Research On Soil Micro-ecological Environment In Casuarina Equisetifolia Woodlands Of Different Stand Ages

Recently, the study of Casuarina equisetifolia were more focused on the casuarinasallelopathy, such as the poison effects and influences on other plants (microbial), but therewere no comprehensive research on C. equisetifolia woodland soil micro ecologicalenvironment. In order to closely combining the actual demand of coastal forest of Hainanprovince, this paper chose the bare land as control, young stand, middle-age stand, and maturestand of C. equisetifolia woodland were test to analyze the soil nutrient, physical andchemical properties, and the microbial biochemical activity intensity. At the same time we usethe traditional classic methods for the separation of soil bacteria, fungi, combined with theBiolog system for the species identification and the function of soil microbial diversity.Furthermore, by using the method of454sequencing technology, we get the microbialmetagenomic sequences. Under the condition of different growth of C. equisetifolia plantationage, woodland soil bacterial community were revealed. The main research results are asfollows:1. With the increase of stands age, the total nitrogen decreased. but significantly higherthan ck, increase the soil total phosphorus and total k did not change significantly, Meanwhile,C. equisetifolia woodlands water content was higher than ck, with strong storage capacity,soil bulk density between ck and C. equisetifolia woodlands was different significantly, but inC. equisetifolia woodlands of different stand ages were not significant, soil bulk density ineach woodland was1.27-1.30g·cm-3, with the increase of stands age, the soil pH is reduced,Organic matter, NH4+, NO3-content, respiration and nitrification of middle-age stand werehigher than other forest, suggested that soil micro ecological environment for the growth ofplants is better in middle-age stand.2. The biochemical active strength results that the woodland forest of ammonification ofmature stand was significantly higher than ck, the nitrification of young stand wassignificantly higher than other woodland. The ammonification and nitrification were notsignificantly related to NH4+, NO3-content, rather than total nitrogen. Furthermore, theammonification and nitrification of soil microorganism were related to soil environmentalconditions and the species of microorganisms were related to the organic nitrogencompounds.3. Based on the daily variation of soil respiration monitoring, the results showed that the diurnal variation of the soil release CO2dynamics, soil respiration intensity firstly increasedand then decreased. In the forest middle-age stand and mature stand’s, the respiration rate wassignificantly higher than young.Meanwhile, C. equisetifolia forest was significantly higherthan ck, it indicated that the total respiration rate of C. equisetifolia forest was larger than ck.From the results, the conclusion could be induced that he number of plant roots, microbial andsoil animals of casuarina was more than ck.4. By using the method of traditional classic of four woodland soil separation andidentification of microorganisms, a total of23bacteria strains and11fungi strains wereisolated,6bacteria strains and4fungi strains were in control soil;6bacteria strains and2fungus strains in the Young stand;7bacteria strains and2fungi strains in the middle-agedstand;4bacteria strains and3fungus strains in the mature stand.5. The soil microbial carbon utilization was higher in bare land and the mature stand thanthe middle-aged and young stand. With increasing stand age, the values of Shannon-Wienerindex (H’) and McIntosh and Simpson diversity indices all increased. The H’ significantlydiffered among different woodlands. However, there were no significant differences in theMcIntosh and Simpson diversity indixes between the young and middle-aged stand. Principalcomponent analysis demonstrated that there was a significant difference in the soil microbialmetabolic activities among different woodlands, in particular concerning Monosaccharide andamino acids. The soil microbial community diversity increased with increasing stand age,which might be due to a joint action among many factors such as litter, the secondarymetabolites of plant root secretion, soil nutrients, and specific soil microorganisms.6. After further study by Roche454platform sequencing, we got65328effectivesequences. We obtained4767OTUs, through OTU abundance of PCA analysis showed thatthe different between young and bare land at close range, The results of clustering analysis theyoung forest were clustered with control, other two kinds forest were clustered two classesseparately. Furthermore, we also found the different forest age C. equisetifolia woodland soilshowed different characteristics of micro ecological environment along with the increasing offorest age.