The spatial distribution of forest carbon sinks and sources in China

Forest ecosystems play an important role in the global carbon cycle.The implementation of the United Nations Framework Convention on Climate Change(UNFCCC) and the Kyoto Protocol has made the study of forest ecosystem carbon cycling a hot topic of scientific research globally.This paper utilized Chinese national forest inventory data sets(for the periods 1984-1988 and 1999-2003),the vegetation map of China(1:1000000),and the spatially explicit net primary productivity(NPP) data sets derived with the remote sensing-based light use efficiency model(CASA model).We quantitatively estimated the spatial distribution of carbon sinks and sources of forest vegetation(with a resolution of 1 km) using the spatial downscaling technique.During the period 1984 to 2003 the forest vegetation in China represented a carbon sink.The total storage of carbon increased by 0.77 PgC,with a mean of 51.0TgCa 1.The total carbon sink was 0.88PgC and carbon source was 0.11 PgC during the study period.The carbon sink and carbon source of forest vegetation in China showed a clear spatial distribution pattern.Carbon sinks were mainly located in subtropical and temperate regions,with the highest values in Hainan Province,Hengduan mountain ranges,Changbai mountain ranges in Jilin,and south and northwest of the Da Hinggan Mountains;carbon sources were mainly distributed from the northeast to southwestern areas in China,with the highest values mainly concentrated in southern Yunnan Province,central Sichuan Basin,and northern Da Hinggan Mountains.Increase in NPP was strongly correlated with carbon sink strength.The regression model showed that more than 80% of the variation in the modeled carbon sinks in Northeast,Northern,Northwest and Southern China were explained by the variation in NPP increase.There was a strong relationship between carbon sink strength and forest stand age.     

庙岛群岛南部岛群无居民海岛植被净初级生产力评估

无居民海岛具有显著的战略地位和重要的生态价值,植被净初级生产力(NPP)评估对维护无居民海岛生态系统稳定性和活力具有重要意义.以庙岛群岛南部岛群中螳螂岛等5个无居民海岛为研究对象,通过遥感手段,对海岛NPP总量和密度及其空间分布特征进行分析.结果显示：1) 全年NPP总量为134.22 tC·a－1,平均密度为274.13 gC·m－2·a－1,并表现出明显的季节差异,各岛NPP平均密度由大到小依次为牛砣子岛、羊砣子岛、螳螂岛、南砣子岛和挡浪岛;2) 不同地表覆盖类型NPP平均密度由大到小依次为阔叶林、针叶林、草地、建设用地和裸地,各岛NPP平均密度与裸地面积占比呈明显的负相关,区域NPP密度与海拔、坡度、坡向和归一化植被指数呈显著正相关;3) 黑松和刺槐是北方无居民海岛人工林的理想树种,持续的人工林种植是提升无居民海岛NPP的重要途径.     

Modern pollen-vegetation relationship based on discriminant analysis across an altitudinal transect on Gongga Mountain, eastern Tibetan Plateau

Quantitative relationship between modern pollen assemblage and altitudinal vegetation belt is crucial for the reconstruction of paleovegetation in the mountain regions.Modern pollen analysis on 70 topsoil samples was conducted across an altitudinal transect(1100-4500 m) on the eastern slope of Gongga Mountain in the eastern Tibetan Plateau with an elevation interval of 50 m.Distributions of major pollen types along the transect indicated a weak correlation between Pinus pollen and the elevation.Distributions of Picea and Abies pollen(percentage sum of 2%-8%) could fairly indicate the elevation range of 2700-3700 m,as well as the subalpine dark coniferous forest and the timberline in the region.High percentage intervals of alpine types of Ericaceae,Cupressaceae and Cyperaceae were correlated to the high-elevation regions(3700-4500 m) dominated by alpine shrub meadow and alpine meadow.Seven altitudinal vegetation belts on the eastern slope of Gongga Mountain were well defined by discriminant analysis conducted on the modern pollen assemblages,as reflected by high values of probability of modern analog.Most of the modern pollen assemblages(88.5%) were typical for the vegetation types at their sampling locations.Thus,the relationship between the modern pollen assemblages and vegetation across the altitudinal transect based on discriminant analysis can be applied to the quantitative reconstruction of paleovegetation changes in the mountain regions of the eastern Tibetan Plateau.     

基于CASA模型的广西植被NPP季节变化研究

植被净初级生产力（Net Primary Productivity，NPP）是判定陆地生态系统碳汇/源的关键要素，不仅直接代表了自然环境条件下植被群落的生产能力，还体现了陆地生态系统的质量水平。本文基于陆地生态系统碳汇模型（CASA模型），利用2019年中分辨率成像光谱仪（MODIS）归一化植被指数（NDVI）数据和其他气象数据，对月、季节、年尺度上的广西植被NPP的空间变化进行估算，分析其时空变化特征，并探讨不同植被类型、气象因子和地形地貌对其的影响。结果表明：2019年广西整体区域的植被NPP平均值为880.56 g C·m^-2·a^-1，植被NPP空间分布呈内陆中心向四周递增、东北部向西南部递增的特点。月植被NPP在时间序列上总体呈现正弦曲线的变化特征，1-8月的植被NPP呈上升趋势，在8月达到峰值，而且9月仍然维持较高值；之后至12月，植被NPP逐步下降。广西植被NPP的季节变化明显，冬季的植被NPP整体最低，区域差异性不突出；夏季的植被NPP整体最高，区域差异性突出。常绿阔叶和混交林分布面积广且其光能利用率较大，对广西植被NPP贡献较大。从月尺度上来看，月植被NPP与月累计降水量主要呈负相关关系，与月平均气温主要呈正相关关系；月平均气温与月植被NPP的偏相关性比月累计降水显著，月平均气温是广西月植被NPP的主要影响因子。在中海拔地区（700-1 300 m），植被NPP并不受喀斯特地质环境背景的影响，喀斯特地区和非喀斯特地区植被NPP相差不大且随着海拔高度的上升趋于稳定。在全球变化背景下，分析广西植被NPP的时空演变规律及其与环境要素之间的关系，可为广西生态环境监测与管理、生物多样性保护、生态服务评估等提供科学参考。     

Estimation of wind erosion rates by using 137Cs tracing technique: A case study in Tariat-Xilin Gol transect, Mongolian Plateau

Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we established the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the 137Cs tracing technique and examined their spatial dynamics. Our results showed that the 137Cs inventories of sampling sites ranged from 265.63=44.91 to 1279.54=166.53 Bq. m-2, and the wind erosion rates varied from 64.58 to 419.63 t. km-2. a-~ accordingly. In the Mongolia section of the transect （from Tariat to Sainshand）, the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect （Inner Mongolia）, the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.     

长江流域森林NPP模拟及其对气候变化的响应

【目的】利用LPJ模型(Lund-Potsdam-Jena model)估算长江流域森林净初级生产力(net primary productivity, NPP),研究长江流域森林NPP时空动态变化及其与气候因素的关系,为长江流域及其他地区的植被监测与生态建设提供依据。【方法】基于LPJ模型模拟的NPP数据及气象资料,对长江流域1982—2013年森林NPP的空间分布和时空动态变化趋势进行分析,采用线性回归分析法分别以时间为自变量和NPP为因变量进行趋势检验,利用相关性分析法分析长江流域森林NPP与气象因子之间的关系。【结果】①长江流域1982—2013年森林年均NPP值为530.41 g/(m²·a),最高值出现在2002年,森林NPP值为578.55 g/(m²·a);最低值出现在1989年,森林NPP值为491.24 g/(m²·a)。②长江流域森林NPP的空间分布由东南沿海向西北逐渐减小,长江中下游森林NPP高于长江上游,森林NPP空间分布格局与水热条件分布格局相一致,长江流域东南部水热条件良好,能够满足植被生长和发展的需要,植被生产力比较高;西北部由于水热条件比较差,不利于植被生长,生产力低下。③长江流域大部分地区森林NPP与气温和降水为正相关关系,森林NPP与气温呈显著正相关,气温与森林NPP之间的相关性强于降水与森林NPP之间的相关性。【结论】长江流域森林NPP呈自东南向西北减少的趋势,且随时间呈波动上升趋势;气候对森林NPP具有显著影响,气温是影响森林NPP的主导因素。     

2007年～2016年湖北省归一化植被指数时空变化特征分析

利用1 km空间分辨率的MODIS数据,对2007年～2016年的归一化植被指数(NDVI)时间序列数据以及NDVI与气象因子、土地利用类型、海拔高度的相关关系进行分析,研究近10 a湖北省植被覆盖度在时间和空间上的变化特征.结果表明：全省年平均NDVI波动上升,从各季节变化线性拟合结果来看,冬季上升程度最大;NDVI月变化呈单峰型,最高值出现在7月份,为0.758,最低值出现在1月份,为0.383;在空间分布上,湖北省西部地区NDVI较大于东部地区,十堰、恩施和神农架林区植被覆盖度高,武汉和鄂州植被覆盖度低;降水量、海拔高度和土地利用类型与NDVI均有较显著的相关性,植被生长对降水的响应具有滞后性;高海拔山地地形区林地大面积分布,是NDVI高值区,低山丘陵和平原上的城镇用地扩张和农业种植活动是NDVI较低的主要原因.     

西北地区植被覆盖时空特征及其对气候变化的响应

目的定量分析西北地区地表植被覆盖的时间变化与空间分布,为其合理开展农业生产,进行环境保护和生态建设提供科学的决策依据。方法利用西北地区1982—2006年GIMMS-NDVI数据,以绿度变化率和偏相关分析法为基础,分析了西北地区不同生态地理分区NDVI的年际变化以及植被覆盖变化对气候要素在空间上的响应。结果近25年来,高原植被覆盖整体呈波动增加的趋势。各生态分区的NDVI均呈增长趋势,并且随着湿润程度和温度的降低,年均NDVI随之减小;1982—2000年降水量在减小,但减小幅度不显著;气温呈显著上升趋势,年均NDVI与气温的相关性较好。结论西北地区的东南部和西北部地区水热组合条件相对于中部地区较好;植被覆盖较好的区域,其改善的趋势明显,相反则不明显;西北地区东部水热组合条件向不利于植被生长方向转变,而西部向利于植被生长的方向发展。     

Comprehensive analysis of the impact of climatic changes on Chinese terrestrial net primary productivity

Recent climatic changes have affected terrestrial net primary productivity (NPP). This paper presents an investigation of the impact of climatic changes on Chinese terrestrial vegetation NPP by analyzing 18 years’ (1982 to 1999) climatic data and satellite observations of vegetation activity. Results indicate that climatic changes in China have eased some critical climatic constraint on plant growth. (1) From 1982 to 1999, modeled NPP increased by 1.42%·a-1 in water-limited regions of Northwest China, 1.46%·a-1 in temperature-limited regions of Northeast China and Tibet Plateau, and 0.99%·a-1 in radia- tion-limited regions of South China and East China. (2) NPP increased by 24.2%, i.e. 0.76 petagram of carbon (Pg C) over 18 years in China. Changes in climate (with constant vegetation) directly contrib- uted nearly 11.5% (0.36 Pg C). Changes in vegetation (with constant climate) contributed 12.4% (0.40 Pg C), possibly as a result of climate-vegetation feedbacks, changes in land use, and growth stimula- tion from other mechanisms. (3) Globally, NPP declined during all three major El Ni-o events (1982 to 1983, 1987 to 1988, and 1997 to 1998) between 1982 and 2000, but Chinese vegetation productivity re- sponded differently to them because of the monsoon dynamics. In the first three events (1982 to 1983, 1987 to 1988, and 1992), Chinese vegetation NPP declined, while in the later two events (1993, 1997 to 1998) increasing obviously.     

喀斯特断陷盆地土地利用对生态系统生产力的影响

为了客观地评估断陷盆地土地利用对生态环境的影响, 从生态系统服务变化反映更深层次的人地之间复杂关系, 本文基于断陷盆地多时间序列土地利用数据和陆地植被净生产力(NPP), 阐明断陷盆地NPP时空变化趋势, 揭示多年间土地利用变化的地类层次变化特征; 运用生命周期评估方法, 定量地分析土地占用和土地转化对石漠化地区陆地植被净生产力的影响, 探讨石漠化治理的生态效益。结果表明: 1) 2000—2015 年间, 断陷盆地大部分区域NPP变化不显著, 少部分区域变化显著, 以上升趋势为主; 2) 在6种地类中, 林地变化平稳, 建设用地增加趋势活跃且强烈, 草地减少趋势活跃且强烈; 3) 林地占用潜在植被生产力与现有NPP之间的差值由西向东逐渐增加, 与林地占用面积减少的空间分布一致, 林地分布影响林地植被净生产力水平; 4) 研究区北部植被自然生长情况较好, 东部地区六盘水市、普安县和陆良县石漠化区域林地植被存在一定程度的天然退化, 林地生态恢复工程效果不明显; 5) 研究区80%的土地转化类型使得NPP增益, 其中使NPP明显提升、有效而普遍的方式是草林转换和退耕还林; 林地转为建设用地则对NPP的损害最大。     

中国不同植被类型净初级生产力变化特征

收集、统计了1993—2011年所发表的98篇涉及我国不同植被NPP数据(模型模拟估算值和实测值)的代表性论文.分析了我国不同植被类型NPP研究结果及其变化和空间分布特征.结果表明:1)模型模拟和实测NPP值都较高的植被类型有热带雨林、季雨林,常绿阔叶林,常绿针叶林、混交林和落叶阔叶林;2)模型模拟的植被NPP值空间分布规律基本表现为从东南沿海地区依次向西北内陆递减;3)在模型模拟与实测NPP值所共有的9种植被类型中,除耕地、灌丛和草地的模型模拟NPP值略大于实测值,其余6种植被类型均小于实测值;4)不同模型对同一种植被类型的模拟结果之间表现出了极大的差异;5)模型模拟平均值与实测值之间的差异相对较小,采用已提出的模型模拟平均值来估算我国不同植被的NPP是基本可行的.     

GPS monitoring of the crustal motion in southwestern China

Through GPS carrier phases observation in southwestern China during 1991–1997, the velocity field within eastern Qinghai-Xizang (Tibet) and its neighbour regions has been established. The velocity of those sites in and west of Chuan-Dian block is mostly 5–10 mm · a^™1 relative to the fiduciary station CHDU (Chengdu), and the motion in Chuan-Qing and Yangtze blocks east of the Xianshuihe-Xiaojiang fault is weak with a velocity of about 0–7 mm · a⁻¹. The velocity vector in these areas indicates a clockwise rotation vortex rather than the so-called intensive eastward pushing or eastward escape. The main pattern of the crustal deformation is a clockwise rotation vortex structure and a differential slip along the boundary fault between different blocks.     

The terrestrial NPP simulations in China since Last Glacial Maximum

Based on Atmosphere-Vegetation Interaction Model （AVIM）, the magnitude and spatial distribution of terrestrial net primary productivity （NPP） in China is simulated during three different geological eras, Last Glacial Maximum （LGM）, Mid-Holocene （MH） and the present. The simulation shows that the glacial-interglacial variation of East Asian summer monsoon in China is the key factor affectfng the NPP change. During the three eras, mean NPPs are 208 g/m^2·a, 409 g/m^2·a, and 355 g/m^2·a. The total NPPs are 2.05 Pg/a, 3.89 Pg/a and 3.33 Pg/a, respectively. The terrestrial NPP in China during warm-humid climate is larger than that during cold-arid eras, and the correlation analysis between NPP and climate factors suggests that temperature is the primary factor affecting the terrestrial NPP during 21 kaBP （LGM）, and for 6 kaBP （MH） and the present the primary factor is precipitation.     

黑龙江省气象因子插值优化及与落叶松NPP相关性分析

【目的】通过比较不同插值方法模拟黑龙江省气象因子,利用最佳插值结果,探寻落叶松样地气象因子与森林植被净初级生产力(NPP)的关系,为黑龙江省落叶松林的生产经营和管理提供科学参考。【方法】以黑龙江省2010年生长季(5—9月)气象因子(日平均气温、日降水量)及1 521块落叶松林固定样地数据为数据源,分别使用反距离加权(IDW)、普通克里金(OK)、多元线性回归(MLR)和混合插值法(包括回归反距离加权(RIDW)和回归克里金(RK))5种插值方法对生长季月均气温和月均降水量进行插值及比较,以最佳插值方法得到黑龙江省2010年生长季月均气温和月均降水量空间分布。根据东北地区树种生物量异速模型估算落叶松样地单位面积森林地上生物量(AGB)和净初级生产力,并与样地气象因子进行相关性分析。【结果】5种插值方法中RK的生长季月均气温和月均降水量均方根误差(RMSE)分别为0.420和10.110,均优于其他插值方法。生长季月均气温由南至北降低的同时落叶松NPP随之降低,月均降水量自西向东增大,落叶松NPP随之升高。生长季月均气温、月均降水与NPP的Pearson相关系数分别为0.221和0.241,二者P值都小于0.01,呈极显著相关。【结论】考虑地形因子和多元回归模型结果残差的RK方法可以更好地模拟黑龙江省生长季月均气温和月均降水量。生长季落叶松NPP在经、纬度方向上分布趋势与气温、降水量相同,且落叶松NPP与生长季月均气温和月均降水量均有一定相关性,其中与降水量相关性更为明显。     

Methane emissions from wetlands on the Qinghai-Tibet Plateau

The areal extent of cold freshwater wetlands on the Qinghai-Tibet Plateau (QTP) is estimated at 0.133 × 10⁶ km², suggesting a significant methane potential. Methane fluxes from wet alpine meadows, peatlands,Hippuris vulgaris mires and secondary marshes were 43.18, 12.96, −0.28 and 45.90 mg · m⁻² · d⁻¹, respectively based on the transect flux studies at the Huashixia Permafrost Station (HPS) from July to August 1996. Average CH₄ fluxes in the thaw season were extrapolated at 5.68 g · m⁻² according to the areal percentage of wetland areas in the Huashixia region. The CH₄ fluxes at four fixed sites, representative of similar ecosystems, ranged from −19.384–347.15 mg · m⁻² · d⁻¹, and the average CH₄ fluxes varied from 6.54 to 71.97 mg · m⁻² · d⁻¹ at each site during the observation period from April to September 1997. The CH₄ emissions at each site during the entire thaw season was estimated from 1.21 to 10.65 g · m⁻², displaying strong spatial variations. Seasonal variations of CH₄ fluxes also were observed at four sites: CH₄ outbursts occurred upon the spring thaw in May and June, CH₄ fluxes increased afterwards with rising soil temperatures. Episodic fluxes were observed in summer, which influenced the average CH₄ fluxes considerably. Annual CH₄ emissions from cold wetlands on the QTP were estimated at about 0.7–0.9 Tg based on the distribution of wetlands, representative CH₄ fluxes, and number of thaw days. The centers of CH₄ releasing were located in the sources of the Yangtze and Yellow rivers, and Zoigê Peatlands.     

基于GIS平台的我国太阳能光伏发电潜力研究

太阳能光伏(PV)系统在我国的应用十分广泛,但还缺乏其在不同区域的资源利用潜力分析.建立了太阳能光伏发电潜力评估方法,通过搭建实验台研究3种常用太阳能光伏系统的转换效率和环境参数的关系,并拟合出光伏效率方程.借助地理信息系统(GIS)平台的空间分析功能研究我国各地太阳能辐射强度频数和发电潜力空间分布.通过分析发现单晶硅组件在我国西北和北方地区高达200kWh/(m2·a)以上,适宜发展PV系统,而西南地区仅约130kWh/(m2·a),可以为各地发展太阳能和制定能源发展规划提供参考.     

Suitability assessment of deep groundwater for drinking, irrigation and industrial purposes in Jiaozuo City, Henan Province, north China

Groundwater has been a major natural resource for human consumption in north China. It is necessary to appreciate the suitability of deep groundwater for drinking, agricultural irrigation, and industrial uses in this region. To this end, a total of 47 groundwater samples were collected from the study area; by comparing the concentrations of different hydrochemical variables with quality standard values, the variable fuzzy set (VFS) was applied to calculate the groundwater quality index (GQI) for various purposes, respectively. Afterward GQI spatial distribution maps were constructed using a geographic information system (GIS) tool to delineate spatial variations of groundwater quality. In this case study, the GQI spatial distribution maps reveal that the areas covered by "Maximum Permissible" groundwater for varying purposes (drinking, irrigation, and industrial) is 1377.2; 2354.7; and 3854.8 km2, respectively. The groundwater in the eastern part of the study area is suitable for drinking, with the southwestern region as the irrigation water source; the entire study area is acceptable for use in industrial, except the western part of Jiaozuo City. Therefore, the GQI spatial distribution maps can provide useful information for non-technical decision makers for better sustainable groundwater resources management.     

大气波动不稳定与林区降水分布(Ⅰ)

<正>本文从描述大气运动的涡度方程出发,用参数展开法求得二维平面运动的波动解。指出在气流受到森林或林区山地的阻挡时,在林区中心线两侧,可以形成不同类型的水平气流切变,这种气流切变通过产生波动不稳定能量而造成了林区降水的特殊分布。当基本气流为西风气流时,平地林区中心线北侧降水量明显大于南侧;对于山地林区,这种因气流切变造成的波动不稳定能量使得偏北坡降水日数增多,甚至多于水气含量较充沛的偏南坡。用我国小兴安岭林区和长白山林区的降水资料分别作为平地和山地的代表,对上述理论结果作了验证,得出了令人满意的结果。     

Methane emissions from terrestrial plants over China and their effects on methane concentrations in lower troposphere

Methane (CH₄) is the most important greenhouse gas and reactive trace gas in the atmosphere. Recently, it has been reported that terrestrial plants can emit CH₄ under aerobic conditions, which may call for reevaluation of the inventory of CH₄ emissions in China. In this paper, those emissions over China and their effects on CH₄ concentrations in lower troposphere were investigated. Firstly, based on the work of Keppler et al., the aerobic plant CH₄ emission model (PLANTCH4) for China was established. And by using the database of normalized difference vegetation index (NDVI) derived from NOAA/AVHRR, the distribution of net primary productivity (NPP) over China was simulated, and thereby, for the first time, the amount and distribution of the newly identified source in China were estimated. Secondly, with the aid of the three-dimensional atmospheric chemistry model system (MM5-CALGRID), the effects of the emissions were studied. The results show that the annual aerobic plant CH4 emissions over China amount to 11.83 Tg, i.e. nearly 24% of Chinese total CH₄ emissions. And the major fraction (about 43%) comes from forests. When those emissions are considered in modeling, computed countrywide mean surface concentration of CH₄ is 29.9% higher than without them, with a maximum increase of 69.61 μg·m⁻³ in the south of Yunnan Province. In conclusion, to study CH₄ emissions from terrestrial plants over China may have important implications for correctly estimating the contribution of China to global CH₄ budget, and may call for a reconsideration of the role of CH₄ in global and regional environment and climate change. Supported by National High-Tech Research & Development Program of China (Grant No. 2006AA06A307), National Basic Research Program of China (Grant Nos. 2006CB403706 and 2006CB403703), and the Program for New Century Excellent Talents in University, and Nanjing University Talent Development Foundation     

贵州喀斯特山区农业结构调整与农村经济发展初探——以清镇示范区为例

党和国家西部大开发战略，国务院对当前和今后一个重要时期要集中力量进行的5个全局性重点工作之两点是：调整和优化农业结构，增加农民收入；加强生态环境保护和建设，退耕还林（草）。文章以贵州省清镇示范区为例，在农业产业结构现状分析的基础上，对贵州省喀斯特山区农业结构调整和农村经济发展提出了建议：1）走农业产业化经营之路；2）建立和完善农业市场体系；3）加强农民教育；4）有效转移农村剩余劳动力。