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1.
农果复合系统营养物质的盈亏平衡特征   总被引:5,自引:0,他引:5  
采用盈亏平衡分析方法,对黄土高原南部3个村农果复合型生态农业的营养物质平衡进行了研究.结果表明,施肥是农果复合生态系统营养物质的主要输入途径.输入的营养物质中,化石能所占比重较大,而有机肥投入相对不足.农果复合生态系统内用于循环的N、P、K仍远低于营养物质N、P、K的输出量.3村营养物质的产投比虽有差异,但总体水平仍很低.  相似文献   

2.
生物生产力的“4P”概念、估算及其相互关系   总被引:44,自引:3,他引:41  
生物生产力是指从个体、群体到生态系统、区域乃至生物圈等不同生命层次的物质生产能力,它决定着系统的物质循环和能量流动,也是指示系统健康状况的重要指标。表示生物生产力的概念有总初级生产力(GP P)、净初级生产力(NPP)、净态生态系统生产力(NEP)和净生物群区生产力(NBP),本文简称“4P”。主要探讨了“4P”概念的内涵和估算以及全球变化对它们的影响;通过生态系统的碳循环,建立“4P” 之间的相互联系,并对若干衍生概念进行定义。尽管生态系统的最终产物(NBP或现存量)占光合总产量的很少一部分,但它是决定物质再生物的资本,维持和决定生态系统的物质再生产。  相似文献   

3.
基于能值分析的广东省生态经济系统综合研究   总被引:11,自引:2,他引:9  
运用能值理论与分析方法,从自然子系统、社会子系统、经济子系统3个侧面,系统与子系统2个层面,对广东省生态经济系统1990年以来的发展态势进行了定量分析.结果表明,广东省属于高度发展地区,系统高度依赖于反馈能值的投入,虽然污染治理卓有成效,但并未从整体上解决环境压力不断增大的矛盾,区域自身可持续发展能力低.广东省对于国际市场的信赖性日益提高,但在大量资源型产品出口和高技术产品进口的不等价交换中处于实际的亏损地位.依靠科技,提高产出品附加值,发挥落后地区自然和人力资源优势,以及发达地区的经济拉动力,是全面提高区域可持续发展能力的关键.  相似文献   

4.
以陕西省淳化县西坡村农果复合系统为例,对比分析了2008和2010年农业、果业、畜牧业、人类子系统的能流路径、能流投入、产出结构和能量循环指数.结果表明:2008—2010年间,研究区农果复合系统总投入下降了1.6%,总产出却增长了56.7%,产投比增加了59.4%.各子系统(农业子系统、果业子系统、畜牧业子系统和人类子系统)的能量产投比分别增长了36.6%、21.0%、10.0%和3.8%;西坡村仍需坚持"稳定农业、发展畜牧业和强化果业"的发展方针,以促进农果复合系统的发展和优化升级.  相似文献   

5.
生物多样性研究及其问题   总被引:62,自引:6,他引:56  
岳天祥 《生态学报》2001,21(3):462-467
围绕生物多样性主要有3个理论问题需要进一步深入研究,(1)生物多样性与生态系统稳定性的关系:本世纪70年代以前,生态学家普遍认为,稳定性随生物多样性增加而提高;自70年代初一些理论生态学家向这一普遍看法提出挑战以来,在物种多样性层次出现了观点截然不同的两大阵营;(2)生物多样性和土地生产力的关系:达尔文(1872)的研究表明,生物多样性有利于土地生产力的提高,这一结论已被许多国家运用于指导农业实践;然而,本世纪70年代以来,一些生态学家向达尔文的这一观点提出了异议;(3)生物多样性与景观连通性:本世纪90年代以来,一些景观生态学家认为,景观连通性与生物多样性有正相关关系,但目前为数不多的研究还不能肯定这一结论的正确性。通过总结生物多样性的研究历史,发现,以上的急诊和结论基于27种不同的分析模型;并且这些模型中的大多数在理论上是不完善的,认为,运用理论上合理的模型、有关概念的统一正确定义和全面系统的实验对以上急诊和结论进行更进一步的论证与实证是必要的。  相似文献   

6.
姜晓艳  吴相利 《生态学报》2021,41(21):8396-8407
把握城市独特的生态-经济-社会系统协调优化特性是实现林业资源型城市可持续发展的重要前提。研究从生态、经济、社会3个维度构建了林业资源型城市复合系统的测度评价指标体系,应用熵值法、耦合协调度模型,采用2005-2018年时段生态、经济、社会数据,对伊春协调发展状况进行实证测度评价,运用障碍度模型分析影响系统协调发展的主要因素,采用GM (1,1)灰色预测模型进行发展预测。结果表明:(1)综合发展指数呈上升态势,促进生态-经济-社会综合发展的主要动能历经了从生态到经济,再到生态为主要动力的发展过程,三个子系统发展水平呈趋同态势,推动三维系统的均衡协同是未来发展的重要方向;(2)三维系统耦合度稳定在较高水平,系统间相互依赖、相互作用程度较高,协调度呈波动上升,实现了由勉强协调、经济滞后发展向良好协调、同步发展的转变,协调状态趋向良好;(3)三维系统中社会子系统对协调发展的障碍度最大;人口自然增长率、建成区绿化覆盖率、GDP增长率、第三产业就业人数比重4个指标是制约近期协调发展的主要障碍因子;(4)2019-2030年,生态、经济、社会子系统发展指数及协调度的预测值均呈上升态势,生态-经济-社会复合系统将向更高级的协调发展状态演进,经济发展将再次成为促进生态-经济-社会综合发展的主要动力;加强生态建设,引领生态创新,大力发展生态经济,提高社会发展水平,着力降低障碍因子对协调发展的阻力作用,实现生态-经济-社会的联动健康发展是伊春未来重要的努力方向。  相似文献   

7.
基塘农业生态工程模式的能值评估   总被引:20,自引:5,他引:15  
应用能值分析方法及最新推出的评价系统可持续发展能力的能值指标(EISD),分别对珠江三角洲三水市的3种基塘农业生态工程模式进行了系统层和子系统层的能值比较研究。结果表明,模Ⅲ的可持续发展性能最强,其EISD比模式Ⅰ、Ⅱ分别高出58.3%和29.7%;种植业子系统经济效益好,但环境压力大。是模式内可持续发展性最差的子系统;畜牧业子系统生产环效果不佳,但增益环效果明显;渔业子系统经济效益好,环境压力小。是系统内可持续发展性最强的子系统。引入翘嘴鳜的生态经济边际效益显著。  相似文献   

8.
海拔对全缘叶绿绒蒿植株性状和花特征的表型选择分析   总被引:1,自引:0,他引:1  
为了研究海拔差异对植株性状、花特征表型选择的影响,以青藏高原高寒草甸的全缘叶绿绒蒿(Meconopsis integrifolia)为研究材料,于盛花期内,测定不同海拔(4 452、4 081和3 681 m)种群中个体植株性状、花特征、单果结实数并进行统计分析,采用线性回归模型估计不同海拔种群间植株性状、花特征所受的表型选择(选择差与选择梯度)。结果表明:(1)随着海拔升高,全缘叶绿绒蒿植株性状、花特征及单果结实数显著降低,海拔越高的种群中株高越矮、叶面积越小、花数越少、花越小、单果结实数越低。(2)不同海拔种群中各性状的表型选择存在差异,较低海拔(3 681 m)种群中花数、花大小具有显著的选择差和选择梯度,表现为花越多、花越大的个体雌性适合度越高;海拔较高(4 081 m)的种群中株高、叶面积及花数更容易受到选择,表现为植株越高、叶面积越大、花越多的个体雌性适合度越高;海拔最高(4 452 m)的种群中叶面积与花数的选择梯度接近显著。(3)植物性状分化伴随着海拔的变化而呈现出差异,较低海拔种群中花特征容易受到选择,而较高海拔种群中可能由于传粉者稀少、资源限制等因素使得株高、叶面积更容易受到选择。  相似文献   

9.
滨海盐沼湿地植被净初级生产力变化对土壤因子的响应   总被引:2,自引:0,他引:2  
以辽河三角洲滨海盐沼湿地为研究区,基于遥感数据、气象数据、野外调查和实验室分析数据,采用CASA模型模拟并分析该区域植被净初级生产力(Net Primary Productivity,NPP)的变化特征,利用统计分析方法定量分析土壤因子对植被NPP的影响。结果表明:(1)研究区植被NPP空间分异显著,区域变异系数为43.71%,且同种植被类型内部NPP也变化显著;(2)N、P和K对芦苇NPP的限制形式是协同限制,且随土壤电导率的增加呈抛物线形式,因子敏感性从大到小依次为K、P和N;营养限制程度从大到小依次为K、N和P;(3)土壤水盐对芦苇NPP的影响也基本符合抛物线模式,芦苇NPP对土壤电导率的敏感性和土壤电导率对芦苇NPP的影响程度都大于土壤含水量,且土壤含水量越高,芦苇NPP对土壤电导率的敏感性越低。本文最终得出只有各土壤因子达到组合最优时,芦苇NPP才最大,这对滨海盐沼湿地植被的管理和保护具有重要意义。  相似文献   

10.
农业活动对生物多样性的影响   总被引:43,自引:3,他引:40       下载免费PDF全文
农业生产活动如土地的农业利用、耕作、作物间套种植方式、放牧、农药化肥的使用以及农业动植物遗传改良(包括外来种引入)等是农业生产力提高的重要途径,同时也是影响生物多样性的重要因素之一。土地的不合理开发利用易导致生境破碎、生物多样性下降;大规模的机械耕作导致土壤动植物区系的变化,甚至某些物种的消失;农药(除草剂、杀虫剂等)的高度使用使非靶标动植物受到伤害;品种改良、外来种的引入以及远缘外源遗传物质的利用(如远缘杂交和DNA导入分子育种)在丰富了遗传多样性的同时导致农作物类型和品种的简单化、一些古老的地方种和农家种等传统资源丢失等;而一些合理的农业措施(间套作、实行有机农场等)将有利于生物多样性的保持。农业活动注重的是农业生产力的提高而往往忽视其对农业系统中野生动植物(包括有害和无害)的影响以及野生动植物在维持系统稳定和平衡的作用。本文论述农业活动对生物多样性的影响以及生物多样性保护对提高农业生产力的作用,启示人们采取合理的农业活动方式,合理管理有害生物,减少农业活动对生物多样性的负面影响。  相似文献   

11.
城市生态系统现状评价的生命力指数   总被引:6,自引:0,他引:6  
苏美蓉  杨志峰  陈彬  赵彦伟  徐琳瑜 《生态学报》2008,28(10):5141-5148
鉴于城市生态系统的生命特征,采用比拟思想,引入城市生命体概念到城市生态系统现状评价中,以全面而形象地反映城市生态系统的发展状况。构建了包括生产力、生活态、生态势和生机度的城市生命力指数框架,并进一步给出了具体的评价指标体系、评价模型及评价结果分级标准。以重庆万州为例,开展了城市生命力指数评价的案例研究。评价结果表明,2000~2005年间,万州城市生命力指数处于较衰弱状态,但一直在平稳上升,应通过一定的生态规划措施,提高万州城市生态系统的生产力、生活态、生态势及生机度,尤其要注重增强生态系统的生机与活力,以实现城市生命力的继续提升。  相似文献   

12.
为保护热带雨林,改变现有砂仁栽培模式,探讨改雨林下种砂仁为次生林下种砂仁的可行性.比较研究了热带雨林和次生林下砂仁的生长状况和产量.砂仁种植对雨林生物量和生产力影响显著,对次生林的影响不显著.2种林下砂仁4类植株的密度和生物量的大小顺序均为壮株、衰老株、苗和笋.雨林和次生林下砂仁笋和苗的总数分别为衰老株数量的3.95和1.66倍,远多于衰老株数量,表明砂仁能够维持种群稳定.雨林下砂仁苗多为长势较弱的老苗,绝大多数最终不能生长成壮株.2种林下砂仁壮株密度和生物量差异不显著。但次生林下砂仁衰老株、苗和笋的密度和生物量显著高于雨林,表明次生林下砂仁更新比雨林下快.次生林下砂仁产量为78.068kg·hm^-2,略高于雨林.值得注意的是。砂仁产量很低,茎生物量比很高(0.6以上),果实生物量比极低(0.01),增产潜力较大.次生林的生物量低于雨林,透光率高于雨林。土壤水分含量与雨林接近,有利于砂仁的生长发育。可以在次生林下种植砂仁。  相似文献   

13.
Much of the primary forest in the eastern United States that was converted to farmland between 1600 and 1900 has reverted back to second growth forest as a result of agriculture abandonment. This reversion back to forest gives soil productivity a chance to recover, though the rates of recovery are not well understood. Understanding the legacy effects of past disturbances like agriculture can provide important insights to support ecological restoration efforts on disturbed soils. Our goal with this study was to further understand the effects of forest development on soil productivity after agriculture abandonment. We used a chronosequence approach to examine soil properties over a 60‐year temporal scale of forest development on abandoned agricultural lands in Saratoga and Rensselaer Counties in New York, U.S.A. We measured soil properties within this chronosequence to test the hypothesis that there would be measurable recoveries of soil physical properties and fertility over time. We observed rapid recovery of physical properties (lower bulk density and higher macroporosity) of surface soils within 5–10 years after agricultural abandonment. However, we found a legacy effect of agricultural compaction still evident in subsoils, with soil strength measurements indicating that past agricultural practices still limited root growth 55–60 years after abandonment. Soil percent organic matter and mineralizable nitrogen (N) both increased with forest development, but biomass accumulation may be slowed by limited root growth in the subsoil due to high strength. We recommend assessing subsoil physical properties when developing ecological restoration plans for agricultural lands.  相似文献   

14.
Atriplex sagittata is a heterocarpic species producing three types of fruits which differ in morphology and ecological properties. This study focused on variation in biomass allocation into particular fruit types under different density and fertilization levels. The reduction in total weight under stressful conditions was accompanied by a reduction of reproductive structures in terms of both total fruit production and mean fruit weight. Allocation of biomass to particular fruit types under different density-fertilization treatments showed considerable variation. The non-dormant, bracteolate fruit type (termed C) contributed 80–90% to the total fecundity and its production was not affected by density-fertilization treatments. The production of this fruit type is higher in the upper part of the maternal plant stem. Production of the very dormant ebracteate fruit type (termed A) increased under favourable conditions and was greater on the lower part of the stem, whereas more of the so-called type B fruit (covered by bracteoles and exhibiting dispersal and dormancy characteristics intermediate between types A and C) was produced under suboptimal conditions and was concentrated in the middle part of the plant body. This pattern contradicts to some extent the theory that deeply dormant and less dispersible fruits will be produced under stressful conditions and may be considered a new model for the behaviour of plants with more than two heterocarpic fruits. The type B fruit, intermediate in both morphology and ecological behaviour, provides a continuum between extreme strategies. Received: 8 February 1998 / Accepted: 19 November 1998  相似文献   

15.
四川桤柏混交林生物量的研究   总被引:16,自引:0,他引:16  
 对四川省盐亭县桤柏混交林单株干重、平均净生产量、林分生物量和生产力动态的系统研究表明:桤木和柏木不同器官生物量随年龄积累变异显著,积累最多的是树干,其它器官积累较少。桤木各器官平均净生产量在2~12年上升,在12~14年左右达到峰值,随后下降,其生物量结构和垂直分布也程相同的趋势,表明桤木在16年以后已成熟,主伐年龄可定在18~20年间。柏木叶积累量的增长在幼龄期有“超前现象”。其各器官平均净生产量在2~18年内增长呈“J”型曲线.生物量结构和垂直分布仍处于剧烈分化期。在我国人工混交林中,桤柏混交林的生物量和生产力都比较高。  相似文献   

16.
Increasing crop productivity to meet rising demands for food and energy, but doing so in an environmentally sustainable manner, is one of the greatest challenges for agriculture to date. In Ireland, Miscanthus × giganteus has the potential to become a major feedstock for bioenergy production, but the economic feasibility of its cultivation depends on high yields. Miscanthus fields can have a large number of gaps in crop cover, adversely impacting yield and hence economic viability. Predominantly positive effects of Miscanthus on biodiversity reported from previous research might be attributable to high crop patchiness, particularly during the establishment phase. The aim of this research was to assess crop patchiness on a field scale and to analyse the relationship between Miscanthus yield and species richness and abundance of selected taxa of farmland wildlife. For 14 Miscanthus fields at the end of their establishment phase (4–5 years after planting), which had been planted either on improved grassland (MG) or tilled arable land (MT), we determined patchiness of the crop cover, percentage light penetration (LP) to the lower canopy, Miscanthus shoot density and height, vascular plants and epigeic arthropods. Plant species richness and noncrop vegetation cover in Miscanthus fields increased with increasing patchiness, due to higher levels of LP to the lower canopy. The species richness of ground beetles and the activity density of spiders followed the increase in vegetation cover. Plant species richness and activity density of spiders on both MT and MG fields, as well as vegetation cover and activity density of ground beetles on MG fields, were negatively associated with Miscanthus yield. In conclusion, positive effects of Miscanthus on biodiversity can diminish with increasing productivity. This matter needs to be considered when assessing the relative ecological impacts of developing biomass crops in comparison with other land use.  相似文献   

17.
A huge number of hypotheses have been put forward to explain the substantial diversity in economic performance we see in the present-day. There has been a growing appreciation that historical and ecological factors have contributed to social and economic development. However, it is not clear whether such factors have exerted a direct effect on modern productivity, or whether they influence economies indirectly by shaping the cultural evolution of norms and institutions. Here we analyse a global cross-national dataset to test between hypotheses involving a number of different ecological, historical, and proximate social factors and a range of direct and indirect pathways. We show that the historical timing of agriculture predicts the timing of the emergence of statehood, which in turn affects economic development indirectly through its effect on institutions. Ecological factors appear to affect economic performance indirectly through their historical effects on the development of agriculture and by shaping patterns of European settler colonization. More effective institutional performance is also predicted by lower-levels of in-group bias which itself appears related to the proportion of a nation's population that descends from European countries. These results support the idea that cultural evolutionary processes have been important in shaping the social norms and institutions that enable large-scale cooperation and economic growth in present-day societies.  相似文献   

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周连第  胡艳霞  王亚芝  雷庆国 《生态学报》2012,32(23):7346-7354
国内外学术界和决策者对于循环农业给予了相当关注,但关于循环农业研究,从产业经济角度进行定量分析目前仍处于相对匮乏状态.以京郊典型的尖岩村农业生物循环农业范式为案例,采用能值方法,以翔实的数据描述了从种植、养殖到食用菌生产的各个阶段能量输入与输出,通过能值评估指标体系判断在整个循环产业链条中,各生产环节对环境经济产生的影响,结果显示:(1)农业生物循环系统的能值投资率(2.57)较养殖(116.23)、食用菌子系统(158.73)低;环境负荷率(1.40)也较养殖子系统(7.24)、食用菌子系统(13)低,表明,该循环模式可减少对自然资源和外来经济投入的依赖,能够获得自身的资源补偿.(2)农业生物循环系统的净能值产出率和可持续发展指数较高,说明,该模式有较强的获利性,是较理想的产业系统,在北京郊区推广价值较高.  相似文献   

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