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171.
Capped waste sites often are vegetated with commercial turf grasses to increase evapotranspiration and prevent erosion and
possible exposure of the barrier. Fertilizer, frequent watering, and mowing may be required to establish the turf grass and
prevent invasion by trees and shrubs. Oldfield vegetation of grasses and forbs is a possible sustainable alternative to turf
grass communities. To determine if oldfield vegetation can establish on caps, we (1) compared establishment of a dominant
oldfield grass and a commercial turf grass under different combinations of new closure cap management: spring or summer planting
and presence or absence of amendments to alleviate drought (watering, mulch) or increase soil fertility (fertilizer, lime,
a nitrogen-fixing legume); (2) surveyed existing caps to determine if oldfield species establish naturally; and (3) performed
a greenhouse experiment to compare growth of two native grasses under low and amended (added water, soil nutrients) conditions.
Both the commercial grass and oldfield species established under new cap conditions; fertilizer, water, and mulch improved
vegetation establishment in spring or summer, but legumes decreased grass cover. In the greenhouse, both native grasses grew
best with amendments; however, substantial stem and root length were obtained with no fertilizer and only once-weekly watering.
Existing vegetated caps supported planted grasses and naturally established oldfield species. Overall, the results indicate
native grasses can establish on new caps and oldfields can serve as a management model; further work is needed to determine
the management strategy to maintain herbaceous vegetation and slow woody species invasion. 相似文献
172.
The term "barren hills" has been a keyword for land degradation in the uplands of Vietnam for over a decade. Nevertheless, the "barren" land is still not adequately ecologically characterized. In this work, we analyze land use-induced changes in vegetation and soil properties along a sequence of barren hills types formed on one physiotope. The study is undertaken in the Bac Kan province, one of the poorest upland regions where livestock plays an important role. A transition from an old-growth laurel forest to a sparse manmade grassland is characterized by a total of 177 species, rapid species turnover, and discrete dominants, and an overwhelming effect of disturbance history on both soil and vegetation patterning. Land degradation is most apparent in land use-induced maintenance of arrested successions, and the regeneration course is shifted towards drier formations. We hypothesize a conceptual model as an aid to understanding the process of early fallow differentiation in response to the patterned, fine-scale disturbances. The larger-scale implications of the observed trends in regeneration potentials deviation, and, in particular, the effect of water buffaloes in halting fallow successions, are discussed. 相似文献
173.
1988-2017年洞庭湖共记录浮游植物8门110属,其中蓝藻门15属、绿藻门45属、硅藻门28属、裸藻门7属、甲藻门4属、隐藻门4属、金藻门5属、黄藻门2属。洞庭湖所出现的物种主要是绿藻门、硅藻门和蓝藻门,分别占全湖种类的40.9%、25.5%和13.6%,而其他5门只占20.0%。洞庭湖浮游植物优势种群从20世纪90年代初的以隐藻和硅藻为主转变为目前以硅藻和绿藻为主,在个别湖区(如大小西湖)已经出现以蓝藻为优势种群的现象,洞庭湖已经到了由中营养到轻度富营养化的转折点。洞庭湖浮游植物密度呈显著上升趋势,由20世纪90年代左右的2.06×104 cells/L上升到目前的32.3×104 cells/L。东洞庭湖浮游植物种类和密度显著高于西洞庭湖和南洞庭湖。近30年来分析表明浮游植物密度和种类都与总氮显著正相关,都与溶解氧显著负相关。 相似文献
174.
水生植物群落在湖泊生态修复过程中作用显著,但目前人工重建的水生植物群落抗外界干扰能力弱,群落稳定性差,这就需要我们对人工重建的水生植物群落结构及其演替的生态学过程进行研究,从而探索受损群落的修复途径。于2003年在富营养化水体中采用物理生态工程进行了水生植物群落的重建研究,对群落演替动态变化过程进行了持续3年的观测。结果表明:水生植物之间发生生态位重叠时,其结果往往是以一个物种取代另一个物种,随着生态位重叠程度下降,种间关系和群落结构趋于稳定;而当物种空间位置错开时,生长期相近的物种共存则变为可能,因此在群落的构建过程中应当避免同时引入生态位重叠较高的物种,应注意植物间时间序列及空间结构的分离;此外还通过物种间的竞争表现,对几种常见水生植物构建的群落稳定性做了初步探讨. 相似文献
175.
Mike F. Quartacci Barbara Irtelli Roberto Gabbrielli 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2697-2703
Due to relatively high chelant dosages and potential environmental risks it is necessary to explore different approaches in the remediation of metal-contaminated soils. The present study focussed on the removal of metals (As, Cd, Cu, Pb and Zn) from a multiple metal-contaminated soil by growing Brassica carinata plants in succession to spontaneous metallicolous populations of Pinus pinaster, Plantago lanceolata and Silene paradoxa. The results showed that the growth of the metallicolous populations increased the extractable metal levels in the soil, which resulted in a higher accumulation of metals in the above-ground parts of B. carinata. Root exudates of the three metallicolous species were analysed to elucidate their possible role in the enhanced metal availability. The presence of metals stimulated the exudation of organic and phenolic acids as well as flavonoids. It was suggested that root exudates played an important role in solubilising metals in soil and in favouring their uptake by roots. 相似文献
176.
177.
喀斯特小流域植被-土壤系统钙的协变关系研究 总被引:7,自引:0,他引:7
分析和探讨了贵州花江峡谷查尔岩小流域不同生态系统中土壤和植物中总钙与不同存在形态钙的含量及其相互之间的关系。研究区土壤中,不仅总钙含量(平均1.8%)高,而且交换态钙含量(平均占总钙含量的50.9%)也很高,与土壤总钙含量显著正相关。植物总钙含量(平均在1.2%-3.2%之间)高,且在不同层次间有较大的差别,灌木层钙含量(平均2.3%)大于草本层(平均1.2%)。不同物种间钙含量变化也较大,在研究区所有物种中构树钙含量最高(平均3.2%)。植物中三种形态钙(水溶性钙、乙酸溶性钙、盐酸溶性钙)含量以水溶性钙含量最高,但并不随植物总钙含量的增加而增加,且在不同植被中含量相差较大。植物、土壤总钙及土壤交换态钙含量,都随着次生林、草灌、灌草、稀疏灌草的演替有增加的趋势。土壤-植被间钙含量的相关性分析表明,高钙的土壤环境是导致植物钙生物吸收系数高的主要原因。 相似文献
178.
179.
采用高通量测序技术,探究了黄河三角洲光板地和4种盐生植被(翅碱蓬、獐茅、白茅和罗布麻)下土壤真菌群落结构组成及分布特征,揭示其与盐生植被演替的关系.结果表明,随盐生植被正向演替,土壤质量有不断改善的趋势.轻度耐盐群落(罗布麻群落、白茅群落)土壤中真菌丰富度相对较高,其Shannon多样性指数分别为5.21、5.84;在重度耐盐群落(翅碱蓬、獐茅)土壤中真菌丰富度较低,其Shannon多样性指数分别为4.64、4.66.在不同演替阶段时,土壤真菌群落结构差别相对较大(Unifrac Metric值为0.48~0.67).土壤中全氮含量是影响真菌OTU数、ACE指数和Shannon指数的主要因素.5个土壤样本共获得60174条有效序列,可归到子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、壶菌门(Chytridiomycota)、球囊菌门(Glomeromycota)、毛霉亚门(Mucoromycotina)5个真菌门;其中,子囊菌门在重度耐盐植物群落(翅碱蓬、獐茅)中相对丰度较高(2.69%、69.97%),担子菌门在轻度耐盐群落(罗布麻群落、白茅群落)中相对丰度较高(9.43%、6.64%). 相似文献
180.
景观水体富营养化模拟过程中藻类演替及多样性指数研究 总被引:2,自引:0,他引:2
采用微宇宙培养法,模拟微污染景观水体富营养化过程,研究其浮游藻类演替状况及生物多样性指数结果表明,最终优势藻种为黄藻门.通过计算9种生物多样性指数(Margalef's、PIE(种间相遇几率)、Menhinick's、Shannon-wiener、Simpson's、McNaughton's dominance index、Species、OD(多样性测度指数)、Monk)对景观水体富营养化过程中浮游植物演替趋势进行评价,发现其中仅2种多样性指数适于静态景观水体富营养化研究,分别为Monk多样性指数及Menhinick's多样性指数,而其它指数都不够准确. 相似文献