基于生态足迹的甘孜州生态安全动态研究

利用生态足迹评价模型计算甘孜州1995~2007年生态足迹,并分析甘孜州的生态安全状况。甘孜州人均生态足迹从1995年的1.480467hm2增加到2007年的1.766288 hm2,以耕地与草地为主;人均生态承载力从1995年的5.646667 hm2减少到2007年的5.328501 hm2,减幅较小,生态承载力结构具有不对称性,以林地与草地为主;人均生态盈余从1995年的4.1662hm2减少到2007年的3.562213hm2,林地人均生态盈余基本稳定在5.0 hm2左右,是甘孜州人均生态盈余的主要贡献者;生态压力指数在0.280852~0.350215波动,生态占用指数在0.528738~0.718585波动,生态协调性指数在1.875003~2.327831波动。结果表明甘孜州生态环境处于安全状态,社会经济发展与生态环境的协调性较差。     

河南省2000—2007年人均生态足迹动态变化及其驱动力分析

利用生态足迹理论,分别计算河南省2000—2007年的人均生态足迹和人均生态承载力,以定量研究河南省的可持续发展状态。在此基础上选取人均GDP、城市化率、恩格尔系数、第三产业比重、居民消费水平、人均固定资产、投资农业现代化程度、人均耕地面积等8项经济驱动因子,利用主成分分析法进一步定量分析社会经济发展对人均生态足迹动态变化的驱动作用。结果表明,河南省人均生态足迹从2000年的1.745796hm2增加到2007年的3.019299hm2,而生态承载力由2000年的0.373397hm2下降到2007年的0.361618hm2,导致生态赤字逐年增大,且人均生态足迹高于全国以及相邻省份;社会经济强烈驱动着人均生态足迹的变化,其中人均GDP、城市化率、居民消费水平、农业现代化程度等与人均生态足迹有较强的相关性,是影响区域人均生态足迹动态变化的主要因素。     

基于生态足迹的石家庄市生态承载力评价

以石家庄市为例,运用生态足迹模型,对1996—2006年间的生态足迹、生态承载力、生态赤字等进行了测算与纵向对比分析,并与国内外其他地区进行横向对比分析。结果表明,石家庄市人均生态承载力由1996年的0.3616hm2/人下降到2006年的0.3227hm2/人,而同期的人均生态足迹从2.4893hm2/人增加到4.690hm2/人,生态足迹和生态赤字水平远超过国内大部分地区的平均水平,呈逐年递增的趋势,反映出石家庄市的土地生态系统安全性不高。     

重庆市生态足迹动态特征及趋势研究

生态足迹是一种简单有效衡量区域可持续发展能力的量化指标。基于生态足迹理论和方法,分析了重庆市2003—2012年的人均生态足迹、人均生态承载力、万元GDP生态足迹,探讨了三者的动态特征及其变化趋势。结果表明:12003—2012年重庆市的人均生态足迹由1.3444hm2增加到2.0712hm2,人均生态承载力由1.0138hm2增加到1.2439hm2,生态赤字持续扩大;2万元GDP生态足迹由1.6400hm2下降到0.6000hm2,资源利用效率显著提高;3重庆市的生态足迹结构不合理,资源供需矛盾比较突出。在此基础上,对重庆市2014—2020年人均生态足迹和人均生态承载力进行了趋势预测分析。结果显示,在不改变当前诸因素的前提下,重庆市的生态足迹还将持续增加,而人均生态承载力将会小幅提升,但仍会导致人均生态赤字持续扩大的趋势。最后从创新技术、改变生产和生活模式、淘汰落后产能、平衡区域发展和强化生态意识等方面提出了减少生态赤字的措施,对重庆市山地资源的可持续利用、三峡库区生态保护等政策的正确制定提供了理论指导和实证支持,同时也具有强化社会树立生态赤字危机意识的现实意义。     

基于改进生态足迹模型的成都市可持续发展状况分析

在介绍生态足迹的概念和计算方法及目前的研究成果的基础上,分析生态足迹模型存在的缺陷和不足,提出了生态足迹改进模型,对成都市2003年至2007年的生态足迹进行了计算,并对成都市的可持续发展状况进行分析.结果表明:成都市人均生态足迹从2003年的1.1221hm2增长到2007年的1.1914hm2,人均生态承载力从2003年的0.2902hm2减少到2007年的0.2580hm2.根据在改进模型下的指标计算结果,近5年来成都市经济有了一定发展,但仍处于相对落后的阶段,而且生态压力大,生态与经济的协调性差,生态建设和经济发展的任务还很艰巨.     

基于生态足迹的焦作矿区生态补偿研究

运用生态足迹理论,对焦作市2004-2010年的生态赤字和生态补偿进行分析,预测了其生态赤字和所支付生态补偿金额的趋势.结果表明:焦作市的人均生态赤字从2004年的2.3548 hm2增加到2008年的3.2426 hm2,随后又下降到2010年的2.9989hm2,但总趋势是增加的,处于不可持续状态.生态补偿的金额在2008年达到最大值8.42亿元,其后有所下降.预测出2015年的人均生态赤字为1.1438 hm2/人,生态补偿基金为7.50亿元,生态赤字和生态补偿基金均有所减少,可见焦作城市转型初见成效.     

基于生态足迹模型的重庆市可持续性动态测度与分析

重庆市作为长江流域上游唯一的直辖市,在促进城乡统筹改革和区域协调发展大局中具有重要战略地位,其可持续发展任重道远。运用生态足迹方法分析了重庆市2005年~2012年生态足迹的动态变化,并利用生态足迹和生态足迹强度指数等指标对其进行可持续性评估。结果表明:重庆市人均生态足迹由2005年的1.4527 hm2/cap增至2012年的1.9105 hm2/cap,人均生态赤字由0.9887hm2/cap上升至2012年的1.4224hm2/cap;人均生物资源足迹与人均能源生态足迹所占百分比平均为62.78%,37.22%;万元GDP生态足迹由2005年的1.33 hm2/万元降至2012年的0.56hm2/万元;生态足迹强度指数由2005年的3.13上升为2012年的3.91。结合重庆市加快5大功能区建设基础上提出人口控制、优化能源结构和提高环境保护标准、划定重庆市长江上游生态文明区生态红线、调整农业结构布局等方面政策建议。     

秸秆还田下氮肥用量对玉米产量及土壤无机氮的影响

研究连续2年秸秆还田下氮肥用量对玉米产量、氮肥利用率及土壤硝态氮的影响,结果表明,玉米产量随着施氮量的增加逐渐增加,施氮量达到216 kg·hm^-2时,产量最高,施氮量超过216 kg·hm^-2时产量有降低的趋势。相同施氮处理玉米产量年际变化明显,2010年较2009年产量提高0.69％~4.75％。氮肥利用率、氮肥农学利用率和氮收获指数随着秸秆还田年限的增加,均有不同程度的增加。2年0~100 cm土层土壤硝态氮含量均以施氮240 kg·hm^-2最高,且有向土壤深层迁移的趋势,对浅层地下水构成潜在的威胁。与施氮240 kg·hm^-2相比,施氮168、192 kg·hm^-2和216 kg·hm^-2处理0~100 cm土壤无机氮残留量2年平均减少39.87％、35.84％和29.38％。相同施氮处理,0~100 cm土壤无机氮累积量2010年较2009年略有降低。综合考虑玉米产量、氮肥利用率与生态环境效益,该地区最适施氮量200 kg·hm^-2左右。     

原油在土壤中迁移及降解的研究

为了解原油在土壤中淋滤及降解的规律，剖析了大庆老油田开发区贮油池土壤含油状况，进行了自然植被不同类型土壤的浇油、室内原油淋滤模拟及栽培试验。结果表明：贮油池土壤原油淋滤深度绝大部分集中在0～30cm，以下原油明显减少（除沙化土壤外）；盐碱土集中在0～10cm；草甸黑钙土集中在0～50cm；柱内油水混合渗透试验，80％集中在0～20cm；原油覆盖土壤表面时清水淋渗较弱，在0～20cm内残留94％；加原油的土壤降解试验，平均降解59．92％，范围为53．94％～62．25％，盆栽试验平均降解61．99％，范围为55.12％～70．68％。     

基于Landsat／TM和ETM＋的理塘草地沙化趋势及其驱动力分析

文章利用1989、1994、2000和2005年的4期Landsat／TM,ETM＋遥感影像,在几何校正、辐射定标、大气校正的基础上计算了归一化植被指数（NDVI）,建立最小二乘法线性回归方程对多时相NDVI进行同化处理,基于二分模型提取植被覆盖度并转换成荒漠化指数（DI）,对理塘县城附近约103．1km2范围的分类研究结果表明：（1）分为无沙化、轻度、中度、重度和严重沙化5级,其中2005年中度、重度和严重沙化面积分别为2．562km2、2．925km2和1．576km2;中度沙化比1989年减少9．69％,重度和严重沙化分别增多35．79％和161．8％;（2）2005年中度以上沙化面积比1989年增加1．470km2,增加了26．3％,年增加率为1．47％;（3）沙化面积呈前期小、中期大幅增加、后期增加减缓的总体趋势;（4）降水量和风速因子的变化趋势有利于缓解沙化,气温变化趋势没有反映出对沙化的促进作用。人类活动是造成沙化趋于恶化的主要因素;（5）沙化增加趋势与同类研究结果一致。     

Spatio-temporal patterns of soil phosphorus enrichment in Everglades water conservation area 2A

The Florida Everglades have undergone significant ecological change resulting from anthropogenic manipulation of historical regimes of hydrology, nutrient loading, and fire. Water Conservation Area 2A (WCA-2A) in the northern Everglades has been a focal point for the study of ecological effects of nutrient loading, especially phosphorus (P), from the nearby Everglades Agricultural Area (EAA). The overall objective of our study was to evaluate recent (1990 to 1998) changes in the spatial extent and patterns of soil P enrichment in Everglades WCA-2A. Surface soil was sampled to a depth of 10 cm at 62 sites within WCA-2A during 1998 for analysis of total phosphorus (TP) content. Geostatistical methods were used to create an interpolated grid of soil TP values across WCA-2A. Comparison of the results of this study with a similar study performed in 1990 showed that the extent of soil P enrichment in surface soil and sediments increased between 1990 and 1998, as evidenced by increased coverage of highly P-enriched soil near the primary surface inflows and a general increase in the concentration of soil TP in the interior regions of WCA-2A. Approximately 73% (31 777 ha) of the total land area of WCA-2A was considered P-enriched (soil total P > 500 mg kg(-1)) in 1998, compared with 48% of the land area (20,829 ha) in 1990, an average increase of 1,327 ha yr(-1). Study results indicate that the soil P enrichment "front" has advanced further into the relatively unimpacted interior of WCA-2A during the past several years.     

Plant and soil responses to biosolids application following forest fire

Soil stability and revegetation is a great concern following forest wildfires. Biosolids application might enhance revegetation efforts and enhance soil stability. In May 1997, we applied Metro Wastewater Reclamation District (Denver, CO, USA) composted biosolids at rates of 0, 5, 10, 20, 40, and 80 Mg ha(-1) to a severely burned, previously forested site near Buffalo Creek, CO to improve soil C and N levels and help establish eight native, seeded grasses. The soils on the site belong to the Sphinx series (sandy-skeletal, mixed, frigid, shallow Typic Ustorthents). Vegetation and soils data were collected for four years following treatment. During the four years following treatment, total plant biomass ranged from approximately 50 to 230 g m(-2) and generally increased with increasing biosolids application. The percentage of bare ground ranged from 4 to 58% and generally decreased with increasing biosolids rate. Higher rates of biosolids application were associated with increased concentrations of N, P, and Zn in tissue of the dominant plant species, streambank wheatgrass [Elymus lanceolatus (Scribn. & J.G. Sm) Gould subsp. lanceolatus], relative to the unamended, unfertilized control. At two months following biosolids application (1997), total soil C and N at soil depths of 0 to 7.5, 7.5 to 15, and 15 to 30 cm showed significant (P < 0.05) linear increases (r2 > 0.88) as biosolids rate increased. The surface soil layer also showed this effect one year after application (1998). For Years 2 through 4 (1999-2001) following treatment, soil C and N levels declined but did not show consistent trends. The increase in productivity and cover resulting from the use of biosolids can aid in the rehabilitation of wildfire sites and reduce soil erosion in ecosystems similar to the Buffalo Creek area.     

Modeling nitrogen and water management effects in a wheat-maize double-cropping system

Excessive N and water use in agriculture causes environmental degradation and can potentially jeopardize the sustainability of the system. A field study was conducted from 2000 to 2002 to study the effects of four N treatments (0, 100, 200, and 300 kg N ha(-1) per crop) on a wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping system under 70 +/- 15% field capacity in the North China Plain (NCP). The root zone water quality model (RZWQM), with the crop estimation through resource and environment synthesis (CERES) plant growth modules incorporated, was evaluated for its simulation of crop production, soil water, and N leaching in the double cropping system. Soil water content, biomass, and grain yield were better simulated with normalized root mean square errors (NRMSE, RMSE divided by mean observed value) from 0.11 to 0.15 than soil NO(3)-N and plant N uptake that had NRMSE from 0.19 to 0.43 across these treatments. The long-term simulation with historical weather data showed that, at 200 kg N ha(-1) per crop application rate, auto-irrigation triggered at 50% of the field capacity and recharged to 60% field capacity in the 0- to 50-cm soil profile were adequate for obtaining acceptable yield levels in this intensified double cropping system. Results also showed potential savings of more than 30% of the current N application rates per crop from 300 to 200 kg N ha(-1), which could reduce about 60% of the N leaching without compromising crop yields.     

川西北高寒草地沙化土壤特征及治理模式探讨——以阿坝州红原县为例

通过对川西北高寒草地不同类型的沙化样地0—10cm,10～20cm和20～30cm土壤有机质、pH和含水量进行分析。结果表明：（1）随着沙化程度加重,土壤有机质含量和土壤含水量明显降低;（2）随着土层深度增加,土壤有机质含量降低;未沙化、轻度沙化样地的土壤含水量随土层深度增加而降低,重度沙化样地则相反;（3）中度和重度沙化样地土壤pH约7．0,未沙化和轻度沙化pH值在6．5左右;沙地土壤有机质与pH值呈显著负相关关系,沙化土壤有机碳与水分损失是一个正反馈。鉴于川西高寒草地特殊环境,探讨了选用适宜的多年生高原药用植物或者其他高价值资源植物作为固沙材料,将治沙与经济发展相结合,建立高寒沙化草地治理模式。     

Soil carbon stocks and changes in the Republic of Ireland

The soil carbon (C) stock of the Republic of Ireland is estimated to have been 2048 Mt in 1990 and 2021 Mt in 2000. Peat holds around 53% of the soil C stock, but on 17% of the land area. The C density of soils (tCha(-1)) is mapped at 2 km x 2 km resolution. The greatest soil C densities occur where deep raised bogs are the dominant soil; in these grid squares C density can reach 3000 tCha(-1). Most of the loss of soil C between 1990 and 2000-up to 23 MtC (1% of 1990 soil C stock)-was through industrial peat extraction. The average annual change in soil C stocks from 1990 to 2000 due to land use change was estimated at around 0.02% of the 1990 stock. Considering uncertainties in the data used to calculate soil C stocks and changes, the small average annual 'loss' could be regarded as 'no change'.     

Changes in Land Cover and Subsequent Effects on Lower Fraser Basin Ecosystems from 1827 to 1990

/ European settlement began in the Lower Fraser Basin (LFB) inwestern British Columbia in 1827 and has impacted the basin ecosystem in anumber of ways, especially affecting the vegetation. Using previouslypublished data, air photos, and other historical material for the area,estimates of land cover were made for the years prior to 1827 and for 1930and 1990. The area of coniferous forest changed from 71% prior to 1827to 50% in 1930 to 54% in 1990. However, prior to 1827, only27% of the forest would have been immature (<120 years old), while40% would have been immature in 1930 and 73% of the forest wasimmature in 1990. The amount of wetland area decreased from 10% to1% of the study area while urban and agricultural area increased to26% of the study area by 1990. The changes in land cover have hadadverse effects on soil, water, and air quality; aquatic life; and plant andanimal populations. Estimates of changes in net primary production andorganic soil carbon suggest a decline over the past 170 years, although thelatter rate of decrease has slowed since 1930. As human populations in theLower Fraser Basin continue to increase, the quality of air, water, and soilwill continue to decline unless measures are taken.KEY WORDS: Human impact; Land cover; Net primary productivity; Organiccarbon in soil     

Do Postfire Mulching Treatments Affect Plant Community Recovery in California Coastal Sage Scrub Lands?

In recent years, the use of postfire mulch treatments to stabilize slopes and reduce soil erosion in shrubland ecosystems has increased; however, the potential effects on plant recovery have not been examined. To evaluate the effects of mulching treatments on postfire plant recovery in southern California coastal sage scrub, we conducted a field experiment with three experimental treatments, consisting of two hydromulch products and an erosion control blanket, plus a control treatment. The area burned in 2007, and treatments were applied to six plot blocks before the 2008 growing season. Treatment effects on plant community recovery were analyzed with a mixed effects ANOVA analysis using a univariate repeated measures approach. Absolute plant cover increased from 13 to 90% by the end of the second growing season, and the mean relative cover of exotic species was 32%. The two hydromulch treatments had no effect on any plant community recovery response variable measured. For the erosion control blanket treatment, the amount of bare ground cover at the end of the second growing season was significantly lower (P = 0.01), and greater shrub height was observed (P < 0.01). We conclude that postfire mulch treatments did not provide either a major benefit or negative impact to coastal sage scrub recovery on the study area.     

Population crisis and desertification in the Sudano-Sahelian region

People living in the area just south of the Sahara Desert in Africa face their 3rd major drought since 1900. This drought brings about famine. Drought and famine are only manifestations of more profound problems: soil erosion and degradation. They diminish land productivity which aggravates the population's poverty. Yet soil erosion and degradation occur due to an expanding population. Continued pressures on the land and soil degradation results in desertification. The UN Environment Programme's Assessment of the Status and Trend of Desertification shows that between 1978-84 desertification spread. Expanding deserts now endanger 35% of the world's land and 20% of the population. In the thorn bush savanna zone, most people are subsistence farmers or herdsmen and rely on the soils, forests, and rangelands. Even though the mean population density in the Sahel is low, it is overpopulated since people concentrate in areas where water is available. These areas tend to be cities where near or total deforestation has already occurred. Between 1959-84, the population in the Sahel doubled so farmers have extended cultivation into marginal areas which are vulnerable to desertification. The livestock populations have also grown tremendously resulting in overgrazing and deforestation. People must cook their food which involves cutting down trees for fuelwood. Mismanagement of the land is the key cause for desertification, but the growing poor populations have no choice but to eke out an existence on increasingly marginal lands. Long fallow periods would allow the land to regain its fertility, but with the ever-increasing population this is almost impossible. Humans caused desertification. We can improve land use and farming methods to stop it.     

Assessment and prediction of overall environmental quality of Zhuzhou City,Hunan Province,China

Fuzzy comprehensive assessment was applied to assess the quality of air, water and soil in Zhuzhou City, Hunan Province, China based on the monitoring data of 1997 and National Environmental Quality Standards of China. Results show that Zhuzhou air quality belonged to Class II with industry and traffic as the main control areas and SO2 as the major pollutant. Water quality within the Zhuzhou section of the Xiang River belonged to Class IV, with the Xiawan section as the main control area and NH3-N as the major pollutant. Soil environmental quality with respect to heavy metal pollution belonged to Class III, with Cd as the major pollutant. For those pollutants showing significant differences between the years of 1990-1997, predictions were made for the environmental quality for the period 1998-2003. According to the assessment results, cleaner production in the key pollution sources and the establishment of a municipal sewage treatment plant are proposed to improve the environmental quality of Zhuzhou City.     

The Effects of Long Time Conservation of Heavily Grazed Shrubland: A Case Study in the Northern Negev,Israel

One of the major reasons for desertification is unrestricted grazing leading to vegetation depletion, soil erosion and degradation, phenomena often considered irreversible in the short term. Here, we compare soil and biological parameters of degraded and conserved, recently rehabilitated arid shrubland in the Northern Negev, Israel. The study area was restored by conservation efforts including a strictly controlled grazing regime initiated in 1992. The visually recognizable improvement in the ecology of the restored shrubland is reflected in significant improvement in all examined biotic (herbaceous biomass, shrub patch density, and insect activity), and soil parameters (nutrients, organic matter content, moisture, and water infiltration). The difference is created predominantly by restoration of large biological patches composed of shrubs and other perennial plants often associated with ant or termite nests, where the most significant increases in productivity and soil quality were observed. In the conserved shrubland such patches covered 35 or 25 % of the area (in a normal and a drought year, respectively). In the degraded shrubland 5 % or less of the area was occupied by such patches that were much smaller and of lower biological complexity. With respect to plant biodiversity, six plant species were found only—and 18 others became significantly more common—in the rehabilitated area. The results of this article indicate that functional arid drylands can be restored within <16 years relying on strict conservation management with reduced grazing intensity.