Study On The Mechanism Of Dissolution In The Peak Forest-lake Basin Of Southeast Of Yunnan Province

Karst ecosystem is an essential part of the earth surface system and special part of the purpose of this paper is to through the analysis of southeast yunnan,the Peak Forest-lake Basin District lobular sheep hoof nail limestone thickets,fragrant wood three kinds of secondary forest,the yunnan pine forest plant community and served,stone ditch,stone pit,soil niche dissolution velocity difference characteristics,combined with the indoor microscope observation,reveals the key factor of dissolution.Through the analysis of the physical and chemical properties and local microclimate of the soil profile of the limestone shrub,the secondary forest and the pine forest of Yunnan in the experimental watershed of Cauliflower-stem,it was found that the positive succession of the plant community was beneficial to the dissolution.The dissolution rates of different plant communities and different nicotes were significantly different.soil slope>stone ditch>stone surface>Stone pit.The main conclusions are as follows:?1?Precipitation has an obvious control effect on the dissolution rate.At those black different plant communities niche rainy season dissolution rate were higher than in dry season dissolution rate,such as lobular sheep hoof nail brush dissolution rate is 73.27mg·m^-2·d^-1.The rainy season,dry season dissolution rate 16.54mg·m^-2·d^-1the rainy season is 4.4 times that of the dry season fragrant wood secondary dissolution rate 113.21mg·m^-2·d^-1.The rainy season dry season dissolution rate 16.67mg.mg·m^-2·d^-1,the rainy season is 6.8 times that of the dry season,the pine forest dissolution rate 83.24mg·m^-2·d^-1.The rainy season,The dissolution rate in the dry season was 38.51mg·m^-2·d^-1,and the rainy season was 2.1 times that in the dry season.In summary,it is not difficult to find that the dissolution rate of rainy season accounts for more than 70 in the whole year,which is significantly related to the proportion of rainy season precipitation in the study area.The total rainfall of black rainy season accounts for 82.3%of the whole year?rainy season is From May to October,and dry season is from December to March of the next year?.?2?Soil physicochemical properties of three typical plant communities have a dominant effect on subsoil dissolution rate.Under different niches of the same plant community in the same season,different species of the same plant community in different seasons,and different niches of different plant communities in different seasons,rock dissolution rates were significantly different.The dissolution rates of rock-face,pit,shigou and slope were different in each plant community,and the dissolution rates of subsoil were all 2.2 times higher than that of subsoil.For example,the annual dissolution rates of subsoil were 43.64mg·m^-2·d^-11 and 19.88mg·m^-2·d^-1,respectively,with a ratio of 2.21.?3?Soil physicochemical properties of three typical plant communities had different effects on dissolution rates.Soil moisture,soil porosity,soil SOM,soil CO₂,soil pH and soil DOC vary greatly in different plant communities,and the effects of soil physical and chemical properties on dissolution are also different.For example,the correlation between soil water and dissolution rate is R²=0.94,soil porosity is R²=0.98,soil CO₂ is R²=0.92,soil SOM is R²=0.91,soil pH is R²=0.97,and soil DOC is R²=0.92.Among them,the correlation between soil porosity and soil pH and dissolution rate was significantly higher than other indexes,and the significant correlation between soil pH and dissolution rate was basically consistent with the research conclusions of scholars represented by Zhen Xiaojun.?4?The forward succession of plant communities is conducive to the dissolution rate,in which the mineral composition,chemical substances,joints and fissures of rocks have a certain influence on the dissolution rate.The overall situation of the dissolution marks in the secondary forest of faint scent wood was obviously more complex than that in the shrub and yunnan pine forest,which was also more complex than that in yunnan pine forest,mainly reflected in the area and depth of dissolution marks.The difference of dissolution patterns in the shrub,the secondary forest and the pine forest was in line with the dissolution rate,and it also proved that the forward succession of plant community was beneficial to the dissolution rate.microstructure of dissolution is mainly based on rock lithology and fractures,joints and three key elements,and from external conditions?temperature,rainfall,soil physical and chemical properties,etc.?,in the early dissolution,the rocks on its micro cracks to appear first,continued intervention in dissolution after form small hole,then gradually development evolution,the evolution of the basic point to the line,line to face,the law of the center to the surrounding radiation,corrosion morphology are mainly honeycomb,patch shape,radial,arc curved shape,strip,ring,beads,scattered.Under the influence of rock composition,the dissolution forms are honeycomb,patch,radial,arc bend and ring.Along the joints and fissures,there are bands,beads and dispersions.