基于SBE法的呼和浩特市道路行道树景观评价

采用SBE法对呼和浩特市内14条主要道路的28组行道树景观进行了美景度评价。提炼出8个美景度评价影响因子,并建立了呼和浩特市道路行道树景观评价指标体系;选定3组测试者,结合调查中拍摄的道路行道树景观照片填写调查问卷,并对数据进行收集、汇总和分析;根据美景度计算公式得出各行道树景观的SBE标准值,分析测试群组之间的相关性以及各行道树景观的差异性;最后,运用SPSS17.0数据处理软件,根据各景观因子的平均得分值给出呼和浩特市道路行道树景观的优化意见。     

A method for calculating numerical estimates of gear selectivity curve

The present paper proposes a method for estimating the numerical curve of gear selectivity without the assumption of function of selectivity curve and estimating confidence intervals, using data of catch per unit effort at length for several nets of different mesh sizes obtained from fishing experiments. The paper assumes such geometric similarity as the selectivity is the same if the rate of fish length to mesh size is the same. The basic idea is due to a technique of numerical integration that uses the derivatives at various points. The natural logarithm of selectivity is expressed by an approximation equation using its cumulated derivatives. The values of derivatives at various lengths are calculated from the data. The confidence intervals are made from the bootstrap samples. The method was applied to the data of catch at length by mesh size of gill net for pink salmon Oncorhynchus gorbuscha . Data collection, modification and issues of the method are discussed.     

Efficiency of presence-absence sampling used to estimate the mean abundance of fish eggs

ABSTRACT:   Statistical properties of estimators relating to the mean abundance of fish eggs were investigated using the data from the presence-absence sampling (PAS) and counting sampling (CS). PAS, which focuses on the presence-absence of eggs in a sample, is more cost-effective yet is unlikely to give more precise estimates than CS, which counts the number of eggs. But when limitations are given on the sampling cost and number of sampling stations, PAS may have advantages. This study shows that the mean square error (MSE) of the maximum likelihood estimator (MLE) based on PAS may become smaller than the MSE of the MLE based on counting data when the number of observations for PAS becomes larger. The observation number for PAS is determined, which minimizes the MSE of a combined estimator from the two MLE under a restriction of the total cost of observation. A dual problem is also solved. It is shown that MSE of the MLE in PAS is a monotone increasing function of the oversight probability. PAS becomes more informative as the distribution of the number of eggs is more aggregated.     

Age estimation of the wild population of Japanese mantis shrimp <Emphasis Type="Italic">Oratosquilla oratoria</Emphasis> (Crustacea: Stomatopoda) in Tokyo Bay,Japan, using lipofuscin as an age marker

ABSTRACT:   In this study, the age composition of the Japanese mantis shrimp, Oratosquilla oratoria , in Tokyo Bay, central Japan, was investigated using lipofuscin, an autofluorescent pigment, as an age marker. Lipofuscin in a histological section of protocerebral bridge cell mass (PBCM) in the brain was identified by confocal microscopy, and its concentration was quantified by image analysis. Modal analysis of the lipofuscin concentration showed four regularly-spaced modes that could each be regarded as a distinct age group. This implied a constant lipofuscin accumulation in PBCM at a 6.5 × 10⁻²% volume fraction per year; it also implied the existence of individuals that are at least 4 years old. The lipofuscin concentration was found to be a more appropriate index than body length for estimating the age of O. oratoria , because the modal analysis on the body–length histogram failed to detect apparent age groups. This was probably a result of the declining growth rate with age and the individual variations in growth through molting leading to considerable overlap in the size between different age groups. The lipofuscin analysis suggested that fast-growing individuals in each cohort are recruited to the fishery, and most individuals attain the exploitable size between 2 and 3 years of age.     

非急性水污染对渔业影响的定量估算方法的探讨

由于水域污染，导致水产生物受害变质，糜烂乃至死亡，其危害所及不仅破坏自然水体中的生态平衡，减少生物多样性，恶化人类的生存环境，而且直接或间接地导致渔业资源的重大损失。 水污染导致渔业资源受损的事件一般可分为二类，一类是局部水域发生突发性的急性污染事故，如工业废水的超标排放，装载污染物质的船舶泄漏、排放等。急性污染事故对渔业资源造成的损失主要通过对事故现场的调查、取证及相应的统计，估算而获得损失的数额［１，２］。另一类是大江、大湖、大海等开放性大水面在非急性污染事故下，因受各类污水的长期排放，水质…     

澳洲坚果树体生物量的数学估测

以4龄、8龄、25龄H2澳洲坚果树为试材,采用个体收获法,分别采集澳洲坚果树根、茎、叶,并测其鲜重和水分系数,同时测定各龄树干周、树冠周长,分别以树龄、干周、树冠周长为自变量,树体总干重和各器官干重为因变量,用12种数学模型进行回归分析,筛选最适合数学模型及最适易测因子,为澳洲坚果树体生物量估测提供合适数学模型及参数。结果表明：①在12种数学模型中,以Richards模型R2值最大,在3种因子中,以干周为自变量的R2值最大; ②以干周(X,单位为cm)为自变量,澳洲坚果树树体总干重、根、茎、叶干重为因变量(Y,单位为kg)的Richards数学模型分别为：Y总干重＝768.304×{1＋0.376×exp[-0.066×(X－57.658)]}-2.66,Y根＝206.353×{1＋2.66×exp[-0.316×(X-59.026)]}-0.376,Y茎＝455.588×{1－0.059×exp[-0.042×(X－56.289)]}16.95,Y叶＝65.20×{1＋15.404×exp[-1.108×(X-52.856)]}-0.065。     

生态系统服务价值时空变化和权衡及其与人类活动强度关联性分析——以慈利县为例

为了探究以林业为主的县域生态系统服务价值时空变化与权衡特征,分析生态服务价值与人类活动强度的关联性,为今后林业县域生态保护和恢复政策的制定和实施以及生态文明建设的推进提供依据。应用修正的生态系统服务价值估算模型、相关性分析法和双变量空间自相关分析法,评估及分析了慈利县长时间序列下生态系统服务价值时空变化以及生态系统服务内部和生态系统服务与人类活动强度之间的权衡协同关系。结果表明:(1)慈利县生态系统服务价值总量呈增长趋势,林地对于生态系统服务价值的贡献相对较高。(2)生态系统服务价值较高的区域主要集中在慈利县的东部、中部、西北部和南部,价值较低的地区主要集中于中东部; 中部、南部和西北部区域价值上升较为明显。(3)协同关系在慈利县生态系统服务权衡协同关系中占主导地位。生态系统服务价值和人类活动强度呈负相关关系。综上,近40年来慈利县实现了经济发展与生态保护的双赢局面,未来应将生态保护重心放在林地的生态质量上。     

闽北丝栗栲的单木级生物量模型及估算参数

[目的]研究丝栗栲单木级生物量模型及估算参数。[方法]以闽北典型的阔叶树种——丝栗栲为研究对象,基于20株标准木的测量数据建立丝栗栲的单木级生物量模型和生物量估算参数。[结果]①筛选出总量及各部分生物量模型分别是B=0.095D2.561(整株)、B=0.026(D2H)0.986(树干)、B=0.004D2.916(树枝)、B=0.002D3.074(树叶)、B=0.085D2.536(地上)和B=0.010D2.718(地下)。②生物量换算系数的平均值为0.853 mg/m3(n=20,SD=0.167);生物量扩展系数的平均值为1.403(n=20,SD=0.260);根茎比的平均值为0.189(n=20,SD=0.046)。[结论]该研究为亚热带常绿阔叶林的森林生物量准确估算提供了必要的数据支撑。     

基于马克思必要劳动和剩余劳动观的农业部门剩余劳动力估算研究

针对用工荒和就业难并存的现实悖论,基于马克思的必要劳动和剩余劳动的观点,使用我国1978 ～ 2010年时间序列数据对我国农业部门潜在剩余劳动力进行点估计和区间估计.结果表明,我国目前农业部门的潜在剩余劳动力数量大约在2亿左右,并且我国的劳动力供给潜在优势持续时间最短为20年左右,最长为30年左右.要充分利用劳动力供给的潜在机遇,必须尽快调整和优化产业结构,加强农业生产技术研发和农业劳动力培训力度,并加速城乡发展的一体化进程.     

江西九连山国家级自然保护区森林生态系统服务价值评估

根据九连山自然保护区生态定位研究站的长期观测资料和相关研究成果,调查和搜集九连山森林资源二类调查、森林旅游、林产品等相关数据,对九连山自然保护区森林生态系统服务价值进行评估。九连山自然保护区森林生态系统服务总价值约为11.9亿元/a,高于保护区所属地龙南县2013年财政总收入。其中,维持生物多样性价值最大,约10.8亿元,占总价值的90.8%;涵养水源价值最小,只占总价值的0.06%。各项功能价值顺序为：维持生物多样性价值＞土壤保持价值＞净化空气价值＞固碳价值＞生态旅游价值＞涵养水源价值。本次评估量化了九连山自然保护区亚热带森林生态系统服务,使九连山自然保护区干部职工进一步深化对自然保护工作意义的认识,也为九连山自然保护区的保护和发展提供新的依据,为人们正确认识自然保护区的价值提供数据支持。