The Effect Of Management Modes Of Rocky Desertification In Southwestern Hunan To Soil Microbial Biomass And Enzyme Activity

Rocky desertification in karst area has not only exacerbated the deterioration of the environment, but also become important factor that limits of socio-economic sustainable development in many regions. Soil microbial and enzyme activity are important components of forest ecosystems. Materialre cycling and biochemical processes involved in the ecosystem are important indicators to reflect soil fertility. This study takes different modes in the region of karst rocky desertification in southwestern Hunan as objectives, by using sample survey design and laboratory analysis methods, and ocuses on comparative study of soil microorganisms, number of microbial biomass and soil enzyme activities, under different management models, to improve research on ecological restoration in the region of rocky desertification, and to rich the content of Restoration Ecology. The main results of the research are as follows:1. The average soil bulk density of POPF (1.60g/cm3) is the highest and KPPF (1.38g/cm3) is the lowest in different management modes land, Soil bulk density of different management models increases, with the increase of soil depths. The differences of soil water content between the different management modes soil (0-15cm) reached significant levels (p<0.05). For0-30cm soil layer, the average of soil water content is between16.03and23.73%, KPPF is maxinmum, POPF is minimum. The soil pH value increased with increasing soil depth, with the other four kinds of management modes neutral or weakly alkaline, except that LPMF is weakly acidic. The average levels of differences between different management modes soil (0-15cm) layer of organic matter was significantly (p<0.05), In addition to closing off outside, the monthly change in trend is basically the same,(0-30cm) soil average content varied from24.65to40.63g/kg, pure woodland Luan tree maximum, Liquidambar+wetland pine mixed forest minimum. For the total nitrogen content of (0-30cm) soil under different management, KPPF is maximine (2.00g/kg), and LPMF (1.06g/kg) is minimum. But the difference was not significant (p>0.05), and monthly variation in total N content is basically the same with monthly changes of soil organic matter's content. The total P content's differences of soil layers Between different management modes are not significant (p>0.05). For0-30cm soil layer, K's total content is2.49- 3.32g/kg, the average content of Ca's2.62-21.30g/kg, and Mg's content3.64to4.16g/kg.2. Bacteria is most among the number of soil microbes under different management modes, accounting for more than84%of the total number of soil microbial, followed by Actinomycetes, accounting for between6.38-14.28%, and Fungi is least, only from0.37to0.79%. Number of different management modes soil microbial obvious differences in differences between the different months, but the monthly variation are not obvious, the number of Bacteria of the overwhelming majority in May, Fungi, Actinomycetes in November. Soil microbial(0-30cm) total number of Bacterial counts in LPMF to a maximum, KPPF land at least, the number Fungi of KPPF up to, LPMF at least, Actinomycetes count to PLMF to a maximum of LPMF to a minimum.3. Different management modes soil biomass carbon, nitrogen content increased with soil depth is reduced, but the difference was not significant (p>0.05) between the different soil, different management model soil (0-30cm) layer of microbial biomass carbon LPMF the highest, NRF to the minimum, and the average content of the same soil layer microbial biomass carbon were no significant differences (p>0.05). Soil (0-30cm) layer of microbial biomass N to the highest KPPF, POPF minimum, but the difference was not significant (p>0.05), and the average content of the same soil layer of microbial biomass N was no significant difference (p>0.05).4. Soil enzyme activities of the different management modess (except the outside of the catalase activity) decrease with the increase of soil depth, the same soil urease activity are KPPF highest, PLMF a minimum, but the differences were not significant (p>0.05),0-15cm layer soil invertase activity, the highest NRF to the lowest LPMF, and the difference between the highest and lowest reached a significant level (p<0.05), catalase activity KPPF to the highest, the LPMF lowest, but no significant difference (p>0.05), alkaline phosphatase activity of the LPMF to the highest PLMF to a minimum, between the highest and lowestthe difference reached a significant level (p<0.05). Soil urease activity and monthly variation is not entirely consistent, but the highest activity occurred mainly in July, down to a certain extent in November. Soil invertase activity in the large difference in different months, at a higher value is basically May, July; November, January month at a low value. Soil catalase enzyme activity overall performance of the highest in September, other months no significant difference. The maximum alkaline phosphatase activity in January.5. Between the number of different management modes of soil microorganisms and soil nutrient, there is aclear correlation, NRF, PLMF, LPMF of bacteria, actinomycetes there are significant between the total number of bacteria, microbes and organic matter of correlation KPPF, the total number of POPF soil microbes and organic matter correlation is not significant, KPPF only soil fungi and organic matter was significantly correlated. The number of bacteria and total N in NRF and POPF of soil is significantly correlated, KPPF, PLMF, LPMF of soil actinomycetes and total N correlation significantly, with the exception of the POPF, LPMF soil actinomycetes count of Mg, the total K content significantly, the management modes soil microbial quantity and total P, total K, all of Ca, Mg do not exist in a significant correlation.6. Soil urease enzyme, catalase, invertase, phosphatase of the enzyme and nutrient content exists a certain correlation with the soil the total K, Mg content mostly significant negative correlation, and soil organic matter, total N total P content of more thanshowed a significant positive correlation.Except that soil phosphatase enzyme activity, soil bacteria, fungi, actinomycetes was significantly correlation the other three enzyme activities with bacteria, fungi, actinomycetes bacteria count related to sex are not significant with, soil phosphate enzyme, urease, sucrose enzyme, hadwas significant or very significant correlation between catalase activity and SMBC, SMBN, SMBC, and SMBN showed a significant correlation between soil bacteria and actinomycetes showed a significant correlation.During the early period of Rocky desertification's comprehensive management, NRF and KPPF show obvious advantages in soil nutrients, soil microbial number, soil microbial biomass, and enzyme activity, LPMF is more prominent in soil microbial quantity and phosphatase activity, and PLMF also presents certain advantages in Soil microbial quantity and the invertase activity. All above shows that different management modes are of various characteristics for the evolutionary process of soil quality under the situation of rocky desertification.