高光谱遥感在植被特征识别研究中的应用

总结了高光谱遥感在植被物种识别、结构特征分析、理化信息提取等主要领域的应用研究现状; 分析了高光谱遥感在植被特征识别中所涉及的光谱特征优化、混合光谱分解、图像分类识别等关键性技术环节的最新进展; 剖析了目前研究中存在的主要问题, 并对今后的发展态势进行了展望。     

Mangroves of China: a brief review

The distribution, ecology, conservation and management of Chinese mangroves are reviewed. Mangroves naturally occur along the southeast Chinese coast and traverse the provinces of Hainan, Guangdong, Guangxi, Fujian and Taiwan, intermittently extending from 18°N. Thirty-seven mangrove tree species, representing 20 families and 25 genera, have been documented, with thermophilic eurytopic species being the dominant components. A remarkable decrease of species richness is evident from Hainan (18–20°N) to Fujian (23.5–27°N) (35 vs. 9 species). The existing mangrove area is ≈ 17 800 ha, accounting for slightly more than 0.1% of the world's total. Nearly two-thirds of China's mangroves have been lost during the past 40 years, largely due to conversion for rice-farming, embankment for aquaculture ponds and, recently, rapid urban development. A total of 201 papers on Chinese mangroves was published between 1950 and 1995, 178 of which are in Chinese; thus, they are not easily accessible to the international scientific community. Most of the work was conducted after 1985 (91% of the papers published) and research emphasized floristics with little attention to managementrelated issues. The net primary production of the Chinese mangroves shows a latitudinal trend, also significant deviations from predictions on models generated using non-Chinese data. Although 28 Chinese institutions have dealt with mangrove research, only five maintain long-term projects. The bulk of research has been carried out in six mangrove reserves: Qinglan, Dongzhai (Hainan), Mai Po (Hong Kong), Futian (Guangdong), Shankou (Guangxi) and Jiulongjiang (Fujian). Twelve mangrove reserves have been established so far in mainland China, one in Hong Kong (Mai Po) and one in Taiwan (Tanshui). These reserves cover an area of over 19000 ha, of which 8445 ha are mangroves (47% of existing mangrove area). Six measures that can facilitate mangrove conservation and management are recommended: (a) declare more mangrove areas as nature reserves; (b) set up a national mangrove committee and mangrove research centre to foster research and management; (c) develop concrete management guidelines; (d) enact protective legislation and ensure its strict enforcement; (e) launch education programmes in the major mangrove reserves; and (f) stop further nonsustainable exploitation of mangroves and their habitats.     

江苏省宜兴市毛竹资源利用历史变迁及现状

毛竹是森林资源的重要组成部分,研究毛竹资源利用及竹产业可持续发展极具现实意义。文章基于历史文献调查和对江苏省宜兴市竹材加工企业的问卷调查,分析了1916—2021年宜兴地区毛竹资源利用的历史变迁及发展现状。结果表明,宜兴市竹材加工业在20世纪60年代通过引进国外先进生产技术而得以迅速发展,在竹制品种类、加工方式等方面发生了明显变化。现阶段竹材加工企业以年轻中小企业为主,研发能力弱,竹制品同质性明显且附加价值低,主要盈利模式为薄利多销。文章建议,建立区域竹材储备体系以确保竹原材料稳定供给,竹产业与旅游业结合发展提高竹制品附加价值,同时积极响应“以竹代塑”倡议开发新产品,为推进宜兴竹产业可持续性发展提供新机遇。     

Effects of Terrain on Litter Decomposition and Nutrient Release in Typical Steppe of Eastern Gansu Loess Plateau

Terrain can influence vegetation composition, diversity, and biogeochemical cycling in grassland ecosystems. Solar radiation, soil temperature, and moisture distribution are dependent on terrain, which, in turn, can affect plant community structure, rate of litter mass decomposition, and carbon, nitrogen, and phosphorus release. A litter decomposition experiment was conducted over 12 mo at a site representing typical steppe grasslands to better understand the effects of terrain on biogeochemical cycling. The study site had both northeast (shaded) and southwest (sunny) facing aspects with each aspect having three slopes: 15°, 30°, 45°. Litterbags were used for collection of plant community litter from each location. The results indicated that slope and aspect both have significant effects on decomposition rate of litter mass and release rate of C, N, and P. The most rapid decomposition rate of litter mass was on 45° sunny slopes (k value 1.82 × 10^‒3 d⁻¹). The most rapid release of C was on 30° shaded slopes with release rate of 4.54 g C yr^‒1. The release rate of N decreased with increasing slope steepness but was more rapid on shaded compared with sunny slopes. The most rapid release of P (10.51 mg P yr^‒1) occurred on 45° shaded slopes. The total effects of solar radiation and soil temperature on litter mass decomposition were larger, with 0.91 and 0.93, respectively. Soil temperature, litter functional diversity, and initial C/N had positive effects on the litter C release. The release of litter N was mainly promoted by soil temperature. Soil moisture appeared to promote the release of litter P. Overall, terrain influenced litter mass decomposition and C, N, and P release by its effect on the distribution of solar radiation, soil temperature and moisture, and through modification of functional diversity, initial C/N ratios, and water content of litter in typical steppe.     

Modeling the optimal ecological security pattern for guiding the urban constructed land expansions

Rapid urbanization has induced numerous ecological and environmental issues seriously threatening the ecological security. The ecological security pattern (ESP), an effective way for protecting the ecological security, is becoming increasingly important in reconciling the rapid urbanization and ecology protection in urban planning practices. Based on the cost-distance analysis method, we constructed a three-rank (basic, moderate and strict-rank) composite ESP of Gaoming (Guangdong, China) aiming at protecting the survivals and habitat securities of rare vegetations, wild animals and human beings. The proposed composite ESP is established on five equal-weighted individual ESPs (namely Geology-ESP, Hydrology-ESP, Atmosphere-ESP, Biodiversity-ESP and Farmland-ESP) for geologic disasters prevention, flood prevention and drinking water protection, air pollution prevention, biodiversity conservation and farmland protection, respectively. Our results show that under the basic, moderate, and strict- rank ESPs, the integration and connectivity of the ecological components are constantly improved, but the connectivity between neighboring urban patches decline gradually. The moderate-rank ESP proves to be the optimal spatial pattern for balancing the conflicts between urban development and ecological protection. Notably, the ESP that considers the security of atmosphere and farmland securities, which protects the regional farmlands better and well balance the expansions of industrial and residual lands, proves to be much more reasonable.     

山东省降雨侵蚀力多年变化特征分析

 降雨侵蚀力变化特征分析是揭示土壤水蚀对降水变化响应的基础,为水土保持规划及管理提供依据。利用1951—2008年山东省22个气象站的降雨资料,采用Mann-Kendall非参数检验等方法,计算并分析了该省58年降雨侵蚀力变化的时间及空间特征。结果表明:山东省年降雨侵蚀力序列总体上未呈现显著增减趋势,这与占全年比例最高的夏季降雨侵蚀力未有明显变化相关;但通过季、月值的时间序列检验,春、冬季降雨侵蚀力有明显的升高趋势,特别2、5和12月升高显著。空间分布上,山东各地降雨侵蚀力变化趋势的差异明显,分布有国家级、省级水土流失重点治理区的鲁中南呈明显升高趋势,应作为未来防治重点区域。     

氯化胆碱和维生素K3饲料添加剂中二噁英类化合物浓度及其单体分布特征

本试验旨在调查2种常用饲料添加剂氯化胆碱和维生素K3中二噁英类化合物浓度及其单体分布特征。共检测17个氯化胆碱和29个维生素K3样品,二噁英化合物分别采用加速溶剂萃取仪和自动纯化系统进行提取和净化,并采用同位素稀释-高分辨气相色谱/高分辨双聚焦磁式质谱联用技术(HRGC/HRMS)进行准确定量分析检测。结果表明:氯化胆碱与维生素K3中二噁英类化合物浓度分别为4.370和13.871 pg/g,它们的毒性当量平均浓度分别是0.184和0.379 pg WHO-TEQ/g,其中有1个氯化胆碱样品和5个维生素K3样品中毒性当量浓度超过欧盟限量标准值(0.75 pg WHO-TEQ/g)。2种饲料添加剂均以八氯二苯并呋喃(OCDF)为最主要的污染同系物,毒性当量的主要贡献均以2,3,4,7,8-五氯二苯并呋喃(2,3,4,7,8-PeCDF)和1,2,3,4,7,8-六氯二苯并呋喃(1,2,3,4,7,8-HxCDF)为主,分别为42%和55%。污染同系物分布特征以氯化二苯并呋喃(PCDFs)为主要优势污染物。PCDFs在氯化胆碱和维生素K3中的贡献率分别占总浓度的88%和97%。     

城市“农家乐”旅游发展探讨——以深圳市为例

以深圳"农家乐"旅游的发展经验为案例,对城市"农家乐"旅游发展进行可行性分析,希望对于"农家乐"旅游的发展模式提供一定的参考。