森林生态系统健康评价指标在中国的应用

1IntroductionDuring recent two decades, the idea of "health" as an appropriate paradigm to assess the condition of ecosystems, is watchword of contemporary ecosystem management. The phrase "forest ecosystem health" has been used with increasing frequency in the context of forestry and natural resource management. Many scientists give the definitions from socio-economic and ecological perspectives (Rapport, 1992; USDA Forest Service, 1993; O'Laughlin, 1996; Allen, 2001). Forest health is a …     

森林生态系统健康评价指标及其在中国的应用

根据1995～1998年的遥感资料、1980～1997年全国气象资料以及1949～2001年的森林统计资料以及全国300多个森林样地调查资料，在生态系统健康理论基础上，以活力(V)、组织结构(D)和恢复力（R)为评价指标，对中国森林生态系统的健康状况进行了评价，并对中国森林生态系统健康的空间格局进行了分析。我国森林生态系统健康指数高的区域主要分布在热带雨林季雨林以及天然林分布的区域，而蒙新林区和暖温带林区的健康指数较低，且由南到北逐渐降低。温度和降水对森林生态系统健康的空间格局有较大的影响。通过生态系统健康指数与活力、组织结构和抵抗力的相关分析可知，抵抗力对生态系统健康影响最大，其次是组织结构，影响力最小的是活力。     

秦巴山区马尾松林和油松林的空间分布及亚热带与暖温带界线划分

秦岭不仅是中国南北的地理分界线,也是中国亚热带和暖温带的气候分界线,在中国地理生态格局中占有重要的地位和作用。由于过渡带的复杂性、过渡性和异质性以及划分指标、研究目的的不同,学术界关于这一南北地理—生态分界线的具体位置一直有争论。为了进一步揭示秦巴山区过渡带的特征,明确中国南北地理—生态分界线的位置,本文选择马尾松（Pinus massoniana）林和油松（Pinus tabulaeformis）林这两类分别代表中国南方亚热带针叶林和北方温带针叶林的植被,结合研究区SRTM地形数据、气温和降水数据等,以年降水、最冷月（1月）气温、最热月（7月）气温和年均温为气候指标,详细分析了这两类植被在秦巴山区的空间分布及二者分界线处的气候条件。结果表明：① 马尾松林和油松林的分界线及相应位置的气候指标可以作为亚热带与暖温带界线划分的植被—气候指标之一。秦巴山区亚热带针叶林（马尾松林）与温带针叶林（油松林）的分界线位于伏牛山南坡至汉中盆地北缘一线（秦岭南坡）海拔1000~1200 m处;分界线处气候指标稳定：年降水750~1000 mm,年均温12~14 ℃,最冷月气温0~4 ℃,最热月气温22~26 ℃。② 通过综合的植被—气候指标来划分秦巴山区亚热带和暖温带的界线,能更科学地确定气候带分界线的位置及过渡带的特征,更全面地反映地表植被—气候格局的变化。此外,秦巴山区亚热带与暖温带的界线应该是由亚热带与暖温带针叶林分界线、阔叶林分界线、灌丛分界线等组成的一个过渡带。本文的研究结果为亚热带与暖温带划分指标的选取提供了一定的科学依据。     

中国森林生态系统的植物碳贮量及其影响因子分析

利用中国第四次(1989~1993年)森林资源清查资料,指出中国森林植被的总碳贮量和碳密度分别为 3 778.1Tg(1Tg = 10¹² g)和41.321 Mg/hm²(1 Mg= 10⁶ g),其分布很不均衡,东北和西南各省的碳贮量和碳密度较大。中国森林碳贮量约占世界的1.1%,森林碳密度低于世界平均水平,但中国森林以中、幼龄林为主,占80%以上,表明中国森林植被具有巨大的固碳潜力,对全球碳循环具有重要作用。同时,采用多元线性回归模型、标准系数法定量分析了气候因子对森林植被碳贮量的影响程度,指出气温对森林植被碳贮量的贡献大于降水。     

祁连山水源涵养林区降水及温度时空变化研究

研究大气降水及温度的时空变化对建立气候预警系统有重要的意义。利用气象和水文自动监测仪器沿环境梯度和植被类型对祁连山水源涵养林区温度及降水时空变化进行了动态监测。结果表明,祁连山西水林区降水呈单峰曲线型,主要集中在夏季,占全年降水的72%;在环境梯度上差异较大,表现为乔灌交错带处(3 300 m)降水为最大,交错带以下随海拔的升高降水增大,交错带以上由于降水复杂性导致随海拔的升高而减少;在年际上差异更大,2004年以前降水量随年份的增大有下降趋势,2004年以后降水量增幅较大。祁连山西水林区气温从1986年以来逐渐上升,但年均气温大多在0 ℃以下,最低为-1.33 ℃,从2003年以来气温迅速上升,年均温最高为2.5 ℃,通过研究发现24 a以来气温上升了3.83 ℃;由于气温的上升,导致土壤温度上升较快,尤其是表层和深层土壤温度上升更快,该结论与当前的众多结论是相吻合的。     

基于GIS的北京山区优势林分生态位分析

应用生态位理论,以北京山区森林资源为研究对象,分析优势林分的空间分布及其资源利用和环境适应能力的差异。基于GIS方法,建立优势林分空间分布数据库以及资源梯度信息数据库,分别采用Levins公式和Smith公式,在水分、热量、光照和土壤质量4维环境因子梯度上测定了研究区8个优势林分的生态位宽度,采用Pianka公式测定生态位重叠。结果表明:Smith公式考虑资源可利用性,得到的生态位宽度更能客观地反映优势林分资源空间利用程度;研究区各优势林分重叠度普遍较大,反映了对环境要求的相似性及资源共享的趋势性。     

近30年东北亚南北样带气候变化时空特征分析

以东北亚南北样带为研究区,基于NCDC气象数据,采用统计分析、线性趋势分析和累积距平分析法,对近30 a来东北亚地区的气候变化进行了系统研究。结果显示：1980~2010年,样带温度变化整体以升温态势为主,1996年后进入偏暖阶段,显著升温区年升温速率在0.05℃/a以上。降水变化整体表现为南减北增的空间分异格局,南部在1999年后进入偏少阶段,北部在2004年后进入偏多阶段,降水显著减少区,年降水量减少速率在5 mm/a以上;降水显著增加区,年降水量增加速率在5 mm/a以上。     

青藏高原高寒草地净初级生产力(NPP)时空分异

基于1982-2009 年间的遥感数据和野外台站生态实测数据,利用遥感生产力模型(CASA模型) 估算青藏高原高寒草地植被净初级生产力(NPP),分别从地带属性(自然地带、海拔高程、经纬度)、流域、行政区域(县级) 等方面对其时空变化过程进行分析,阐述了1982 年以来青藏高原高寒草地植被NPP的时空格局与变化特征。结果表明:① 青藏高原高寒草地NPP多年均值的空间分布表现为由东南向西北逐渐递减;1982-2009 年间,青藏高原高寒草地的年均总NPP为177.2×10¹² gC·yr^-1,单位面积年均植被NPP为120.8 gC·m^-2yr^-1;② 研究时段内,青藏高原高寒草地年均NPP 在112.6~129.9 gC·m^-2yr^-1 间,呈波动上升的趋势,增幅为13.3%;NPP 增加的草地占草地总面积的32.56%、减少的占5.55%;③ 青藏高原多数自然地带内的NPP呈增加趋势,仅阿里山地半荒漠、荒漠地带NPP呈轻微减低趋势,其中高寒灌丛草甸地带和草原地带的NPP增长幅度明显大于高寒荒漠地带;年均NPP增加面积比随着海拔升高呈现"升高—稳定—降低"的特点,而降低面积比则呈现"降低—稳定—升高"的特征;④ 各主要流域草地年均植被NPP均呈现增长趋势,其中黄河流域增长趋势显著且增幅最大。植被NPP和盖度及生长季时空变化显示,青藏高原高寒草地生态系统健康状况总体改善局部恶化。     

Dust storms evolution in Taklimakan Desert and its correlation with climatic parameters

Based on the sand dust storms data and climatic data in 12 meteorological stations around sand dust storm originating areas of the Taklimakan Desert, we analyzed the trends of the number of dust storm days from 1960 to 2005 as well as their correlations with temperature, precipitation, wind speed and the number of days with mean wind speed ≥ 5 m/s. The results show that the frequency of dust storm events in the Taklimakan region decreased with the elapse of time. Except Ruoqiang and Minfeng, in the other 10 meteorological stations, the frequency of dust storm events reduces, and in 4 meteorological stations of Kuqa, Korla, Kalpin and Hotan, the frequency of dust storm events distinctly decreases. The temperature has an increasing trend, while the average wind speed and the number of days with mean wind speed ≥ 5 m/s have decreasing trends. The correlation analysis between the number of days of dust storms and climatic parameters demonstrates that wind speed and the number of days with mean wind speed ≥ 5 m/s have strong positive correlation with the number of days of dust storms, with the correlations coefficients being 0.743 and 0.720 (p<0.01), respectively, which indicates that strong wind is the direct factor resulting in sand dust storms. Whereas precipitation has significant negative correlation with the number of days of dust storms (p<0.01), and the prior annual precipitation has also negative correlation, which indicates that the prior precipitation restrains the occurrence of sand dust storms, but this restraining action is weaker than the same year’s precipitation. Temperature has negative correlation with the number of dust storm days, with a correlations coefficient of –0.433 (p<0.01), which means that temperature change also has impacts on the occurrence of dust storm events in the Taklimakan region.     

Impact of land cover changes and topography on soil quality in the Kasso catchment,Bale Mountains of southeastern Ethiopia

This study assessed land cover change and topographic elevation on selected soil quality parameters in the Kasso catchment, southeastern Ethiopia. Twenty‐seven soil samples collected from 0–30cm depth under four land cover types across three elevation gradients were analysed for selected soil quality parameters. Results indicated that soil particle size distribution is different (p<0.001) in the catchment because of the effect of land cover change and elevation. Most cultivated lands occupy lower elevations where clay accumulates as a result of its movement from higher to lower elevations. Ploughing accentuates weathering, making cultivated lands richer in finer materials. Cation exchange capacity and exchangeable magnesium and potassium negatively correlated with elevation, total nitrogen and available phosphorous. Conversion of natural vegetation to cropland contributed to changes in pH (p<0.05), exchangeable calcium (p<0.01), potassium (p<0.001), available phosphorous (p<0.01) and nitrogen (p<0.01) contents. Parameter soil degradation index results showed that soil organic carbon, nitrogen, available phosphorous and exchangeable potassium contents declined and bulk density increased because of the land cover change. This negative effect on agricultural development and environmental health of the catchment makes an integrated land resource management approach indispensable for sustaining agricultural productivity and the environmental health of the Kasso catchment.     

A dynamic relationship between the leaf phenology and rainfall regimes of Hawaiian tropical ecosystems: A remote sensing approach

Hypertemporal MODIS time series data provide a unique opportunity to investigate a dynamic relationship between leaf phenology and the climatic pattern of diverse, cloud‐prone Hawaiian ecosystems. Harmonic analysis summarized the complex greenness signals of Hawaiian tropical ecosystems into two main phenological wave forms – a moisture‐limited and a light‐limited type. Greenness maximums occurred during the wet season in dry and mesic ecosystems, and during the dry season in wet forests. The magnitude and periodicity of greenness fluctuations were also rainfall‐dependent. The annual greenness amplitude increased with increasing mean annual precipitation (MAP) in dry and mesic ecosystems. In wetter environments where MAP was greater than 3000 mm, however, annual greenness amplitude decreased with MAP. Annual greenness periodicity was stronger in drylands than in wet forests, and it weakened as annual precipitation increased. This result shows that rainfall is less important as a limiting factor in wet forests than it is in drylands. Therefore, leaf phenology is not governed by rainfall seasonality as forest wetness increases in the region.     

宁夏罗山油松(Pinus tabulaeformis)树轮宽度对气候因子的响应分析

 树轮样本采自宁夏罗山油松纯林的下限和上限。建立了下限和上限的树轮宽度标准化年表,分析了树轮宽度与降水、气温、湿润指数(P/T)的相关关系,结果显示,下限和上限树轮宽度指数都与当年3月、5月、春季以及年降水量显著正相关,与7月气温显著负相关;下限树轮宽度标准化年表与气候要素的相关系数一般大于上限的相关系数,而且下限树轮宽度与前一年9月、秋季降水以及夏季气温的相关也达到显著水平,表明下限树轮宽度标准化序列对降水和气温单一气候要素的变化较敏感;下限和上限的树轮宽度指数和湿润指数(P/T)呈正相关关系,而且上限树轮宽度和3—8月湿润指数的正相关达到99%的置信水平,说明罗山油松纯林上限树轮宽度标准化序列对水热组合的响应较敏感。     

Characteristics of evapotranspiration from a permafrost black spruce forest in interior Alaska

Here, the year 2011 characteristics of evapotranspiration and the energy budget of a black spruce forest underlain by permafrost in interior Alaska were explored. Energy balance was nearly closed during summer, and the mean value of the daily energy balance ratio (the ratio of turbulent energy fluxes to available energy) from June to August was 1.00, though a large energy balance deficit was observed in the spring. Such a deficit was explained partly by the energy consumed by snowmelt. Ground heat flux played an important role in the energy balance, explaining 26.5% of net radiation during summer. The mean daily evapotranspiration of this forest during summer was 1.37 mm day^?1 – considered typical for boreal forests. The annual evapotranspiration and sublimation yielded 207.3 mm year^?1, a value much smaller than the annual precipitation. Sublimation accounted for 8.8% (18.2 mm year^?1) of the annual evapotranspiration and sublimation; thus, the sublimation is not negligible in the annual water balance in boreal forests. The daytime average decoupling coefficient was very small, and the mean value was 0.05 during summer. Thus, evapotranspiration from this forest was mostly explained by the component from the dryness of the air, resulting from the aerodynamically rough surface of this forest.     

Heterogeneity of water-retention capacity of forest and its influencing factors based on meta-analysis in the Beijing-Tianjin-Hebei region

Water retention is important in forest ecosystem services.The heterogeneity analysis of water-retention capacity and its influencing factors is of great significance for the construction of water-retention functional areas,restoration of vegetation,and the protection of forest ecosystems in the Beijing-Tianjin-Hebei region.A total of 1366 records concerning water-retention capacity in the canopy layer,litter layer,and soil layer of forest ecosystem in this region were obtained from 193 literature published from 1980 to 2017.The influencing factors of water-retention capacity in each layer were analyzed,and path analysis was used to investigate the contribution of the factors to the water-retention capacity of the three layers.The results showed that mixed forests had the highest water-retention capacity,followed by broad-leaved forests,coniferous forests,and shrub forests.In addition,no matter the forest type,the ranking of the water-retention capacity was soil layer,canopy layer,and litter layer from high to low.The main influencing factors of water-retention capacity in forest canopy were leaf area index and maximum daily precipitation(R2=0.49),and the influencing coeffi-cients were 0.34 and 0.30,respectively.The main influencing factors of water-retention ca-pacity in the litter layer were semi-decomposed litter(R2=0.51),and the influencing coefficient was 0.51.The main influencing factors of water-retention capacity in the soil layer were non-capillary porosity and soil depth(R2=0.61),the influencing coefficients were 0.60 and 0.38, respectively.This study verifies the simulation of the water balance model or inversion of remote sensing of the water-retention capacity at the site scale,and provides scientific basis for further study of the impact of global change on water retention.     

Are There Differences in the Response of Natural Stand and Plantation Biomass to Changes in Temperature and Precipitation? A Case for Two-needled Pines in Eurasia

A comparative discussion of the advantages and disadvantages of natural stands and plantations, including in terms of their productivity and stability, began from the moment of the first forest plantings and continues to this day. In the context of the progressive replacement of natural forests by plantations due to deforestation, the question of how will change the carbon storage capacity of forest cover when replacing natural forests with artificial ones in a changing climate becomes extremely relevant. This article presents the first attempt to answer this question at the transcontinental level on a special case for two-needled pine trees (subgenus Pinus L.). The research was carried out using the database compiled by the authors on the single-tree biomass structure of forest-forming species of Eurasia, in particular, data of 1880 and 1967 of natural and plantation trees, respectively. Multi-factor regression models are calculated after combining the matrix of initial data on the structure of tree biomass with the mean January temperature and mean annual precipitation, and their adequacy indices allow us to consider them reproducible. It is found that the aboveground and stem biomass of equal-sized and equal-aged natural and plantation trees increases as the January temperature and precipitation rise. This pattern is only partially valid for the branches biomass, and it has a specific character for the foliage one. The biomass of all components of plantation trees is higher than that of natural trees, but the percent of this excess varies among different components and depends on the level of January temperatures, but does not depend at all on the level of annual precipitation. A number of uncertainties that arose during the modeling process, as well as the preliminary nature of the obtained regularities, are noted.     

咸阳市三原县新庄不同植被土层含水量研究

通过测定咸阳市三原县新庄2005和2006年降雨正常年份人工林地土壤含水量得知,从地表向下土层含水量呈由高到低再到高的变化;2005年草地和玉米地土层含水量由上向下呈逐渐增高趋势,比同年12龄杨树林地和13龄中国梧桐林地平均含水量高约7%。2003年降水量达880 mm丰水年后,人工林土壤干层中水分完全恢复,人工林出现持续近4年茂盛生长期,预计2007年该区将会再次出现发育弱的土壤干层。     

Spatial Patterns of Forest Ecosystem Services and Influencing Factors in the Ganjiang River Basin

As the major component of terrestrial ecosystems, forests play an irreplaceable role in providing ecosystem services and products (e.g. biodiversity, carbon sequestration, water yield and timber). Spatially quantifying ecosystem services and interactions will shed light on sustainable forest management. Main forest ecosystem services including carbon storage, water yield, soil retention and wood volume in the Ganjiang River Basin (GRB) were evaluated and mapped through the integrated use of InVEST3.1.0, CASA modeling and ArcGIS10.2, and relationships between forest ecosystem services and natural or social-economic factors were quantified and discussed based on ArcGIS10.2 and SPSS19.0. Results showed that the spatial pattern of the four ecosystem services is heterogeneous. Forests dominated by broad-leaved forest and bamboo forest in mountainous regions around the GRB provided the largest carbon storage and wood volume services, while forests dominated by Masson pine plantations or Chinese fir plantations in the northeast provided the largest water yield service. The spatial pattern of the soil retention service is more discrete than others, and forests in the southwestern regions showed larger soil erosion modulus than in the northeastern regions. Ecosystem services are closely related to the environmental process and human activities. With altitude or slope increases, the carbon storage and wood volume of forests increased and water yield depth and soil retention decreased. When the regional total population decreased or GDP per capita increased, carbon storage and wood volume increased. Further research into the interactions between environmental factors and ecosystem services is needed in order to understand environmental constraints when dealing with ecological problems.     

基于SWAT模型的森林分布不连续流域水源涵养量多时间尺度分析

为解决森林分布不连续流域森林水源涵养功能及其多时间尺度特征的定量评价问题,根据分布式水文模型（SWAT）的特点,提出了反映森林斑块空间分布的水文响应单元划分方法,以及基于水量平衡法的森林不连续分布流域森林水源涵养量计算公式。以东南沿海的晋江流域为例,构建了2006年土地利用条件下的日时间步长SWAT模型,统计分析了2002—2010年降水条件下森林水源涵养量的时空变化规律。结果表明：① 构建的晋江流域SWAT模型精度较高,面积阈值为零生成的水文响应单元比较准确地反映流域森林斑块分布,提出的森林水源涵养量计算公式适用于森林空间分布不连续流域森林水源涵养量的多时间尺度分析,为流域森林水源涵养功能评价提供了一个新的方法。② 晋江流域森林水源年涵养量271.41~565.25 mm;月涵养量-29.15~154.59 mm;日尺度的极端降水期皆为正值,极端枯水期都为负值。表明年际之间不存在森林水源涵养的蓄丰补枯调节作用,但在年内的部分月份得到体现,而日尺度的森林蓄丰补枯功能充分发挥。从而揭示了不同时间尺度森林水源涵养量及其蓄丰补枯功能的差异。     

Topography-Controlled Soil Water Content and the Coexistence of Forest and Steppe in Northern China

The semi-arid forest-steppe ecotone in China is characterized by a patchy pattern of forest and steppe, with forest patches restricted to shady slopes. To address the effect of topography on forest distribution through regulation of available water, we calculated evaporation as a function of slope aspect and inclination. Field vegetation records from randomly selected sites with minimum slope inclination were used to test the simulated forest distribution. Seasonal and diurnal changes of surface soil temperature and moisture of shady and sunny slopes were recorded. Soil water content was measured during two growing seasons on both sunny and shady slopes with the same forest type at three sites located along the mean annual precipitation (MAP) gradient. Evaporation decreases with slope inclination on shady slopes, but increases with inclination on sunny slopes. The shady slope received 35% of the annual direct solar radiation received by the sunny slope when the slope inclination was 25°, and the contrast in annual direct solar radiation between the shady and sunny slopes further widens as slope inclination increases. Steeper shady slopes can support forests in dryer climates, with log-linear regression revealing a minimum slope inclination for forest distribution along the MAP gradient. The simulated minimum slope inclination for forest growth was larger than the observed minimum inclination, and the difference was greater in wetter conditions. A larger forest area fraction was considered to lead to a reduction in soil temperature and evaporation, as verified by soil temperature and moisture records and soil water content measurements. The slope-specific forest distribution in the semi-arid region of China can be explained by a topography-controlled soil water supply. Lower evaporation, resulting from lower direct solar radiation on shady slopes, allows shady slopes to retain a water supply sufficient for sustaining forests, and the existence of forests on shady slopes further reduces evaporation. Different tree species coexist at the xeric timberline due to regulation by slope inclination and aspect.     

How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis,Northwest China

Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes,China, to assess effects of groundwater-depth change on the canopy leaf area index(LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.