Changes Of Nutrient Elements In Succession Sequence Of Soil And Plant Communities

The glacier retreat area is one of the most active and dynamic parts of the earth's surface system.The carbon accumulation process in the soil development in the glacier retreat area is obvious,and the soil is formed rapidly.In the process of formation of vegetation and soil,biological and non-biological factors have complex interactions.The study of soil nutrient migration and vegetation succession in glacier retreat areas is very important for revealing the mechanism of early ecosystem biogeochemical cycle processes.Studying the status of soil nutrients and primary vegetation succession in this region and understanding the synergistic relationship between them can provide theoretical guidance and data support for the management of damaged ecosystems and the realization of rapid and stable recovery.The study selected Hailuogou glacier retreat area.We selected five sampling points(1980,1970,1958,1930,1890)in the entire retreat sequence to collect rhizosphere and non-rhizosphere soil,aggregates,litter and plant samples.The analysis of physical and chemical properties and nutrients was completed at laboratory.We used statistical analysis methods to analyze the experimental results to study the characteristics of soil nutrients,plant nutrients and the synergistic changes of the them in the process of primary succession in the glacier retreat area.The characteristics of the vegetation development were also reaserched.The relationship between the above-ground and underground parts in the process will be understood.The main results and conclusions are as follows:(1)The proportion of large aggregates in A horizon(>0.25mm)gradually increased with the increase of soil development time,while in Chorizon,the proportion firstly increased with soil development time and then decreased at1930 and increased at1890.The concentration of C and N in soils showed a gradually increasing trend with soil development,while P showed a trend of increasing and then decreasing.The concentration of C and N nutrients in the rhizosphere soil was significantly higher than that in the non-rhizosphere soil.C:N and C:P both increased and then decreased,while N:P showed a gradual increasing trend.The concentration of available metal nutrients in the soil accounts for about one hundrud of the total,and Ca,Mg,Fe,Mn,and Cu gradually decreased with the development time increasing.However,Kdid not show a clear trend.The analysis of the factors which affects the concentration of different elements found that there is no significant correlation between soil C?N and soil physical and chemical properties,but P has a significant correlation with soil p H.The C?N and P are all related to the enzymes that cycles in the soil.For metal nutrients,whether in terms of total or effective content,soil physical and chemical properties,especially water content and p H,are the key factors affecting their concentration.(2)The analysis of nutrient concentration in typical plants(Hippophae,Populus purdomii,Piceabrachytyla)found that the nutrient content in plant leaves is higher than that in roots.There was no significant difference in the C and N concentrations in the needles of one-year Piceabrachytyla(Franch.)E.Pritz.The C concentration in the needles of three-year Piceabrachytyla(Franch.)E.Pritz was lower at the last point.At the last point,one-year Piceabrachytyla(Franch.)E.Pritz needles had the highest concentration of P.The concentration of elements in litterfall was lower than leaves and higher than roots.There was no significant difference in C? N and P in fine roots in the entire vegetation succession sequence.For metal nutrients,there was a difference in concentration between different sampling points in one-year Piceabrachytyla(Franch.)E.Pritz needles.But there was no significant difference for three-year leaves.Comparing the element concentrations in plants in the global and other Chinese regions,it can be found that the N content in Hailuogou glacier retreat areawas significantly lower than the average N content of the plants in the Chinese region.And P concentration is lower than the global average and the average plant P content in China.The results of the N:P analysis showed that there was no restriction of P in Hailuogou area.However,there may be restriction of N in this area.(3)The estimation results of the stock of C,N,and P in the soil-plant-litter found that the stock of C and N in the soil and plants gradually increased with the increase of the glacier retreat time,while the stock of P decreased slightly.The stock of Pwas gradually increasing in plants.The stock of C,N,and P in litter are lowerthan other plant tissue.The combined analysis of the available metal nutrient K and the K content in plants found that the K content in litter and fine roots was positively correlated with the K in the soil,while the K concentration in one-year Piceabrachytyla(Franch.)E.Pritzhad no clear relationship between different tissue.