【作者】 李勇；

【导师】 王建力；

【作者基本信息】 西南大学 ， 第四纪地质学， 2011， 硕士

【摘要】 我国西南岩溶地区的石漠化问题突出,形势十分严峻,主要表现为：“水土流失→石漠化→岩溶水文地质灾害→岩溶生态系统退化”的恶性循环,每年石漠化面积按2%递增,导致土地资源流失、非地带性干旱和人民生命财产损失,这不但加剧了岩溶地区的贫困状况,还威胁到长江和珠江中下游的生态安全,石漠化治理刻不容缓。近半个世纪以来,我国科学家、岩溶工作者在石漠化治理的理论和实践等方面取得可喜成绩,但对草本植物在石漠化治理中的作用尚不够重视,同时也存在现有治理模式移植困难的局限。本研究依托科技部“十一五”支撑计划项目引种岩垂草,利用地理学、恢复生态学和系统论的原理与方法,对比研究岩垂草地、撂荒地和传统耕地的生态特点、水保效益及其土壤理化性质的差异等指标,利用灰色理论指导数字建模,运用灰色关联分析法进行生态效益综合评估,初步结论如下：1、岩垂草生物效应的对比研究：(1)岩垂草覆盖度高,达100%,移栽后不到90d,其覆盖度就达到100%,生长速度快。撂荒地的盖度一般在60%左右。耕地土壤裸露面积大,植被覆盖度有限,一般为50%。本研究讨论了岩垂草盖度与地表径流的关系,认为：盖度在30%以下时,岩垂草的减流效果不大,在30%—40%时,效果明显增加,当达到80%—100%时,地表径流显著减少。(2)岩垂草根系发达,增长速度快,平均根长22.3cm,根平均密度2100条/m2,根生物量达780g/m2。2、岩垂草对土壤物理性质的影响：(1)岩垂草对土壤温度的影响表现为夏季降温,冬季升温。在7月的地温测定中,2年生岩垂草地在Ocm、l0cm和20cm处的地温均比传统耕地低,分别是1.2℃、3.2℃和3℃,其地温日变幅在Ocm、l0cm和20cm处比传统耕地低2.8℃、1.8℃和1.2℃；在12月的地温测定中,2年生岩垂草地在Ocm、l0cm和20cm处的地温均比传统耕地高,分别是1.2℃、2.4℃和2.1℃,土壤保温效果较好。(2)岩垂草地、传统耕地和撂荒地三种不同覆被土壤的含水量有差异,从高到低的次序为：2年生岩垂草地>1年生岩垂草地>撂荒地>传统耕地。在夏季(6月),2年生岩垂草地在Ocm和20cm处的土壤含水量均比传统耕地高,分别增加12.6%和17.9%；在冬季(12月),2年生岩垂草地在Ocm和20cm处的土壤含水量也比传统耕地高,分别是增加13.7%和14.1%；(3)、岩垂草能减小土壤容重,增加土壤孔隙度,提高土壤渗透性能。3、岩垂草对土壤化学性质的影响：岩垂草能提高土壤肥力,使土壤有机质、全N和全K明显增加。4、岩垂草水土保持效益的研究：(1)、对地表径流的影响。岩垂草能显著减小径流系数,在不同降水量和降水强度下,2年生岩垂草地径流系数比耕地减少47.5%、60.4%和55.6%。1年生地岩垂草径流系数比耕地减少37.3%、52.1%和50%。另外,径流系数的变化与降水量和降水强度有关,降水量大、降水强度高时,不同植被覆盖的土壤地表径流系数均有所提高,但岩垂草地增幅最小。(2)、对土壤侵蚀量的影响。在相同条件下岩垂草地土壤侵蚀量最小,2年生岩垂草地土壤侵蚀量分别占耕地土壤侵蚀量的4.89%、5.21%和5.5%,方差分析表明,岩垂草与耕地不同土壤侵蚀量的F=100.0192>FCrit=7.708647,差异明显。说明岩垂草减少土壤侵蚀作用显著。另外,2年生岩垂草地的径流系数分别占耕地的径流系数的52.5%、39.6%和44.4%,比例高于土壤径流系数对比值,说明岩垂草保土效果优于其保水效果。5、根据灰色理论的成果,简化灰色关联分析法,得到2年生岩垂草地与耕地的相似关联度r3==0.886,1年生岩垂草地与耕地的相似关联度r2=0.90,撂荒地与耕地的相似关联度r1=0.944,说明2年生岩垂草生态效益最好,1年生岩垂草生态效益次之,撂荒地生态效益相对接近耕地。6、本研究发现,撂荒地的多项生态效益指标优于传统耕地。是因为土地撂荒减少了人类干扰,并且重庆岩溶区的夏季水热条件较好,有利于植被从“草被→灌丛→小乔木”方向演替,使土壤机能缓慢恢复,退化岩溶生态系统得到改善。更多还原

【Abstract】 The problem of rocky desertification in karst areas is becoming more and serious in south-west China, of which is characterized by a vicious cycle:water loss and soil erosion→rocky desertification→karst hydrological and geological disaster→karst ecosystem degeneration. Rocky desertification increases annually by 2%, which leads to soil erosion, non-zone drought and loss of lives and properties to mankind. It not only aggravates the poverty situation in karst regions, but threatens the ecological security of lower-middle of Yangtze River and Zhujiang River.In the past half century, the scientists of karst have made a lot of achievments both in theories and practice of rocky desertification rehabilitation. But the importance of herbaceous plants against on the rocky desertification were not gotten attention, also it is difficult to transplant the modles of rock desertification.Based on the principles and methods of geogrophy, restoration ecology and system theory, supported by project of the eleventh five-year plan, contrastive studies on the the physioecological characteristics, soil and water conservation benefits and the differences about soil physical and chemical properties in Phyla Nodiflora land, abandoned land and tillage were done through digital modeling of Grey Theory and evaluating of comprehensive ecological benefits of grey association analysis method. Some preliminary conclusions are obtained as follows:First, biological effects about Phyla Nodiflora:(1) The coverage rate of the Phyla Nodiflora land is 100% after transplanting 90 days. The coverage rate of the abandoned land is about 60%. The coverage rate about tillage is limited to less than 50%, because of little vegtation coverage. We discussed the relationaship between the coverage rate of Phyla Nodiflora and the surface runoff, of which that the effect of reduction of the surface runoff is not very effective when the coverage rate is less than 30%, while the effect of reduction of the surface runoff will increase when coverage is 30%-40%, and surface runoff decrease rapidly when coverage rate is 80%-100%. (2)Phyla Nodiflora is rich root, and growing rapidly. The average root length is 22.3cm, and average root density is 2100 per meter quare, and root biomass is 780 kilogram per meter quare.The second, influence of Phyla Nodiflora on physical properties of soils:(1)The soil temperature decreased in summer and increased in winnter,when soil were covered by Phyla Nodiflora.In summer, the soil temperature covered by 2 years Phyla Nodiflora is lower than the temperature of tillage at Ocm,10cm and 20cm of which is 1.2℃,3.2℃and 3℃respectively. The daily of variation of soil temperature covered by 2 years of Phyla Nodiflora decreased 2.8℃,1.8℃and 1.2℃than the daily of variation of soil temperature of tillage at Ocm,10cm and 20cm. In winter, the soil temperature covered by 2 years Phyla Nodiflora is higher than the temperature of tillage at Ocm,10cm and 20cm of which is 1.2℃,2.4℃and 2.1℃respectively. The Phyla Nodiflora land has a good warm-keeping effect. (2)There are different in the soil moisture of Phyla Nodiflora land, abandoned land and tillage, Which followed the order:2 years of Phyla Nodiflora land> 1 year Phyla Nodiflora land>abandoned land> tillage. In summer, the soil moisture of 2 years of Phyla Nodiflora land is higher than the soil moisture of tillage at Ocm and 20cm. The growth rate is 12.6% and 17.9%, respectivly. In winter The growth rate is 13.7% and 14.1%, respectivly.(3) Phyla Nodiflora can reduce soil bulk density and increase soil porosity and enhance soil permeability.The third, influence of Phyla Nodiflora on chemical properties of soils:Phyla Nodiflora can improve soil fertility, increase soil organic matter, total nitrogen and total potassium.The forth, influence of Phyla Nodiflora on water-soil conservation effect:(1) Phyla Nodiflora can reduce funoff. The runoff coefficient of 2 years of Phyla Nodiflora land decreased by 47.5%, 60.4% and 55.6% than that of tillage under different precipitation. The runoff coefficient of 1 year Phyla Nodiflora land decreased by 37.3%,52.1% and 50% than that of tillage. There is a relationship between the variation of runoff coefficient and precipitation. The runoff coefficient of soil covered different plant increased when rainfall and rainfall intensity become higher. But the growth average of runoff coefficient of Phyla Nodiflora land is smallest. (2) The soil erosion amount of Phyla Nodiflora land is smallest in the same condition. The amount of soil erosion of 2 years of Phyla Nodiflora land account for 4.89%,5.21% and 5.55% of tillage, respectively. The difference is remarkble for the F=100.0192>Fcrit=7.708647 of soil erosion amount between Phyla Nodiflora land and tillage.At the same time, the runoff coefficient of 2 years of Phyla Nodiflora land account for 52.5%,39.6% and 44.4% of tillage, respectively. It indicated that conservation of soil of Phyla Nodiflora is better than control of water.The fifth, according to gravy theory, simplified gray association analysis method, the similarity correlation degree of 2 years of Phyla Nodiflora land and tillage is r3=0.886, and the similarity correlation degree of 1 year of Phyla Nodiflora land and tillage is r2=0.90, the similarity correlation degree of abandoned land and tillage is r1=0.944, which indicated that the ecological effect of 2 years of Phyla Nodiflora is the best.The sixth, we find out the ecological indicators of abandoned land are better than whose of tillage. Because it reduces of human interence by abandoning land and there are good temperature and rainfall conditions in Chongqing karst area, it is suited for the succession from grass to shrub to small tree, and recoverying of soil function, and improving karst ecosystem.更多还原