Vegetation-permafrost relationships in the zone of sporadic permafrost distribution in the Kamchatka Peninsula

Studies on vegetation and permafrost table depth in the zone of sporadic permafrost distribution in the Uksichan River valley (the central Kamchatka Peninsula) have provided evidence that these components of biogeocenosis are interrelated and develop coordinately. In open larch forests with green forest mosses dominating in the ground vegetation layer, the permafrost table lies approximately 60 cm below the soil surface. When the ground vegetation layer is dominated by sphagnums, the permafrost table rises to 40–20 cm. In areas with a dwarf shrub-lichen ground layer, the soil thaw depth increases. A hypothesis is proposed that cyclic successional replacement of plant communities may take place in open larch forests on permafrost soils, including four consecutive stages with dominance of green mosses, sphagnums, lichens, and dwarf shrubs. In areas disturbed by fires, pioneer moss or herbaceous communities develop in the ground layer.     

Modeling distribution changes of vegetation in China under future climate change

Climatic change will result in great changes in vegetation. In this paper, a biogeographical model, the BIOME1, was used to predict potential vegetation distribution in China under climate change. Firstly, the BIOME1 was validated according to the climate–vegetation relationships in China. Kappa statistics showed that the validated BIOME1 was able to capture the geographical patterns of vegetation more accurately. Then, the validated BIOME1 was used to predict the distribution of vegetation of China under two climatic scenarios produced by a Regional Circulation Model, RegCM2/CN. The simulation results showed obvious northward shifts of the boreal, temperate deciduous and evergreen and tropical forests, a large expansion of tropical dry forest/savanna and reduction of tundra on the Tibetan Plateau. Three vulnerable regions sensitive to climate changes are pointed out, i.e., Northern China, the Tibetan Plateau and Southwestern China (mainly Hengduan Mountains in Yunnan Province and west of Sichuan Province). In recent decades, China has experienced dramatic industrialization and population growth, which exert strong pressure on the environment of China. The consequences of climate changes warrant more attention for maintaining a sustainable environment for China.     

不同类型农户对宅基地退出的响应

利用重庆市梁平县农户的调查数据,运用Logistic模型,探讨了户籍制度改革下不同类型农户宅基地退出意愿及其影响因素。结果表明：(1)在现有退地补偿政策下农户意愿普遍偏低,不同类型农户退地意愿存在一定的差异性;(2)影响纯农户宅基地退出的因素有户主年龄、家庭拥有的房屋数量、对政策的支持度和退地收益;影响Ⅰ兼业户宅基地退出的因素有家庭宅基地面积大小、对政策的支持度和退地收益;影响Ⅱ兼业户宅基地退出的因素有家庭小孩数、对政策的支持度和退地收益;影响非农户宅基地退出的因素有户主年龄、户主文化程度、家庭人口数、宅基地面积和退地收益;其中,退地收益是影响各类农户退地决策最显著的因素,对政策的支持度是农户退地决策影响力最大的因素。研究认为,影响各类农户退地决策的因素存在差异,其核心问题还在于退地政策。政府应根据不同类型农户的特征完善目前的农村宅基地退出政策,这有助于提高农户的参与意愿,顺利推进户籍制度和农村土地制度的改革     

不同利用方式对江西省农田土壤碳氮磷生态化学计量特征的影响

根据江西省2013年采集的16582个农田耕层(0～20 cm)土壤样点数据,运用实地调查、经典统计学与地统计学等相结合方法,研究了江西省耕地土壤碳氮磷生态化学计量特征的空间变异性及不同农田利用方式对其的影响.研究结果表明:江西省耕地土壤有机碳(SOC)、全氮(TN)和全磷(TP)平均含量分别为17.90、1.58和0.52 g·kg~(-1),土壤碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)平均值分别为11.72、38.29和3.38,土壤C∶N∶P比平均值为34.44∶3.03∶1,说明P是江西省耕地土壤主要的限制因素.此外,由于碳、氮、磷三者之间并不存在显著的两两相关性,表明江西省耕地土壤中不存在稳定的"Redfield ratio";半方差函数表明,江西省土壤碳、氮、磷生态化学计量特征具有中等程度的空间变异性,其空间变异特征主要受到随机性因素的影响;经ANOVA检验显示,不同农田利用方式对土壤碳氮磷生态化学计量特征影响显著(p0.05),土壤SOC和TN平均含量依次表现为:两季水田水旱轮作一季水田一季旱地两季旱地,土壤TP平均含量依次表现为:两季旱地两季水田一季水田一季旱地水旱轮作,土壤C∶N依次表现为:两季水田两季旱地一季水田水旱轮作一季旱地,土壤C∶P平均值依次表现为:水旱轮作两季水田一季水田一季旱地两季旱地,土壤N∶P平均值依次表现为:水旱轮作一季旱地两季水田一季水田两季旱地.总体而言,土壤碳、氮、磷生态化学计量比的变化特征是农田利用方式和环境因子综合作用的结果,土壤C∶N∶P比对土壤碳、氮、磷储量及养分的限制性具有重要的指示作用.     

取芯管取芯过程管壁温度变化特性试验*

为给冷冻取芯过程中瓦斯解吸模拟试验提供依据,依托自主研制的取芯管管壁温度自动采集装置,研究不同取芯深度及煤体破坏类型下取芯过程管壁温度变化特性。结果表明:在原生结构煤中取芯时,取芯过程管壁温度变化主要分为3个阶段,即稳定不变阶段、快速上升阶段与缓慢下降阶段,分别对应进钻、取芯与退钻过程;在构造煤中取芯时,管壁温度变化可分为缓慢上升阶段、快速上升阶段与缓慢下降阶段,分别对应进钻、取芯与退钻过程。在构造煤中,取芯深度越大,取芯管管壁升温幅度越大,取样过程中管壁温度峰值越大,且在取芯过程中,取芯管管壁温度传感器B1,B2,B3存在温升滞后现象;同一取芯深度,煤体破碎程度越大,取芯管管壁升温幅度越小,取芯结束时取芯管管壁温度越低。     

青海省的主要灾害类型与防灾减灾对策

论述了青海地区常见的主要灾害类型及危害,并提出了防灾减灾的对策。     

洪水灾害的遥感监测分析系统研究

给出了洪水灾害的遥感监测分析系统,该系统利用遥感信息资料,应用遥感图像处理软件为主要工具,辅助地理信息,分析洪水水情,确定洪灾量级、危害区域及其土地利用类型等,并可比较真实地再现洪灾场景,为防洪规划提供可靠的辅助决策依据。     

Economic incentives drive the conversion of agriculture to aquaculture in the Indian Sundarbans: Livelihood and environmental implications of different aquaculture types

Expansion of aquaculture in the Sundarbans Biosphere Reserve (SBR) is irreversibly replacing agricultural land and the drivers of this change are disputed. Based on in-depth interviews with 67 aquaculture farmers, this paper characterizes major aquaculture types in the SBR, their impacts, and identifies drivers of conversion from agricultural land. Aquaculture types included traditional, improved-traditional, modified-extensive, and semi-intensive systems. Extensive capture of wild shrimp larvae is environmentally harmful but constitutes an important livelihood. Semi-intensive aquaculture of exotic shrimp (Litopenaeus vannamei) has much higher unit-area profitability than other types but involves greater financial risk. Profitability is the main driver for the transition from agriculture, but environmental factors such as lowered crop yields and cyclone impacts also contributed. Many conversions from agriculture to aquaculture are illegal according to the stakeholders. Existing legislation, if enforced, could halt the loss of agriculture, while the promotion of improved-traditional aquaculture could reduce the demand for wild seed.     

凯氏法测定土壤全氮的方法改进

采用凯氏法测定土壤全氮对9种不同类型的土壤进行测定,通过实验比较不同的还原剂、氧化剂和催化剂,发现以五水合硫代硫酸钠做还原剂,以硫酸为主要氧化剂,以K2SO4＋CuSO4＋TiO2做催化剂,具有操作简便、省时、无污染的优点。该方法加标回收率82.5%～96.0%,标样测试相对误差1.4%,精密度1.9%～10.8%,检出限14mg/kg。     

牛粪自然好氧发酵微生物变化规律

以新鲜牛粪进行好氧堆肥,每间隔3d取样,以牛肉蛋白胨、高氏一号、PDA、豆芽汁为培养基,以稀释法,进行发酵微生物分离、培养、计数和鉴定.结果表明,新鲜牛粪中微生物主要为细菌;发酵过程中,细菌数量大于放线菌、霉菌约104～ 105倍,细菌是发酵过程中的优势微生物;中温性细菌是升温阶段主要作用菌群;嗜热放线菌及嗜热细菌是高温阶段优势菌群;霉菌是降温阶段优势菌群.进一步鉴定表明,细菌类群中的芽孢杆菌、纤维单胞菌,放线菌类群中的小多孢菌、小单孢菌、高温放线菌,霉菌类群中的木霉、曲霉、青霉等为发酵过程中的优势种类.酵母菌未参与发酵过程.