景观破碎化对物种的影响依赖于斑块属性,斑块属性体现了斑块的类型、面积、形状及其与周围斑块间关系。然而,在破碎化农业景观中这些斑块属性对关键物种的联合影响仍知之甚少。选取中国海南地区的典型农业破碎化景观,实测了180个斑块中...景观破碎化对物种的影响依赖于斑块属性,斑块属性体现了斑块的类型、面积、形状及其与周围斑块间关系。然而,在破碎化农业景观中这些斑块属性对关键物种的联合影响仍知之甚少。选取中国海南地区的典型农业破碎化景观,实测了180个斑块中三类关键物种,分别为害虫-橡胶材小蠹虫(Xyleborus affinis)、传粉昆虫-中华蜜蜂(Apis cerana)和天敌物种-玉米螟赤眼蜂(Trichogrammatid ostriniae Pang et Chen),刻画了各斑块属性,包括斑块类型、斑块面积、形状指数、距天然林距离、是否与橡胶接触、景观中天然林所占比例、是否有林下植物,并使用3种机器学习模型(神经网络、随机森林、支持向量机)拟合斑块属性与三类物种丰富度关系,解析斑块属性的相对重要性。结果表明,与支持向量机和神经网络相比,随机森林模型对三个物种的丰富度预测效果均最好,其R2在橡胶材小蠹虫、中华蜜蜂和赤眼蜂中分别达到0.785、0.845和0.798;基于随机森林模型的结果表明,斑块类型对橡胶材小蠹虫和中华蜜蜂丰富度相对重要性高于其他斑块属性;斑块面积对赤眼蜂丰富度影响高于其他斑块属性,且与斑块类型存在交互作用;橡胶林中橡胶材小蠹虫与中华蜜蜂丰富度高于天然林和其他斑块类型,玉米螟赤眼蜂丰富度则在天然林与农田中最高。研究揭示了斑块属性对不同物种丰富度的相对影响,阐明了斑块类型在不同物种中的重要作用,并证实了机器学习是推导斑块属性对物种影响的有效方法。展开更多
The expanding demand for biofuel feedstock may lead to large-scale con- scription of land for monoculture production ofbiofuel crops with concomitant substantial negative impacts on biodiversity. We compared moth dive...The expanding demand for biofuel feedstock may lead to large-scale con- scription of land for monoculture production ofbiofuel crops with concomitant substantial negative impacts on biodiversity. We compared moth diversity in light-trap samples from corn, miscanthus, switchgrass and native prairie, to determine whether there is an observ- able relationship between plant species diversity and moth abundance and diversity. Moth alpha diversity was highest in prairie and was higher in switchgrass than in the other two biofuel crops. Beta diversity generally was low among the biofuel crops, and prairie shared lower beta diversity with switchgrass than with corn or miscanthus. Analysis of variance showed no significant differences in moth abundance per species among treatments. The alpha and beta diversity index findings are consistent with those of other studies on arthro- pods in biofuel crops and provide evidence to suggest that large-scale conversion of acreage to biofuel crops may have substantial negative effects on arthropod biodiversity both within the cropping systems and in the surrounding landscape.展开更多
The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions...The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions have been widely developed and applied for managing forest trees in conventional forest reserves without much consideration for trees outside forest reserves. The aim of this study is to evaluate and propose a suitable probability distribution function for trees in Agricultural landscapes. The study examined 3-parameter lognormal, Lognormal, 3-parameter Gamma, Gamma, 3-parameter Weibull and Weibull distribution functions, using the Maximum Likelihood method for fitting tree diameter at breast height. Three hundred and thirty-two temporary farmlands were randomly selected from which stem diameter of all living trees, with diameter ≥ 10.0 cm, were measured. Results of the statistical analysis showed that the 3-parameter lognormal distribution gave a superior description of the stem diameter with the least values of Anderson Darling (1.627) and Akaike Information Criterion (5962.0) statistics. Hence, the 3-parameter lognormal distribution function was found suitable for the stem diameter of trees in Agricultural landscapes in the study area.展开更多
With the acceleration of urban construction,theme park has been playing a significant role in improving urban ecological environment,leisure and entertainment of the public,scientific popularization and education,demo...With the acceleration of urban construction,theme park has been playing a significant role in improving urban ecological environment,leisure and entertainment of the public,scientific popularization and education,demonstration of special functions.With the planned Waterage Park in Yangling Demonstration Zone,Shaanxi Province as an example,agricultural theme parks were discussed from 3 aspects of planning concept,scenic spots layout,and folk cultural design,then the landscapes,characteristic scenic spots,ecological agriculture,folk culture and new high-tech agricultural fruits within those theme parks were comprehensively analyzed,the planning and design of such parks were further studied,which are all of instructive significance for the theoretical studies and construction of agricultural theme parks.展开更多
文摘景观破碎化对物种的影响依赖于斑块属性,斑块属性体现了斑块的类型、面积、形状及其与周围斑块间关系。然而,在破碎化农业景观中这些斑块属性对关键物种的联合影响仍知之甚少。选取中国海南地区的典型农业破碎化景观,实测了180个斑块中三类关键物种,分别为害虫-橡胶材小蠹虫(Xyleborus affinis)、传粉昆虫-中华蜜蜂(Apis cerana)和天敌物种-玉米螟赤眼蜂(Trichogrammatid ostriniae Pang et Chen),刻画了各斑块属性,包括斑块类型、斑块面积、形状指数、距天然林距离、是否与橡胶接触、景观中天然林所占比例、是否有林下植物,并使用3种机器学习模型(神经网络、随机森林、支持向量机)拟合斑块属性与三类物种丰富度关系,解析斑块属性的相对重要性。结果表明,与支持向量机和神经网络相比,随机森林模型对三个物种的丰富度预测效果均最好,其R2在橡胶材小蠹虫、中华蜜蜂和赤眼蜂中分别达到0.785、0.845和0.798;基于随机森林模型的结果表明,斑块类型对橡胶材小蠹虫和中华蜜蜂丰富度相对重要性高于其他斑块属性;斑块面积对赤眼蜂丰富度影响高于其他斑块属性,且与斑块类型存在交互作用;橡胶林中橡胶材小蠹虫与中华蜜蜂丰富度高于天然林和其他斑块类型,玉米螟赤眼蜂丰富度则在天然林与农田中最高。研究揭示了斑块属性对不同物种丰富度的相对影响,阐明了斑块类型在不同物种中的重要作用,并证实了机器学习是推导斑块属性对物种影响的有效方法。
文摘The expanding demand for biofuel feedstock may lead to large-scale con- scription of land for monoculture production ofbiofuel crops with concomitant substantial negative impacts on biodiversity. We compared moth diversity in light-trap samples from corn, miscanthus, switchgrass and native prairie, to determine whether there is an observ- able relationship between plant species diversity and moth abundance and diversity. Moth alpha diversity was highest in prairie and was higher in switchgrass than in the other two biofuel crops. Beta diversity generally was low among the biofuel crops, and prairie shared lower beta diversity with switchgrass than with corn or miscanthus. Analysis of variance showed no significant differences in moth abundance per species among treatments. The alpha and beta diversity index findings are consistent with those of other studies on arthro- pods in biofuel crops and provide evidence to suggest that large-scale conversion of acreage to biofuel crops may have substantial negative effects on arthropod biodiversity both within the cropping systems and in the surrounding landscape.
文摘The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions have been widely developed and applied for managing forest trees in conventional forest reserves without much consideration for trees outside forest reserves. The aim of this study is to evaluate and propose a suitable probability distribution function for trees in Agricultural landscapes. The study examined 3-parameter lognormal, Lognormal, 3-parameter Gamma, Gamma, 3-parameter Weibull and Weibull distribution functions, using the Maximum Likelihood method for fitting tree diameter at breast height. Three hundred and thirty-two temporary farmlands were randomly selected from which stem diameter of all living trees, with diameter ≥ 10.0 cm, were measured. Results of the statistical analysis showed that the 3-parameter lognormal distribution gave a superior description of the stem diameter with the least values of Anderson Darling (1.627) and Akaike Information Criterion (5962.0) statistics. Hence, the 3-parameter lognormal distribution function was found suitable for the stem diameter of trees in Agricultural landscapes in the study area.
文摘With the acceleration of urban construction,theme park has been playing a significant role in improving urban ecological environment,leisure and entertainment of the public,scientific popularization and education,demonstration of special functions.With the planned Waterage Park in Yangling Demonstration Zone,Shaanxi Province as an example,agricultural theme parks were discussed from 3 aspects of planning concept,scenic spots layout,and folk cultural design,then the landscapes,characteristic scenic spots,ecological agriculture,folk culture and new high-tech agricultural fruits within those theme parks were comprehensively analyzed,the planning and design of such parks were further studied,which are all of instructive significance for the theoretical studies and construction of agricultural theme parks.
