城市植被与城市植被学

城市植被是指城市里覆盖着的生活植物，它具有完全不同于自然植被的性质、特点、以及生境条件，属人工植被类群．研究城市植被的种类组成、结构、类型、动态和功能、以及城市植被与城市环境间的相互关系的科学，应称为城市植被学或城市植物群落学．它是植被学或植物群落学的分支学科，一个新的学科。

印度西高止山Agastyamalai地区生物多样性层隙分析的植被学途径

在印度,历史上按某种特定方式已建立的保护区一直很少注意到某一地区的资源保护价值。这里着重研究印度西高止山(WG)Agastyamalai地区的保护区群。我们分析了该地区从本世纪初到1960年期间以及从1960年到1990年期间的森林面积减少和土地利用变化。研究中采用GIS技术对该地区的保护区进行了生物多样性层隙分析,绘制了现有植被类型的详细分布图,并利用这一植被图生成了分别与植物种类丰富度、植物特有种分布区、独特的植物生境区以及典型特有动物种群栖息地分布等相对应的多层专题图。将这些专题图与保护区网络分布图相叠加,显示了资源保护价值高但未能合理保护的地区。在这一研究地区出现森林采伐率高,一些生物多样性价值高的地区未列入最高级别的保护对象。我们提出这一方法旨在进一步建立一种资源保护的利用价值指数,以确定资源保护与管理的重点。

广西姑婆山植被的群落学特征

采用植物群落学研究方法,以广西姑婆山森林公园典型植物群落的6个样地调查资料为基础,研究广西姑婆山森林公园的植被群落学特征。结果表明:广西姑婆山森林公园植物群落中共有维管植物284种,隶属于75科143属,科、属的分布型以热带为主,反映了该群落以热带为主的亚热带区系特征;植被群落主要以革质、全缘、单叶、中型叶和高位芽类型的植物组成,体现了亚热带季风阔叶林类型的主要特征,强烈反映了植被对该区植物较适宜的温度和湿度,即较好的低纬水热组合,清晰地反映了亚热带湿润季风的气候特征。该群落植物各多样性指数表明其物种多样性较为丰富。

基于GIS的中国2大草地分类系统类的兼容性分析

以植被-生境学分类(vegetation-habitat classification system of grassland,VHCS)方法为基础的定性的中国草地分类系统,以及定量的气候-土地-植被综合顺序分类系统(comprehensive and sequential classification system of grassland,CSCS)是我国常用的2大草地分类系统。在实际应用中,因"草原"和"草地"概念的重叠、混淆和交叉,以及定性分类和定量分类的差异,造成了操作上的困扰,研究结果亦不便相互交流。本研究通过2大系统一级单位-"类"的分类指标、名称和属性的对比,分析了2个系统"类"的兼容性,建立了两者间的对应关系,并利用基本同期的CSCS分类图和数字化的中国草地资源图(VHCS),以内蒙古自治区和甘肃省为例,在ArcGIS平台上进行了验证分析。研究结果表明:1)以广义草原或草地概念为基础的CSCS是一个大系统,兼容了以中国为例的VHCS分类系统;2)兼容VHCS的CSCS的类,两者在分类指标、名称和属性方面均能达到统一;3)空间叠置分析表明,若不考虑森林和非地带性类,内蒙古和甘肃区域2个分类系统分类结果的兼容性分别达到61.4%和61.1%;有差异的区域,基本上表现出草地实际调查结果(VHCS)是比原生潜在草地(CSCS)在更恶劣气候条件下的低分类级别的草地类,说明人为干扰已超过了原生草地生态系统的生存阈限,导致草地逆行演替;4)对CSCS与VHCS分类结果的对比分析研究,可科学地揭示人为干扰下草地的演替状态,并明确草地恢复和重建的目标。

Development of Plant Embryology in China

The development of plant embryology in China can be roughly divided into three stages: (1) the initial stage, (2) the stage of establishing plant embryology as a branch of plant sciences, and (3) the stage when plant embryology evolves into plant reproductive biology with its vigorous development. It is in the third stage that research work in this field in China has developed rapidly and many of the significant achievements obtained are described in more details in this review. Researches of experimental embryology are not included in this paper.

Study on the Pollen Rain in Lanzhou University in Spring in 2009

[Objective] The aim was to explore the relationship of pollen types and blooming plants,pollen fertility and meteorological factors during the falling process of pollen in the atmosphere.[Method] The falling record of pollen in Lanzhou University in spring in 2009 was obtained by 10 m platform natural falling method.The pollen falling number,duration,relationship among falling types and surrounding plants,as well as weather were discussed.[Result] Main pollen types included Populus L.,Salix,Paulownia and Platanaceae.Its pollen falling number,duration was consistent with the flowering period of corresponding plants in the garden;the classification and richness of falling of pollen was influenced by wind.The larger the wind was,the richer the variety become.There was basically no pollen from outside.The authors failed to observe the distinct changes of palynological assemblage in sandy storm weather.[Conclusion] The study could lay basis for the study of the modern progress of natural plants pollen.

Diversity of desert rangelands of Tunisia

Plants are important components of any rangeland.However,the importance of desert rangeland plant diversity has often been underestimated.It has been argued that desert rangelands of Tunisia in good ecological condition provide more services than those in poor ecological condition.This is because rangelands in good condition support a more diverse mixture of vegetation with many benefits,such as forage for livestock and medicinal plants.Nearly one-quarter of Tunisia,covering about 5.5 million hectares,are rangelands,of which 87% are located in the arid and desert areas(45% and 42%,respectively).Here,we provide a brief review of the floristic richness of desert rangelands of Tunisia.Approximately 135 species are specific to desert rangelands.The predominant families are Asteraceae,Poaceae,Brassicaceae,Chenopodiaceae,and Fabaceae.These represent approximately 50% of Tunisian desert flora.

Application of Hydrogen Peroxide as an Environmental Stress Indicator for Vegetation Management

Adaptive vegetation management is time-consuming and requires long-term colony monitoring to obtain reliable results. Although vegetation management has been widely adopted, the only method existing at present for evaluating the habitat conditions under management involves observations over a long period of time. The presence of reactive oxygen species （ROS） has long been used as an indicator of environmen- tal stress in plants, and has recently been intensely studied. Among such ROS, hydrogen peroxide （H202） is relatively stable, and can be conveniently and accurately quantified. Thus, the quantification of plant H202 could be applied as a stress indicator for riparian and aquatic vegetation management approaches while evaluating the conditions of a plant species within a habitat. This study presents an approach for elucidating the applicability of H202 as a quantitative indicator of environmental stresses on plants, particularly for vegetation management. Submerged macrophytes and riparian species were studied under laboratory and field conditions （Lake Shinji, Saba River, Eno River, and Hii River in Japan） for H202 formation under various stress conditions. The results suggest that H202 can be conveniently applied as a stress indicator in environmental management.

Vegetation Evolution with Degenerating Soil Ecology Under Unequal Competition

A vegetation evolution model influenced by a degeneration of soil ecological functions was set up. Three ideal communities of a) trees, b) shrubs, and c) herbage populations were first simulated. Then numerical simulations of the evolutionary and developmental processes of a natural forest community, which is composed of over 100 species,were conducted. Results of the study showed that a) in all communities, soil degeneration not only drove some weaker species to extinction, but also a few dominant ones; b) there were different response scales with species in an ideal tree metapopulation that could persist as long as a thousand years, with shrubs in an ideal shrub metapopulation that could persevere for several hundred years, and with species in an ideal herbage metapopulation that could become extinct within 10 years; and c) each metapopulation experienced three evolutionary stages during adaptation to the environment: a) the stage of compelled adaptation or resistance, b) the adjusted stage, and c) the stabilized stage.

Effects of fire disturbance on forest hydrology

Fire is quite a common natural phenomenon closely related to forest hydrology in forest ecosystem. The influence of fire on water is indirectly manifested in that the post fire changes of vegetation, ground cover, soil and environment affect water cycle, water quality and aquatic lives. The effect varies depending upon fire severity and frequency. Light wildland fires or prescribed burnings do not affect hydrology regime significantly but frequent burnings or intense fires can cause changes in hydrology regime similar to that caused clear cutting.

Comparison of the spatio-temporal dynamics of vegetation between the Changbai Mountains of eastern Eurasia and the Appalachian Mountains of eastern North America

The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.

The Linkage between Natural Vegetation, Water Dynamics and Pyrite （FeS2） Oxidation in Tidal Lowlands

The research aimed to analyze the linkage between natural vegetation, water dynamics and pyrite （FeS2） oxidation in tidal lowlands. The research was carried out in tidal lowland Pulau Rimau, South Sumatra from February to December 2010. The field observations are done by exploring several transect on land units. The field description refers to Soil Survey Staff. Water and soil samples were taken from selected key areas for laboratory analyses. The vegetation data were collected by making sample plots placed on each vegetation type with plot sizes 10 m × 10 m for secondary forests and 5 m × 5 m for shrubs and grass. The observations of surface water level were done during the river receding with units of meter above sea level （m.asl）. The results shows that pyrite formation is largely determined by the availability of natural vegetation as S （sulfur） donors, climate and uncontrolled water balance and supporting faunas such as crabs and mud shrimp. Climate and water balance as well as supporting faunas is the main supporting factors to accelerate the process of formation pyrite. Oxidized pyrite increases soil pH thus toxic to fish, arable soils, plant growth, disturbing the water quality and soil nutrient availability. Oxidized pyrite is predominantly accelerated by the dynamics of river water and disturbed natural vegetation by human activities, and the pyrite oxidation management approach is divided into three main components of technologies, namely water management, land management and commodity management.

Effects of topography and vegetation on distribution of rare earth elements in calcareous soils

This study investigated the impact of topography and vegetation on distribution of rare earth elements(REEs)in calcareous soils using methods of single extraction and mass balance calculation. The purposes of the study were to set a basis for further research on the biogeochemical REE cycle and to provide references for soil–water conservation and REE-containing fertilizer amendments. The results show a generally flat Post-Archean Average Australian Shale—normalized REE pattern for the studied calcareous soils. REE enrichment varied widely. The proportion of acidsoluble phases of heavy REEs was higher than that of light REEs. From top to bottom of the studied hills, dominant REE sources transitioned from limestone in-situ weathering to input from REE-containing phases(e.g., clay minerals,amorphous iron, REE-containing fluids). Our results indicate that the REE content of calcareous soils is mainly controlled by slope aspect, while the enrichment degree of REEs is related to geomorphological position and vegetation type.Furthermore, the proportion of acid-soluble phases of REEs is mainly controlled by geomorphological position.

A new approach of extracting vegetation points from urban airborne LiDAR data

Urban vegetation has been an important indicator for the evaluation of eco-cities, which is of great significance to promote eeo-city construction. We study and discuss the commonly used urban vegetation extrac-tion methods. The extraction of vegetation points in this study is completed through mathematical statistics, mean-square error, successive differences and iterative algorithm which are based on the analysis of different spatial morphological characteristics in urban point clouds. Linyi, a city of Shandong Province in China, is se-lected as the study area to test this method and the result shows that the proposed method has a strong practicali- ty in urban vegetation point cloud extraction. Only 3D coordinate properties of the LiDAR point clouds are used in this method and it does not require additional information, for instance, return intensity, which makes the method more applicable and operable.

Remote Sensing Indices to Measure the Seasonal Dynamics of Photosynthesis in a Southern China Subtropical Evergreen Forest

The accurate measurement of the dynamics of photosynthesis in China’s subtropical evergreen forest ecosystems is an important contribution to carbon(C) sink estimates in global terrestrial ecosystems and their responses to climate change. Eddy covariance has historically been the only direct method to assess C flux of whole ecosystems with high temporal resolution, but it suffers from limited spatial resolution. During the last decade, continuous global monitoring of plant primary productivity from spectroradiometer sensors on flux towers and satellites has extended the temporal and spatial coverage of C flux observations. In this study, we evaluated the performance of two physiological remote sensing indices, fluorescence reflectance index(FRI) and photochemical reflectance index(PRI), to measure the seasonal variations of photosynthesis in a subtropical evergreen forest ecosystem using continuous canopy spectral and flux measurements in the Dinghushan Nature Reserve in southern China.The more commonly used NDVI has been shown to be saturated and mainly affected by illumination(R^2=0.88, p <0.001), but FRI and PRI could better track the seasonal dynamics of plant photosynthetic functioning by comparison and are less affected by illumination(R^2=0.13 and R^2=0.51, respectively) at the seasonal scale. FRI correlated better with daily gross primary production(GPP) in the morning hours than in the afternoon hours, in contrast to PRI which correlated better with light-use efficiency(LUE) in the afternoon hours. Both FRI and PRI could show greater correlations with GPP and LUE respectively in the senescence season than in the recovery-growth season. When incident PAR was taken into account, the relationship between GPP and FRI was improved and the correlation coefficient increased from 0.22 to 0.69(p < 0.001). The strength of the correlation increased significantly in the senescence season(R^2=0.79, p < 0.001). Our results demonstrate the application of FRI and PRI as physiological indices for the accurate measurement of the seasonal dynamics of plant community photosynthesis in a subtropical evergreen forest, and suggest these indices may be applied to carbon cycle models to improve the estimation of regional carbon budgets.

Spatial and temporal variation of vegetation phenology and its response to climate changes in Qaidam Basin from 2000 to 2015

Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.

Study on Distribution Pattern of Plant Diversity of Forest Vegetation in Luofu Mountain,Guangdong

Through sample plot survey and statistic analysis,this paper adopts ecological method to study the characteristics of plant diversity of forest vegetation in Luofu Mountain,Guangdong.The results show that there is a great plant diversity of forest vegetation in Luofu Mountain owing to the ascendancy of aqueous and thermal condition in subtropical zone.The total number of species in 4 500 m2 sample plot(s)are 170 with 3 870 individual plants in total;Dahl species richness index(D)is 44.932;Simpson diversity index(L,D)is 0.022,0.022;Simpson(1982)diversity index(D)is 3.806;Pielou evenness index(E)is 0.984 and Hulbert evenness index(E)is 0.815;Shannon-wiener diversity index(information index H')is 4.188;Asymmetry index(r)is 0.185.These indexes show that a better habitat will bring about plant diversity of forest vegetation,and the diversity of zonal vegetation shows that the higher latitude is,the less species of vegetation can be found.Besides,vertical change of plant diversity of forest vegetation in Luofu Mountain is obvious.Its species richness index and plant diversity index show that monsoon evergreen broad-leaved forest is the tallest,mountain evergreen broad-leaved forest follows as the second and conifer-broad-leaved mixed forest is the shortest.The Wilson β-diversity index,which is obtained by comparison between forest vegetation below 300 m and forest vegetation between 600-900 m,is 0.621.Calculated from comparison between forest vegetation in 600-1 100 m and forest vegetation in 900-1 100 m,the Wilson β-diversity index is 0.727;by comparing forest vegetation below 300 m with forest vegetation in 900-1 100 m,the Wilson β-diversity index is 1.877.This shows that the plant diversity of forest vegetation is affected by the change in gradient of elevation.

Relationship Between Vegetation Restoration and Soil Microbial Characteristics in Degraded Karst Regions: A Case Study

The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade.In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanism of degraded karst regions,we measured microbial biomass C and basal respiration in soils during vegetation restoration in Zhenfeng County of southwestern Guizhou Province,China.The community level physiological profiles(CLPP) of the soil microbial community to were estimated determine if vegetation changes were accompanied by changes in functioning of soil microbial communities.The results showed that soil microbial biomass C and microbial quotient(microbial biomass C/organic C) tended to increase with vegetation restoration,being in the order arboreal community stage > shrubby community stage > herbaceous community stage > bare land stage.Similar trend was found in the change of basal respiration(BR).The metabolic quotient(the ratio of basal respiration to microbial biomass,qCO 2) decreased with vegetation restoration,and remained at a constantly low level in the arboreal community stage.Analyses of the CLPP data indicated that vegetation restoration tended to result in higher average well color development,substrate richness,and functional diversity.Average utilization of specific substrate guilds was highest in the arboreal community stage.Principle component analysis of the CLPP data further indicated that the arboreal community stage was distinctly different from the other three stages.In conclusion,vegetation restoration improved soil microbial biomass C,respiration,and utilization of carbon sources,and decreased qCO 2,thus creating better soil conditions,which in turn could promote the restoration of vegetation on degraded karst regions.

A unified canopy bidirectional reflectance (BRDF) model for row ceops

Row sowing is a basic crop sowing method in China,and thus an accurate Bidirectional Reflectance Distribution Function (BRDF) model of row crops is the foundation for describing the canopy bidirectional reflectance characteristics and estimating crop ecological parameters.Because of the macroscopically geometric difference,the row crop is usually regarded as a transition between continuous and discrete vegetation in previous studies.Were row treated as the unit for calculating the four components in the Geometric Optical model (GO model),the formula would be too complex and difficult to retrieve.This study focuses on the microscopic structure of row crops.Regarding the row crop as a result of leaves clumped at canopy scale,we apply clumping index to link continuous vegetation and row crops.Meanwhile,the formula of clumping index is deduced theoretically.Then taking leaf as the basic unit,we calculate the four components of the GO model and develop a BRDF model for continuous vegetation,which is gradually extended to the unified BRDF model for row crops.It is of great importance to introduce clumping index into BRDF model.In order to evaluate the performance of the unified BRDF model,the canopy BRDF data collected in field experiment,"Watershed Allied Telemetry Experiment Research (WATER)",from May 30th to July 1st,2008 are used as the validation dataset for the simulated values.The results show that the unified model proposed in this paper is able to accurately describe the non-isotropic characteristics of canopy reflectance for row crops.In addition,the model is simple and easy to retrieve.In general,there is no irreconcilable conflict between continuous and discrete vegetation,so understanding their common and individual characteristics is advantageous for simulating canopy BRDF.It is proven that the four components of the GO model is the basic motivational factor for bidirectional reflectance of all vegetation types.

The dynamical evolution theory of the isolated oasis system

Assume that an oasis and its surrounding desert consist of an isolated system without mass and energy exchange with the outer environment.The characteristics of oasis evolution have been explored under the condition of system energy conservation.The results show that oasis evolves with two equilibrium states.The first equilibrium suggests a stable expansive and an unstable degraded oasis whereas the second equilibrium indicates a stable shrink and an unstable increase of the oasis area.If one equilibrium state is unstable,the components of the isolated system(oasis and desert) would tend to be no energy exchange and they each reach to energy balance respectively.Oasis would maintain its initial area in this case.Further analyses point out that the two equilibrium states have completely different characteristics.In the first equilibrium state,a higher vegetation albedo,lower soil albedo and larger canopy resistance,and direr soil both contribute to the oasis area expansion,accompanying an excessive large desert soil and vegetation canopy temperature difference(SCTD).In the second equilibrium state,however,a lower vegetation albedo,higher soil albedo and small canopy resistance,and wetter soil benefit the oasis area to stay near its initial value,following a moderate SCTD.The convergent trajectories of the initial values in phase space are influenced by the separatrices of the equilibrium points.Higher temperature is an advantage factor for initial values convergent to the oasis expansion solution.