Changes in global potential vegetation distributions from 1911 to 2000 as simulated by the Comprehensive Sequential Classification System approach

Vegetation classification models play an important role in studying the response of the terrestrial ecosystem to global climate change. In this paper, we study changes in global Potential Natural Vegetation (PNV) distributions using the Comprehensive Sequential Classification System (CSCS) approach, a technique that combines geographic information systems. Results indicate that on a global scale there are good agreements among maps produced by the CSCS method and the globally well-accepted Holdridge Life Zone (HLZ) and BIOME4 PNV models. The potential vegetation simulated by the CSCS approach has 6 major latitudinal zones in the northern hemisphere and 2 in the southern hemisphere. In mountainous areas it has obvious altitudinal distribution characteristics due to topographic effects. The distribution extent for different PNV classes at various periods has different characteristics. It had a decreasing trend for the tundra and alpine steppe, desert, sub-tropical forest and tropical forest categories, and an increasing trend for the temperate forest and grassland vegetation categories. The simulation of global CSCS-based PNV classes helps to understand climate-vegetation relationships and reveals the dynamics of potential vegetation distributions induced by global changes. Compared with existing statistical and equilibrium models, the CSCS approach provides similar mapping results for global PNV and has the advantage of improved simulation of grassland classes.     

植被-气候关系遥感分析研究进展

对当前植被-气候关系遥感分析研究进行了总结.过去几十年内,全球不同尺度、区域和时间序列的植被变化对气候变化表现出了明显响应.植被的生长变化与气温和降水的变化密切相关.而大尺度上土地覆被类型的变化及植被覆盖的变化对局地及区域的气候产生重要的反馈作用.当前植被-气候关系研究的常用的遥感数据源较多,但也存在单一遥感数据源时间...     

川西高山高原过渡带植被对气候变化的响应

植被是陆地生态系统的主体,被认为是人类环境评价和监测的重要参数,利用遥感技术来监测植被生长及其对气候因子的响应成为当前全球变化研究的热点之一.川西高山高原区是我国地势最高一级的青藏高原向川西南山地和四川盆地的过渡地带,属生态环境脆弱区,对全球气候变化敏感.基于MODIS植被产品及气温、降水站点数据对2001-2010年川西高山高原过渡带的气温和降水的年际变化、NDVI的时空演变及其与气候因子的相关关系,较好的揭示了研究区的植被生长对气候因子变化的响应特点.研究结果表明:NDVI与降水量和气温均呈正相关关系.温度是春季植被生长的主要影响因素,降水量是秋季植被生长的主要影响因素.     

Impacts of climate change on ecosystem in Priority Areas of Biodiversity Conservation in China

Priority Areas of Biodiversity Conservation （PABCs） are the key areas for future biodiversity conservation in China. In this study, we used 5 dynamic global vegetation models （DGVMs） to simulate the ecosystem function changes under future climate change scenario in the 32 terrestrial PABCs. We selected vegetation coverage, vegetation productivity, and ecosystem carbon balance as the indicators to describe the ecosystem function changes. The results indicate that woody vegetation coverage will greatly increase in the Loess Plateau Region, the North China Plain, and the Lower Hilly Region of South China. The future climate change will have great impact on the original vegetation in alpine meadow and arid and semiarid regions. The vegetation productivity of most PABCs will enhance in the coming 100 years. The largest increment will take place in the southwestern regions with high elevation. The PABCs in the Desert Region of Inner Mongolia-Xinjiang Plateau are with fastest productivity climbing, and these areas are also with more carbon sink accumulation in the future. DGVM will be a new efficient tool for evaluating ecosystem function changes in future in large scale. This study is expected to provide technical support for the future ecosystem management and biodiversity conservation under climate change.     

考虑局部归一化高度的双分支语义分割网络

归一化数字表面模型是表征地物高度、辅助遥感影像分类的重要特征,但是其片状、精度不稳定的特性制约了分类精度的提升.针对这个问题,该文提出了一种考虑局部归一化高度的双分支输入语义分割网络,一方面设计了一种双分支输入结构,分别提取地物的光谱特征和几何特征,并通过跳跃连接进行特征融合以充分学习地物多模态信息;另一方面提出了一种新的地物高度表征方法,结合深度神经网络受GPU显存限制只能处理较小区域影像的特点,在输入的数字表面模型局部区域内计算高度特征.最后通过在ISPRS标准数据集上对三种网络框架进行对比试验,证明了相较于仅使用光谱影像,该文方法总体精度提升了4.5%～4.7%,比使用归一化表面模型作为高度特征的分类方法具有更高的分类精度、计算效率和自动化程度.     

1990—2010年间我国北方农牧交错带植被覆盖度变化归因

以我国北方传统农牧交错带为研究区,以植被归一化指数(NDVI)表征地表植被覆盖度,对土地利用数据和降水量、气温等气象数据两大类影响因子进行相关性分析.研究发现:1990—2010年该地区主要土地利用类型发生了显著的相互转化,但占优势的仍是草地、耕地和林地,土地利用和景观结构未发生重大变化.研究期间,北方农牧交错带耕地、林地和未利用土地植被覆盖度均有所增加,草地植被覆盖度有所减少.植被覆盖度与年均降水量呈极显著相关性,1990—2010年农牧交错带降水呈减少趋势,植被覆盖度上升趋势明显.植被覆盖度与同期年均气温数据也呈现一定的正相关性,1990—2010年农牧交错带气温变化属于升温趋势,植被覆盖度上升趋势明显.研究表明北方农牧交错带植被覆盖度变化是在全球气候变化和人类活动的双重影响下发生的,土地利用变化和降水、气温气象数据两种因素对植被覆盖度的影响具有明显的地域性特征,土地利用变化因子的影响由于受政策和人类活动的参与而正逐渐占据着主导地位,而气候条件中,气温升高对植被覆盖度具有一定的正相关性,降水量因子在径流量充沛地区影响作用较弱,但在水源缺乏,人类活动干预较少农牧交错带西北地区仍然有着重要的影响作用.     

青藏高原植被活动对降水变化的响应

为揭示气候变异对青藏高原植被生长的影响,根据2000-2004年间增强型植被指数(EVI)数据和研究区内43个气象台站的气候资料,研究了近5年来青藏高原植被活动及其与气候因子的关系。结果显示,青藏高原植被的EVI呈现由东南向西北递减的分布格局,降水是导致植被覆盖空间变化的主要因素;2000?2004年青藏高原植被活动的年际变化总体上不显著,局部出现较大变异;EVI的变异系数(CV)与年降水的变异系数显著正相关,说明降水波动是引起植被活动变化的主要因素。此外,EVI 的CV与年降水量存在着显著的负相关关系,表明年降水量越大的地区植被活动的年际变化越小,即植被的稳定性越大。     

树木生长对气候变化的响应研究进展

树木生长对气候变化的响应将深刻影响区域植被动态、陆地生态系统生物地化循环、气候反馈及其人类福祉.持续的气候变暖、极端气候事件及自然和人为干扰的增加深刻地影响树木生长动态的时空格局.本文综述了近几十年全球气候变化的整体概况,着重探讨了气候变化对树木生长的影响机制以及树木生长对气候系统的反馈,并就树木生长响应气候变化研究中可能存在的问题和研究前景进行了探讨.提出未来树木生长响应气候变化关系的研究应考虑树木生长响应气候变化的时空差异,加强对树木死亡时空格局及内在机理的认识,重点关注不断增加的极端气候事件及火、虫灾干扰对树木生长的非线性影响机制,并融合地面观测、遥感及陆面动态植被模型模拟等多种分析手段综合分析树木生长对气候变化响应机制的尺度效应及内在机理.     

Species-specific responses of Late Quaternary megafauna to climate and humans

Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.     

中国植被物候研究进展及展望

本文围绕气候变化背景下的中国植被物候研究,梳理了植被物候对气候变化的响应机制,分析了中国植被物候变化对陆地生态系统碳、水和能量循环的影响,植被物候变化对局地气候的反馈机制以及通过大气环流对气候系统的影响．主要结论:1)中国植被生长季开始日期提前1~6 d?(10 a)–1,结束日期推迟2~5 d?(10 a)–1,生长季显著延长;2)中国中高纬度地区植被对温度的响应明显高于亚热带和热带地区,温度在控制植被物候的过程中起到多重作用,降水主要影响干旱和半干旱地区的植被物候;3)植被生长季延长增加陆地生态系统生产力,增加中国碳汇;4)植被物候变化改变植被的蒸散发量,从而改变我国的流域尺度河流径流;5)在中国大部分地区,植被物候变化对气候系统产生负反馈作用,甚至影响大气环流过程．中国植被物候的研究越来越多,但仍存在亟待解决的科学问题,比如未来中国植被物候研究需要更加关注遥感数据反演精度,明确物候响应气候变化机制的尺度效应,结合机器学习等智能算法改进物候模型提高物候模拟精度,并重视农作物物候,加强物候与森林管理结合研究以提高我国生态系统碳汇能力,积极面对碳中和带来的机遇与挑战．      

Lagged effects of ocean climate change on fulmar population dynamics

Environmental variation reflected by the North Atlantic Oscillation affects breeding and survival in terrestrial vertebrates, and climate change is predicted to have an impact on population dynamics by influencing food quality or availability. The North Atlantic Oscillation also affects the abundance of marine fish and zooplankton, but it is unclear whether this filters up trophic levels to long-lived marine top predators. Here we show by analysis of data from a 50-year study of the fulmar that two different indices of ocean climate variation may have lagged effects on population dynamics in this procellariiform seabird. Annual variability in breeding performance is influenced by the North Atlantic Oscillation, whereas cohort differences in recruitment are related to temperature changes in the summer growing season in the year of birth. Because fulmars exhibit delayed reproduction, there is a 5-year lag in the population's response to these effects of environmental change. These data show how interactions between different climatic factors result in complex dynamics, and that the effects of climate change may take many years to become apparent in long-lived marine top predators.     

植被动态的格局与过程

植被动态是当前生态学研究的热点之一，本文论述了植被动态的双重性、途径和方向、平衡性以及干扰。讨论了植被动态的时空格局，及以种群过程为基础的、沿时间尺度的植被动态的格局与过程的理论框架。最后论述了基于种群过程的植被动态的机制。     

我国植被与环境关系研究进展

植被与环境关系研究是植被生态学的重要领域之一,在过去的几十年里,人们发展了许多数量方法,用来分析植物群落与其环境如气候、土壤、地形等的关系,这些方法可分为两类,一类是多元分析,如植物群落的排序和分类;另一类是植被－气候分类系统,生态学家利用这些方法并结合数理统计,解释植被梯度和环境变化的,分析表明,我国学十分重视这类研究并做了大量工作,有方法介绍和改进,但更多的是应用,目前,新技术特别是遥感和地     

归一化植被指数与主要气候因子耦合关系研究

以我国归一化植被指数时间序列数据集和历年各气象台站气温和降水量等气候因子数据为基础,分析我国归一化植被指数、气温和降水量的时序变化特征,同时通过研究讨论我国归一化植被指数与气候因子之间的耦合关系.研究表明:MODIS-NDVI、气温、降水量三个因子的平均变化趋势相近,均表现出周期性.并且,MODISNDVI与气候因子具有正相关关系,气温影响降水量,而气温和降水量共同影响MODIS-NDVI,即影响植被长势和生物量的变化.     

太行山长城岭南山东北坡植被的研究

本文研究了太行山长城岭南山东北坡的植被分布及其特征。结果表明,从山麓至山顶,由于气候条件随海拨的逐渐升高而产生了明显的垂直变化,从而导致了植被分布的垂直变化。从山麓至山顶依次分布有落叶阔叶林、针阔混交林、针叶林和落叶阔叶灌丛等四个植被型、并因人为干扰落叶阔叶林正向针阔叶混交林和针叶林方向演替。     

Variety distribution pattern and climatic potential productivity of spring maize in Northeast China under climate change

This study was based on the daily meteorological data of 101 meteorological stations from 1971 to 2000 and the 0.25°×0.25° grid data from 1951 to 2100 simulated by RegCM3 under the future A1B climatic scenario published by National Climate Center,in combination with the demand of climatic condition for maize growth in Northeast China.The trajectory of agricultural climatic resources and the effects of climate change on variety distribution and climatic potential productivity of spring maize in Northeast China under future climate change were analyzed.The main agro-climatic resource factors include:the initial date daily average temperature stably passing 10℃(≥10℃),the first frost date,the days of growing period,the ≥10℃ accumulated temperature,and the total radiation and precipitation in the growing period.The results showed that:(1) in the coming 100 years,the first date of ≥10℃ would be significantly advanced,and the first frost date would be delayed.The days of growing period would be extended,the ≥10℃ accumulated temperature and the total radiation would be significantly increased.However,no significant change was found in precipitation.(2) Due to the climate change,the early-maturing varieties will be gradually replaced by late-maturing varieties in Northeast China,and the planting boundaries of several maize varieties would be extended northward and eastward.(3) There would be a significant change in the climatic potential productivity of maize in Northeast China with the high-value gradually moving towards northeast.(4) It was an effective way to increase the climatic potential productivity of maize by appropriate adjustment of sowing date.     

Projected increase in continental runoff due to plant responses to increasing carbon dioxide

In addition to influencing climatic conditions directly through radiative forcing, increasing carbon dioxide concentration influences the climate system through its effects on plant physiology. Plant stomata generally open less widely under increased carbon dioxide concentration, which reduces transpiration and thus leaves more water at the land surface. This driver of change in the climate system, which we term 'physiological forcing', has been detected in observational records of increasing average continental runoff over the twentieth century. Here we use an ensemble of experiments with a global climate model that includes a vegetation component to assess the contribution of physiological forcing to future changes in continental runoff, in the context of uncertainties in future precipitation. We find that the physiological effect of doubled carbon dioxide concentrations on plant transpiration increases simulated global mean runoff by 6 per cent relative to pre-industrial levels; an increase that is comparable to that simulated in response to radiatively forced climate change (11 +/- 6 per cent). Assessments of the effect of increasing carbon dioxide concentrations on the hydrological cycle that only consider radiative forcing will therefore tend to underestimate future increases in runoff and overestimate decreases. This suggests that freshwater resources may be less limited than previously assumed under scenarios of future global warming, although there is still an increased risk of drought. Moreover, our results highlight that the practice of assessing the climate-forcing potential of all greenhouse gases in terms of their radiative forcing potential relative to carbon dioxide does not accurately reflect the relative effects of different greenhouse gases on freshwater resources.     

Impact of land surface degradation in northern China and southern Mongolia on regional climate

Clear evidence provided by the singular value decomposition (SVD) analysis to the normalized difference vegetation index (NDVI) and precipitation data identifies that there exists a sensitive region of vegetation-climate interaction located in the transitional zone over northern China and its surrounding areas, where the vegetation cover change has the most significant influence on summer precipitation over China.““ Comparison of reanalysis data with station data provides a good method to assess the impacts of land use change on surface temperature, and the most obvious contribution of land use change may be to lead to notable warming over northern China in the interdecadal time scale. Based on the new statistical results, a high-resolution regional integrated environmental model system (RIEMS) is employed to investigate the effects of land surface degradation over the transitional zone and its surrounding areas (northern China and southern Mongolia) on the regional climate. Land degradation results in the decreases in precipitation over northern and southern China, and the increase in between, and increased and decreased temperature over vegetation change areas and the adjacent area to the south, respectively. Not only would it change the surface climate, but also bring the significant influence on the atmospheric circulation. Both the surface climate and circulation changes generally agree to the observed interdecadal anomalies over the last five decades. These integrated statistical and simulated results imply that land surface degradation over the transitional zone in northern China and its surrounding areas could be one of the main causes responsible for the climate anomalies over China, especially the drought over northern China.