共查询到20条相似文献,搜索用时 109 毫秒
1.
河西走廊农户生态系统农田能流和物流数量特征的研究 总被引:6,自引:0,他引:6
河西走廊农户生态系统农田能流和物流数量特征的研究李发弟(甘肃农业大学畜牧系,兰州730070)QuantintiveCharacteristicsofEnergyFlowandNutrientCyclingofFarmlandinaFarmEcosysteminHexiCorridor¥LiFadi(DepartmentofAnimalHusbandry,GansuAgriculturalUnitversity).ChineseJour-nalofEcology,1993,12(6):37-40.Quantitativecharacteristicsofenergyflowandnutrientcyclingoffarmlandsubsysteminafarmecosys-teminHexiCorridorwerestudied.Theresultsshowedthatthedeflreeofopening,inputandoutputwerehigh,theratioofoutputtoinputofsubsidyenergy,nitrogenandphosphorusofthefarmlandsubsy 相似文献
2.
蝮蛇类凝血酶基因的分析及表达研究 总被引:17,自引:1,他引:17
从蝮蛇(AgkistrodonhalysPalas)毒腺中抽提总RNA,经RTPCR扩增该基因,克隆后经全序列测定,蝮蛇类凝血酶palase的cDNA长708个核苷酸,即编码236个氨基酸;根据同源性,推测该类凝血酶palase的活性中心为His41、Asp86和Ser182;二硫键为Cys7Cys139、Cys26Cys42、Cys74Cys234、Cys118Cys188、Cys150Cys167和Cys178Cys203;该蝮蛇毒类凝血酶cDNA序列及推导的氨基酸序列均为首次报道。构建T7启动子控制下的palase的大肠杆菌表达质粒,IPTG诱导palase获得表达。 相似文献
3.
丘陵地区农户生态系统演替分析 总被引:1,自引:1,他引:1
丘陵地区农户生态系统演替分析曹凑贵(华中农业大学,武汉430070)EvolutionaryAnalysisonHousekoldEcosysteminHIIIyRegions¥CaoCougui(CentralChinaAgriculdturalUniversity,Wuhan430070).ChineseJournalofEcology,1993,12(2):53-54.Thecharacteristicsofdifferenttypehouseholdecosystemsandtheirevolutionarycorrelationsareanalyzedusingfuzzyclusteringandsystemsyntheticevolutionmethods,Thecauseanddirectionofagriculturaldevelopmentinhillyregionsarerevealedandsuggestionsondevelopingeco-agriculturalconstructioninlowerproductivehillyregionsaremade.Keywords:ho 相似文献
4.
辽西走廊农业生态系统区位优势分析梁文举(中国科学院沈阳应用生态研究所,110015)LocationalSuperiorityAnalysisofAgroecosystemsinWestLiaoningCorridor¥LiangWenju(InstituteofAppliedEcology,AcademiaSinica,Shenyang110015).ChineseJournalofEcology,1993,12(2):59-60.Basedontherelativeaggregationdegreesamonghierarchiesofdifferentagroecosystems,theauthorpro-posedthatlocationalquotientmodelcouldbeusedtomeasurethelocationalsuperiorityofagroecosystem.Themainpurposeofthispaperistoprovideascientificbasisforchoosingagriculturalmarketablebasesandestablishingahig 相似文献
5.
浸润垄作稻田土壤生态系统的研究 总被引:7,自引:0,他引:7
浸润垄作稻田土壤生态系统的研究魏朝富,高明,车福才,邓春(西南农业大学土化系重庆630716)AStudyonInfiltrated-RidgedPaddySoilEcosystem¥.WeiChaofu;GaoMing,CheFuchai;DengChun(SouthwestAgriculluralUniversity,).ChineseJournalofEcology,1993,12(3):26-30;Thispaperdealswichaninfiltrated-ridgedpaddysoilecosystemwhichisconstructedbyridgingandcon-tinuousfurrowinfiItratiOnirrigation,ComparingwithlevelinfiItratedpaddysoilecosystem,thisecosys-temhascoexistedgas-liquid,gas-solidandliquid-solidinterfaces,enlargessoilsurfaceby38%andincreasescuItivatedlayerby5-10cm. 相似文献
6.
温度,pH对菌根真菌生长影响的研究 总被引:10,自引:0,他引:10
温度、pH对菌根真菌生长影响的研究韩桂云,齐玉臣,刘忱,周玉芝(中国科学院沈阳应用生态研究所,110015)EffectsofTemperatureandpHonMycorrbizalFungusGrowth¥HanGuiyun;QiYuChen;LiuChen;ZhouYuzhi(InstituteofAppliedEcology,AcademiaSinica,Shenyang110015).ChineseJournalofEcology,1993,12(1):15-19。TheeffectsoftemperatureandpHonthegrowthof19purestrainsofmycorrhizalfungiareinvestigated.TheoptimumtemperatureandpHarefoundandrelationshipsbetweenadaptablerangesoftemperatureandpHformycorrhizalfungusgrowthandtheirecologicaldistributionareindicated.Keywords:temperature,pH, 相似文献
7.
8.
村落生态系统的概念及特征 总被引:15,自引:3,他引:12
村落生态系统的概念及特征王智平,安萍(中国科学院石家庄农业现代化所,050021)ConceptationandCharacteristicsofVillageEcosystem.¥WangZhiping;AnPing(InstituteofA-gr... 相似文献
9.
中国南方低丘红壤区人工复合生态系统模式建造研究 总被引:2,自引:0,他引:2
中国南方低丘红壤区人工复合生态系统模式建造研究徐盛荣,吴珊眉,李辉信(南京农业大学土壤农业化学系,210014)ModelingofArtificialComplexEcosysteminLow-hillyRedSoilRegionofSouthCbina¥.XuShengrong;WuShanmei;LiHuixin(DepartmentofSoilScienceandAgriculturalChemistry,NanjingAgriculturalUniversity).ChineseJournalofEcology,1993,12(2):39—40.Thispaperresearchesintothemodelingofartificialcomplexecosystemincorporatingcrop,fruit,forestandanimalhusbandrywithinacatchmentarea,whichisabasicunitoflowhillyregioninsouthChina.Themodelproducessignificantandcomprehensiveprofits.Fi 相似文献
10.
《天然产物研究与开发》2002,14(2)
20 0 1 :January 17~ 2 0 ,2 0 0 1:IndependentPharmacyChainConference ,ScottsdalePrincessResort,Scottsdale ,Arizona .Contact:NCPAExhibitsmanager( 70 3) 6 83~ 36 19(fax) .February 2 0~ 2 3,2 0 0 1:EXPO 2 0 0 1,NationalCommunityPharmacistsAssociation ,ChainDrugMarketingAssociation ,NationalHomeI… 相似文献
11.
12.
农林生态系统中营养元素N,P,K流动的网络分析 总被引:4,自引:1,他引:4
对农林业系统沙兰杨-小麦-玉米群落类型中N、P、K流动网络分析表明,系统中N、P、K的循环指数分别为0.071、0.039、0.139,均小于传统的循环系数(CC等于回归量/吸收量),而在群落中的总滞留时间分别为22.41、79.72、26.57a. 相似文献
13.
对农林业系统沙兰杨-小麦-玉米群落类型中N、P、K流动网络分析表明,系统中N、P、K的循环指数分别为0.071、0.039、0.139,均小于传统的循环系数(CC等于回归量/吸收量),而在群落中的总滞留时间分别为22.41、79.72、26.57a. 相似文献
14.
Stoichiometry of nutrient recycling by vertebrates in a tropical stream: linking species identity and ecosystem processes 总被引:5,自引:0,他引:5
Michael J. Vanni Alexander S. Flecker James M. Hood & Jenifer L. Headworth 《Ecology letters》2002,5(2):285-293
Ecological stoichiometry offers a framework for predicting how animal species vary in recycling nutrients, thus providing a mechanism for how animal species identity mediates ecosystem processes. Here we show that variation in the rates and ratios at which 28 vertebrate species (fish, amphibians) recycled nitrogen (N) and phosphorus (P) in a tropical stream supports stoichiometry theory. Mass-specific P excretion rate varied 10-fold among taxa and was negatively related to animal body P content. In addition, the N : P ratio excreted was negatively related to body N : P. Body mass (negatively related to excretion rates) explained additional variance in these excretion parameters. Body P content and P excretion varied much more among taxonomic families than among species within families, suggesting that familial composition may strongly influence ecosystem-wide nutrient cycling. Interspecific variation in nutrient recycling, mediated by phylogenetic constraints on stoichiometry and allometry, illustrates a strong linkage between species identity and ecosystem function. 相似文献
15.
Increased resource use efficiency amplifies positive response of aquatic primary production to experimental warming 下载免费PDF全文
James M. Hood Jonathan P. Benstead Wyatt F. Cross Alexander D. Huryn Philip W. Johnson Gísli M. Gíslason James R. Junker Daniel Nelson Jón S. Ólafsson Chau Tran 《Global Change Biology》2018,24(3):1069-1084
Climate warming is affecting the structure and function of river ecosystems, including their role in transforming and transporting carbon (C), nitrogen (N), and phosphorus (P). Predicting how river ecosystems respond to warming has been hindered by a dearth of information about how otherwise well‐studied physiological responses to temperature scale from organismal to ecosystem levels. We conducted an ecosystem‐level temperature manipulation to quantify how coupling of stream ecosystem metabolism and nutrient uptake responded to a realistic warming scenario. A ~3.3°C increase in mean water temperature altered coupling of C, N, and P fluxes in ways inconsistent with single‐species laboratory experiments. Net primary production tripled during the year of experimental warming, while whole‐stream N and P uptake rates did not change, resulting in 289% and 281% increases in autotrophic dissolved inorganic N and P use efficiency (UE), respectively. Increased ecosystem production was a product of unexpectedly large increases in mass‐specific net primary production and autotroph biomass, supported by (i) combined increases in resource availability (via N mineralization and N2 fixation) and (ii) elevated resource use efficiency, the latter associated with changes in community structure. These large changes in C and nutrient cycling could not have been predicted from the physiological effects of temperature alone. Our experiment provides clear ecosystem‐level evidence that warming can shift the balance between C and nutrient cycling in rivers, demonstrating that warming will alter the important role of in‐stream processes in C, N, and P transformations. Moreover, our results reveal a key role for nutrient supply and use efficiency in mediating responses of primary producers to climate warming. 相似文献
16.
17.
Xiao‐Tao Lü Sasha Reed Qiang Yu Nian‐Peng He Zheng‐Wen Wang Xing‐Guo Han 《Global Change Biology》2013,19(9):2775-2784
Human activities have significantly altered nitrogen (N) availability in most terrestrial ecosystems, with consequences for community composition and ecosystem functioning. Although studies of how changes in N availability affect biodiversity and community composition are relatively common, much less remains known about the effects of N inputs on the coupled biogeochemical cycling of N and phosphorus (P), and still fewer data exist regarding how increased N inputs affect the internal cycling of these two elements in plants. Nutrient resorption is an important driver of plant nutrient economies and of the quality of litter plants produce. Accordingly, resorption patterns have marked ecological implications for plant population and community fitness, as well as for ecosystem nutrient cycling. In a semiarid grassland in northern China, we studied the effects of a wide range of N inputs on foliar nutrient resorption of two dominant grasses, Leymus chinensis and Stipa grandis. After 4 years of treatments, N and P availability in soil and N and P concentrations in green and senesced grass leaves increased with increasing rates of N addition. Foliar N and P resorption significantly decreased along the N addition gradient, implying a resorption‐mediated, positive plant–soil feedback induced by N inputs. Furthermore, N : P resorption ratios were negatively correlated with the rates of N addition, indicating the sensitivity of plant N and P stoichiometry to N inputs. Taken together, the results demonstrate that N additions accelerate ecosystem uptake and turnover of both N and P in the temperate steppe and that N and P cycles are coupled in dynamic ways. The convergence of N and P resorption in response to N inputs emphasizes the importance of nutrient resorption as a pathway by which plants and ecosystems adjust in the face of increasing N availability. 相似文献
18.
基于参与式方法的农牧户生计现状评估——以内蒙古太仆寺旗为例 总被引:1,自引:0,他引:1
运用参与式方法调查了内蒙古农牧交错区太仆寺旗不同类型农牧户的生计现状,分析了不同类型农牧户的生计策略、制约因素和提高途径.结果表明:纯农型家庭规模小,年龄结构偏大,整体文化水平低,生计策略单一,脆弱性和风险较大,引入非农生产活动是降低生计风险和提高生活水平的重要途径;纯牧型家庭以放牧为主要谋生方式,草场脆弱性对其生产活动影响很大,发展环境友好型高产农牧业是解决生计问题和环境问题的有效途径;农业兼业型和牧业兼业型家庭规模大,年龄结构轻,劳动力分工多样化,从事非农活动的比例较大,生活水平较好,尤以牧业兼业型家庭收入更高. 相似文献
19.
Aboveground-belowground linkages are recognized as divers of community dynamics and ecosystem processes, but the impacts of plant-neighbor interactions on these linkages are virtually unknown. Plant-neighbor interactions are a type of interspecific indirect genetic effect (IIGE) if the focal plant’s phenotype is altered by the expression of genes in a neighboring heterospecific plant, and IIGEs could persist after plant senescence to affect ecosystem processes. This perspective can provide insight into how plant-neighbor interactions affect evolution, as IIGEs are capable of altering species interactions and community composition over time. Utilizing genotypes of Solidago altissima and Solidago gigantea, we experimentally tested whether IIGEs that had affected living focal plants would affect litter decomposition rate, as well as nitrogen (N) and phosphorous (P) dynamics after the focal plant senesced. We found that species interactions affected N release and genotype interactions affected P immobilization. From a previous study we knew that neighbor genotype influenced patterns of biomass allocation for focal plants. Here we extend those previous results to show that these changes in biomass allocation altered litter quality, that then altered rates of decomposition and nutrient cycling. Our results provide insights into above- and belowground linkages by showing that, through their effects on plant litter quality (e.g., litter lignin:N), IIGEs can have afterlife effects, tying plant-neighbor interactions to ecosystem processes. This holistic approach advances our understanding of decomposition and nutrient cycling by showing that evolutionary processes (i.e., IIGEs) can influence ecosystem functioning after plant senescence. Because plant traits are determined by the combined effects of genetic and environmental influences, and because these traits are known to affect decomposition and nutrient cycling, we suggest that ecosystem processes can be described as gene-less products of genetic interactions among the species comprising ecological communities. 相似文献
20.
Fire and nitrogen (N) addition, both widely used grassland restoration strategies, strongly influence community composition and ecosystem functioning. However, little is known about their effects on plant nutrient resorption from senescing leaves, especially in semi-arid ecosystems. We evaluated the effects of fire, N addition (5.25 g N m−2 yr−1) and their potential interactions on nutrient resorption in five plant species in a semi-arid grassland in northern China. Foliar nutrient concentrations and resorption proficiencies and efficiencies varied substantially among species and functional groups. Fire increased green leaf N concentration ([N]g) and decreased N resorption proficiency (N RP), P resorption proficiency (P RP) and P resorption efficiency (P RE). N addition led to higher [N]g and lower N resorption, whereas it did not affect P related responses. There was no interaction between fire and N addition to affect all response variables except for green leaf P concentration ([P]g). These results suggest that fire and N addition can influence ecosystem nutrient cycling directly by changing resorption patterns and litter quality. Given the substantial interspecific variations in nutrient content and resorption and the potentially changing community composition, both fire and N addition may have indirect impacts on ecosystem nutrient cycling in this semi-arid grassland. 相似文献