红树林生态系统遥感监测研究进展

随着现代遥感技术的迅速发展,遥感监测已经成为红树林生态系统变化监测的重要手段和方法。从遥感技术在生态系统变化监测应用领域入手,综述了国内外红树林遥感监测的发展历程,系统总结了遥感技术在红树林湿地动态、种间分类、群落结构(叶面积指数、冠幅、树高等)、生物量、灾害灾情(病虫害、风暴潮等)、景观格局动态、驱动力、红树林湿地保护与管理等领域应用现状,归纳了不同应用领域遥感监测的理论、方法及研究现状。指出我国在红树林遥感监测中存在的不足。提出红树林遥感监测应在分类标准体系规范化、分类精度提升、红树林生态学特征参数(物种多样性、优势度等)、生态系统环境空间演变过程及遥感监测的尺度效应方面加大研究力度。充分发挥区域综合监测模型在红树林生态系统变化遥感监测中的作用。     

遥感用于森林生物多样性监测的进展

随着物种和栖息地的丧失,全球范围的生物多样性保护已经成为迫切的需要。航空航天技术的迅猛发展使遥感成为能提供跨越不同时空尺度监测陆地生态系统生物多样性的重要工具,这方面的研究在欧美等国已经有了小范围的开展,在国内刚刚起步。国外关于生物多样性遥感探测的方法基本有3种:1.利用遥感数据直接对物种或生境制图,进而估算生物多样性;2 .建立遥感数据的光谱反射率与地面观测物种多样性的关系模型;3.与野外调查数据结合直接在遥感数据上进行生物多样性指数制图。研究表明,物种直接制图法只能应用于较小的范围;生境制图的方法,应用广泛,技术相对成熟,研究范围局限于几百公里的范畴,但不能获取生境内部的多样性信息。光谱模型技术目前正处于探索阶段,对于植被复杂、生物多样性高的地域,具有较大的应用潜力。在遥感数据上直接进行生物多样性制图在加拿大已经得到了应用。     

基于站点的生物多样性星空地一体化遥感监测

科学制定生物多样性保护和恢复政策, 需要空间上连续、时间上高频的物种和生境分布以及物种迁移信息支持, 遥感是目前能满足该要求的有效技术手段。近年来, 遥感平台和载荷技术高速发展, 综合多平台、多尺度、多模式遥感技术, 开展基于站点的星空地一体化遥感观测试验, 可以对地表进行时空多维度、立体连续观测, 为生物多样性遥感监测提供了新的契机。本文总结了使用遥感技术监测生物多样性的主要方法, 回顾了典型的星空地一体化遥感观测试验。综述以往研究发现, 一方面, 现有遥感试验还缺少对生物多样性直接监测指标的观测, 另一方面, 生物多样性遥感监测方法也缺少星空地多维立体观测平台的支撑, 亟需加强两者的融合, 开展基于站点的生物多样性星空地一体化遥感监测研究。以设于我国四川王朗大熊猫国家级自然保护区内的王朗山地生态遥感综合观测试验站为例, 展示了星空地一体化遥感综合观测试验平台在生物多样性监测中的应用潜力。星空地一体化遥感观测可以提供物种和生境的综合定量信息, 与生态模型有机结合, 可以刻画生物多样性的时空格局与动态过程, 有助于挖掘过程机理, 提高生物多样性监测的信息化水平。     

全球视角下的中国生物多样性监测进展与展望

生物多样性强烈的时空尺度依赖性和多层次性决定了生物多样性现状与变量的分析需要在不同生态系统进行多空间尺度、全面和连续的监测。因此, 构建生物多样性研究监测网络是生物多样性保护和研究的基础工作。近年来, 对地观测组织-生物多样性观测网络(GEO BON)、亚太生物多样性监测网络(APBON)等全球、区域以及国家尺度的生物多样性监测网络蓬勃发展。中国陆续在国家尺度上建立了针对生态系统和物种的长期监测网络, 其中, 中国生物多样性监测与研究网络(China Biodiversity Observation and Research Network, Sino BON)于2013年启动建设, 在我国主要生态系统和环境梯度设置30个监测主点和60个监测辅点, 目前已建成10个专项网对动物、植物和微生物进行监测, 并建立了以数据标准与汇交、近地面遥感为核心的综合监测中心。Sino BON打造了从地下、地面到森林林冠的多尺度、多类群(功能群)以及多营养级交互为重点的监测与研究平台, 为理解生物多样性变化趋势及其驱动因素、研究生物多样性维持机制, 以及国家履行《生物多样性公约》、保护生物多样性和生物资源提供详实可靠的生物多样性变化数据。为进一步支撑国家生物多样性治理能力、深化全球多样性保护合作, 我国生物多样性监测亟需在监测技术、监测区域、数据标准、综合信息平台等方向谋求更大的发展。     

植被光能利用率研究进展

光能利用率是表征植物固定太阳能效率的指标,指植物通过光合作用将所截获/吸收的能量转化为有机干物质的效率,是植物光合作用的重要概念,也是区域尺度以遥感参数模型监测植被生产力的理论基础。传统的研究方法是通过生物量收获法分别确定植物生长和辐射量,求年或生长季比值;涡度相关技术作为目前直接测定植被冠层与大气间的CO2和水热交换量的唯一方法,使从冠层到景观水平的光能利用率估计成为可能。由于植被类型的差异和气候环境的综合影响使光能利用率表现出显著的空间异质性和时间动态性。在全球尺度上,利用耦合大气CO2观测、卫星遥感和大气辐射传输模型的反演模拟,发现净初级生产力的光能利用率存在明显的地理分异。影响光能利用率时空变异性的因子包括植物内在因素(如叶形、叶羧化酶含量)和外在环境因素。针对光能利用率的时空特征及其波动,建立在通量观测及模型分析基础上的跨尺度模拟,将成为今后该领域的研究重点。     

江苏省农作物最大光能利用率时空特征及影响因子

基于遥感数据的光能利用率模型被广泛应用于计算陆地生态系统的生产力,但其结果对最大光能利用率(εmax)参数非常敏感。由于该参数存在明显的时空变异性,在区域尺度上难以确定。利用MODIS遥感数据、分县产量统计数据和VPM模型推算了2001—2010年江苏省各县逐年的农田εmax,分析了其时空变化特征及其可能原因。结果表明,在2001—2010年期间,江苏省61个县区农田εmax平均值的变化范围为0.757—3.435 g C/MJ,呈现北高南低、中间高四周较低的空间分布特征;各县区农田的εmax都呈现出上升趋势,但在2001—2006年期间存在明显的年际波动,2002年、2004年和2006年的εmax相对较低,2007年后全省农田εmax稳定上升;εmax的年际波动呈现由北向南递减的趋势;全省大部分地区εmax的年际变化与单位耕地面积农用化肥施用量呈正相关性,苏北北部尤为明显;同时也与C4作物产量所占比例相关。研究表明在利用光能利用率模型计算农田生产力时,需要发展能考虑εmax时空变化的参数化方案。     

航空航天遥感在物种多样性研究与保护中的应用

人类活动导致全球范围内生物多样性丧失日趋严重。物种多样性是研究最为深入以及最贴近生物多样性管理的层次。物种多样性的研究往往受到多时空尺度生态过程的影响, 传统物种多样性调查方法受到人力物力影响, 局限性大, 物种多样性的研究与管理亟需整合不同来源的数据。遥感技术从传统的光学遥感阶段发展到不同平台、不同维度相结合的多源遥感阶段, 并逐渐进入以高空间分辨率和高光谱为特征、以激光雷达为前沿发展方向的综合遥感阶段。遥感技术因为其监测范围广、能监测人迹罕至地区以及长期可重复等特性, 为研究不同时空尺度的生态学科学问题提供了更新更优的研究手段。本文围绕种群动态、种间关系与群落多样性、功能属性及功能多样性以及生物多样性保护管理等生物多样性研究热点问题, 系统地论述了航空航天遥感技术在物种多样性研究与保护领域的应用, 总结了航空航天遥感技术在研究与物种多样性有关的主要生态学问题中的机遇与挑战。我们认为航空航天遥感技术利用多光谱甚至高光谱与激光技术从空中监测物种多样性, 从不同视角、基于不同光源提供了物种多样性不同侧面的信息, 能够减小地面调查强度, 在大范围和边远地区的物种多样性调查研究中有着至关重要的作用。依据光谱特性的物种判别以及依据激光雷达的三维结构量测将促进生物多样性的研究与管理, 加强遥感学家和生物多样性研究者的沟通交流将有助于促进不同时空尺度的生物多样性与遥感技术的结合。     

利用聚类算法监测森林乔木物种多样性

该研究基于机载激光雷达(LiDAR)和高光谱数据, 从森林物种叶片的生理化学源头探寻生化特征与光谱特征的内在关联, 探讨生化多样性、光谱多样性与物种多样性之间的响应机制, 选择最优植被指数并结合最优结构参数, 通过聚类方法构建森林物种多样性遥感估算模型, 在古田山自然保护区开展森林乔木物种多样性监测。研究结果表明: (1)从16种叶片生化组分中, 筛选出叶绿素a、叶绿素b、类胡萝卜素、叶片含水量、比叶面积、纤维素、木质素、氮、磷和碳可通过偏最小二乘法用叶片光谱有效模拟(R² = 0.60-0.79, p < 0.01), 并选择有效的植被指数: 转换型吸收反射指数/优化型土壤调整指数(TCARI/OSAVI)、类胡萝卜素反射指数(CRI)、水波段指数(WBI)、比值植被指数(RVI)、生理反射指数(PRI)和冠层叶绿素浓度指数(CCCI)表征相应的最优生化组分; (2)基于机载LiDAR数据利用结合形态学冠层控制的分水岭算法获得高精度单木分离结果(R ² = 0.77, RMSE = 16.48), 同时采用逐步回归方法从常用的森林结构参数中选取树高和偏度作为最优结构参数(R ² = 0.32, p < 0.01); (3)基于6个最优植被指数和2个最优结构参数, 以20 m × 20 m为窗口通过自适应模糊C均值方法进行聚类, 实现了研究区森林乔木物种丰富度(Richness, R ²= 0.56, RMSE = 1.81)和多样性指数Shannon-Wiener (R ² = 0.83, RMSE = 0.22)与Simpson (R ² = 0.85, RMSE = 0.09)的成图。该研究在冠层尺度上获取了与物种多样性相关的生化、光谱和结构参数, 将单木个体作为最小单元, 利用聚类算法直接估算物种类别差异, 无需判定具体的树种属性, 是利用遥感数据进行区域尺度森林物种多样性监测与成图的实践, 可为亚热带地区常绿阔叶林的物种多样性监测提供借鉴。     

遥感植被指数与植物多样性的相关性及空间分布特征研究——以海口市主城区为例

植物多样性监测是开展物种保护与植被景观规划的重要基础,对实施生物多样性的优先区域保护具有重要意义。该文以海口市主城区为例,利用Landsat 8遥感数据与样方实测数据分析了植被指数与植物多样性指数之间的相关性,根据相关性分析结果构建植物多样性遥感监测数学模型,并筛选出最优模型用于监测研究区植物多样性的空间分布状况。结果表明:Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数与MSAVI植被指数相关系数最高,呈显著相关性(P<0.01)。通过一元线性数学回归模型得到的海口市植物多样性空间分布特征与实际情况相符,植物多样性水平较高的区域主要分布在火山口、东寨港和羊山湿地一带,且具有明显的空间自相关性。根据研究结果建议继续实施严格的保护措施,加强生态修复与保护工程,提高植被覆盖率和生物多样性水平。     

Forest species diversity mapping based on clustering algorithm

该研究基于机载激光雷达(LiDAR)和高光谱数据, 从森林物种叶片的生理化学源头探寻生化特征与光谱特征的内在关联, 探讨生化多样性、光谱多样性与物种多样性之间的响应机制, 选择最优植被指数并结合最优结构参数, 通过聚类方法构建森林物种多样性遥感估算模型, 在古田山自然保护区开展森林乔木物种多样性监测。研究结果表明: (1)从16种叶片生化组分中, 筛选出叶绿素a、叶绿素b、类胡萝卜素、叶片含水量、比叶面积、纤维素、木质素、氮、磷和碳可通过偏最小二乘法用叶片光谱有效模拟(R² = 0.60-0.79, p < 0.01), 并选择有效的植被指数: 转换型吸收反射指数/优化型土壤调整指数(TCARI/OSAVI)、类胡萝卜素反射指数(CRI)、水波段指数(WBI)、比值植被指数(RVI)、生理反射指数(PRI)和冠层叶绿素浓度指数(CCCI)表征相应的最优生化组分; (2)基于机载LiDAR数据利用结合形态学冠层控制的分水岭算法获得高精度单木分离结果(R ² = 0.77, RMSE = 16.48), 同时采用逐步回归方法从常用的森林结构参数中选取树高和偏度作为最优结构参数(R ² = 0.32, p < 0.01); (3)基于6个最优植被指数和2个最优结构参数, 以20 m × 20 m为窗口通过自适应模糊C均值方法进行聚类, 实现了研究区森林乔木物种丰富度(Richness, R ²= 0.56, RMSE = 1.81)和多样性指数Shannon-Wiener (R ² = 0.83, RMSE = 0.22)与Simpson (R ² = 0.85, RMSE = 0.09)的成图。该研究在冠层尺度上获取了与物种多样性相关的生化、光谱和结构参数, 将单木个体作为最小单元, 利用聚类算法直接估算物种类别差异, 无需判定具体的树种属性, 是利用遥感数据进行区域尺度森林物种多样性监测与成图的实践, 可为亚热带地区常绿阔叶林的物种多样性监测提供借鉴。     

Depletion of the mangroves of Continental Asia

The mangroves located around the Bay of Bengal and along the coast ofSouth China Sea are of special interest for many reasons. This coastlinereceives three major tropical rivers (Ganges, Irrawaddy, Mekong) and it hasthe world's largest mangrove stands in a single block (the Sunderbans). Thecontrasted climatic conditions from sub-arid (southeastern India), to moist(coastal Cambodia), and the extreme diversity of human impacts in one ofthe world's highest population densities (West Bengal in India andBangladesh), have created a mosaic of mangrove types that are floristicallyrich and with different histories, different ecological frameworks and distinct evolutionary trends.For the first time, we draw together remote sensing data along withessential structural and physiognomic parameters of mangrove forest areas.We have devised a sufficiently accurate coastal mapping methodologyproviding statistics on the actual areal extent of mangrove types andsub-types, both at local and continental scales. Some results are entirelynew, and others provide comparison with existing data. The exact extentof mangroves in Myanmar was previously unknown. Using remote sensingwe also demonstrate the magnitude of the ongoing deforestation in thiscountry. The current location and status of mangrove forests in the affectedarea are described using the methodology which is also being applied inother sites around the world.     

Applying remote sensing techniques to monitor shifting wetland vegetation: A case study of Danshui River estuary mangrove communities,Taiwan

The purpose of this study is to apply different remote sensing techniques to monitor shifting mangrove vegetation in the Danshui River estuary in Taipei, Taiwan, in order to evaluate a long-term wetland conservation strategy compromising between comprehensive wetland ecosystem management and urban development. In the Danshui estuary, mangrove dominated by Kandelia candel is the major vegetation, and a large area of marsh with freshwater grasses has been protected in three reserves along the river shore. This study applied satellite imagery from different remote sensors of various resolutions for spectral analysis in order to compare shifting wetland vegetation communities at different times. A two-stage analytical process was used for extracting vegetation area and types. In the first-stage, a normalized difference vegetation index (NDVI) was adopted to analyze SPOT, Landsat, and QuickBird imagery to obtain the spatial distribution of vegetation covers. In the second stage, a maximum likelihood classification (MLC) program was used to classify mangrove and non-mangrove areas. The results indicated that the spatial distribution of mangroves expanded 15.18 and 40 ha in two monitoring sites in 10 years, demonstrating the success of establishing reserves for protecting mangrove habitats. The analytical results also indicated that satellite imagery can easily discern the difference in characteristics between imagery of mangrove and other vegetation types, and that the logistical disadvantages of monitoring long-term vegetation community changes as well as evaluating an inaccessible area may be overcome by applying remote sensing techniques.     

Modern pollen rain in mangroves from San Andres Island, Colombian Caribbean

The precise characterisation of present-day mangrove ecosystems from modern pollen rain facilitates the accurate use of fossil pollen data for late Quaternary sea level and environmental reconstructions. Here, we investigate whether the analysis of pollen rain data corroborates existing floristic and structural characterisation of different mangrove types at the Caribbean island of San Andrés, Colombia. At 82 plots along 20 transects of four distinct mangrove types, samples were obtained of (i) surface sediments for pollen analysis, and (ii) a range of environmental parameters (including inundation levels, salinity and pH). This information was compared to previously sampled mangrove composition and tree basal area. In surface sediment samples 82 pollen taxa were found, from which 19 were present in the vegetation plots. However, because pollen may be transported by wind and/or watercourses, the overall floristic composition of the different forest types may not necessarily be reflected by the pollen spectra. Local vegetation (i.e. mangroves and beach) represented > 90% of the pollen spectra, while the regional one (i.e. hinterland forests) represented < 5% of it. Unlike the four mangrove types that were previously described in the vegetation, the analysis of pollen samples suggested only three distinct types of forest.The groups were characterised based on (i) the dominance of at least one of the true mangrove species from pollen data ordination and the presence of associated species, and (ii) their relationship with environmental parameters. Rhizophora was present in all plot samples, but did not contribute to forest type separation. In fact, just three true mangrove species proved reliable indicators of (i) high salinity and fringe mangroves (i.e. Avicennia), (ii) high pH levels and landward mangroves (i.e. Conocarpus), and (iii) natural or anthropogenic caused disturbance of forest stands (Laguncularia and associated Acrostichum fern). Hence our study confirms that mangrove pollen spectra can be accurately used to describe different mangrove environments for fossil based palaeoecological reconstructions.     

Qualitative distinction of congeneric and introgressive mangrove species in mixed patchy forest assemblages using high spatial resolution remotely sensed imagery (IKONOS)

This paper is a preliminary report of the ability of IKONOS multispectral satellite imagery with a very high spatial resolution of 1 metre to distinguish two mangrove species in Sri Lanka belonging to the same genus (Rhizophora apiculata and R. mucronata). Not only is this an advancement for the monitoring of forests, it is even more important considering their patchy nature in Sri Lankan mangroves (in contrast to classically zoned forests). Apart from congeneric distinction, intro‐gressive species (Acrostichum aureum) can also be detected from IKONOS imagery, which is important in the early warning for cryptic ecological changes that may affect mangrove species composition (both floral and faunal) and functioning. The results tabulate the usage of various image composites, transformations and classifications, and indicate the danger of too much detail in remote sensing, and the need to apply an optimum resolution. We also highlight that the highest resolutions (as in pansharpened multispectral composites) remain invaluable for visual ecological investigations, which are not at all outdated by new digital satellite images of (sub)metre spatial resolution and their possibility for computer‐aided analysis.     

Faunal impact on vegetation structure and ecosystem function in mangrove forests: A review

The last 20 years witnessed a real paradigm shift concerning the impact of biotic factors on ecosystem functions as well as on vegetation structure of mangrove forests. Before this small scientific revolution took place, structural aspects of mangrove forests were viewed to be the result of abiotic processes acting from the bottom-up, while, at ecosystem level, the outwelling hypothesis stated that mangroves primary production was removed via tidal action and carried to adjacent nearshore ecosystems where it fuelled detrital based food-webs. The sesarmid crabs were the first macrofaunal taxon to be considered a main actor in mangrove structuring processes, thanks to a number of studies carried out in the Indo-Pacific forests in the late 1970s and early 1980s. Following these classical papers, a number of studies on Sesarmidae feeding and burrowing ecology were carried out, which leave no doubts about the great importance of these herbivorous crabs in structuring and functioning Old world ecosystems. Although Sesarmidae are still considered very important in shaping mangrove structure and functioning, recent literature emphasizes the significance of other invertebrates. The Ocypodidae have now been shown to have the same role as Sesarmidae in terms of retention of forest products and organic matter processing in New world mangroves. In both New and Old world mangroves, crabs process large amounts of algal primary production, contribute consistently to retention of mangrove production and as ecosystem engineers, change particle size distribution and enhance soil aeration. Our understanding of the strong impact of gastropods, by means of high intake rates of mangrove products and differential consumption of propagules, has changed only recently. The role of insects must also be stressed. It is now clear that older techniques used to assess herbivory rates by insects strongly underestimate their impact, both in case of leaf eating and wood boring species and that herbivorous insects can potentially play a strong role in many aspects of mangrove ecology. Moreover, researchers only recently realized that ant–plant interactions may form an important contribution to our understanding of insect–plant dynamics in these habitats. Ants seem to be able to relieve mangroves from important herbivores such as many insects and sesarmid crabs. It thus seems likely that ants have positive effects on mangrove performance.     

The assessment of mangrove biomass and carbon in West Africa: a spatially explicit analytical framework

Mangrove forests are highly productive and have large carbon sinks while also providing numerous goods and ecosystem services. However, effective management and conservation of the mangrove forests are often dependent on spatially explicit assessments of the resource. Given the remote and highly dispersed nature of mangroves, estimation of biomass and carbon in mangroves through routine field-based inventories represents a challenging task which is impractical for large-scale planning and assessment. Alternative approaches based on geospatial technologies are needed to support this estimation in large areas. However, spatial data processing and analysis approaches used in this estimation of mangrove biomass and carbon have not been adequately investigated. In this study, we present a spatially explicit analytical framework that integrate remotely sensed data and spatial analyses approaches to support the estimation of mangrove biomass and carbon stock and their spatial patterns in West Africa. Forest canopy height derived from SRTM and ICESat/GLAS data was used to estimate mangrove biomass and carbon in nine West African countries. We developed a geospatial software toolkit that implemented the proposed framework. The spatial analysis framework and software toolkit provide solid support for the estimation and relative comparisons of mangrove-related metrics. While the mean canopy height of mangroves in our study area is 10.2 m, the total biomass and carbon were estimated as 272.56 and 136.28 Tg. Nigeria has the highest total mangrove biomass and carbon in the nine countries, but Cameroon is the country with the largest mean biomass and carbon density. The resulting spatially explicit distributions of mangrove biomass and carbon hold great potential in guiding the strategic planning of large-scale field-based assessment of mangrove forests. This study demonstrates the utility of online geospatial data and spatial analysis as a feasible solution for estimating the distribution of mangrove biomass and carbon at larger or smaller scales.     

Carbon and nutrient exchange of mangrove forests with the coastal ocean

Mangrove forests exchange materials with the coastal ocean through tidal inundation. In this study, we aim to provide an overview of the published data of carbon (C) and nutrient exchange of mangrove forests with the coastal ocean at different spatial scales to assess whether the exchange is correlated with environmental parameters. We collected data on C (dissolved and particulate organic C; DOC and POC) and nutrient exchange (dissolved and particulate nitrogen, N and phosphorus, P) and examined the role of latitude, temperature, precipitation, geomorphological setting, hydrology, dominant mangrove species and forest area in explaining the variability of the exchange. We identified that there are a range of methodologies used to determine material exchange of mangroves with the coastal zone, each methodology providing data on the exchange at different spatial scales. This variability of approaches has limited our understanding of the role of mangroves in the coastal zone. Regardless, we found that mangrove forests export C and nutrients to the coastal zone in the form of litter and POC. We found that precipitation is a major factor influencing the export of C in the form of litter; sites with low annual precipitation and high mean annual temperatures export more C as litter than sites with high precipitation and low temperature. Furthermore, export of POC is higher in zones with low mean annual minimum temperature. Identification of broad-scale trends in DOC and dissolved nutrients was more difficult, as the analysis was limited by scarcity of suitable studies and high variability in experimental approaches. However, tidal amplitude and the concentration of nutrients in the floodwater appears to be important in determining nutrient exchange. The strongest conclusion from our analysis is that mangrove forests are in general sources of C and nutrients in the form of litter and POC and that they are most likely to be exporting C subsidies in dry regions.     

红树林对水体净化作用研究进展

红树是一类生长在热带及亚热带海岸潮间带的湿地植物,具有净化水体的功能。近年来红树林净化水体方面的研究有不少进展,主要包括促进水体中悬浮物的沉降,利用其丰富的底栖生物对有机物的吸附和降解,以及其植株和底泥对重金属和营养盐的富集和吸收。但是红树林的净化容量是有限的,超负荷的污水排放会导致明显的或潜在的生态风险。在实际应用中,只有在充分的监控和限制条件下,才可有限地将红树林作为生活污水排放地。该研究的发展方向主要有污染物迁移转化过程中各因素的相互作用、红树林的对环境的综合改善能力以及实际应用中对生态风险的量化分析和监测等几方面。     

近地遥感在森林冠层物候动态监测中的应用

近地遥感技术是原位观测森林冠层物候的重要手段,具有高时间分辨率的优点,而且空间尺度适中,是实现物候尺度推绎的有力工具.本研究首先评述了利用3种光学传感器(辐射表、光谱仪和数码相机)监测森林物候的近地遥感方法;结合帽儿山通量观测站的实测数据分析识别物候期的不确定性来源,发现最重要的误差来自物候提取方法;剖析近地遥感与其他物候观测方法的衔接以及该技术自身存在的问题.最后提出该领域的重点研究方向: 加强冠层光学(或冠层结构)物候与功能(生理、生态过程)物候的联系;整合各区域冠层物候观测网络,实现冠层尺度的全球物候联网观测与数据共享;充分发挥近地遥感的优势,整合多源多尺度物候数据;发展近地遥感物候模型,改进动态全球植被模型中物候模拟.