共查询到20条相似文献,搜索用时 62 毫秒
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从石竹科植物多荚草(Polycarpon prostratum(Forssk.)Aschers.et Schwein.ex Aschers)中分离得到3个新的柴胡皂甙类化合物:prostratoside A ̄C(1 ̄3)。它们的结构通过波谱方法分别鉴定为:3-O-{β-D-xylopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-「β-D-glucopyranosy 相似文献
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辽宁省灾害区划初探 总被引:2,自引:0,他引:2
辽宁省灾害区划初探尹功成,梁文举(辽宁省农业区划研究所,沈阳110031)(中国科学院沈阳应用生态研究所,110015)AnApproachtoCalamityDivisioningofLiaoningProvince¥.YinGongcheng(LiaoningInslituteofAgri-culturalDivisioning,Shenyang110031),LiangWenju(InsliluteofAppliedEcology,AcademiaSinica,Shenyang110015).ChineseJournalofEcology,1993,12(4):61-65.NaturalcalamitiesoccurwhenvariOusnaturalphenomnaendangerlife,mindsandproperties,butsomepotentialenvironmentaldisasterssuchasrnan-madeandanthropogenousnaturaldisastersdevelopslow-lyandprofoundly,whlchareunobviousandnotr 相似文献
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90年代农村发展与农业生态研究彭廷柏(中国科学院长沙农业现代化研究所,410125)RuralDevelopmentandAgro-ecologicalResearchin1990s¥.PengTingbai(ChangshaInstituteofAgri-culturalModernization,AcademiaSinica,410125).ChineseJournalofEcolegy,1993,12(2):2-3.InordertoapproachtherelatedproblemsofChina’sagro-ecologicalresearchin1990s,thispaperana-lyzedthenewtrendsofstructuralchangesinruraleconomyandagro-ecology.underconditionofsocialistmarketeconomyexpoundedsomeviewpointsonthecoordinativedevelopmentofagro-ecologyandagro-economy,thestrengtheningofabsorbi 相似文献
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从生态位观点评价苏南地区种植业结构调整 总被引:1,自引:0,他引:1
从生态位观点评价苏南地区种植业结构调整高德明(南京农业大学农学系,210014)EvaluationofCroppingStructureAdjustlnentsinSouthernJiangsufromtheViewpointsofNicbeTkeory¥.GaoDeming(DepartmentofAgronomy,NanjingAgriculturalUniversity,210014).ChineseJournalofE-cology,1993,12(2):43-44.AccordingtotheconcreteconditionsinsouthernJiangsu,thesignificance,necessityandpossibilityofad-justingcroppingstructureareevaluatedfromtheviewpointsofnichetheory.Theefficienciesoftwocrop-pingsystemsinutilizingpaddyfieldnichesareanalyzedandtheresultsshowthatthecroppingpat 相似文献
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新疆农业绿洲生态建设的探讨 总被引:1,自引:0,他引:1
新疆农业绿洲生态建设的探讨夏爱林(新疆农业科学院土壤肥料研究所,乌鲁木齐830000)AnApproachtotheEcologicalConstructionofAgriculturalOascsinXinjiang¥XiaAilin(InstituteofSoilandFertilizers,XinjiangAcademyofAgriculturalSciences,Uromqi830000).ChineseJournalofEcolo-gy,1993,12(1):67-70。Comparedwithotheraridareasoftheworld,theagriculturaloasesinXinjiangpossessthefollowingcharacters:1.theyaredesertandirrigated,andwateristhemainfactorfortheirsubsistenceanddevel-oprnent,2.thereareabundantlight,heatandwaterresourcesandgreatpotentialforincreasingtheirprod 相似文献
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农业系统生产力(ASP)的量化及其现状分析 总被引:6,自引:0,他引:6
农业系统生产力(ASP)的量化及其现状分析卢进登,韩纯儒(北京农业大学农学系,100094)QuantificationofAgrosystemProductivity(ASP)andAnalysisonitsCurrentSituationinCbina¥.LuJin-deng;HanChunru(BeijingAgriculturalUniversityfBeijing100094).ChineseJournalofEcology,1993,12(2):21-22.BasedonabriefanalysisontheformationprocessofASP,itsconceptisdescribedandanintegratedindi-catorforitsquantification—ASP2isputforwards.Fromthose,theASPlevelsinvariousregionsofChinaareanalyzedand8levelsaredividedbyusing.Hierarchicclusteringmethod.It’s:clarifiedthatAS-PIisamore 相似文献
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InhibitionofAcrosomalEnzymesbyGossypolIsRelatedtoItsAntifertilityActionYUANYu-ying;(袁玉英)ZHANGYan-lin;(张燕林)SHIQi-xian(石其贤)(Zhe... 相似文献
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生物固氮─—生态农业的一个重要启动因素陈士平(辽宁省农业科学院土壤肥料研究所,沈阳110161)BiologicalNitrogenFixation—AnImportantRunningFactorofEcologicalAgriculture¥.ChenShiping(SoilandFertilizerInstilute,LiaoningAcademyofAgriculturalSciences,Shenyang110161).ChineseJournalofEcology,1993,12(2):31—33.LeguminousgreenmanurecropssuchassweetcloverandAstragalushuangheensis,canprovidedefiniteamountofbiologicallyfixed-NtomakeN-budgetbalance,promotesoilphysicalandchemicalproper-ties,reducesoilandwatererosion,andthus,increaseperunitareayieldandtotaloutputwhe 相似文献
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基于SOFM网络对黄土高原森林生态系统的养分循环分类研究 总被引:2,自引:0,他引:2
对森林生态系统进行分类是认识森林生态过程的根本途径,传统的从结构角度对森林生态系统分类只能反映森林的外在特征,而无法从功能角度区别森林的本质差异.通过对黄土高原3个生物气候区18个不同森林生态系统的养分循环特征测算和分析,选取了能全面反映养分的积累和分布(生物量、枯落物积累量、养分积累量)、循环通量(年吸收量、年存留量、年归还量)以及养分循环效率(循环系数、利用系数、养分生产力)等多方面指标作为分类指标体系,利用自组织映射特征网络(SelfOrganizing Feature Maps,SOFM)聚类方法,从养分循环的角度将黄土高原森林生态系统划分为2个一级类型,6个二级类型.该分类结果与实际较符,从而探索了森林生态系统的功能分类方法,也验证了SOFM网络模型应用于森林养分循环分类的可行性. 相似文献
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SUMMARY The major concepts involved in nutrient cycling in wetlands are discussed using phosphorus and nitrogen as examples. The differences in nutrient cycling patterns between hydrologically contrasting wetlands, and the significance of fluctuating water levels in wetlands, are stressed. In South Africa, some research into nutrient cycling in submerged aquatic macrophyte communities has been undertaken, but very little information is available on these processes in wetlands dominated by emergent vegetation forms. Generally, the information available on nutrient cycling processes in South African wetlands is of limited applicability to the assessment of nutrient cycling in whole wetland systems. Therefore, rational wetland management strategies require further research on nutrient cycling. 相似文献
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黄土残塬沟壑区刺槐人工林生态系统的养分循环通量与平衡分析 总被引:14,自引:5,他引:14
根据养分平衡原理测算了黄土高原残塬沟壑区刺槐人工林生态系统的生物化学循环和生物地球化学循环通量及循环率,以相对聚散度反映了养分循环通径上的各养分元素的相对富集化或稀释化程度,结果表明了刺槐人工林生态系统的养分循环为土壤亏损,系统积累型的总流动趋势。 相似文献
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灌木层及主要灌木树种在蒙古栎林养分循环中的地位和作用 总被引:4,自引:0,他引:4
本文对次生蒙古栎林中的灌木层及主要灌木树种(毛榛子,溲疏和刺五加)在林分分生物循环中的地位与作用进行了研究。研究结果表明,虽然灌木层在生物量,养分量,存留量,归还量等方面在林分中次于乔木层,但循环速率为0.68,高于乔木层(0.60),又高于林分(0.64),在林分养分步入良性循环中起着重要的不可缺少的作用,毛棒子和溲疏是灌木中的优势或亚优势树种,是在养分良性循环中具有突出贡献的树种,是重点保护的 相似文献
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John T. Finn 《Journal of theoretical biology》1982,99(3):479-489
Two hypotheses of nutrient cycling during succession are considered. First, Odum's hypothesis that nutrient cycles “tighten” as succession proceeds, i.e. cycling within the system increases. Second, Vitousek and Reiners' hypothesis that the ratio of output to input will decrease at first as net ecosystem production (NEP) increases and then return to unity as NEP approaches zero. The two hypotheses are compatible and this is demonstrated using a simple model of nutrient cycling during succession. This suggests two independent processes involved in nutrient conservation, namely, nutrient accumulation and nutrient cycling. 相似文献
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Nutrient cycling is fundamental to ecosystem functioning. Despite recent major advances in the understanding of complex food web dynamics, food web models have so far generally ignored nutrient cycling. However, nutrient cycling is expected to strongly impact food web stability and functioning. To make up for this gap, we built an allometric and size structured food web model including nutrient cycling. By releasing mineral nutrients, recycling increases the availability of limiting resources for primary producers and links each trophic level to the bottom of food webs. We found that nutrient cycling can provide a significant part of the total nutrient supply of the food web, leading to a strong enrichment effect that promotes species persistence in nutrient poor ecosystems but leads to a paradox of enrichment at high nutrient inputs. The presence of recycling loops linking each trophic level to the basal resources weakly affects species biomass temporal variability in the food web. Recycling loops tend to slightly dampen the destabilising effect of nutrient enrichment on consumer temporal variability while they have opposite effects for primary producers. By considering nutrient cycling, this new model improves our understanding of the response of food webs to nutrient availability and opens perspectives to better link studies on food web dynamics and ecosystem functioning. 相似文献
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Benthic cyanobacterial mats are increasing in abundance worldwide with the potential to degrade ecosystem structure and function. Understanding mat community dynamics is thus critical for predicting mat growth and proliferation and for mitigating any associated negative effects. Carbon, nitrogen, and sulfur cycling are the predominant forms of nutrient cycling discussed within the literature, while metabolic cooperation and viral interactions are understudied. Although many forms of nutrient cycling in mats have been assessed, the links between niche dynamics, microbial interactions, and nutrient cycling are not well described. Here, we present an updated review on how nutrient cycling and microbial community interactions in mats are structured by resource partitioning via spatial and temporal heterogeneity and succession. We assess community interactions and nutrient cycling at both intramat and metacommunity scales. Additionally, we present ideas and recommendations for research in this area, highlighting top-down control, boundary layers, and metabolic cooperation as important future directions. 相似文献
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受干扰的生态系统Ⅰ.柞蚕林的养分循环 总被引:4,自引:0,他引:4
本文通过田间实验与测试揭示了柞蚕林养分循环状态和干扰因素对养分平衡的影响。结果表明,地下部储存的养分占总积累的比重较大。同时叶部养分向树体转移能力较强。柞蚕林二级生产力是以收获蚕茧为主要形式,其养分输出水平对系统的养分平衡产生的影响主要表现对树体养分内循环方面。林木养分储量的下降是造成生产力衰退的重要原因。对养分循环格局的认识有助于对该系统干扰强度进行调控,以增强柞蚕林生态系统的稳定性。 相似文献
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Growing interest in possible global climate change has underlined the need for better information concerning the way in which carbon partitioning between ecosystem components is influenced by constraints on nutrient availability. Micro-organisms play a fundamental role in the cycling of carbon and nutrients in all ecosystems but the role of fungi in particular is pivotal in boreal forest ecosystems. Traditional models of nutrient cycling are based on methods and concepts developed in agricultural systems where microorganisms are considered primarily as nutrient processors providing plants with inorganic nutrients. The filamentous nature of fungi, their ability to translocate carbon and nutrients between different substrates and the capacity of ectomycorrhizal fungi to utilise organic nutrients have all been largely ignored. In this article, a new model is suggested which emphasises competition for organic nutrients between decomposer organisms and plants, with the plants depending on their associated mycorrhizal fungi for nutrient acquisition. Antagonistic interactions involving nutrient transfer between decomposer and mycorrhizal fungi are proposed as important pathways in nutrient cycling. Due to the nutrient conservative features of decomposer fungi, inorganic nutrients are considered less important for plant nutrition. The implications of the new nutrient cycling model on the carbon balance of boreal forests are discussed. 相似文献