1983―2015年中国西南地区干旱综合损失率与SPI的关系研究

【目的】揭示1983―2015年中国西南地区干旱综合损失率与SPI的关系。【方法】利用1983―2015年西南地区旱灾资料研究了西南地区旱灾在1983―2015年的变化规律及发生概率;利用40个代表站点1960—2015年的月降水量资料计算月、季和年尺度SPI值,进一步研究了1983―2015年不同时间尺度的干旱综合损失率与SPI的相关关系。【结果】1983―2015年西南地区干旱的受灾率、成灾率、绝收率和综合损失率的多年平均值分别为11.79%、5.84%、1.30%和4.86%,除云南的旱灾呈不显著上升趋势外,其他省份和整个西南地区的旱灾呈下降趋势,各省旱灾情况较为接近,其中云南和贵州的旱灾情况比广西和四川严重,西南地区干旱综合损失率大于6%的概率为29.8%。【结论】除云南省干旱综合损失率与5月SPI值最为相关外,其他省份和西南地区干旱综合损失率都与8月、夏季和年尺度的SPI值的相关性最大。     

1971─2012年长江中下游地区水稻洪涝时空分布特征

【目的】为长江中下游地区地区性防涝排涝部署提供依据。【方法】基于1971─2012年长江中下游地区426个气象站点逐日降水资料,通过分析洪涝发生频率、洪涝强度和洪涝发生站次比,研究了长江中下游地区年度洪涝灾害时空分布特征和覆盖水稻关键生育期洪涝灾害时空演变特征。【结果】研究区中度、重度洪涝发生频率所占比最大,中度洪涝发生频率主要集中在湖北、湖南、江西、浙江;重度洪涝发生频率集中在湖南、江西、浙江;特涝发生频率集中在安徽北部与江苏。同时,1971─2012年间研究区域洪涝发生影响范围总体年际尺度变化不明显,洪涝强度20世纪90年代最强,但整体有降低趋势。从研究区水稻物候期来看,影响范围最广强度最大集中发生在7─8月,早稻与一季稻分别处于灌浆成熟期与拔节孕穗期。【结论】在研究区域加强农业气象监测密度,重点可在研究区内(安徽北部、江苏、湖南、江西、浙江)早稻进入灌浆期与一季稻拔节孕穗期前期进行水利设施建设,依靠研究区地势特点与农田生态自身环境稳定性,预防和排除水稻洪涝灾害。     

区域水土保持生态修复模式及效果评价——以长江流域两当河上游为例

根据长江流域两当河上游的环境特点,提出了自然力与人工辅助相结合的水土保持生态修复技术及建设模式,包括退化林地修复模式、荒山荒坡修复模式、农地修复模式和生态辅助措施.并应用遥感技术和地面人工调查相结合的方法,对生态修复模式实施的效果进行评价.结果表明,两当河退化生态系统修复效果明显,农田退化系统恢复效果显著,植被盖度提高,种群数量增加,生态系统向良性演变.     

嘉陵江上游不同植被恢复模式土壤微生物及土壤酶活性的研究

以嘉陵江上游水土流失定位观测站内5种植被恢复模式为研究对象,对土壤微生物、土壤酶活性以及理化性质进行了研究。结果表明:①退化生态系统进行植被恢复后土壤微生物数量明显增加,上层>下层,且随季节不同而有明显变化;②5种植被恢复模式脲酶、蔗糖酶活性均明显高于对照地,3种土壤酶活性随季节变化明显且因林分而异;③5种植被恢复模式土壤氮素的转化率除湿地松纯林外均明显高于对照地,土壤氮素转化率与3种酶均呈极显著的相关关系,与土壤中细菌、放线菌数量之间也呈正相关关系,但相关系数未达显著水平;④火烧迹地灌丛土壤养分含量最高,微生物数量最大,脲酶、蔗糖酶活性最强,土壤的结构性最好。     

一次罕见的油松林霜冻灾害及其成因分析

本文报道一例罕见的晚霜对油松林的危害。调查表明油松初生嫩叶在活跃生长期如遇-2.7℃以下的低温,部分林木的初生嫩叶梢端即可受害;林木个体的耐寒力有很大差异。地形因子(主要是坡向、海拔)对成灾与否具有支配作用,它使受害林分在空间的分布里不连续格局。     

Effects of construction defects on hydraulic performance of Kalpani distributary, NWFP, Pakistan

The hydraulic performance of canals designed to deliver water by proportional allocation is highly dependent on the accuracy of construction of water division structures. If construction is inaccurate then inequity of water delivery is built into the system from the onset. A survey of hydraulic performance of Kalpnai distributary in NWFP Pakistan immediately after construction showed that the canal could only deliver 90% of designed discharge due to deficiencies in construction of two siphons, and that the tail end of the canal only received 70% of designed discharge. When operated at 70% of design discharge tail end reaches received 50% of designed discharge. Measurements of outlet structures showed that 57% of structures were built as intended and had not been damaged. All orifice outlets delivered more than 115% of design discharge and on average delivered 40% more than intended. Only 20% of open flumes were within 10% of design width, while 58% were more than 30% wider. As a result of these construction defects many watercourses were able to obtain much higher discharges than intended. The lack of control gates means there is no managerial remedy to redress the existing inequity. The only solution is to reconstruct a high proportion of outlet structures. Potential causes of poor construction are many, including lack of involvement of the agency responsible for subsequent operation, lack of dialogue with water users, and lack of accountability built into the project framework.     

神府─东胜煤田建设对土地资源的影响──大柳塔地区土地资源动态分析

大柳塔地区是神府─东胜煤田一、二期工程开发建设、生活服务、交通设施及行政指挥中必,这里集中了该煤田几乎所有的国家统配煤矿和85%以上的地方及群众兴办的煤矿.强烈的人为活动对该区土地资源的开发和利用产生了极大的影响,使历史上形成的土地利用结构发生了重大改变;沿主川道分布的良田（水浇地）锐减,新的水土流失,土地沙漠化及土地的污染对土地资源在数量和质量上都构成了严重威胁.本研究以1987年的彩红外航片像片和开矿前的图文资料作为本底依据,参考1992年陆地卫星资料,采用实地调绘方法,编制了两期土地利用现状图,清查了研究区内采矿和建设活动引起的土地资源数量、质量及其利用方式的时空变化特征和存在问题:提出了土地保护与建设,以及退化土地的恢复与重建的对策.     

Offsetting global CO2 emissions by restoration of degraded soils and intensification of world agriculture and forestry

Increase in atmospheric concentration of CO₂ from 285 parts per million by volume (ppmv) in 1850 to 370 ppm in 2000 is attributed to emissions of 270 ± 30 Pg carbon (C) from fossil fuel combustion and 136 ± 55 Pg C by land‐use change. Present levels of anthropogenic emissions involve 6·3 Pg C by fossil fuel emissions and 1·8 Pg C by land‐use change. Out of the historic loss of terrestrial C pool of 136 ± 55 Pg, 78 ± 12 Pg is due to depletion of soil organic carbon (SOC) pool comprising 26 ± 9 Pg due to accelerated soil erosion. A large proportion of the historic SOC lost can be resequestered by enhancing the SOC pool through converting to an appropriate land use and adopting recommended management practices (RMPs). The strategy is to return biomass to the soil in excess of the mineralization capacity through restoration of degraded/desertified soils and intensification of agricultural and forestry lands. Technological options for agricultural intensification include conservation tillage and residue mulching, integrated nutrient management, crop rotations involving cover crops, practices which enhance the efficiency of water, plant nutrients and energy use, improved pasture and tree species, controlled grazing, and judicious use of inptus. The potential of SOC sequestration is estimated at 1–2 Pg C yr⁻¹ for the world, 0·3–0·6 Pg C yr⁻¹ for Asia, 0·2–0·5 Pg C yr⁻¹ for Africa and 0·1–0·3 Pg C yr⁻¹ for North and Central America and South America, 0·1–0·3 Pg C yr⁻¹ for Europe and 0·1–0·2 Pg C yr⁻¹ for Oceania. Soil C sequestration is a win–win strategy; it enhances productivity, improves environment moderation capacity, and mitigates global warming. Copyright © 2003 John Wiley & Sons, Ltd.     

Regeneration of sylvopastoral lands in the Sahel zone under village management conditions

This article reports the results of a study aimed to develop an approach for the rehabilitation of sylvopastoral lands that would be applicable and sustainable under local village-management conditions. Stabilization measures involved protection against exploitation activities during a period of five years, with accompanying low-cost restoration measures (all locally known) including (i) alignments of dead wood along the contour, (ii) spreading (mulching) of dead wood, and (iii) alignments of small stones along the contour. Monitoring demonstrated remarkable and continuing regeneration of the vegetation, with restoration measures clearly accelerating such regeneration. Low-intensity grazing did not appear to be harmful. The study also demonstrated the synergy between the herbaceous and woody plant layers. However, village management of the area was increasingly neglected, and after the five-year period exploitation levels reverted back to normal, so that the results will not be sustained. This was due to neglect of socio–economic issues, including insufficient insight into the norms and values attributed by the villagers to such low potential sylvopastoral lands. Future research should focus on the socio–economic aspects of land rehabilitation, as technical means are widely known, including appropriate low-cost measures based on local practices. Recommendations focus on principles and steps to be undertaken for successful and sustainable land rehabilitation. © 1998 John Wiley & Sons, Ltd.