试论城乡开发自然生态补偿的植被还原原理

针对城乡土地开发带来的植被破坏建立一种作为生态补偿的植被还原机制。本文列举国外的若干实例,说明在我国实行这一机制在技术和经济上的可行性。并提出植被还原的“绿当量”概念和针对开发项目造成的植被减少实行种植补偿的计算方法。     

Breeding birds in short-rotation coppices on farmland in central Sweden—the importance of Salix height and adjacent habitats

Plantations of short-rotation coppice (SRC) have a potential for being a useful measure to stop the ongoing impoverishment of farmland biodiversity by increasing structural diversity, and decreasing cultivation intensity and use of pesticides in intensively managed farmland landscapes. The aim of this study was to investigate the relative importance of the structure of the plantation and composition of adjacent habitats for breeding birds in 41 SRCs (meansize±S.E.=9.4±1.6 ha). Mean number of species per ha in the SRCs was 2.8±0.3 species and there were more farmland birds (32 species, 808 territories) than forest birds (22 species, 400 territories). A major result of the present study was the strong influence of adjacent habitats on bird community composition (18 of 22 analysed species affected). There were large differences in bird communities between forest-bordered and open-bordered sites, but occurrence of residual habitats (i.e. other habitats than forest, pastures, shrub areas and arable fields) was also associated with occurrence of several species. The second factor of major importance for the bird fauna was the height of the plantations. Most species (14) were associated with tall plantations (>2 m), seven species were associated with plantations of intermediate (1–2 m) height, and six species were associated with plantations of low height (<1 m). A comparison of ecological traits between species classified as preferring SRC and species classified as avoiding SRC suggests that nest height was the only ecological character associated with a preference for Salix habitats, i.e. species with nests on the ground or in shrubs were more abundant in Salix habitats than in farmland landscapes in general. However, a broad spectrum of species was found in the SRCs and many of these seemed to be dependent on habitat features outside the plantations. Planting of Salix in intensively managed farmland plains will have positive effects on bird diversity by increasing the structural diversity of the landscape. In contrast, plantations on infields in forest-dominated landscapes will have negative effects, since the mosaic structure (i.e. mixture of open and forested habitats) positive for most farmland birds will disappear, and Salix plantations favour relatively few forest species. Additionally, Salix could be planted along sharp edges between coniferous plantations and open farmland in order to increase the complexity of the ecotone in intensively managed forest-farmland landscapes.     

Hydrocarbon and elemental carbon signatures in a tropical wetland: biogeochemical evidence of forest fire and vegetation changes

Evidence of changing vegetation in the tropical wetland (Rawa Danau, west Java, Indonesia) over the past 7428 years is illustrated by elemental (soot) carbon (EC) and n-alkane composition of sedimentary geolipids. In this study, vegetation changes and relevant controlling factors (e.g. forest fire and climate change) were documented on a decadal to centennial scale. The n-alkane composition that changes with depth might record changes in sources of organic matter (OM) in the wetland. The presence of EC (0.01–0.24% of organic carbon: OC) during late (0–1700 cal. year BP) and mid (3500–4500 cal. year BP) Holocene (at depths 0–50 cm, and 160–210 cm) indicated that large-scale forest fires severely affected the tropical vegetation. The hydrocarbon indices (CPI: carbon preference index, MCN: mean carbon number, and HVI: hydrocarbon vegetation index) significantly correlated with one another while a comparison of EC profile with the profiles of hydrocarbon indices indicated that n-alkane composition of the geolipid in lake sediment could record signatures of changes in catchment vegetation. Forest fire and vegetation changes might be related to regional climatic shifts relating to ENSO activity as well as being influenced by human influences.     

Driver glare exposure with different vehicle frontlighting systems

Introduction: Highway safety performance at night has received less attention in research than daytime, despite the higher accident rates occurring under night-time conditions. This study presents a procedure to assess the potential hazard for drivers created by headlight glare and its interaction with the geometric design of highways. Method: The proposed procedure consists of a line-of-sight analysis performed by a geoprocessing model in geographic information systems to determine whether the rays of light that connect headlights and oncoming drivers are obstructed by either the roadway or its roadsides. Then, the procedure checks whether the non-obstructed rays of light are enclosed by a given headlight beam. Different hypotheses were set concerning the headlight beam features, including the horizontal spread angle and whether the headlights are fixed or swiveling. A highway section was selected to test and validate the procedure proposed. A 3D recreation of the highway and its environment derived from a LiDAR point cloud was used for this purpose. Results: The findings disclose how glare is produced on tangents, horizontal curves, transitions between them and sequences of curves. The effect of visual obstructions conveniently placed is also discussed. Conclusions: A greater glare incidence is produced as the horizontal headlights spread angle increases. Swiveling headlights increase glare on highways left curves and reduce it on right curves. Practical Applications: The procedure and conclusions of this study can contribute to develop more effective glare avoidance technologies as well as identify and assess glare-prone sections. The glare evaluation assists in evaluating glare countermeasures such as deciding whether to place a vegetation barrier and where.     

大连地区生态植被所排放VOC的估算研究

根据实测的太阳总辐射在全波段的辐射照度Q（Wm^-2）估算出光合有效辐射照度UPAR（μmolm^-2S^-1）,利用各类植物的排放因子,估算出大连地区生态植被所排放的VOC,结果表明,生态植被所排放VOC的日变化规律即与植物本身有关又与气温和太阳辐射有关,区域内年排放VOC的总量为256.5t。     

Topical scientific and practical issues of wildland fire problem

Problem of wildfires has not been resolved anywhere in the world. Mere increase of technical power does not lead to desirable results. Forests of developed countries burn as actively as those in Africa or in Russia. The main reasons of wildfire problem are as follows: (1) Constant wandering of dry seasons over the planet causing outbreaks of wildfires. (2) Unpredicted self-development of ordinary wildfires into awful fire disasters. (3) Difficulties in delivery and use of heavy machines on hardly accessible territories. (4) Absence of a perfect technique for economic evaluation of how effectively the wildfire control system works. (5) Absence of the system of payments encouraging wildfire fighters. To solve the problem of wildfires in Russia it is necessary to: (1) Create the Russian wildfire behaviour and fire effects prediction system on the basis of the developed classification of vegetation fuels and methods of their mapping as well as maximum utilization of forest inventory information and Geographic Information System (GIS). (2) Elaborate a technique of proper wildfire monitoring including estimation of vegetation damage. (3) Improve daily rating of regional fire danger. (4) Improve fire-preventive arrangement of the territory covered by vegetation, the main goal being creation of favourable conditions for active fire management. (5) Choose the main direction in elaboration of fire-fighting means and methods taking into account their universality, simplicity, reliability, etc. (6) Elaborate an improved technique for estimation of economic effectiveness of the wildfire control system. (7) Develop international cooperation of scientists and professionals in fire management.     

长江上游生态建设工程与植被覆盖时空变化的响应特征研究

"退耕还林"、"天然林保护"等重大生态建设工程在长江上游实施已有十余年,剖析重大生态建设工程实施以来长江上游植被覆盖时空变化特征与生态建设投入间的响应关系,对区内未来生态建设的布局具有重要指导意义。以年际时间序列的SPOT-VEGETATION NDVI遥感数据为基础,利用遥感及地理信息系统技术,趋势拟合等方法,研究长江上游地区2002年至2013年植被覆盖时空动态变化特征。并以县级行政区为单元,分析长江上游植被覆盖时空变化与生态建设工程投入的响应关系。结果表明:研究区内植被指数NDVI(Normalized Difference Vegetation Index)整体呈现缓慢增加趋势,年均增长率为1.06%,主要体现为中等植被覆盖向高植被覆盖转化;植被覆盖增加区域远远大于植被覆盖减少区域,其中增加的区域占整个长江上游流域的86.02%,主要分布于秦巴山地以北、云贵高原以及横断山区中小起伏的山地;植被覆盖减少区域占6.09%,主要分布于汶川地震灾区以及成都,重庆、昆明等大型城市群及其周边。其次,近10 a生态建设重大工程投资对长江上游植被覆盖增长起促进作用,在研究区内有261个县级行政区具有较好的造林效率,达县级行政区总数的90%,集中分布于云贵、川陕交界处及西部高山、高原区。     

Estimation of the annual scavenged amount of polycyclic aromatic hydrocarbons by forests in the Pearl River Delta of Southern China

Leaves of six main tree species from the Pearl River Delta (PRD) in Southern China were collected to identify the interspecific variability, the spatial variability and the seasonal variations of polycyclic aromatic hydrocarbons' (PAHs) concentrations, and to calculate the amount of PAHs removed by leaves. PAHs concentrations in pine needles were much higher than in broad-leaves and leaves from urban/industrial areas (Baiyunshan and Heshan) exhibited two times greater concentrations than leaves from the rural area (Dinghushan). Seasonal variations of PAHs in leaves occurred with lesser concentrations in September. Leaves in PRD scavenged 3.7 ± 0.9 t PAHs y⁻¹, accounting for about 10% of the total amount emitted in this region. This result suggests that forests play an important role in the fate of PAHs.     

Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

The seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk was studied in a high altitude pasture in the Alps (1900 m a.s.l.). PCB contamination in vegetation shows a concentration peak in June, which is mainly interpreted as the consequence of a temporary PCB enrichment of the air layer above the ground due to net emission fluxes from the soil. A three compartment dynamic model was developed to test this hypothesis. The North/South enrichment factor in the vegetation was 1.5-1.6 for penta- and hexa-substituted congeners and 1.7 for hepta- and octa-PCBs, according to the effect of temperature on compounds having higher K_oa values. Milk concentrations followed the vegetation seasonal trend. The congener abundance in milk is in agreement with the biotransformation susceptibility, absorption efficiency and residence time of the different congeners in dairy cows.