Research Of Carbon And Nitrogen Storage Of Rubber And Eucalyptus Plantations In Hainan Island

Rubber and eucalyptus plantations,as the main artificial forests in Hainan island,play an important role in maintaining the stability of the ecological system in the area and ensuring the normal play of the ecological effects.This study estimated the carbon and nitrogen storage of Hainan different ages rubber(5、10、15、20、25、30 year)and eucalyptus(2、4、6 year)plantation ecosystem,and analyzed its spatial distribution pattern,which was based on the field investigation and taking county and city as the standard.At the same time,it evaluated the carbon sequestration capacity of rubber forest and eucalyptus forest in each region from the carbon sequestration rate and carbon sequestration potential of these two indicators of the initial estimate.Finally,according to the data of the survey(2011)and review(2015)period,the change of carbon storage of rubber forest ecosystem in Danzhou area was analyzed.The main results are as follows:(1)The average level of every stand age ecosystem carbon storage were 139.21、145.71、151.23、185.37、223.04、248.68 t hm-2;while the nitrogen storage were 10.76、10.39、9.58、8.74、10.07、12.38 t-hm-2.Among it,the carbon storage of the tree layer accounted for 10.36%～53.38%,and the nitrogen storage of the tree layer accounted for 1.30%～10.65%,the proportion increased with increasing age;The average carbon storage in understory layer was 0.897±0.213 t·hm-2,while the nitrogen storage was 0.0446±0.0056 t·hm-2;The average carbon storage in litter was 1.018±0.239 t·hm-2,and the nitrogen storage was 0.0612±0.0078 t·hm-2,understory and litter layer made the least contribution to the carbon and nitrogen storage.The carbon storage of the soil layer accounted for 45.76%～88.18%,and the nitrogen storage of the soil layer accounted for 88.46%～97.54%,The carbon and nitrogen storage of the rubber plantation ecosystem was mainly concentrated in the soil layer.(2)The total carbon and nitrogen s torage in Eucalyptus plantation increased with the increasing forest age,and the carbon storage were 102.92±25.34、145.30±30.12 and 183.47±45.69 t·hm-2,the nitrogen storage were 10.26±2.38、1.49±3.33 and 12.53±3.61 t.hnr2.Among it,the carbon storage of the tree layer accounted for 1.87%-29.35%,and the nitrogen storage of the tree layer accounted for 0.11%-3.67%,it showed significant differences,and increased with age.The average carbon storage in understory layer was 0.864±0.233 t·hm-2,while the nitrogen storage was 0.0379±0.0076 t·m-2;The average carbon storage in litter was 1.056±0.189 t ·hm-1,and the nitrogen storage was 0.0416±0.0102 t·hm-2,understory and litter layer made the least contribution to the carbon and nitrogen storage.The carbon storage of the soil layer accounted for 69.39%-96.39%,and the nitrogen storage of the soil layer accounted for 95.76%～99.13%,The carbon and nitrogen storage of the rubber plantation ecosystem was mainly concentrated in the soil layer.(3)The carbon sequestration rates of Hainan rubber plantation were 4.73 and 5.27 Mg hm-2·a-1,respectively,and the carbon sequestration potential were 66.65 and 79.70 Mg hm-2,respectively.Compared with the rubber plantation in Xishuangbanna and the Southeast Asia tropical rain forest,the carbon sequestration rate was small.The carbon sequestration rates of Hainan eucalyptus plantation were 11.82 and 20.14 Mg hm-2·a-1,respectively,and the carbon sequestration potential were 27.35 and 39.58 Mg hm-2,respectively.The carbon sequestration rate of Eucalyptus in Hainan Island area was greater than that of the local rubber forest and the tropical rain forest in South East Asia.(4)According to the analysis of rubber plantation in Danzhou in 2011 and 2015,it showed that:The growth of carbon storage in tree layer of 5.10.15.20-year were 18.80(143.73%)、6.10(12.63%)、17.58(31.01%)、26.26(44.23%)t·hm-2relatively.While the 25 and 30 year old rubber plantation tends to aging,rubber latex reducing productivity,so the forests were neglected.Considering the severe influence of typhoon and some trees had been cut down,carbon storage decreased.During the review period,the soil carbon storage was significantly higher than that of the investigation period.The growth of carbon storage in plantation ecosystem of 5、10、15、20-year were 50.05(53.45%)、43.25(26.46%)、69.75(52.78%)and 43.73(28.88%)relatively.