CARBON FIXATION OF CYANOBACTERIAL–ALGAL CRUSTS AFTER DESERT FIXATION AND ITS IMPLICATION TO SOIL ORGANIC CARBON ACCUMULATION IN DESERT

Enhanced carbon fixation in soil crusts may facilitate the restoration of damaged ecosystems, but this requires greater knowledge of carbon fixation patterns and mechanisms. We measured the net photosynthetic rate (P_n) and estimated annual carbon fixation (ACF) in cyanobacterial–algal crusts after desert fixation in the Tengger Desert, northwestern China. The accumulated carbon fixation since the establishment of a restoration site was also calculated. In addition, stepwise regression analysis was used to study the relation between P_n and ACF and the physicochemical properties of crusts. Results showed that P_n was significantly higher at a more established 51‐year‐old restoration site (1·57 µmol m⁻² s⁻¹) than at a younger 15‐year‐old site (0·92 µmol m⁻² s⁻¹). The ACF also increased significantly with restoration time, but in two temporal phases, a slower ACF phase between 15 and 26 years of restoration (0·28–0·7 gC m⁻² y⁻¹) and a high ACF phase after 43–51 years of restoration (3·3 gC m⁻² y⁻¹). Stepwise regression analysis revealed that P_n was significantly correlated with chlorophyll a and crust cover, whereas ACF was only correlated with crust cover. Accumulated carbon fixation increased from 2·9 gC m⁻² after 15 years to 35·4 gC m⁻² at 51 years following establishment of the restoration site. The accumulated carbon fixation was positively correlated with soil organic carbon content. This study demonstrated that carbon fixation by cyanobacterial–algal crusts increased progressively after desert fixation. Artificial measures, like the establishment of these restoration zones, can facilitate the colonization and development of biological soil crusts and are an effective biological tool for desert soil restoration. Copyright © 2011 John Wiley & Sons, Ltd.     

基于抽样调查地块实测数据的省级水稻单产遥感估算

利用统计局抽样调查地块实割实测标准单位面积产量数据及空间位置信息,在研究水稻种植区MOD09GA、MYD09GA EVI （enhanced vegetation index）数据结合使用可行性分析的基础上,进行湖南省省级水稻单产遥感估算。结果表明：在水稻种植区,水稻生长期间有超过50%、85%、95%的MOD09GA与MYD09GA EVI偏差绝对值分别小于0.03、0.08、0.1。水稻遥感估产模型以二次非线性模型或回归模型精度较高,且时相集中在水稻生长的孕穗期到抽穗期。在省级水平上,与实测值相比,基于统计局统计抽样调查地块实割实测标准单位面积产量数据的水稻单产遥感拟合结果相对误差小于2%,预测结果的相对误差接近5%,且实测值与模拟值集中分布在1∶1线附近,说明预测结果与统计值在空间分布上具有较好的一致性。     

Changes in the genetic structure of Bacteria and microbial activity in an agricultural soil amended with tannery sludge

The application of tannery sludge to soils is a form of recycling; however, few studies have examined the impacts of this practice on soil microbial properties. We studied effects of two applications (2006 and 2007) of tannery sludge (with a low chromium content) on the structure of the bacterial community and on the microbial activity of soils. We fertilized an agricultural area in Rolândia, Paraná state, Brazil with different doses of sludge based on total N content, which ranged from 0 to 1200 kg N ha⁻¹. Sludge remained on the soil surface for three months before being plowed. Soils were sampled seven times during the experiment. Bacterial community structure, assessed by denaturing gradient gel electrophoresis (DGGE), was modified by the application of tannery sludge. Soon after the first application, there was clear separation between the bacterial communities in different treatments, such that each dose of sludge was associated with a specific community. These differences remained until 300 days after application and also after the second sludge application, but 666 days after the beginning of the experiment no differences were found in the bacterial communities of the lowest doses and the control. The principal response curve (PRC) analysis showed that the first sludge application strongly stimulated biological activity even 300 days after application. The second application also stimulated activity, but at a lower magnitude and for a shorter time, given that 260 days after the second application there was no difference in biological activity among treatments. PRC also showed that the properties most influenced by the application of tannery sludge were enzymatic activities related to N cycling (asparaginase and urease). The redundancy analysis (RDA) showed that tannery sludge’s influence on microbial activity is mainly related to increases in inorganic N and soil pH. Results showed that changes in the structure of the bacterial community in the studied soils were directly related to changes of their biological activity.     

我国红树林研究人员统计与分析

以1989～2005年《中国期刊全文数据库》、《中文科技期刊数据库》收录的红树林研究文献为依据,采用文献计量学的方法,对我国红树林研究人员的地区分布、人员数量及文献量的年际变化、核心作者群、核心机构、核心期刊等方面进行统计与分析。     

效应分析试验设计法

By proposing the concept of the maximum effect, this paper set up a new effective method of experiments design by using simple statistical calculations. The method has improved the direct-viewing analysis and the variance analysis of the orthogonal design     

广西珍贵乡土速生树种任豆苗木生长节律研究

利用Logistic方程对任豆1年生播种苗的苗高、地径年生长节律进行拟合,并根据因素数列几何形状发展态势的接近程度,将苗木的生长量与影响苗木生长的气象因子空气温度、空气相对湿度、降水量和日照时数组成一个灰色系统,进行面积关联度分析。结果表明：Logistic方程拟合效果显著,年生长量表现出明显的“慢-快-慢-快-慢”的节律,采用有序样本聚类分析方法将苗木的生长过程划分为出苗期、生长前期、速生期和生长后期4个时期。关联度分析表明,空气温度对苗木的高生长影响最大,相对湿度影响最小;而日照时数对苗木的粗生长影响最大,相对湿度影响最小。     

不同品种(系)饲草高粱国家区域试验分析

采用非参数统计分析方法对2005—2006年国家饲草高粱区域试验参试品种(系)的试验结果进行了分析。结果表明:除苏波丹外,其他品种均比较适宜在全国各区试点所在地区种植。7个不同生态类型的饲草高粱品种(系)的产量不是有规律地变化,具有不同的生态特征。不同生态区组间引种、引用时应对引种地区的气候、栽培技术和本地的条件进行比较,以便确定引种饲草高粱的范围,达到有效利用。用传统的多因素随机区组设计和多年多点品种区域试验的非参数统计分析方法来度量2005—2006年全国高粱区试饲草组区试资料的区域适应性(稳产性)、丰产性及试验地点对品种差异的分辨力等进行了客观评价,该统计分析方法直观,意义明确,计算简便,值得借鉴、学习、推广使用。     

蕨菜生长过程中大量元素年动态变化研究

为探明蕨菜各部位对养分的吸收、运转及利用的年变化规律,对蕨菜不同部位中大量矿质元素的年动态变化进行了研究。结果表明:蕨菜需要大量元素数量由大到小顺序为KNCaMgP;随着蕨菜的生长,各种元素在蕨菜体内大量累积,地上部分积累集中在4至8月份,而地下部分积累集中在7至10月份;食用茎N、P、Mg元素含量基本呈下降趋势,说明食用茎营养主要来自蕨菜的根状茎传输。     

南岭泡金山矿产集采区土壤重金属空间分布及风险评价

为探究典型多金属矿产集中开采区土壤重金属分布情况及其潜在风险,以南岭泡金山地区即湘南桥条江小流域矿采区为研究区,采集352个表层土壤样品,对Cr、Cd、Pb、Zn、Cu、Ni和As这7种重金属元素进行测试分析,综合运用数统和地统方法分析研究区整体及不同影响因素下土壤重金属的空间分布特征,并对其进行风险评价。结果表明,研究区表层土壤重金属均受到了不同程度的污染,矿区及其下游沿河地区污染严重,空间变异程度略高,复合污染、点源污染情况突出。土壤重金属含量基本随pH及有机质含量升高而升高;不同土地利用方式下土壤Cr、Ni、Cd含量变化不明显,草地、林地中Pb、Zn、Cu、As含量较高;不同地质背景条件下土壤重金属含量在成矿母岩(花岗岩体)、含矿围岩(D_2s+h)及矿区中下游干流一级阶地(Qx~Ⅰ)含量较高。研究区Cd、Pb、As单元素潜在生态风险水平较高,整体处于低-中等潜在生态风险水平,但矿区及其周边、下游沿河地区潜在生态风险为高或极高等级,可能会对北江流域产生一定影响,应该引起警惕予以重视。     

关于支持向量机VC维问题证明的研究

支持向量机是基于统计学习理论的新一代学习机器,本文主要阐述了支持向量机中关于VC维的理论,并就一类函数集的VC维的大小给出理论上的证明。