甘肃省祁连山水源涵养林研究院

[Objective]To establish a scientific and reasonable evaluation system of Xanthoceras sorbifolia resources in Hexi,Gansu Province,and to make comprehensive evaluation and screening of excellent varieties of Xanthoceras sorbifolia suitable for local application,to provide a theoretical basis for the development of Xanthoceras sorbifolia ecological industry in arid and semi-arid regions of Hexi Corridor.[Method]Using the analytic hierarchy process(AHP)to build an analytical model to calculate the index weight,using the principle of grey relational grade analysis(GRA)to build"Ideal varieties"and reference series,and calculating the weighted grey relational grade,the 17 introduced new germplasm were evaluated and sorted from adaptability,ornamental and high yield,and finally completed comprehensive evaluation and screening.[Result]On the basis of verifying the rationality of the analytic hierarchy process AHP-RRB-model,the weight values obtained were used to calculate the weighted correlation degree of each germplasm evaluation index,the results showed that the weighted correlation degree of SW-2,SH-2,NSJH,NSZH,LD was above 0.8(including 0.8)and classified as Grade Ⅰ germplasm NSF,LX,ZS-7,ZS-9,SW-1,SH-5,SH-5 were classified as Grade Ⅱ germplasm according to the weighted grey correlation between 0.7 and 0.8(including 0.7).The weighted grey correlation degree of SKX,NH-1,ZS-4,LG-4,LG-8,ZS-1 was less than 0.7 and classified as Grade Ⅲ germplasm.[Conclusion]The grade I germplasm has high ornamental value,high seed yield,large oil yield and strong adaptability,and its comprehensive scores are close to"Ideal variety"grade Ⅱ plants have either high ornamental value,general oil potential and low yield,or high yield and good oil yield,but general ornamental value.In a word,their comprehensive characters are slightly worse than those of grade Ⅰ plants,the germplasm with high ornamental value should be applied in urban landscaping,and the germplasm with high yield and oil yield should be widely planted in Xanthoceras sorbifolia industrial development base,it is suitable for high yield garden,grade Ⅲ germplasm has poor comprehensive characters,and its ornamental value,yield and oil yield are all average,but this kind of planting is not suitable for local planting,or need to do further introduction and domestication and screening work.

[Objective]The soil water content of different land types in the typical desert-oasis transition zone of Hexi Corridor and Zhangye City,Gansu Province were taken as the research objects to clarify the dynamic changes of soil water content and its relationship with climatic factors,and to reveal the spatial heterogeneity,dynamic changes and the interaction between soil water content and climatic factors in this region,and to provide theoretical basis local ecological protection and desertification prevention and control.[Method]Through field sampling,indoor experiments,data analysis and processing,the changes of soil water content in the and saline-alkali areas of the desert-oasis transition zone in 0-20,20-40,40-60,60-80 cm soil layers were analyzed.The correlation between climatic factors and soil water content was analyzed by Pearson bivariate correlation analysis and the response degree of soil water content to climatic factors was analyzed by grey correlation method.[Result]1)The soil water content in the desert area generally low,with relatively high water content in the 0-20 cm soil layer,which decreased with the increase of depth;the soil water content in the-alkali area was generally high,with the water content increasing first and then decreasing with the increase of depth,and the water content in the 40-60 cm soil layer was the highest.The coefficient of variation of soil water content in different soil layers was at a low level of variation,indicating that its change was stable.The soil water content in the desert and saline-alkali areas showed different change trends in different months,with the highest water content in the 40-60 cm soil layer in the desert area and the lowest in the 60-80 cm soil layer;the highest water content in the saline-alk area was in the 40-60 cm or 60-80 cm soil layer,and the lowest was in the 0-20 cm layer;2)Soil water content was significantly positively correlated with precipitation and relative humidity,and negatively correlated with wind speed,evaporation and temperature to varying degrees.ipitation and relative humidity had a significant effect on soil water content in the desert area,and precipitation and evaporation had a prominent effect in the saline-alkali,and the grey correlation analysis further revealed the greater effect of relative humidity and precipitation on soil water content in different soil layers.[Conclusion]The soil water content the desert area was generally low,while that in the saline-alkali area was generally high.The soil water content of different land types showed different change trends in months,and there were differences among the soil layers,but the overall change was relatively stable.The distribution of soil water content was affected by seasonal precipitation,evaporation soil texture.

[Objective]To explore the changes of soil physical and chemical properties and enzyme activities of four vegetation types in desert saline-alkali lands in the Hexi Corridor and their influencing factors,and to provide a theoretical basis for soil nutrient cycling and regulation mechanism in desert saline-alkali lands.[Methods]Taking the desert saline-alkali soil in the Hexi Corridor as the research object,four typical vegetation types,including Lycium ruthenicum Murr.single community(HH),L.ruthenicum and Phragmites australis community(HL),L.ruthenicum and Alhagi camelorum Fisch.community(HT),L.ruthenicum and Tamarix chinensis Lour.community(HC),were selected.Three replicate plots were set up for each vegetation type.Through the combination of field investigation and indoor analysis,soil physical and chemical properties(including organic carbon,total nitrogen,total phosphorus)and enzyme activities(including urease,alkaline phosphatase,nitrate reductase,nitrite reductase)of the four vegetation types were measured.Variance analysis and redundancy analysis were used to evaluate the differences in soil physical and chemical properties and enzyme activities,and the influencing factors were analyzed.[Results]In the soil of the four different vegetation types in the Hexi Corridor,organic carbon content increased with the increase of soil depth,being the highest in HC and the lowest in HH,and the difference was significant(p<0.05).Total nitrogen content decreased with the increase of soil depth,being the highest in HH and the lowest in HC,and the difference was significant(p<0.05).There was no significant change in total phosphorus(p>0.05).The activities of urease,alkaline phosphatase,nitrate reductase and nitrite reductase decreased with the increase of soil depth,showing the phenomenon of surface aggregation.The activities of alkaline phosphatase,nitrate reductase and nitrite reductase were significantly different among different vegetation types(p<0.05),being the highest in HL,HH and HT,and the lowest in HT,HC and HH,respectively.Total nitrogen content was significantly positively correlated with urease and nitrate reductase activities(p<0.05).In the 20-40 cm soil layer,organic carbon content was significantly negatively correlated with urease and nitrate reductase activities(p<0.05).[Conclusion]The changes of different vegetation types and soil layers cause significant changes in soil physical and chemical properties,and then regulate the changes and distribution of soil enzyme activities.Soil total nitrogen and organic carbon contents are the key factors affecting soil enzyme activities,and can better explain the distribution and change characteristics of soil enzyme activities.

Based on soil temperature and humidity and meteorological data at different elevations during the 2020-2021 growing season in the Pailugou watershed of Qilian Mountain,this study analyzed the variation char-acteristics of soil temperature and humidity and the relationship with meteorological factors,and determined the main meteorological factors affecting soil temperature and humidity.The results showed that:(1)soil tempera-ture tended to increase and then decreased during the growing season(2020),with a gradual increase in soil tem-perature from May to August(3.93℃)and a decrease from September to October(2.44℃).Meanwhile,soil temperature showed a fluctuating increase with increasing elevation and a gradual decrease with increasing depth of soil layer.(2)Soil moisture showed considerable variation within the growing season,with a general trend of increase and then decrease(2020),with the lowest soil moisture in May(0.164 m3·m-3)and the highest soil moisture in September(0.318 m3·m-3).(3)The variation of soil moisture increases with elevation and decreases with the depth of the soil layer.(4)The main meteorological elements affecting soil temperature are air tempera-ture and relative humidity,while soil moisture is mainly affected by air temperature and vapor pressure deficit.