运用改进单纯形法拟合Logistic曲线的研究

Ｌｏｇｉｓｔｉｃ方程是研究有限空间内种群增长规律的重要工具之一本文运用改进单纯形法最优拟合Ｌｏｇｉｓｔｉｃ曲线,结果表明改进单纯形法具有较强的拟合非线性方程的能力,对生物实验及生态、生理学中诸多非线性曲线的参数估计具有普遍意义．     

遥感在植被净第一性生产力研究中的应用

植被净第一性生产力 (简称ＮＰＰ)是指绿色植物在单位面积、单位时间内所累计的有机物数量 ,是由光合作用所产生的有机质总量中扣除自养呼吸后的剩余部分。它直接反映了植物群落在自然环境条件下的生产能力。据研究 ,在假使生态系统的呼吸作用保持恒定的条件下 ,植被ＮＰＰ每增长 2 %就会净吸收 1Ｇｔ(10 15ｔ)的Ｃ(碳物质 ) [3 8] 。所以 ,近几年来各国学者对ＮＰＰ的研究倍受重视 ,尤其在国际生物学计划 (ＩＢＰ)期间进行了大量的植物ＮＰＰ的测定 ,并以测定资料为基础联系环境因子建立模型对植被ＮＰＰ的区域分布进行评估 ,极大地促进了…     

Stories Remote Sensing Images Can Tell: Integrating Remote Sensing Analysis with Ethnographic Research in the Study of Cultural Landscapes

Although remote sensing techniques have become important methodologies in geographical studies, their quantitative tradition and empirical strength have discouraged their use in ethnographically based research of cultural landscapes. Using Uxin Ju of Inner Mongolia in China as a case study, this paper, adopting the approach of mixed methods, explores the integration of remote sensing techniques with ethnographic research in the study of cultural landscapes. In particular, it examines how remote sensing techniques, combined with ethnographic methods, can contribute to the study of cultural change and human perceptions as they relate to the landscape. Remote sensing analysis offers additional stories about changes in the landscape–stories not told by interviewees, or stories that supplement the account of interviewees. These stories provide important insights into cultural change and culture–landscape relationships. Through this case study, I argue that remote sensing techniques can greatly enhance ethnographic research in the study of cultural landscapes.     

Dynamic Modelling of Northeast China Transect Responses to Global Change-A Regional Vegetation Model Driven by Remote Sensing Information

A remote sensing driven dynamic simulation model was developed for terrestrial ecosystems. The model was encoded in C language under the environment of SPAMOD, a spatial simulation tool developed under MS Windows. The model was applied to Northeast China Transect to simulate the dynamics of green and non-green biomass of 12 vegetation categories as well as soil water of 3 layers. The green biomass was converted to normalized difference vegetation index (NDVI) of AVHRR remote sensing, and compared with the observed NDVI from 1986 to 1990. The model was also compared with ground measurements of biomass and productivity along the transect. Ambient CO2 concentration, monthly mean air temperature and monthly precipitation were regarded as the three basic driving variables for global change study. The model also included the effects of temperature and precipitation on sunshine fracti6n, relative humidity, radiation, soil water and eventually plant growth. For each CO2 and climatic scenario, the model was run for an equilibrium solution. The results indicated that the natural vegetation of the transect was very sensitive to variation of temperature and CO2 concentration. With CO2 remained unchanged and temperature increased by 4 CE, the induced increase in evapotranspiration could reduce the average biomass and net primary productivity (NPP) over the whole transect by 32.1% and 41.9 % respectively. In contrast, a 20 % increase in precipitation alone could lead to an increase of the average biomass and NPP by 8.1% and 13.4% respectively. Under the present climatic conditions, CO2 doubling could increase the average biomass and NPP by 12.2% and 17.1% respectively. Because of compensation between the positive effects of CO2 and precipitation increase and the negative effect of temperature increase, a comprehensive interaction among CO2 doubling, a 20% increase of precipitation and a 4 ℃ increase of temperature altogether can lead to approximately a 2% reduction in the biomass and NPP of the natural vegetation over the whole transect.     

枯草芽孢杆菌B115优化培养及其对气单胞菌的抗菌效果的研究

采用正交实验设计确定了枯草芽孢杆菌（Bacillus subtilis）B115的基础培养基成份为：胰蛋白胨1％,酵母膏0．25％,氯化钠0．5％;添加成份最优组合为（NH4）2SO4 0.1％,（K2HPO4＋KH2PO4）（1．4＋0．6）％和柠檬酸三钠0．1％;添加成分最优组合与基础培养基培养产量比较,表明添加K^＋、NH4^＋和柠檬酸三钠能极显著地促进B115的生长。研究了B115对致病性气单胞菌的抗菌效果,结果表明：B115对BSK-10和CL990920有明显抑、杀菌效果,对TL970424无抑菌效果。     

A Bootstrap-Based Covariate Selection Method for Modeling the Risk of Lightning-Induced Fires at a Local Scale: A Case Study in Northwest Spain

In lightning-induced fire risk prediction models, the number of potential predictors is usually high, with some redundancy among them. It is therefore important to select the best subset of predictors that obtain models with the greatest discrimination capacity. With this aim in mind, the logistic generalized linear model was used to estimate lightning-induced fire occurrence using a case study of the province of León (northwest Spain). A bootstrap-based test was used to obtain the optimal number of predictors and to model this optimal number of predictors displaying the largest area under the receiver operating characteristics curve. The results show that of the 16 variables initially considered, only three were necessary to obtain the model with the best discriminatory capacity for estimating lightning-induced fire occurrence. Moreover, this model can be considered equivalent to another nine alternative models with three covariates. Both the optimal and the equivalent models are useful in the spatially explicit assessment of fire risk, the planning and coordination of regional efforts to identify areas at greatest risk, and the design of long-term wildfire management strategies. The methodology used for this case study can be applied to other wildfire risk assessment situations where multiple and interconnected covariates are available.