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211.
After a formerly grazed salt marsh was released from cattle grazing, changes in plant species composition were monitored for
20 yr, using vegetation maps and permanent plots. Three areas, differing in age and nutrient status were compared. The number
of plant species and plant communities decreased.Elymus athericus (Elytrigia pungens) became dominant in most plant communities after 5–20 yr on the oldest and most productive salt marsh. In younger areas it
took more time forE. athericus to become dominant. At least 7 cm of clay seemed to be a prerequisite for this plant species to increase in dominance. The
results from monitoring over decades are discussed in view of the knowledge on succession over centuries as derived from a
chronosequence. 相似文献
212.
BRADLEY W. COMPTON‡ KEVIN McGARIGAL ‡ SAMUEL A. CUSHMAN‡ † LLOYD R. GAMBLE‡ 《Conservation biology》2007,21(3):788-799
Abstract: Pool-breeding amphibian populations operate at multiple scales, from the individual pool to surrounding upland habitat to clusters of pools. When metapopulation dynamics play a role in long-term viability, conservation efforts limited to the protection of individual pools or even pools with associated upland habitat may be ineffective over the long term if connectivity among pools is not maintained. Connectivity becomes especially important and difficult to assess in regions where suburban sprawl is rapidly increasing land development, road density, and traffic rates. We developed a model of connectivity among vernal pools for the four ambystomatid salamanders that occur in Massachusetts and applied it to the nearly 30,000 potential ephemeral wetlands across the state. The model was based on a modification of the kernel estimator (a density estimator commonly used in home range studies) that takes landscape resistance into account. The model was parameterized with empirical migration distances for spotted salamanders ( Ambystoma maculatum ), dispersal distances for marbled salamanders ( A. opacum ), and expert-derived estimates of landscape resistance. The model ranked vernal pools in Massachusetts by local, neighborhood, and regional connectivity and by an integrated measure of connectivity, both statewide and within ecoregions. The most functionally connected pool complexes occurred in southeastern and northeastern Massachusetts, areas with rapidly increasing suburban development. In a sensitivity analysis estimates of pool connectivity were relatively insensitive to uncertainty in parameter estimates, especially at the local and neighborhood scales. Our connectivity model could be used to prioritize conservation efforts for vernal-pool amphibian populations at broader scales than traditional pool-based approaches. 相似文献
213.
南方红豆杉种子的化学成分分析 总被引:10,自引:0,他引:10
对南方红豆杉种子 (种仁 )的化学成分分析表明 :南方红豆杉干重 (DW)种子粗蛋白、粗脂肪、淀粉、可溶性糖的质量分数wDW分别为 9.92g (10 0g) -1,72 .86g (10 0g) -1,4 .15g (10 0g) -1,0 .38g (10 0g) -1;氨基酸的wDW为 9.10g (10 0g) -1,其中必需氨基酸占总氨基酸量的 2 8.0 5 % ;种子油脂肪酸组成以不饱和的油酸和亚油酸为主 ,其相对含量为 4 8.4 %和 4 2 .2 % ;种子元素质量分数分别为 :wDW(N) =15 87.2mg (10 0g) -1,wDW(P) =5 6 5 .4mg (10 0g) -1,wDW(K) =2 6 1.1mg(10 0g) -1,wDW(Ca) =18.4mg (10 0g) -1,wDW(Mg) =35 0 .5mg (10 0g) -1,其余微量元素含量由多到少依次为Zn >Fe>Na>Cu >Mn .表 4参 6 相似文献
214.
SeedtreatmentandinhibitionofplantpathologyofchitosanJiangTingda;MaRuixia;QiRuinung;ZhangChunping(ResearehCenterforEco-Environ... 相似文献
215.
216.
Raden Ajeng Koesoemo Roekmi Kanagaratnam Baskaran Lloyd HC Chua 《Natural resources forum》2018,42(2):108-122
Community‐based water supply (CBWS) is an example of how a community manages common pool resources (CPR). This results in an alternative approach to solve water supply problems in developing countries by enhancing community participation in managing water supply. This research evaluates the sustainability of five CBWS projects in Cikarang, Indonesia by using Ostrom's design principles, with additional sustainability factors found in the Sustainable Development Goal (SDG) on drinking water and groundwater sustainability. Quinn et al. (2007) criteria were used in the analysis, and the results show that the management of four CBWS institutions were absent and one CBWS institution was weak. With regards to the SDG's drinking water target, the CBWS institutions were unable to comply with safe water standards, and in terms of groundwater sustainability, efforts to monitor and sustain groundwater tables were absent. Results from this research suggest that more focus must be placed on water quality and groundwater sustainability for CBWS projects. 相似文献
217.
Habitat loss and fragmentation alter the composition of bird assemblages in rainforest. Because birds are major seed dispersers in rainforests, fragmentation‐induced changes to frugivorous bird assemblages are also likely to alter the ecological processes of seed dispersal and forest regeneration, but the specific nature of these changes is poorly understood. We assessed the influence of fragment size and landscape forest cover on the abundance, species composition, and functional properties of the avian seed disperser community in an extensively cleared, former rainforest landscape of subtropical Australia. Bird surveys of fixed time and area in 25 rainforest fragments (1–139 ha in size across a 1800 km2 region) provided bird assemblage data which were coupled with prior knowledge of bird species’ particular roles in seed dispersal to give measurements of seven different attributes of the seed disperser assemblage. We used multimodel regression to assess how patch size and surrounding forest cover (within 200 m, 1000 m, and 5000 m radii) influenced variation in the abundance of individual bird species and of functional groups based on bird species’ responses to fragmentation and their roles in seed dispersal. Surrounding forest cover, specifically rainforest cover, generally had a greater effect on frugivorous bird assemblages than fragment size. Amount of rainforest cover within 200 m of fragments was the main factor positively associated with abundances of frugivorous birds that are both fragmentation sensitive and important seed dispersers. Our results suggest a high proportion of local rainforest cover is required for the persistence of seed‐dispersing birds and the maintenance of seed dispersal processes. Thus, even small rainforest fragments can function as important parts of habitat networks for seed‐dispersing birds, whether or not they are physically connected by vegetation. Respuestas de Aves Dispersoras de Semillas al Incremento de Selvas en el Paisaje Alrededor de Fragmentos 相似文献
218.
Ali Azizi Amineh Ghorbani Bahram Malekmohammadi Hamid Reza Jafari 《Journal of Environmental Planning and Management》2017,60(10):1785-1808
Although mismanagement of groundwater resources has resulted in their destruction over centuries, climate change is speeding up this process more than ever. On the one hand, urgent action by government bodies is needed to address the challenge. On the other hand, a vast body of literature proves that bottom-up collective action, although requiring a longer time period, is a better solution to manage such resources. This research aims to address this dilemma. The groundwater resource in Ardabil plain in Iran, which has long been managed solely through government intervention, has been chosen as a case study to explore the opportunities and limitations of managing a critically endangered area from a common pool resource perspective. Our study suggests that managing Ardabil groundwater resources should be conducted on two scales. The bottom-up institutional agreements should take place at village scale while the government should stay in charge of the overall organization at plain scale. 相似文献
219.
Kristan Cockerill Peter A. Groothuis Tanga McDaniel Mohr Courtney Cooper 《Journal of Environmental Planning and Management》2016,59(8):1341-1359
Public perceptions about water quantity and water as a common pool resource are understudied in humid regions. As water demand increases, the need to more closely manage water, even in humid areas, will increase, requiring better understanding how people perceive their water supply, how they view paying for water conservation and how water user characteristics influence attitudes. A survey finds correlations between utilizing an individual water source (e.g. well or spring) and attitudes toward water management and conservation. Compared to respondents with a shared water source, those with an individual source believe they are segregated from regional water concerns. They are less willing to pay for water management or conservation measures and less supportive of any government intervention in water management. These results suggest that planners and water managers may face resistance to conservation policies or any policy based on the idea of water as a common pool resource. 相似文献
220.
通过对海南椰子生产现状的分析,本文指出了建立优质良种椰子种苗生产示范基地的必要性和重要性,并针对一些需要解决的问题,提出了加快海南椰子产业发展的建议。 相似文献