东北林区森林资源可持续特征模型研究

本文从法正林的数学模型出发 ,利用天然同龄林的固定小班间隔近 4 0a的龄级转移观测资料 ,经龄级转移期的处理 ,构造出天然林林龄可持续转移模型P′S′ =λS′ ,其中特征根λ均为 1。分析稳定状态S′的结构 ,发现了天然林林龄滞留转移现象 ,并由此获得天然同龄林可持续的林龄向量应是呈递增的等差级数。根据滞留量的大小 ,可以把天然林可持续转移模型分成 3类。并指出产生上述现象的林学机理是林木枯损概率随着林木年龄的加大而增长。

土地生产力的内涵、系统观与可持续技术

在高土地生产力水平的条件下，影响土地生产力可持续性的因素是多方面的。树立土地生产力的系统观并采用综合的可持续的技术体系，全面提高农业土地生产力水平十分必要。可持续的农作技术体系的基本特征：集约性、持续性、综合性和适用性。

区域创新生态系统可持续运行建设路径研究

基于区域创新生态系统理论,联合生态系统可持续性特征,对区域创新生态系统可持续运行内涵与影响要素进行理论阐释,以我国内地31个省市为样本,运用模糊集定性比较分析(fsQCA)方法,结合可持续创新种群结构、可持续能力和可持续创新潜力3个维度,重点探究区域创新生态系统高水平可持续运行建设路径。根据维度要素的不同组合构型,归纳出4条区域创新生态系统实现高水平可持续运行的建设路径;相对于其它要素,创新种群新颖性与政府创新投入对系统高水平可持续运行更重要。研究结论有助于拓展区域创新生态研究视角,为不同地区优化创新生态系统、提高系统可持续运行水平和实现高质量发展提供参考。

全球红树林时空变化及演变趋势

红树林是全球重要的生态系统,了解红树林的时空变化特征及演变趋势对开展红树林的保护、恢复及可持续管理具有重要意义。基于谷歌地球工程(Google Earth Engine,GEE)云平台,利用全球红树林分布数据和陆地卫星(Landsat)系列光学影像特征指数数据,结合Theil-Sen中值趋势分析、Mann-Kendall检验、Hurst指数等方法,分析了全球红树林的时空分布特征、时空演变趋势及其可持续特征。结果表明:1990—2020年全球红树林面积呈先下降后上升趋势,总面积减少52174.18km^(2),年平均流失率达1.2%,红树林面积减少最多的地区为东南亚,其次为澳大利亚和新西兰、南美洲和东南非洲;红树林呈退化趋势变化的面积(81.44%)明显多于改善区域的面积(17.43%),其中澳大利亚和新西兰的退化趋势最为明显;2015—2020年全球红树林变化趋势有所改善,有73.85%的区域在未来是可持续的,持续改善区域面积(38.58%)大于持续退化区域面积(33.06%),且改善区域的可持续性明显高于不可持续性,表明2020年之后全球红树林整体上呈改善趋势变化。全球红树林时空变化特征和演变模式,可为生物多样性保护、沿海经济发展、生态环境的可持续改善提供重要支撑,对评估联合国2030可持续发展目标实现的状况具有重要影响。

Resource Characteristics and Sustainable Utilization of Codonopsis convolve, a Tibetan Medicinal Plant

In this paper, the resources of Codonopsis convolvulacea subsp. Vinciflora in 13 counties of Tibet were investigated and analyzed by field investigation, sample point-sample set-sample survey, market investigation and expert visit. The results showed that among the 13 counties, the distribution area of C. convolvulacea ranked as Gongbujiangda County 〉 Zuogong County 〉 Milin County 〉 Mozhugongka County 〉 Lang County 〉 Duilongdeqing County 〉 Chayu County=Jiali County= Mangkang County=Dingqing County=Baqing County=Suo County=Nimu County. The Gongbujiangda County showed the largest distribution, while Zuogong County and Milin County showed relatively small distribution. Chayu County, Jiali County, Mangkang County, Dingqing County, Baqing County, Suo County and Nimu County showed no distribution. The average plant dry weight C. convolvulacea ranked as Duilongdeqing County 〉 Lang County, Gongbujiangda County 〉Milin County 〉Chayu County =Jiali County =Zuogong County =Mangkang County =Dingqing County =Baqing County=Suo County=Mozhugongka County=Nimu County. Among them, Duilongdeqing County showed the largest average plant dry weight. The average plant dry weight of C. convolvulacea in Chayu County, Jiali County, Zuogong County, Mangkang County, Dingqing County, Baqing County, Suo County, Mozhugongka County and Nimu County was all 0 g. The order of biomass of C. convolvulacea in the 13 counties was Mozhugongka County 〉Duilongdeqing County 〉 Lang County 〉 Gongbujiangda County 〉Milin County 〉Zuogong County 〉Dingqing County =Jiali County=Mangkang County=Chayu County=Nimu County=Suo County=Baqing County. Mozhugongka County showed the largest biomass, while the biomass of C. convolvulacea in Dingqing County, Jiali County, Mangkang County, Chayu County, Nimu County, Suo County and Baqing County was all 0 t. The reserve of C. convolvulacea is determined by distribution area habitat and its own growth. In the 13 counties, the reserve of C. convolvulacea ranked as Gongbujiangda County 〉Mozhugongka County 〉 Lang County 〉Zuogong County 〉Milin County 〉Duilongdeqing County 〉Dingqing County=Jiali County=Mangkang County=Chayu County=Nimu County=Suo County=Baqing County. The reserve of C. convolvulacea was biggest in Gongbujiangda County and was relatively small in Dingqing County, Jiali County, Mangkang County, Chayu County, Nimu County, Suo County and Baqing County. Targeting at the problems existing in the utilization of C. convolvulacea, some suggestions are put forward, such as establishment of reserve for medicinal plant ecological industry, artificial cultivation, renewing concept and rational exploitation and utilization. In this paper, the resource characteristics and sustainable utilization of Tibetan medicinal plants were studied so as to provide a theoretical basis for the rational development and utilization of C. convolvulacea in the region.

Effect of discontinuities characteristics on coal mine stability and sustainability： A rock fall prediction approach

Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident.

Functioning Hydraulic and Morphological Sustainability of River Training Works in Bangladesh

River dynamics play the most vital role in the socio-economic of the country. These rivers are highly dynamic in nature which causes extensive riverbank erosion. Active river bank erosion and bed scouring, is apprehended to change the scenario, leading to loss of limited valuable land of Bangladesh. River training is being practiced in Bangladesh since 1960s but the process is very expensive especially in the Ganges and the Jamuna Rivers. Five types of river training works were selected at different reaches. Hydro-morphological characteristics of the major rivers are being evaluated not only in engineering concepts but also in socio-economic and environmental aspects. PRA （participatory rural appraisal） tools were applied to evaluate protection safety, hydraulic and hydrological connectivity, ecological and environmental characteristics, causes of failure and social acceptability. This comparative study is being carried out for closing the gap between the modem river training works and in country experience through adaptation of research findings with a view to effectively arresting river bank erosion. Sirajganj Hardpoint, Chandpur Town Protection work and Nakalia Revetment are found to be suitable and effective. A technically suitable structure may not have good social acceptance without IWRM （integrated water resource management）.

Effect of Water Resources Allocation on Groundwater Environment and Soil Salinity Accumulation under Climate Change

The combined surface and groundwater allocation practice by wells and canals had contributed to the safety of groundwater environment and agriculture sustainable production. The typical area in the People＇s Victory Canal irrigation district was taken as a case, drawing together the irrigation district agriculture water consumption and precipitation from 1954 to 2014 in the People＇s Victory Canal irrigation district, ratios of surface to groundwater irrigation amount, dynamic of groundwater depth and hydrochemical characteristic of groundwater from 2008 to 2014 in the research area, the relationship between groundwater depth and ratio of surface to groundwater irrigation amount was analyzed, in order to ascertain the influence of precipitation on ratios of surface to groundwater irrigation amount and its effect on soil and groundwater environment. The results indicated that positive correlation between the ratios of surface to groundwater irrigation amount and annual precipitation was appeared, affected by climate change, average irrigation amount from surface in the recent 5 years was 2.90 x 108 cubic meters, accounted for 75.52% of total irrigation amount, on the other hand, decreasing tendency of precipitation was obvious, and groundwater depth dynamic in upstream of the branch canals was more dramatic than downstream because of surface water irrigation infiltration, under the unified condition of water use efficiency, ratio of surface to groundwater irrigation amount was negative correlation with area of the groundwater depth beyond 11 m, meanwhile, groundwater depth demonstrated negative correlation with the ratio of surface to groundwater irrigation amount, moreover, alkaline trend of groundwater hydrochemistry during the normal season in the research area was obvious because of phreatic evaporation and the agricultural irrigation from wells, along with irrigation from surface inflow of Yellow River, quality of groundwater hydrochemistry during the dry season was ameliorative greatly. Consequently, it was very important to the agriculture sustainable production that well-canal combined irrigation patterns alleviated extremely alkaline trend of the groundwater hydrochemistry and played a positive role of root layer soil salinity leaching.

A comprehensive assessment of urban vulnerability and its spatial differentiation in China

The urban vulnerability poses a serious challenge to achieving sustainable devel- opment. With the concentration of the population and the economy, cities must manage the higher frequencies and risks of various hazards and are becoming more vulnerable. Re- search on the assessment and regulatory control of urban vulnerability is of great significance for both urbanization quality improvement and sustainable development in China or other countries in the world. Because of the complexity of cities and vulnerability concepts, existing studies have focused on different aspects of urban vulnerability. And the research content of urban vulnerability is scattered and relatively independent, leading to a lack of comparability among the research data and resulting in tremendous difficulties in summarizing the conclu- sions through comparison of independent research data. Therefore the goal of this study was to construct urban vulnerability index （UV/） from the perspective of sustainable development that could assess urban vulnerability comprehensively. In this study, we selected 10 subin- dexes involving 36 specific parameters from four aspects （resources, eco-environmental sys- tems, economics, and social development） to construct a comprehensive index system. We also established the standard values of measurements. Then we take 288 prefecture-level cities in China as a study area and evaluate its overall urban vulnerability and its spatial differentiation. Results indicate that urban vulnerability of China has a remarkable spatial differentiation of both ＂gradient distribution＂ and ＂clustered distribution＂; the extent of urban vulnerability corresponds to city size, the bigger the city, the lower its vulnerability; re- source-based cities are more vulnerable than comprehensive cities; a city＇s economic growth rate does not reflect the extent of its urban vulnerability. Further, we offer a few suggestions to cope with urban vulnerability in China.