Dynamics Of Soil Water And Salt During The Growing Season Of Populus Euphratica In Minqin Oasis

Minqin Oasis located in downstream of the Shiyang River, its longitude isbetween38°5′N and39°6′N and its latitude is between103°02′E and104°02′E. Areaof the oasis is about1000square meters. There are low mountains and deserts aroundthe oasis. The north, west and east is surrounded by the tengery desert and the badainjaran desert, terrain of the oasis is relatively flat and its altitude is between1300and1500m. Soil water and soil salt are the comprehensive reflection of climate,vegetation, terrain, soil condition and other nature factors. What’s more, the basicconditions of ecological system and vegetation construction in arid or semi-arid zoneare the soil water and soil salt. Thus, we take the naturalPopulus euphratica forests ofMinqin Oasis in Gansu province as the study area. Classical statistical andgeostatistical methods were used to explore dynamics of soil salt and water during thegrowing season of natural Populus euphratica in Minqin Oasis. In order to providescientific basis and protection for the ecological environment of Populus euphratica inMinqin Oasis, salinization soil improvement, to make rational use of water resourcesand the sustainable development. The conclusion is as following:（1）Soil water content increased with soil depthin SCKD and SWCD, but itincreased first and then decreased with soil depth in JHCD. In the study area，the soilwater content in the0-20cm of soil was quite low and it was between0.85%and3.40%.The diameter at breast height of a Populus euphratica tree was negativelyrelated with salt water contents．（2）Salt water content varied from season to season，showing a decreasing orderof spring，autumn，and summer. The variation efficient of soil water content in MinqinOasis belonged to middling and strong variability. Variation efficient of the surfacesoil is bigger.（3）Soil salt content of the natural Populus euphratica forests in Minqin Oasisincreased with depth in vertical direction and the most obvious sampling site was theJiahe. Soil salt content of the surface soil was higher. The diameter at breast height ofa Populus euphratica tree was negatively related with salt salt contents.（4）It was found that soil salt content of the spring was the highest, which was followed by the summer and autumn. The variation efficient of soil salt content inMinqin belonged to middling variability and it decreased gradually with the depth invertical direction. During the Populus euphratica growth period, variation efficient ofthe soil salt content in summer, which was followed by the autumn and spring.（5）The nuggets of soil water in study area was between0.08and0.38in springand it decreased gradually with the depth in vertical direction,which showed us thatsome ecological processes can not be ignored from0cm to120cm especially in smallsacl（e<60m）.Namely, the influence Populus euphratica on soil water. The stills of thesuferce soil was higher and it decreased with the depth in vertical direction, whichindicated that variation of the surface soil was bigger. The coefficient of nugget（C₀/C₀+C）was between0.25and0.75, Jiahe and80-120cm soil layer of SWCD belongedto middling spatial correlation degree. In summer, the range of the study areaincreased fluctuatively with the depth in vertical direction and it was between25.08mand70.39m, the differences between them nearly four times. That is to say the processof affecting soil water was vary in different seasons and different depths. In summer,the coefficient of nugget of the surface tended to be small, it was also vary in differentsites. In autumn, the stills（C₀+C）of the suface soil increased obviously, which wasbigger than the spring and summer, while The coefficient of nugge（tC₀/C₀+C）was nochange.（6）The nuggets of soil salt in study area was between0.08and0.38in springand it decreased gradually with the depth in vertical direction, which showed us thatsome ecological processes can not be ignored from0cm to120cm especially in smallsacle（<60m）, which was similar with the soil water. The coefficient of nugget（C₀/C₀+C）was between0.06and0.86. The ranges of soil salt was between51.31m and113.57m, all were greater than the smallest scales15m. The research showed that thescale of soil salt of space mutation in the study area the content has obvious spacestructural. In summer, theoretical model of the different sites and soil layers was ofsignificant difference, nonetheless, coefficient of determination overall was more than0.60, which stated that the variograms model was ideal. While the variograms modelof60-80cm in SCKD and20-40cm in SWCD were poorer. The ranges were between60.31m and124.92m and SWCD was bigger than other two sites. The ranges of soil water and soil salt were different, which can be attributed to the terrain ups and downs.In autumn, the nuggets were no obvious change and the stills tended to reduce. Thebiggest range was at100-120cm of SWCD and it was130.68m.