| Mountain soil presents obvious spatial variability and the variability of soilnutrients depends on altitude, vegetation and slope direction. In this study, based on thefield investigations, I set some 30×30m plots of different slope direction, differentaltitude and different vegetation in Mountain Shegyla in the southeast of Tibet, where Icarried out survey on vegetation, dig soil profile, and collected and analyzed soil samples.I measured pH value and the content of OM, total nitrogen, total phosphorous, totalpotassium, available nitrogen, available phosphorous and available potassium of the soilsamples, and took statistical and correlation analysis on data with SPSS software. Theresults were as follows:1. The climate, vegetation and soil type of Mountain Shegyla presented obviousvertical distribution and the vegetation categories of Mountain Shegyla were complete.From the base of mountain to the top, the climate, vegetation and soil type varied frommountainous warmly-temperate zone—moist coniferous-broad leave mixed forest zone—mountain brown earths, mountainous warmly-temperate zone—cool-moist coniferousforest zone—mountain brown earths, sub-alpine frigid-temperate zone—cold-humiddark coniferous forest zone—mountain dark-brown earths(bleached podzolic soil inpart), alpine frigid-temperate zone—woodland, shrubby and meadow zone—mountainshrubby meadow soils, to alpine desert zone—mountaintop cold desert sparse vegetation—alpine frozen desert soil. 2. The results of statistics on the soil nutrients of Layer A showed that the overallsoil in Mountain Shegyla was acid soil, but soil nutrient content was high, especially richin OM, total nitrogen and total phosphorus. In the mountain, the soil nutrients of LayerA soil showed great vertical spatial variability, with the content of the total nitrogen,total phosphorus and available phosphorus were showing strong variability, while othernutrients were showing moderate variability. In the mountain, the content of soil pHvalue, total potassium, available nitrogen and available potassium presented normaldistribution, while soil OM presented approximate normal distribution.3. Mountain soil nutrients varied significantly according to different slopedirection. The mean value of the content of OM, total nitrogen, available nitrogen andavailable potassium in the east slope soil was higher than those in west slope soil, whileother nutrients in east slope soil were lower than those in west slope soil. Except totalpotassium content, the soil nutrient variability of east slope was lower than that of westslope. The mean value of the content of OM, total nitrogen, total potassium, availablenitrogen, available phosphorus and available potassium of the shady slope was greaterthan that of sunny slope. The soil nutrient variability of shady slope was higher thanthat of sunny slope except for OM and total phosphorus content.4. With the rise of mountain altitude, the variability patterns of soil nutrients wereas follows: the content of OM, available phosphorus and total potassium increases withthe rise of mountain altitude, while the content of available potassium decrease; pHvalue was lower in the middle of the mountain but higher on the top and the base; thecontent of total and available nitrogen varied in opposition to pH value; the content oftotal phosphorus was higher on the base, but had little difference in other places; thecontent of available phosphorus increased with the rise of attitude, while the content ofavailable potassium decreased.5. The result of the analysis on the profiles of four types of forest soils showed:(1) There was obvious variation between these four forest types. And the soil withrich vegetation or broad-leaves forest present higher content of soil nutrients in general.(2) The variability pattern of soil nutrients on the soil profile was as follows: thepH value of upper layer was lower than that of lower layer; the content of OM, total nitrogen and total phosphorus of upper layer was higher than that of lower layer; thecontent of total potassium and available phosphorus of the upper layer was lower thanthat of lower layer; the content of total phosphorus was stable, only lower on surfacelayer.6. The result of the analysis on Podzolic soil profile and alpine timberline soilprofile showed:(1)Podzolic soil mainly distributed in Abies holophylla-Rhododendron mixed forestin Mountain Shegyla within 3700-4200m in altitude. Podzolic layer (layer AB) moved upin soil profile with the rise in altitude, and its thickness decreased and disappears at last.The pH value of Podzolic soil was low, and the nutrient content of Podzolic layer wasusually low. The eluviation of soil nutrient was strong on soil profile.(2)The nutrient content of alpine timberline (Abies georgei var. smithii-Rhododendron spp. forest and Sabina saltuaria- Rhododendron spp. forest) soil wasvery high. The content of OM, total phosphorus and available phosphorus of the Lay Asoil in alpine timberline shady slope was the maximum in the overall soil of themountain. The nutrients of alpine timberline soil on shady slope were superior to thoseon sunny slope, but their nutrients in soil profile changed in the same pattern.7. The result of the analysis on correlation between soil nutrients showed:(1)Soil OM had a conspicuous positive correlation with total nitrogen, availablenitrogen, available phosphorus and a positive correlation with available potassium. Thelinear regression equation respectively was as follows:(?)TN=-0.079+0.035x(r=0.810**),(?)速N=-16.773+37.440x(r=0.710**),(?)速P=2.085+0.562x(r=0.443**),(?)速K=+206.976+5.251x(r=0.378*).(2)Soil pH value had a conspicuous negative correlation with OM, total nitrogenand available nitrogen. The linear regression equation respectively was as follows:(?)OM=26.215-3.537x(r=-0.546**) (?)TN=0.771-0.110x(r=-0.391**)(?)速N=1097.423-157.915x(r=-0.462**)...
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