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591.
区域土地利用变化对土壤磷含量的影响评价研究 总被引:5,自引:0,他引:5
研究土壤磷含量的时空演变规律对改善土地管理水平和提高土壤质量具有重要的指导作用。文章选取江苏省原锡山市作为研究区域,以1982年和2005年土壤全磷和速效磷含量作为研究对象,研究探讨土地利用变化对土壤磷含量的影响,进而表明人类活动对生态系统和环境的影响。通过统计分析表明,20年来原锡山市土壤全磷含量降低0.48g·kg-1,土壤速效磷含量升高26.16mg·kg-1。通过变异函数分析,20年来原锡山市全磷和速效磷的变异函数理论模型都是指数型,但块金方差与基台值的比值、自相关阀值发生了较大变化;Kriging插值分析结果表明,1982年全磷和速效磷的分布比较简单;2005年全磷分布较为简单,土壤速效磷分布较为复杂。Kriging插值分析还表明,20年来原锡山市土壤全磷含量降低,空间变异显著;土壤速效磷含量升高,空间变异显著。 相似文献
592.
人地协同论:可持续发展模型构建的基础 总被引:6,自引:0,他引:6
人地协同论是在陆地系统科学、非线性系统理论基础上建立起来的关于可持续发展的一个数理模型,它以社会与自然的交互作用、交界面性质及其演化规律为研究对象。本文根据系统生态学理论,提出了关于可持续生存的数学定义。 相似文献
593.
丁兆安 《防灾减灾工程学报》1998,(3)
为探索海平面变化与地震相关的前兆信息,利用了连云港验潮站长达43年的验潮资料。结合华北地区4次7级以上强震和江苏及其以东黄海海域18次中强以上地震的震例分析后认为:经基本消除主要干扰因素的连云港平均海平面变化,表征了与地震有关的地壳形变信息。它对监测华北地区强震和江苏及邻近地区的中强震,具有一定的参考价值。 相似文献
594.
David Gerard 《Resources Policy》1998,24(4):251-264
This paper applies a property rights framework to federal mineral lands in the western United States from the enactment of the Mining Law in 1872 until the enactment of the Mineral Leasing Act for fossil fuels in 1920. There are two principal findings. First, the Mining Law appears to have been an effective means for assigning rights to mineral stocks on public lands (at least through 1920). This conclusion is supported by evidence from claim disputes in the West. Second, the impetus for the Mineral Leasing Act did not derive from the different physical characteristics of hardrock minerals and petroleum. The relevance of these conclusions to contemporary mineral policy is also discussed. 相似文献
595.
Franois Oehler Paul Bordenave Patrick Durand 《Agriculture, ecosystems & environment》2007,120(2-4):313-324
We measured denitrification at 15 sites during 1 year in a agricultural catchment in Brittany, France. Our objective was to assess the relative importance of heterotrophic denitrification on the fate of excess nitrogen at the catchment scale, and to quantify the relative importance of riparian areas on the N2O emissions. Using the C2H2 inhibition technique, denitrification rate on soil core and denitrifying enzyme activity (DEA) were each determined, for samples taken from two soil layers: 0–20 and 20–40 cm. Denitrification rates, ranging from 0 to 417 mg N m−2 d−1, were significantly higher in riparian areas than for hillslopes (median of 24.87 against 10.38 mg N m−2 d−1). However, since denitrification rates are significant in the hillslope and given that hillslope surface area is much greater (79% of catchment surface), this domain could be responsible for half of the overall denitrified nitrogen (N). Also, the 20–40 cm deep soil layer was found to account for more than 46% of the denitrification. The DEA indicates the potential for denitrifying activity by the soil under non-limiting conditions, measured values ranged from 76.48 to 530.63 ng N g−1 dry soil h−1. The ratio N2O/(N2O + N2) was about 60% with no clear spatial or temporal trends. Soil moisture appeared to be the main limiting factor for denitrification at the field scale. The results suggest that, for this catchment, denitrification is a major route for nitrogen removal, but a significant proportion of this removal occurs as N2O. 相似文献
596.
气候变化对莱州湾地区水资源脆弱性的影响 总被引:9,自引:0,他引:9
论文首先分析了在现状年(1993年)供水能力和需水条件下,1960~1993年的气候波动对莱州湾地区水资源供需平衡和脆弱性的影响。然后根据未来气候情景分析了在2000规划年和2020规划年供水能力和需水要求下,未来气候变化(2000~2042年)对水资源供需平衡及脆弱性的影响。在农业需水保证率50%时,2000~2019年水资源供需基本平衡,但2020~2042年水资源短缺20~57亿m3。若考虑未来气温的上升,则水资源短缺进一步加大。因此,2020年以后需在调入56亿m3客水资源基础上,从区外调入更多稳定的水量以保证该地区社会经济的可持续发展。 相似文献
597.
江苏省耕地面积变化与经济增长的协整性与因果关系分析 总被引:18,自引:1,他引:18
江苏省近年来随着社会经济的发展,耕地面积急剧减少,土地利用变化和经济增长二者关系更为明显和完整,具有极好的典型性和代表性。论文利用近20年来耕地面积、经济增长与城市化水平之间的长序列统计资料,对江苏省1981~2004年间的耕地面积与经济增长及城市化水平的协整性和因果关系进行了研究。研究表明:耕地面积、GDP与城市化水平均是不平稳的时间序列,直接对其进行回归分析是不严谨的;江苏省耕地面积变化与经济增长之间不具有长期的协整性;江苏省耕地面积与GDP、城市化水平之间只存在单向的因果关系。通过研究,认为目前的土地利用方式极不合理。因此,降低耕地减少速度,提高土地利用效率是非常紧迫的战略问题。 相似文献
598.
Michael Dutschke 《Mitigation and Adaptation Strategies for Global Change》2007,12(2):275-302
In its Article 2, the U.N. Framework Convention on Climate Change policymakers gave themselves a long-term dynamic mandate
under uncertainty. Taking the example of forestry activities in developing countries, the present article discusses whether
land-based climate change mitigation measures in the context of compensation mechanisms for human-induced greenhouse gas emissions
are covered under the UNFCCC's ultimate objective. Both the problem of climate change and human intervention act over long,
yet finite timeframes. The article argues for taking a dynamic 100-year timeframe as reference for present-day activities.
It concludes that increasing biotic carbon storage is legitimate for measures that contribute to biodiversity conservation,
as long as it does not serve as a pretext for neglecting technological change. Among all forestry options, the list of priorities
should be avoiding deforestation and devegetation, sustainable forest management, and afforestation. The problem of saturation
can be encountered by the combination of forestry with the increased use of wood products and bioenergy. Concluding, the article
gathers criteria for forest climate activities in the post-2012 regime.
JEL Classification: Q23, Q54; Q57; Q58 相似文献
599.
Baselines for land-use change in the tropics: application to avoided deforestation projects 总被引:2,自引:0,他引:2
Sandra Brown Myrna Hall Ken Andrasko Fernando Ruiz Walter Marzoli Gabriela Guerrero Omar Masera Aaron Dushku Ben DeJong Joseph Cornell 《Mitigation and Adaptation Strategies for Global Change》2007,12(6):1001-1026
Although forest conservation activities, particularly in the tropics, offer significant potential for mitigating carbon (C)
emissions, these types of activities have faced obstacles in the policy arena caused by the difficulty in determining key
elements of the project cycle, particularly the baseline. A baseline for forest conservation has two main components: the
projected land-use change and the corresponding carbon stocks in applicable pools in vegetation and soil, with land-use change
being the most difficult to address analytically. In this paper we focus on developing and comparing three models, ranging
from relatively simple extrapolations of past trends in land use based on simple drivers such as population growth to more
complex extrapolations of past trends using spatially explicit models of land-use change driven by biophysical and socioeconomic
factors. The three models used for making baseline projections of tropical deforestation at the regional scale are: the Forest
Area Change (FAC) model, the Land Use and Carbon Sequestration (LUCS) model, and the Geographical Modeling (GEOMOD) model.
The models were used to project deforestation in six tropical regions that featured different ecological and socioeconomic
conditions, population dynamics, and uses of the land: (1) northern Belize; (2) Santa Cruz State, Bolivia; (3) Paraná State,
Brazil; (4) Campeche, Mexico; (5) Chiapas, Mexico; and (6) Michoacán, Mexico.
A comparison of all model outputs across all six regions shows that each model produced quite different deforestation baselines.
In general, the simplest FAC model, applied at the national administrative-unit scale, projected the highest amount of forest
loss (four out of six regions) and the LUCS model the least amount of loss (four out of five regions). Based on simulations
of GEOMOD, we found that readily observable physical and biological factors as well as distance to areas of past disturbance
were each about twice as important as either sociological/demographic or economic/infrastructure factors (less observable)
in explaining empirical land-use patterns.
We propose from the lessons learned, a methodology comprised of three main steps and six tasks can be used to begin developing
credible baselines. We also propose that the baselines be projected over a 10-year period because, although projections beyond
10 years are feasible, they are likely to be unrealistic for policy purposes. In the first step, an historic land-use change
and deforestation estimate is made by determining the analytic domain (size of the region relative to the size of proposed
project), obtaining historic data, analyzing candidate baseline drivers, and identifying three to four major drivers. In the
second step, a baseline of where deforestation is likely to occur–a potential land-use change (PLUC) map—is produced using
a spatial model such as GEOMOD that uses the key drivers from step one. Then rates of deforestation are projected over a 10-year
baseline period based on one of the three models. Using the PLUC maps, projected rates of deforestation, and carbon stock
estimates, baseline projections are developed that can be used for project GHG accounting and crediting purposes: The final
step proposes that, at agreed interval (e.g., about 10 years), the baseline assumptions about baseline drivers be re-assessed.
This step reviews the viability of the 10-year baseline in light of changes in one or more key baseline drivers (e.g., new
roads, new communities, new protected area, etc.). The potential land-use change map and estimates of rates of deforestation
could be re-done at the agreed interval, allowing the deforestation rates and changes in spatial drivers to be incorporated
into a defense of the existing baseline, or the derivation of a new baseline projection. 相似文献
600.