我国不同季节陆地植被NPP对气候变化的响应

阐明不同季节陆地植被净第一性生产力(NPP)对全球变化的响应将有助于理解陆地生态系统和气候系统之间的相互作用以及NPP变化机制.本文使用1982～1999年间的AVHRR/NDVI、气温、降水以及太阳辐射等资料,结合植被分布图和土壤质地图,利用生态过程模型,研究不同季节我国陆地植被NPP的年际变化及其地理分异.结果表明,在1982～1999年的18年间,4个季节的NPP都呈显著增加趋势.其中,春季是NPP增加速率最快的季节,夏季是NPP增加量最大的季节.不同植被类型对全球变化的响应有很大差异.常绿阔叶林、常绿针叶林和落叶针叶林NPP的增加主要由生长季节的提前所致,而落叶阔叶林、针阔混交林、矮林灌丛、温带草原及草甸、稀树草原、高寒植被、荒漠以及人工植被NPP的增加主要来自生长季生长加速的贡献.从区域分布看,在四季中春季NPP增加量最大的地区主要集中在东部季风区域;夏季NPP增加量最大的地区包括西北干旱区域和青藏高原的大部分地区、小兴安岭-长白山区、三江平原、松辽平原、四川盆地、雷州半岛、长江中下游部分地区以及江南山地东部;而秋季植被NPP增加量最大的地区主要有云南高原-西藏东部和呼伦湖的周围等地区.不同植被和地理区域NPP的这些响应方式与区域气候特征及其变化趋势有关.     

我国陆地植被净初级生产力变化规律及其对气候的响应

在GIS系统的支持下,利用卫星遥感资料和地面气象观测资料,构建了基于光能利用率的植被净初级生产力(NPP)遥感模型,估算了我国陆地1982—2000年1—12月植被NPP,分析了1982—2000年我国不同植被类型NPP的季节性和年际性变化规律,基于像元空间尺度讨论了植被NPP对气候的响应关系.结果表明,我国植被NPP年内季节性变化规律明显;我国主要植被类型年NPP在1982—2000年基本呈上升趋势,增长幅度最大的是落叶针叶林,增长幅度最小的是草地;1982—2000年,NPP年际间波动最大的植被类型是常绿阔叶林,年际间波动最小的植被类型是草地.通过NPP对气候因子(降水、温度)变化的响应分析表明,我国降水对植被NPP季节性变化的驱动作用高于温度,气候因子(降水、温度)对北方植被NPP季节性变化的驱动作用高于南方;我国气候因子(降水、温度)对NPP年际变化的驱动作用(强度、方向)随季节 及纬度的不同而不同.     

近51年来祁连山植被净初级生产力对气候变化的响应

本研究以分辨率为0.1°×0.1°的植被、土壤和气象数据为驱动,利用大气-植被相互作用模型(AVIM2)模拟了祁连山地区1958~2008年植被净初级生产力(NPP),并对近51年来祁连山地区植被NPP对气候变化的响应进行了分析。结果表明:近51年来祁连山植被(常绿针叶林、落叶针叶林、草地、灌木、农田)在气温升高和降水量增加的影响下,NPP总量呈增加趋势,且增加速率依次为:农田>常绿针叶林>落叶针叶林>草地>灌木。植被NPP的变化与气温和降水量的变化均呈正相关关系,且温度变化对植被NPP的影响大于降水,即温度变化是影响祁连山地区植被NPP变化的主导因素。从区域平均来看,气温年平均上升速率为0.043℃·a-1,降水量的平均增加速率为1.355mm·a-1,在气温和降水量的共同作用下,1958~2008年祁连山地区植被NPP总量呈增加趋势,平均增加速率为0.718g·m-2·a-1。     

中国植被净初级生产力变化的时空格局

利用植被净初级生产力（NPP）遥感估算模型，基于统计学分析方法，研究了1982-2000年我国陆地植被NPP的变化及其年际波动的空间分布特征。结果表明：（1）20年间，我国仅8％的陆地区域植被NPP显著减少，而47％的陆地区域植被NPP显著增加，45％的陆地区域植被NPP变化不明显；（2）从空间分布上看，我国大部地区年NPP增加，仅东部沿海发达地区或工业、城市密集区的年NPP减少，但增减速率在空间上存在明显的差异；（3）1982-2000年间，我国大部地区植被NPP年际波动相对变率较小，但西北地区的荒漠草原，相对变率较大。     

中国西北地区植被NPP多时间尺度变化及其对气候变化的响应

净初级生产力(NPP)是评估植被生长的重要参数,也是评价区域生态环境质量的重要指标。以"一带一路"枢纽地区西北六省为研究区,基于多年连续的GIMMS NDVI资料和气象数据,利用CASA模型,估算了西北六省34年NPP值,利用MK和EEMD方法,揭示了NPP变化的非线性特征,并探究不同时间尺度植被NPP变化对气候变化的响应。研究结果发现:(1)1982—2015年生长季植被NPP总体呈增加趋势,线性增长率为0.718 gCm~(-2) a~(-1);大多数研究区植被NPP短时间内将保持现有变化趋势,尤其是青藏高原、塔里木盆地边缘和内蒙古南部一带。(2)1982—2015年植被NPP以3年周期变化和长期增加趋势为主。其中陕西的南部,甘肃、新疆、宁夏和青海的北部以及内蒙古中部和北部以3年周期变化为主导,而陕西的北部,甘肃、新疆、宁夏的南部以及内蒙古东部以长期变化为主。不同植被类型NPP变化差异明显:针叶林、阔叶林以及混交林以3年周期波动为主,而灌木、草地和农田以3年周期波动和长期增长趋势为主。(3)NPP与气温和降水之间的相关性随着时间尺度的增大逐渐显著。在3年时间尺度上,大多数研究区NPP与气温和降水的相关性很小(P0.05)。6年时间尺度上,NPP与降水量呈正相关的区域向南略有扩散,其中青海南部高寒草甸NPP与降水的相关性由负相关转为正相关。在长期趋势上,NPP与气温和降水量具有非常显著的相关关系,且呈正相关的区域大于负相关的区域。本研究发现多时间尺度能够更好的分析NPP时空特征以及不同时间尺度NPP对气候变化的响应,有助于揭示全球气候变化背景下植被NPP对气候变化的非线性响应机制,评价气候变化的生态坏境风险,为西北六省区域可持续发展和生态环境保护提供理论依据。     

青藏高原草地植被覆盖变化及其与气候因子的关系

 为揭示气候变化对青藏高原草地生态系统的影响及其生态适应机制,利用1982～1999年间的NOAA/AVHRR  NDVI 数据和对应的气候资料,研究了近20年来青藏高原草地植被 覆盖 变化及其与气候因子的关系。结果表明,18年来研究区生长季NDVI显著增加(p=0.015) ,其增加率和增加量分别为0.41% a^－1和0.001 0 a^－1。生长季提前和生长季生长加速是青藏高 原草地植被生长季NDVI增加的主要原因。春季为NDVI增加率和增加量最大的季节, 其增加率 和增加量分别为0.92% a^－1和0.001 4 a^－1;夏季NDVI的增加对生长季NDVI增加的贡献相对较小,其增加率和增加量分别为0.37% a^－1和0.001 0 a^－1。3种草地(高寒草甸、高寒草原、温性草原)春季NDVI均显著增加(p<0.01; p=0.001; p=0.002); 高寒草甸夏季NDVI显著增 加(p=0.027),而高寒草原和温性草原夏季NDVI呈增加趋势,但都不显著(p=0. 106; p=0 .087);3种草地秋季NDVI则没有明显的变化趋势(p=0.585; p=0.461; p=0 .143)。3种草地春季NDVI的增加是由春季温度上升所致。高寒草地(高寒草甸和高寒草原)夏季 NDVI的增加是夏季温度和春季降水共同作用的结果。温性草原夏季NDVI变化与气候因子并没有表现出显著的相关关系。高寒草地植被生长对气候变化的响应存在滞后效应。     

江西省植被净初级生产力的空间格局及其对气候因素的响应

应用遥感-过程耦合模型(GLOPEM-CEVSA),模拟了2000-2006年江西省陆地植被净初级生产力(NPP),分析了其空间格局及其对气候因子的响应.本模型模拟数据与样点实测数据间呈显著的线性相关,复相关系数为0.85 (P＜0.001).在全省主要植被类型中,常绿针叶林的NPP最高(1091.38 g C·m-2·a-1),其次是常绿阔叶林(846.09gC ·m-2·a-1)、灌丛(596.62 gC.m-2.a-1)和草地(325.50gC ·m-2·a-1).不同气候梯度上的NPP分布状况分析表明,在降水低于1900 mm的地区,随降水量增加NPP略有增加但幅度较小且波动较为剧烈;在降水量为1900 ～ 1950 mm的地区,降水越多NPP也越高,且增加显著;但在降水高于1950 mm地区,NPP则随着降水的增加而降低.在气温低于17℃的区域,温度越高NPP也较高,而在温度高于17℃的区域,NPP则随温度增加而降低.进一步分析低(＜17.25℃)、均(17.25 ～18.55℃)、高(＞18.55℃)3个气温区内空间上NPP与降水的关系发现,低温区和均温区主要植被以常绿针叶林为主,NPP较高,而高温区则以农田和灌丛为主,NPP较低且波动较大.     

河南植被水平地带性的分布规律

河南植被纬向性分布与气温有关。北部属温带落叶林区域,典型植被,山地为落叶阔叶林和常绿针叶林,东部平原的农作物为一年两作或两年三作。南部为亚热带常绿阔叶林区域的常绿、落叶阔叶混交林地带,典型植被为含有常绿成分的落叶阔叶林,针叶林由马尾松、黄山松和杉木林组成。河南植被的经向性分布职决于干燥度引起的地带性变化,东部大别山的植被由黄山松林和茶园来表征,南部的桐柏山地带则没有黄山松林和茶园。     

2000-2008年中国东北地区植被净初级生产力的模拟及季节变化

利用GLOPEM-CEVSA模型模拟并分析了中国东北地区2000-2008年植被净初级生产力(NPP)时空分布格局及其影响因素,并以4个森林生态站点(大兴安岭、老爷岭、凉水和长白山森林生态站)为例研究了东北地区森林NPP季节变化特征及其环境驱动.结果表明:2000-2008年,东北地区植被年均NPP为445 g C·m-2·a-1;整个研究区沿长白山山脉到小兴安岭山脉地区以及三江平原部分地区的NPP最高,沿长白山山脉到小兴安岭山脉西侧的辽河平原、松嫩平原东部、三江平原和大兴安岭地区次之,西部稀疏草原和荒漠地区的NPP最低.东北地区森林生态系统年均NPP最高,其次为灌丛、农田和草地,荒漠最低.森林生态系统中,针阔混交林年均NPP最大(722 g C·m-2·a-1),落叶针叶林年均NPP最小(451 g C·m-2·a-1).研究期间,森林NPP无显著年际变化,其中2007、2008年较往年NPP大幅增加,很可能与该地区期间气温上升有关(较往年偏高1 ℃=～2℃).东北地区森林自北向南生长季开始时间逐渐提前,生长季变长.     

气候波动和土地覆盖变化对广东省植被净初级生产力的相对影响

为深入理解人类活动对陆地生态系统的影响,采用CASA(Carnegie-Ames-Stanford Approach)模型估算广东省2000、2005和2010年实际植被净初级生产力(Net primary productivity,NPP),并基于情景模拟法估算气候和土地覆盖类型稳定条件下的植被NPP,对气候波动和土地覆盖变化在植被NPP变化中的相对贡献进行了研究。结果表明:太阳辐射对植被NPP具有显著的正向控制作用,气温与植被NPP表现为显著负相关,降水不是该区域植被生长的限制性因子;各气候因子与植被NPP的相关性具有季节和区域差异性。在气候不变条件下,土地覆盖变化整体上增加了NPP,对NPP变化的相对贡献与城市扩张格局相类似,不同生态区存在差异性,以珠三角区的贡献最大。总之,气候波动对NPP变化的相对贡献较为复杂,取决于气候因子的波动特征以及与NPP的相关性;其它因子(城市热岛、农耕活动和园林管理等)对NPP变化的相对贡献存在很多不确定性,整体上增加了NPP。     

Modelling the vegetation of China using the process-based equilibrium terrestrial biosphere model BIOME3

1 We model the potential vegetation and annual net primary production (NPP) of China on a 10′ grid under the present climate using the processed‐based equilibrium terrestrial biosphere model BIOME3. The simulated distribution of the vegetation was in general in good agreement with the potential natural vegetation based on a numerical comparison between the two maps using the ΔV statistic (ΔV = 0.23). Predicted and measured NPP were also similar, especially in terms of biome‐averages. 2 A coupled ocean–atmosphere general circulation model including sulphate aerosols was used to drive a double greenhouse gas scenario for 2070–2099. Simulated vegetation maps from two different CO₂ scenarios (340 and 500 p.p.m.v.) were compared to the baseline biome map using ΔV. Climate change alone produced a large reduction in desert, alpine tundra and ice/polar desert, and a general pole‐ward shift of the boreal, temperate deciduous, warm–temperate evergreen and tropical forest belts, a decline in boreal deciduous forest and the appearance of tropical deciduous forest. The inclusion of CO₂ physiological effects led to a marked decrease in moist savannas and desert, a general decrease for grasslands and steppe, and disappearance of xeric woodland/scrub. Temperate deciduous broadleaved forest, however, shifted north to occupy nearly half the area of previously temperate mixed forest. 3 The impact of climate change and increasing CO₂ is not only on biogeography, but also on potential NPP. The NPP values for most of the biomes in the scenarios with CO₂ set at 340 p.p.m.v. and 500 p.p.m.v. are greater than those under the current climate, except for the temperate deciduous forest, temperate evergreen broadleaved forest, tropical rain forest, tropical seasonal forest, and xeric woodland/scrub biomes. Total vegetation and total carbon is simulated to increase significantly in the future climate scenario, both with and without the CO₂ direct physiological effect. 4 Our results show that the global process‐based equilibrium terrestrial biosphere model BIOME3 can be used successfully at a regional scale.     

大气CO2升高及气候变化对中国陆地生态系统结构与功能的制约和影响（英文）

在本顶研究中,我们探讨了大气CO2加倍和气候变化条件下,中国陆地生态系统的结构与功能的变化。与多数研究不同的是,我们耦合了两个以地理空间为参照的生态系统模型,即生物地理模型（KBIOME）和生物地球化学模型（TEM）,用此研究现状和未来的环境下,中国的植被分布和年净初级生产力（NPP）的状况,我们采用3个大气环流模型,（GFDL－Q,GISS和OSU）预测的结果代表潜在气候变化。3个气候模型的预测都煌中国将变得更温暖并总体上更湿润。耦合的模型预测中国陆地生态系统的结构与功能都将产生十分显著的变化。植被的变迁表现为：1）中国东部森林带北移,温带常绿阔叶林面积扩大,较南的森林取代较北的类型;2）森林和草地的总面积增加,这是作为取代干旱藻木林、沙漠和高山苔原的结果。年净初级生产力在大气CO2加倍和气候变化条件下,增加30％左右,与其它研究不同的另一点是,我们可能进一步区分生产力变化的原因,在所增加的生产力中,12％－21％是源于生态系统的取代较低产的生态系统的结果。这项研究预测了未来中国植被和生产力潜在的变化并给出了变化的范围,为同类的研究以及有关的政策评估提供了有用的参考信息。     

土地利用约束下中国东部南北样带生产力和植被分布对全球变化的响应

对现有的区域植被动态模拟模型进行了改进,使之包含了土地利用分布格局对植被和生态系统相关过程的影响。改进后的模型被用地研究中国东部南北样带(NSTEC)植被和净第一性生产力对未来气候变化的响应。模拟结果显示土地利用格局对未来气候条件下植被分布的变迁和生产力形成过程有非常显著的影响。与没有土地利用约束的情形相比较,土地利用作为限制条件缓减了植被类型之间的竞争,从而减少了模拟的样带区域内常绿阔叶林,但增加了模拟灌木和草地的分布。土地利用约束使得模拟得到的当前条件下的净第一性生产力更为接近实际情况,且未来气候条件下的生产力改变量更为可信。对未来CO2倍增条件下7个大气环流模型预测的气候情景的模拟结果表明：落叶阔叶林将显著增加,但针叶林、灌木和草原的分布将下降。未来气候条件下NSTEC样带的净第一性生产力总量将增加。预测样带北部的净第一性生产力的变化范围大于样带南部。温度变化比降水变化对样带的生产力具有更强的控制。     

Evaluating Spatial-Temporal Dynamics of Net Primary Productivity of Different Forest Types in Northeastern China Based on Improved FORCCHN

An improved individual-based forest ecosystem carbon budget model for China (FORCCHN) was applied to investigate the spatial-temporal dynamics of net primary productivity of different forest types in northeastern China. In this study, the forests of northeastern China were categorized into four ecological types according to their habitats and generic characteristics (evergreen broadleaf forest, deciduous broadleaf forest, evergreen needleleaf forest and deciduous needleleaf forest). The results showed that distribution and change of forest NPP in northeastern China were related to the different forest types. From 1981 to 2002, among the forest types in northeastern China, per unit area NPP and total NPP of deciduous broadleaf forest were the highest, with the values of 729.4 gC/(m²•yr) and 106.0 TgC/yr, respectively, followed by mixed broadleaf- needleleaf forest, deciduous needleleaf forest and evergreen needleleaf forest. From 1981 to 2002, per unit area NPP and total NPP of different forest types in northeastern China exhibited significant trends of interannual increase, and rapid increase was found between the 1980s and 1990s. The contribution of the different forest type’s NPP to total NPP in northeastern China was clearly different. The greatest was deciduous broadleaf forest, followed by mixed broadleaf- needleleaf forest and deciduous needleleaf forest. The smallest was evergreen needleleaf forest. Spatial difference in NPP between different forest types was remarkable. High NPP values of deciduous needleleaf forest, mixed broadleaf- needleleaf forest and deciduous broadleaf forest were found in the Daxing’anling region, the southeastern of Xiaoxing’anling and Jilin province, and the Changbai Mountain, respectively. However, no regional differences were found for evergreen needleleaf NPP. This study provided not only an estimation NPP of different forest types in northeastern China but also a useful methodology for estimating forest carbon storage at regional and global levels.     

Responses of vegetation structure and primary production of a forest transect in eastern China to global change

Aim A regional model of vegetation dynamics was enhanced to include biogeochemical cycling of nitrogen and was then applied to a forest transect in east China (FTEC) in order to investigate the responses of the transect to possible global change. Location Eastern China. Methods Biomass and nitrogen concentration of green and nongreen portions of vegetation, moisture contents of three soil layers, and total and available soil nitrogen are included as state variables in the enhanced model. The model was parameterized and validated against field observations of biomass, productivity, plant and soil nitrogen concentration, nitrogen uptake, a vegetation index derived from satellite remote sensing and digital maps of vegetation and soil distributions along a forest transect in eastern China (FTEC). The model was applied to FTEC in order to investigate the responsive characteristics of the ecosystems to global climatic change. Scenarios of climate change under doubled CO₂ produced by seven general circulation models (GCM) were used to drive the model. Results The simulations indicated that the model is capable of simulating accurately potential vegetation distribution and net primary productivity under contemporary climatic conditions. The simulations for GCM‐projected future climate scenarios with doubled atmospheric CO₂ concentration predicted that broadleaf forests would increase, but conifer forests, shrubs and grasses would decrease; and that deciduous forests would have the largest relative increase, but evergreen shrubs would have the largest decrease. Conclusions The overall effects of doubling CO₂ and climatic changes on FTEC were to produce an increased net primary productivity (NPP) at equilibrium for all seven GCM scenarios. The inclusion of nitrogen dynamics in the model imposes more constraint on the responses of FTEC to climatic change than the previous version of the model without nitrogen dynamics. Temperature exerts a stronger control on NPP than precipitation, as indicated by the negative correlations between NPP and temperature. The southern portion of FTEC, at latitudes less than 33 °N, show much larger increases in annual NPP than in the north. However, the predicted range of NPP increases is much larger in the north than in the south.     

Climate-induced changes in the vegetation pattern of China in the 21st century

Quantifying climate-induced changes in vegetation patterns is essential to understanding land–climate interactions and ecosystem changes. In the present study, we estimated various distributional changes of vegetation under different climate-change scenarios in the 21st century. Both hypothetical scenarios and Hedley RCM scenarios show that the transitional vegetation types, such as shrubland and grassland, have higher sensitivity to climatic change compared to vegetation under extreme climatic conditions, such as the evergreen broadleaf forest or desert, barren lands. Mainly, the sensitive areas in China lie in the Tibetan Plateau, Yunnan-Guizhou Plateau, northeastern plain of China and eco-zones between different vegetations. As the temperature increases, mixed forests and deciduous broadleaf forests will shift towards northern China. Grassland, shrubland and wooded grassland will extend to southeastern China. The RCM-project climate changes generally have caused positive vegetation changes; vegetation cover will probably improve 19% relative to baseline, and the forest will expand to 8% relative to baseline, while the desert and bare ground will reduce by about 13%.     

湖南城步南山的植被及其合理利用

 城步南山是我国南方规模最大的牧场,总面积138,345亩(9,223公顷)。南山地区的植被,根据生态外貌原则划分为常绿针叶林、常绿落叶阔叶混交林,落叶阔叶林,灌丛、竹丛、草丛,农作物,经济林和果园等10个主要类型。现在的草丛是森林遭受破坏的次生植被。本区在开发利用上,应以发展林业为主,实行林牧结合。山地坡度大于35˚的必须发展林业,25—34˚的坡地要林牧兼顾,小于24˚者可以发展牧业,并营造各类防护林。     

Estimating Carbon Flux Phenology with Satellite-Derived Land Surface Phenology and Climate Drivers for Different Biomes: A Synthesis of AmeriFlux Observations

Carbon Flux Phenology (CFP) can affect the interannual variation in Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands), using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU) by more than 70% and End of Carbon Uptake (ECU) by more than 60%. The Root Mean Square Error (RMSE) of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.