| Rare and endangered plants have experienced a long process of survival of the fittest in natural selection, which recorded the changes of the ancient biological environment. This study has important significance for the ancient geology, the ancient climate and the ancient biology. The water temperature, climate, geology, landform and soil environment were very advantageous to the endemic plants growing and multiply in Mount Fanjing Nature Reserve,The soil physical and chemical properties restricted the growth of forest vegetation and the level of forest production.Through analyzing, this paper a conclusion that soil environment characteristics and soil physical and chemical properties of Abies fanjingshanensis, Davidia involucrata Baill and Taxus wallichiana var. mairei in Low Latitude and High Altitude Area.The results showed that:(1)The soil physical clay of the three endangered or rare plant species( Davidia involucrata Baill、Taxus wallichiana var. Mairei、Abies fanjingshanensis)were 57.07%、47.83% and 25.71%, the soil texture landscape was ranges from heavy loam to light clay,from medium loam to heavy loam and from sandy loam to medium loam. The soil physical clay of the CK1,CK2,CK3 were 51.30%, 61.72% and 49.43%. The three rare plants forest soil structure better than CK and conducive to the growth of rare plants. Soil physical clay contents decreased with increasing of elevation, the soil texture landscape was composed of light clay, heavy loam, medium loam and sandy loam with increasing of elevation gradually.(2) The range of silica-alumina ratio(K)>4 in three endangered or rare plant species forest soil.and smectitic clay is major in these soils. The asilica alumina ratio and comprehensive indicate the degree of development in Davidia involucrata Baill forest soil higher than the CK1. The asilica alumina ratio and comprehensive indicate the degree of development in Taxus wallichiana var. mairei forest soil lower than the CK2. Total silicon,aluminum in Abies fanjingshanensis forest soil was significantly lower than CK3, silica alumina ratio>CK3, the soil processes and the degree of development still slightly different between Abies fanjingshanensis forest and CK3. The result shows the soil total silicon(TSI),totel titanium(TTI), aluminum(Al), total magnesium(TMG) were gradually increased inabundance, and total sulfur(TS) was gradually decreased, total calcium(TCA) was decreased first then increased, and total iron(TFE) showed the opposite trend with decreasing elevation.The high content of clay soil decreased, with fertilizer and water leaching in Davidia involucrata Baill, the ions of Ca、Mg, which weren’t easy to infiltrate, and concentrate in the surface layer of soil. The north side of the ridge slopes broken landscape, high soil humidity,especially big slope degree, were to reduce the soil clay, nutrients contensts. and a large amount of organic matter accumulated, This indicated that the soil was aluminum-silicon yellow brown earth. The results showed that the soil was yellowing and developing allitization in Davidia involucrata Baill and Taxus wallichiana var. mairei forest soil, which indicated that the soil was aluminum-silicon yellow brown earth.(3) Low contents of TP, TK were main nutrient limiting factors in rare plant forest,which reduced the supply source of AP and AK, the other nutrients were suitable or rich. The three endangered or rare plant species forest soil were acidic or extremely acidic. All soil CEC content is higher than CK. TP and TK of Davidia involucrata Baill and Abies fanjingshanensis forest soil was lower than CK, and composite nutrient was better than CK.The content of AK and CEC of Taxus wallichiana var. mairei forest soil is higher CK2, and the other nutrients is lower than CK2.(4)There was a significant positive correlation between the content of coarse sand and AP in Taxus wallichiana var. mairei forest soil. The correlation analysis indicated p H showed the significant negative correlation with medium silt, physical clay and clay. Soil sand and AK in Davidia involucrata Baill forest soil was significantly positive correlation. The positive correlations between AK content, p H and soil sand, and the latter had a significant negative correlation with the content of AP. Fine sand content was the mighty prominent negative correlation with TP content and had a significant positive correlation with AN content, the results showed that TP and AN were concentrated in fine sand. The correlation was found between Medium silt and AN content was significant positively, and was significant negatively with TN content. Fine silt content was the mighty prominent negative correlation with p H, and was positively related to TK content. Clay was significantly negatively correlated with AN content. Physical clay was the mighty prominent positive correlation with AP content, and was negatively related to AK content. TK content and coarse silt was significantly positive correlation, and was highly significantly positively correlated with fine silt. Physical clay was the mighty significantly negative correlation with AP content.Fine sand was negatively correlated with TP content and positively correlated with CEC.Medium silt and fine silt was negatively correlated with p H, respectively. clay was significantly negatively correlated with the content of AP.(5)The C/N, C/P and N/P ratio in Taxus wallichiana var. Mairei and Davidia involucrata Baill forest soil were more than CK. In Abies fanjingshanensis forest soil, the C/N ratio was lower than CK3, the C/P ratio and N/P ratio were more than CK3. The decomposition rate of soil organic matter in Taxus wallichiana var. mairei soil was higher than Taxus wallichiana var. maire’s,which was almost equal to Davidia involucrata Baill. The content of AP in Davidia involucrata Baill soil was higher than others, and it was the lowest in Abies fanjingshanensis soil.The effectiveness of phosphorus in all forest soil were lower than CK.The decomposition of SOM was an agonizingly slow, which restricted the release rate of AP in soil organic matter.(6)The activity of soil enzyme have evident plumb distributing in the three endangered or rare plant species forest soil. Davidia involucrata Baill’s urease, catalase and polyphenol oxidase activity>CK1, phosphatase activity<CK1;Taxus wallichiana var. Mairei`s urease activity> CK2, the other enzyme activity <CK2. The soil polyphenol oxidase activity was almost same in Abies fanjingshanensis and CK3, the remaining enzyme activity was slightly lower than CK3. Catalase activities and phosphatase activities had a significantly positive correlation in Davidia involucrata Baill forest soil. Catalase activities had a significantly negtive correlation with urease activities in Abies fanjingshanensis forest soil. Between enzyme activity and mechanical composition, nutrients have better correlation in Davidia involucrata Baill forest soil, and have poor correlation in the other two woodland.(7)The characteristics of the soil environment of Abies fanjingshanensis forests dead plot(DP) and living plot(LP) showed that the average contents of soil nutrients was no difference between the two speciesof forest soil,total phosphorus content was deficient,and the other nutrients contents were abundant. Sand content was higher in Dp, which reduced the soil’s ability to keep the fertilizer, and soil will be more vulnerable to soil erosion,The distribution of TP and CEC contents in soil were uneven, on the contrary, they were uniform in Lp. The distribution of soil particle and nutrient contents were reasonable, which increased the effective nutrient mobility, and suitable for plant uptake and utilization, Meanwhile, the loss of soil and water has increased.The activities of catalase and phosphatase in Lp soil were higher than Dp, However, Catalase activities in Dp soil was higher than Lp. There was little difference in the activities of polyphenol oxidase in the two Plots. The higher activities of urease and phosphatase were beneficial to nutrient decomposition and absorption. There wasa significant correlation between urease activity and SOM, Sand and polyphenol oxidase activity was significantly positive correlated in Lp, The correlation between soil enzyme activity and soil particle composition and the other nutrients were not significant,TSI and Tal contents were in Dp and Lp of Abies fanjingshanensis forest soil higher than others, the contents of TMg, TFE, TTI and TS were higher in Lp than Dp. The all ratios of silicon and aluminum in soil were than four, the ratio of silicon and aluminum in LP(7.04)was higher than in Dp(6.23), smectitic clay is major in these soils. The soil mineral weathering degree was low in Mount Fanjing,The wet and Alpine soil environment cuased slow soil formation and resulted in the soil layer has thinned in Abies fanjingshanensis forest soil eventually. |
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