ratio,while human activities could independently explain 5.4% of the spatial features only.The spatial distribution of soil C/N ratio in the study has important reference value for managing soil carbon and nitrogen,and for improving ecological function to similar regions.

Threats and Avoidance Measures of Frost Damage of‘Shushanggan’Apricot in the Ili River Valley

[Objectives]To explore the threat factors of frost damage to‘Shushanggan’Apricot in the Ili River Valley,and to provide measures for avoiding frost damage.[Methods]Based on the meteorological data of the Ili River Valley counties and cities during the 12 years from 2010 to 2021 and using the critical low temperature of‘Shushanggan’Apricot as the main factor,we comprehensively analyzed the threats of low temperature in winter in January and late frost in April in spring in the Ili River Valley.[Results]During the 12 years,there were 4 years of low temperature below the critical(-26—-28℃)of‘Shushanggan’Apricot in the Ili River Valley counties and cities in January,accounting for 33.3%,and a total of 59 d.The frequency of occurrence was:Nilka County>Qapqal County>Yining City>Gongliu County>Huocheng County>Khorgos City>Yining County>Tekes County>Xinyuan County.In April,there were 9 years with a low temperature below the critical temperature(-0.6℃)flowering and fruit setting of‘Shushanggan’Apricot,accounting for 75%,and a total of 134 d.The frequency of occurrence was:Nilka County>Tekes County>Gongliu County>Yining County>Huocheng County>Khorgos City>Xinyuan County>Yining City>Qapqal County.The low temperature threats of‘Shushanggan’Apricot suitable cultivation areas were ranked as follows:Nilka County>Gongliu County>Tekes County>Qapqal County>Huocheng County>Yining City>Yining County>Khorgos City>Xinyuan County.Combined with the observation and survey of frost damage on the spot,we comprehensively analyzed and evaluated the cultivation area of‘Shushanggan’Apricot in the Ili River Valley:three counties(Nilka County,Gongliu County,and Tekes County)in the eastern region,except Xinyuan County,suffered frequent late frost damage,are suitable areas for the cultivation of‘Shushanggan’Apricot;three counties and two cities in the western region(Qapqal County,Huocheng County,Yining City,Yining County,Khorgos City)and Xinyuan County in the eastern region are suitable areas for‘Shushanggan’Apricot.The inversion zone at an altitude of 820-1100 in the valley is the superior area for‘Shushanggan’Apricot.[Conclusions]We explored the suitable areas in the origin area of‘Shushanggan’Apricot,and came up with measures to avoid frost damage,to provide a reference for the development of‘Shushanggan’Apricot.

Spatiotemporal characteristics of cultural sites and their driving forces in the Ili River Valley during historical periods

This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites＇ spatiotemporal evolutionary characteristics, human history, and the natural environment. The results indicate that the numbers and proportions of the sites, and the frequency of their oc- currence, exhibited an inverted V-shaped change trend during six historical periods. The ＂high in the east and low in the west＂ spatial distribution pattern of the first three periods shifted to the one the ＂high in the west and low in the east＂ during the latter three periods, demonstrating a change in the spatial center of gravity of human activities. The sites were mainly distributed on slopes of grades 1-5, with their proportions increasing from 75% during the Spring and Autumn Period （770 BC-476 BC）-Qin Dynasty （221 BC-207 BC） to 93.75% during the Qing Dynasty-Modern period. The concentrated distribution of site elevations shifted from grades 4-8 during the Spring and Autumn Period-Qin Dynasty, and the Western Han （206 BC-8）-Southern and Northern Dynasties （420-589）, to grades 1-4 during the latter three periods. The number of sites showed a shifting trend from high-elevation mountains and hills to low-elevation plains, and from high slopes to low slopes. In particular, the sites exhibited a special ＂moist＂ evolutionary pattern of migration from middle and upstream areas to downstream areas, as opposed to the migration pattern of sites located in typical arid areas. The study also considered factors influencing the distribution and spatiotemporal evolution of cultural sites, notably, human factors and natural factors.

Distribution of soil organic carbon under different vegetation zones in the Ili River Valley, Xinjiang

We analyzed and estimated the distribution and reserves of soil organic carbon under nine different vegetation conditions including alpine meadow, meadow steppe, typical steppe, desert steppe, and temperate coniferous forest and so on, in the Ill River valley, Xin- jiang according to data from field investigations and laboratory analyses in 2008 and 2009. The study results show that the soil organic carbon content in the Ili River valley varies with the type of vegetation. In the 0-50 cm soil horizon, the soil organic carbon content is the highest under the vegetation types of alpine meadow and meadow steppe, slightly lower under temperate coniferous forest and typical steppe, and the lowest under the intrazonal vegetation and desert vegetation types. The soil organic carbon content shows basically a tendency to decrease as soil depth increases under various vegetation types except in the case of the intrazonal vegetation. Similarly, the soil organic carbon density is the highest and varies little under the vegetation types of alpine meadow, meadow steppe and temperate coniferous forest, and is the lowest under the desert vegetation type. Both the soil organic carbon content and density in the topsoil of meadows in the Ili River valley are high, so pro- tecting meadows in the Ili River valley, and especially their topsoil, should be a priority so that the potential of change in soil organic carbon in the shallow soil horizon is reduced, and this means maintenance of the stability of the soil carbon pool.

伊犁河三角洲水资源条件变化对景观格局演变的影响

在分析1992—2020年伊犁河三角洲水资源条件和定量评估研究期内土地利用变化的基础上,选取景观类型水平和景观水平指数解析景观格局变化特征,采用皮尔逊相关系数分析了水资源条件变化对景观格局指数的影响。结果表明:乌斯热尔玛水文站年径流总体偏大,巴尔喀什湖年平均水位在2002年发生突变,三角洲水资源补给总体处于增加状态;湿地和稀疏植被面积增大且聚集性增强,裸地向稀疏植被转化且优势度不断下降,林地破碎程度剧烈;景观水平指数在时程上呈阶段性变化,2016年伊犁河三角洲破碎化程度最低,在空间上伊犁河沿岸连通性增强,巴尔喀什湖沿岸景观多样性增加;景观水平指数与巴尔喀什湖年平均水位相关性最高,与乌斯热尔玛水文站年径流量的相关性次之,与伊犁河三角洲年降水量的相关性最低,且景观水平指数对三角洲水资源条件变化存在迟滞响应。

伊犁河谷山地土壤养分化学计量比及其影响因素

探究干旱区山地生态系统中不同海拔梯度土壤化学计量比及影响因子,对揭示土壤养分状况、维持山地生态系统可持续发展具有重要意义。本文以伊犁河谷南部山地沿海拔梯度建立13个样地,以0~20 cm土壤为研究对象,探究土壤养分化学计量比及其影响因素。结果表明:1)土壤酸性随着海拔的升高逐渐增强。土壤有机碳与全氮表现出中高山带含量显著高于低山带,而全磷和全钾则表现为低山带含量较高,中高山带含量较低。2)由于海拔差异,碳氮比表现为中高山带显著高于低山带和高山带;碳磷比表现为中高山带显著高于中低山带;碳钾比表现为中高山带显著高于低山带;氮磷比表现为高山带显著较高,但过渡带与低山带无显著差异;氮钾比表现为高山带显著较高,而中高山带与过渡带无显著差异;不同海拔梯度间磷钾比差异性均不显著。3)土壤理化指标中影响化学计量比的主导因子为土壤有机碳(62.4%)、全磷(15.9%)、全碳(13.7%);环境因子对土壤化学计量比产生影响的主导因子为土壤年均温(27.1%)、植被指数(11.2%)、海拔(12.3%)、大气年均温(3.4%)。研究结果说明,理化指标对土壤化学计量比具有重要影响,并且进一步验证了海拔仍然是影响化学计量比的主导因子,同时揭示了微环境因子对土壤化学计量比的影响不容忽视,为深入研究伊犁河谷山地土壤养分状况提供科学依据。

2000—2022年伊犁河流域植被时空变化特征

伊犁河流域横跨中哈两国,生态环境脆弱,深化对全流域植被变化的认识对于该地区生态可持续发展具有重要意义。基于MODIS的增强型植被指数(EVI)数据,深入研究了2000—2022年整个伊犁河流域植被的时空变化特征,并对比了中国境内外伊犁河流域、不同植被类型、不同高程间植被变化的差异。结果表明:(1)2000年以来伊犁河流域植被总体呈现改善趋势,尤其是哈萨克斯坦境内的植被,然而中国境内植被有退化趋势。植被退化区域的高程集中在1000~3000 m之间;草地和耕地以改善为主,林地则相反。(2)过去20 a间,伊犁河流域植被总体波动较小,但中国境内流域植被的波动性较大。与林地和耕地相比,草地的波动性更大。高程在2500~3000 m区域内的植被波动小。(3)未来伊犁河流域植被状况以持续改善为主,持续改善面积约占全流域面积的52%。草地持续改善的面积占比高于耕地和林地。高程低于1000 m和高于3000 m区域的植被以持续改善为主。研究结果将有助于加深对伊犁河流域植被变化特征的理解,为流域生态环境保护提供科学参考。

牧村景观及其再造——新疆伊犁河流域琼库什台村的个案

新疆伊犁河流域的琼库什台村是一个传统牧村,也是一个中国历史文化名村。该牧村的传统景观由聚落空间、生产空间、生活空间构成并以牧道空间连接为一体,彰显了“人·畜·草”和谐共生的生态智慧。近年来,旅游发展深刻改变了牧村的聚落空间、生产空间与生活空间,创造了新的文化空间,传统生态智慧被创造性转化后融入旅游新业态之中,进而从整体上再造了牧村景观。生态人类学要积极介入景观研究,利用传统景观分析识别和把握地方人群的“生态智慧”,通过景观再造考察理解并阐释人与自然和谐共生的中国式现代化。

不同土地利用方式对农田土壤有机碳组分及土壤微生物量碳的影响

研究不同土地利用方式下农田土壤有机碳组分及微生物量碳的含量特征对指导伊犁河谷土壤资源的合理利用与管理具有重要意义。通过野外实地调查、样品采集、室内分析与地统计相结合的方法,研究伊犁河谷旱地、水浇地、水田、果园、撂荒地5种土地利用方式土壤有机碳(SOC)、颗粒有机碳(POC)、可溶性有机碳(DOC)、轻组有机碳(LFOC)、易氧化有机碳(EOC)和微生物量碳(MBC)的含量特征,比较分析土地利用变化对伊犁河谷农田土壤有机碳组分及微生物量碳的影响。结果表明:土壤TN、AN、AP和AK含量均表现为:水田>水浇地>旱地>果园>撂荒地;水田土壤养分含量显著高于其他4种土地利用方式;土壤SOC含量具有明显的差异特征,主要体现为:水田(25.62 g·kg^(-1))>旱地(13.80 g·kg^(-1))>水浇地(12.19 g·kg^(-1))>果园(11.58 g·kg^(-1))>撂荒地(8.81 g·kg^(-1)),且均达到显著性差异水平(P<0.05)。土壤SOC、DOC、POC、LFOC、MBC含量均呈现出:水田>旱地>水浇地>果园>撂荒地的特征,其差异达到极显著水平,而EOC含量则表现为:水田>水浇地>旱地>果园>撂荒地的特征,其差异达到极显著水平。水田土壤SOC、DOC、POC、LFOC、MBC、EOC含量均显著高于其他4种利用方式。5种土地利用方式土壤SOC与POC、LFOC、DOC之间存在极显著的正相关,其相关系数分别为0.622,0.36,0.489(P<0.01),说明土壤SOC含量是影响土壤POC、LFOC和DOC含量的重要因素。

伊犁河谷流域山区和平原雨滴谱特征统计研究

雨滴谱是理解降水微物理特性和定量降水估测的基础,尤其是在降水机制复杂、时空变异性大的复杂地形中。本文利用Parsivel2激光雨滴谱仪对2020-2022年夏季伊犁河谷流域山区和平原不同降水强度和不同降水类型的雨滴谱特征进行了研究。结果表明:山区和平原降水主要以小雨滴为主,对降水强度R贡献最大的主要是中雨滴。山区降水和平原降水主要出现在午后至傍晚,山区降水大中型雨滴数浓度在各时间段均高于平原。随着雨强增大,雨滴谱的谱宽和各直径档的雨滴数浓度也随之增加,山区降水的大中型粒子数浓度在小雨和大雨时明显大于平原。在相同降水强度和降水类型的情况下,山区降水具有较大的质量加权平均直径(D_(m))和较小的标准化截断参数(log_(10)N_(w))。此外,伊犁河谷流域山区和平原的对流云滴谱均倾向于“大陆性对流簇”。研究发现,两地区降水的μ-Λ关系和Z-R关系也存在显著差异,Z=300R^(1.40)的经验关系显然高估了降水量。研究结果揭示了伊犁河谷流域不同地形条件下的降水微物理特征,为后续利用雷达资料反演降水提供可靠的事实依据。

伊犁河流域近30a洪水灾害时空分布及孕灾环境特征研究

基于1990-2022年伊犁河流域洪水灾情数据集,结合高程、归一化植被指数等孕灾环境因子,研究伊犁河流域洪水灾害时空分布及孕灾环境特征,并分析洪水灾害发生规律和孕灾环境之间的联系。结果表明:(1)研究区洪水灾害可分为3种:暴雨洪水、融雪洪水和混合洪水(暴雨加融雪造成洪水),其中,暴雨洪水灾害最多(占80.0%)、融雪洪水灾害最少(占3.4%);洪水灾害呈流域北部多于南部、东段多于西段的空间分布,尼勒克县最多、霍尔果斯市最少。(2)近30 a来洪水灾害频次呈年际和年代际增多趋势,洪水灾害年均约11.6次·a^(-1),2010年最多(43次),2000-2011年最多(149次)。洪水灾害在夏季最多,春季次之,秋季最少,6月最多(年均3.3次·a^(-1)),10月最少(年均0.06次·a^(-1)),其中暴雨洪水灾害夏季最多,年均9.3次·a^(-1),6月最多(110次),10月最少(2次),混合洪水灾害春多夏少,3月最多(36次),7月最少(8次),年均1.9次·a^(-1),融雪洪水灾害3月最多(12次),只发生于春季,年均0.4次·a^(-1)。(3)孕灾环境敏感性等级综合分布显示,灾害发生过程中,各孕灾因子共同起作用,影响洪水灾害的空间分布和强度。尼勒克县、特克斯县、新源县、昭苏县和霍尔果斯市境内的极高敏感区域分布较多。结合洪水灾害时空分布和孕灾环境等级综合分布可知,洪水灾害多发生在极高敏感区和高敏感区分布较多的流域东段和北部区域。

伊犁河上游流域三种日尺度降水产品性能评估

伊犁河上游喇叭口地形条件导致其降水空间分布极不均匀,有限的地面观测站点难以真实反映日降水时空变化,因此,有必要评估不同降水产品在伊犁河上游的适用性。选用7种统计指标与广义三角帽法分别对三种降水产品(GPM、ERA5、CHIRPS)在伊犁河上游地区的精度与不确定性进行评估。结果表明:(1)ERA5的相关性、探测率、错报率最高,其估计的中雨与大雨降水量最准确;GPM的均方根误差最小,探测率、错报率最低;CHIRPS的相对偏差与平均误差最小,其探测率、错报率均介于GPM与ERA5之间,其估计的小雨降水量最准确;三种降水产品估计的暴雨降水量精度均不高,但ERA5要好于GPM与CHIRPS。(2)ERA5的日降水量不确定性介于GPM与CHIRPS之间,信噪比最大;GPM的日降水量不确定性最小,信噪比介于ERA5与CHIRPS之间;CHIRPS的日降水量不确定性最大,信噪比最小。(3)ERA5的日降水质量好于GPM与CHIRPS,可用于伊犁河上游地区降水特征分析;GPM的日降水量不确定性最小,通过系统校正提升其质量的可能性最大。研究成果可为伊犁河上游流域水文模拟与水资源变化分析提供支撑。

伊犁河谷“三生”空间景观生态风险时空演变与多情景模拟

基于伊犁河谷1990-2020年土地利用数据,利用景观生态风险评价模型探析“生产-生活-生态”(“三生”)空间及景观生态风险格局时空演变特征,借助PLUS模型模拟伊犁河谷2030年生产空间优先、生活空间优先和生态空间优先3种情景下“三生”空间格局及景观生态风险分布特征。结果表明:1990-2020年,伊犁河谷“三生”空间以草地生态空间为主,草地生态空间和林地生态空间面积呈减少趋势,其余空间呈增加趋势;1990,2000,2010,2020年景观生态风险均值分别为0.0355,0.0331,0.0348,0.0346,伊犁河谷景观生态风险呈先下降后上升趋势,风险等级在空间分布上呈现梯度变化;2020-2030年3种情景的景观生态风险均呈上升趋势,景观生态风险均值从大到小为生活空间优先情景、生态空间优先情景、生产空间优先情景。

人类活动及气候变化影响下伊犁河谷生境质量预测研究

生境质量是衡量生态系统服务功能及其健康程度的重要指标,准确预测生境质量的演变对于推动区域生态环境的高质量发展至关重要。耦合系统动力学-斑块生成土地利用模拟(SDPLUS)模型与生态系统服务和权衡的综合评估(InVEST)模型,预测了2035年不同气候情景下(SSP1-2.6、SSP2-4.5、SSP3-7.0、SSP5-8.5)伊犁河谷土地利用/覆被格局变化,并评估了其生境质量时空演变特征。结果表明:(1)1980—2020年,伊犁河谷土地利用类型呈现“4增2减”的变化趋势。2035年4种气候情景下,伊犁河谷林草地面积降幅较大,建设用地扩张趋势较为明显,挤占了城郊优质耕地资源。(2)伊犁河谷生境质量等级与土地利用/覆被类型密切相关。生境高值及较高值区主要分布在地形崎岖的林草地覆被区,低值及较低值区主要分布在人类活动集聚区及南北天山未利用地覆被区。(3)1980—2020年,伊犁河谷生境质量呈现下降趋势。生境质量退化区主要分布在伊犁河-巩乃斯河流域以及特克斯河流域附近。(4)2035年4种气候情景下,伊犁河谷生境指数持续走低。生境指数均值排序为:SSP1-2.6>SSP2-4.5>SSP3-7.0>SSP5-8.5。伊宁市、边境口岸、农牧业基地等区域生境质量存在退化风险。研究结果可为伊犁河谷地区生态修复政策的制定提供参考依据,为干旱区半干旱区生境质量预测提供新思路。

伊犁河谷住宿业空间分布特征及影响因素研究

利用DBSCAN算法、地理探测器方法剖析伊犁河谷住宿业的空间分布特征及其影响因素。结果表明:(1)伊犁河谷住宿业呈现整体分散与局部聚集的空间分布格局,伊宁市和新源县那拉提旅游风景区为高聚集的核心区域。(2)伊犁河谷住宿业被划分为18个空间集群,共5个等级,空间上表现为东南—西北走向,且多数住宿业以旅游景点为中心向外辐射分布。(3)不同因素对住宿业的影响程度具有较大的异质性,其中景区、星级酒店、交通设施和人口等为核心影响要素。

新疆绿洲土地利用隐性形态与土地生态安全协调特征——以伊犁河谷为例

伊犁河谷是维护新疆土地生态安全的重要生态保障区,其土地利用与土地生态安全相协调对区域可持续发展有重要意义。以2005—2020年土地利用数据为基础,采用综合指数模型、改进的耦合协调度模型和灰色关联度模型等方法对伊犁河谷2005—2020年土地利用隐性形态、土地生态安全时空特征以及两者协调特征进行研究。结果表明:(1)2005—2020年伊犁河谷各县市土地利用隐性形态指数总体上缓慢提升,大体呈现以伊宁市为中心,向四周辐射降低的发展态势。(2)2005—2020年伊犁河谷土地生态安全水平表现为波动增长趋势,并与土地利用隐性形态变化密切相关。(3)2005—2020年伊犁河谷土地利用隐性形态与土地生态安全为高耦合关系,中心城市协调性高于边缘城市。(4)伊犁河谷土地利用隐性形态与土地生态安全协调发展程度主要受土地产出效益、土地开发强度、土地产权变化和生态环境的影响。

基于“EVI-ESV”伊犁河谷生态环境评估及生态分区构建

矿山开采为中国经济发展做出贡献的同时也带来一系列生态问题,对区域生态环境进行实时、客观、准确的动态评价显得尤为重要。以伊犁河谷为例,基于2013、2015、2017、2019、2021年的Landsat8遥感影像、夜光遥感数据、土地利用数据和统计年鉴数据从生态脆弱性和生态系统服务价值两方面综合构建伊犁河谷生态分区,避免从单一角度考虑区域生态环境的不足,同时分析自然因素和社会因素对高脆弱-高供给和低脆弱-低供给区域的相关性,探究该区域的主要影响因子,为西北干旱区环境治理及合理利用自然环境的社会供给价值提供科学依据。结果表明,1)2013-2021年伊犁河谷矿区生态环境明显改善,极度脆弱区从2013年的6%下降到2021年的3%,整体逐渐转为微度和轻度脆弱的面积占谷地总面积的30%。2)在整个研究期内耕地、林地、裸地、人造地表生态系统呈上升趋势,这些大部分来源于草地。草地在所有土地利用类型中占比最高且生态供给值最高,均达到51%以上。3)高脆弱-高供给区(Ⅰ)生态分区呈带状分布于南部和东部地区,呈减小发展趋势,低脆弱-低供给区(Ⅲ)生态分区主要分布在北部和中部部分区域,该区域逐年递增且增加的区域大部分来源于第Ⅱ生态分区的转化。4)植被覆盖度、人均生产总值、牧羊单位密度是Ⅰ分区的主要影响因素,Ⅲ分区的主要影响因素为土地利用类型、植被覆盖度、湿度。以Ⅰ、Ⅲ分区的研究结果作为参考,对伊犁河谷的各种影响因素进行调控,生态环境将会得到明显改善。

Impact of land use/cover changes on carbon storage in a river valley in arid areas of Northwest China

Soil carbon pools could become a CO_2 source or sink, depending on the directions of land use/cover changes. A slight change of soil carbon will inevitably affect the atmospheric CO_2 concentration and consequently the climate. Based on the data from 127 soil sample sites, 48 vegetation survey plots, and Landsat TM images, we analyzed the land use/cover changes, estimated soil organic carbon（SOC） storage and vegetation carbon storage of grassland, and discussed the impact of grassland changes on carbon storage during 2000 to 2013 in the Ili River Valley of Northwest China. The results indicate that the areal extents of forestland, shrubland, moderate-coverage grassland（MCG）, and the waterbody（including glaciers） decreased while the areal extents of high-coverage grassland（HCG）,low-coverage grassland（LCG）, residential and industrial land, and cultivated land increased. The grassland SOC density in 0–100 cm depth varied with the coverage in a descending order of HCG〉MCG〉LCG.The regional grassland SOC storage in the depth of 0–100 cm in 2013 increased by 0.25×1011 kg compared with that in 2000. The regional vegetation carbon storage（S_（rvc）） of grassland was 5.27×10~9 kg in2013 and decreased by 15.7% compared to that in 2000. The vegetation carbon reserves of the under-ground parts of vegetation（S_（ruvb）） in 2013 was 0.68×10~9 kg and increased by approximately 19.01%compared to that in 2000. This research can improve our understanding about the impact of land use/cover changes on the carbon storage in arid areas of Northwest China.