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1.
 采用方差比率、2×2列联表的Fisher精确检验、Pearson相关系数和Spearman秩相关系数,通过测定40种乡土植物共780个种对的种间关联性(或相关性),研究延庆山区公路沿线植物群落的种间关系。结果表明:延庆山区公路沿线40种乡土植物物种间总体关联性表现为显著正关联,说明这40种乡土植物种间表现为共存互利关系;Fisher精确检验反映种对间关联与否,Pearson相关系数和Spearman秩相关系数反映种对间的数量变化关系,且Spearman秩相关系数的灵敏度较Pearson相关系数高;Spearman秩相关系数显示有61个种对呈极显著和显著正相关关系,12个种对呈极显著和显著负相关关系;依据Spearman秩相关系数可将40种乡土植物分为3类生态组群,这些组群可充分反映乡土植物对环境相同和相异的适应性,揭示种间关系的内在联系。  相似文献   

2.
在群落调查的基础上,应用χ2检验、Ochiai关联度指数、Pearson相关分析和Spearman秩相关分析,研究了老秃顶子自然保护区水源涵养林群落内16种主要乔木树种的种间联结性和相关性。结果表明,所有种对中,多数种对间关联程度为不显著水平,呈极显著相关和显著相关的种对数相对较少,表明群落内多数乔木树种间关系较松散,未形成明显的总体关联性,群落处于相对稳定状态;种间关系分析中,χ2检验、Ochiai关联度和Pearson相关分析的结果比Spearman秩相关分析结果的灵敏度要低;根据分析结果,结合乔木种群的生物学和生态学特征,可将老秃顶子保护区水源林群落中16种主要乔木树种划分为3个生态种组,同一生态种组内物种的生态要求和资源利用方式相近,联结紧密,而不同种组间联结较为松散。  相似文献   

3.
种间关联分析是认识植物群落的重要基础。针对种间关联参数计算过程复杂、繁琐、易错等特点,以Spearman秩相关分析为例,提出利用Microsoft Excel 2003的基本功能进行数据处理,快速高效地计算出Spearman秩相关值参数,对其他常用的种间关联参数的计算具有推广性。  相似文献   

4.
以毛乌素退化湿地为研究对象,采集芦苇滩地、灌草地、沙地3个不同退化时期9个土壤剖面样本,研究土壤有机碳、全氮、全磷垂直分布,并进行有机碳-全磷、有机碳-全氮Pearson相关性分析和Spearman秩相关分析。结果表明:不同类型退化湿地土壤有机碳、全氮、全磷含量差异明显,随土层深度增加含量减少,并呈现分层特征。研究发现,在土壤剖面深度100cm左右且有黑色泥炭层存在情况下,有机碳、全氮、全磷含量增加。样地土壤有机碳与全氮呈显性线性相关(R=0.989),Spearman秩相关系数为0.944。样地土壤有机碳与全磷呈显性线性相关(R=0.938),Spearman秩相关系数为0.698。  相似文献   

5.
利用方差比率(VR)、χ2检验、Jaccard指数以及改良的Godron M.稳定性测度方法分析了江西省上饶市空心莲子草(Alternanthera philoxeroides)入侵后乡土植物群落中12个主要种的种间联结性以及乡土群落的稳定性.结果表明: 空心莲子草入侵前乡土植物群落总体呈显著正关联, 群落中的正联结种对多, 存在极显著正联结种对; 空心莲子草入侵后, 群落总体呈负关联, 种对正联结数量较入侵前明显减少, 出现显著负联结种对, 群落中由于物种的种间竞争增大, 导致一些物种在群落中不能稳定存在.根据种间联结性分析结果, 空心莲子草入侵后, 联结性较强的乡土植物群落明显分为两个生态种组, 但两组仍存在一定联系.空心莲子草的入侵导致本地群落稳定性下降, 某些物种数量减少, 甚至被替代.由此可见, 空心莲子草对常见乡土种有很大负面影响, 应加强入侵机理及防控研究.  相似文献   

6.
基于2×2联列表,以χ2检验为基础,结合共同出现百分率JI、联结系数AC以及点相关系数PCC,测定了福建省政和县东平镇凤头村受樵采干扰后闽楠林乔木层主要种群的种间联结性。结果表明:闽楠林乔木层联结程度达到显著的种对很少,群落内105个种对中,7对正联结达显著以上水平,98对(占93.3%)联结不显著,种的分布较独立。与未受干扰的闽楠林群落种间联结比较说明,干扰对闽楠林乔木层主要种群种间联结性有一定的影响。并讨论了抽样单元面积分别为100m2、200m2和400m2时种间关联测定的准确性,抽样单元面积为100m2时适宜对闽楠林主要种群进行种间关联测定。  相似文献   

7.
基于PSR模型的七里海湿地生态脆弱性评价研究   总被引：2，自引：0，他引：2  
利用"3S"技术,结合景观生态学、生态健康学及水文地质学理论,选用压力—状态—响应评价模型,选取人口密度、人类干扰指数、初级生产力、分维数、破碎度、斑块形状指数、湿地弹性度指数、湿地服务功能、湿地变化面积等9个评价指标,以200 m×200 m栅格点状单元为基本单元,分析评价七里海湿地的生态环境脆弱性状况。研究结果为:七里海湿地中度脆弱区面积最大,约为28.85 km2,占湿地总面积的30.37%;其次是一般脆弱区,面积约为21.68 km2,占22.82%;再次是重度脆弱区,面积约为20.17 km2,占21.23%;最后是轻度脆弱区和潜在脆弱区,面积分别为16.36 km2和7.94 km2,占17.22%和8.36%。  相似文献   

8.
蝗虫与植被间存在复杂的耦合关系,蝗虫群落特征变化是蝗虫对植被群落重要的生态响应过程。2009年6—8月在黑河上游白大坂草原,通过野外实地调查研究了黑河上游天然草地蝗虫的种类组成、分布频度、群落多样性与植被的相关性。在海拔2 400～2 800m的7个植物群落采集到蝗虫13种,隶属于3科10属,亚洲小车蝗(Oedaleus decoratus)、李氏大足蝗(Gomphocerus licenti)和白纹雏蝗(Chorthippus al-bonemus)是优势种,分别在驴驴蒿(Artemisia dalailamae)、狼毒(Stellera chamaejasme)占优势的群落分布最多;不同植物群落中蝗虫组成、优势种差异明显,蝗虫群落多样性和优势度差异显著(p<0.05),均匀度差异不显著(p>0.05);蝗虫多样性与植被盖度、多样性呈正相关,与高度和优势度呈负相关,蝗虫群落均匀度与植物群落多样性呈负相关,蝗虫多度与植物多样性呈正相关。蝗虫分布和发生数量受蝗虫生物学特性和植物群落组成差异的影响,蝗虫对植物群落选择的多样性反映了蝗虫对生境具有较强的适应能力以及种群内部的协同作用。  相似文献   

9.
杨霄  刘森  贾超  刘扬  于翠翠  朱恒华 《水土保持通报》2021,41(2):162-169,187
[目的] 分析城市湿地形成前后的生态效应,确定影响城市湿地形成发展的关键因素,为城市湿地保护和生态公园的建设提供科学依据。[方法] 以黄河下游流域济南市济西国家湿地公园为研究区,以1990—2019年的遥感影像和实地调查资料为数据源,基于GIS平台,通过空间分析土地利用动态度、转移矩阵和景观指数等研究城市湿地的生态效应,利用灰色关联法研究湿地自然变化的驱动因素。[结果] ①耕地与生态用地的相互转换是济西湿地主要的土地利用变化类型,建设用地与生态用地的相互转换是次要的土地利用变化类型。景观指数和动植物的变化则表明湿地生态多样性增加。②降水和地下水等水资源与湿地面积变化呈正相关,温度与湿地面积变化呈负相关。[结论] 水文气象因素对湿地的自然演化起着重要的作用,是常年性湿地形成的关键。城市规划等人为干扰影响着湿地公园土地利用类型的转化,也是主导城市湿地演变的主要因素。  相似文献   

10.
银川平原芦苇生态特征与土壤因子的关系   总被引：1，自引：1，他引：0  
《土壤通报》2015,(1):99-104
选择银川平原典型芦苇湿地作为靶区,结合统计学分析及冗余分析(RDA),研究了芦苇生态特征与土壤因子的相互关系,结果表明:土壤水分为芦苇生态特征变化的关键驱动因子,土壤水分与芦苇的生态特征呈显著或极显著的相关关系,p H、全盐与芦苇的生态特征呈正相关或负相关,其他土壤因子与芦苇生态特征相关性不大,土壤环境因子对芦苇生态特征的重要性排序为土壤水分p H全盐含量有效磷有机质含量全磷全氮碱解氮,综合分析,土壤水分对芦苇生态特征的影响较大。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引：2，自引：2，他引：0  
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。  相似文献   

12.
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.  相似文献   

13.
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,  相似文献   

14.
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.  相似文献   

15.
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.  相似文献   

16.
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.  相似文献   

17.
Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.  相似文献   

18.
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.  相似文献   

19.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

20.
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.  相似文献   

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