| The forest, as a most complex functional system, has played very important role in the global carbon balance, urban forest defined as the sum of all woody plant trees and their associated plants in urban and peri-urban region is the part of forest resource. In order to construct the city forest having higher ecological value and better functions of improving city environment, a comprehensive and logistical planning for urban forest system is need, However it is not realistic to think that if lack the current information of urban forest vegetation. The carbon storage ability and pattern of trees and woods in city should be the part of the knowledge.This essay, The carbon storage and carbon density of urban forest were estimated using remote sensing technology combined with field survey in urban district of Ma’anshan City, The study area covered340km2, among buildup area of67km2. Through interpreting Ma’anshan City’s TM image by ArcGIS, ERDAS IMAGINE and other software, this paper illustrated the urban forest distribution status of2010, and determined the dynamic of NDVI distribution in1989,1995,2010respectively. The City forest was grouped into4major categories:Park, hill forest, street trees and others. Because of pixel resolutions of30m, only the patches>900m2in area were distinguished.In April2010, total sample boxes were randomly located in the different urban forest categories across the city and field survey was taken for each trees in sample, such as species, DBH and height of every tree were recorded, meanwhile the geographical coordinates of each sample was identified with GPS.The biomass of individual tree in sample was accounted by biomass equation with DBH and tree height, then total biomass of a sample stand could be estimated. A regulation describing the correlation between biomass and NDVI was built. Through the regression model, using the inversion method can get the2010,1995and1989biomass distribution map of Ma’anshan City. Analysis urban forest biomass of various types in Ma’anshan City in2010,compared the dynamic changes of the biomass from1989to2010in the20years in Ma’anshan City. The0.5of transformation coefficient that transformed from biomass to carbon content was employed. Based on this process the total amount of carbon storage and that of different forest types were accounted in the paper. The results as follows:(1) In2010total urban forest patches covered11477.07hm2in the study area, accounting for33.76%of the district area. Among them:hill stand is5874.105hm2, accounting for17.28%; the park is215.78hm2, occupied0.63%; main street trees covering an area is288.38hm2, accounting for0.85%of the district; in addition to other class is 5215.44hm2, occupy15.34%.(2) The relevance regression between biomass of urban forest stand and NDVI was built as y=123.02×10761. The total carbon storage of urban forest patches reached to2.874×105t in study area, The average carbon storage achieved25.041t/hm2for forest stand, and is8.453t/hm2for study area.In2010, the distribution characteristics of carbon storage in whole study area showed that the most part of carbon storage concentrated in the city hill forest, which reached to1.496×105t, occupy52%of the total carbon storage; the park with a total of2.567×103t, accounted to0.9%of total carbon reserves; the street trees along the main roads had total carbon storage of3.530×103t, occupied1.2%of whole carbon storage in the study area; other types of total carbon,1.317×105t, total carbon reserves of45.8%. The carbon storage contribution to study area was very different for different types urban forest it ranked as hill forest> other> street trees>Park. This order was similar to area contribution to study area for the different urban forest types is City forest> other> street trees>Park. In general, the contribution of urban forest carbon storage was related with the its size.(3) Based on the biomass amount per hectare land, the land was divided into the following5classes:None biomass, or Ot/hm2; rarely, the value is>0～<20t/hm2;less, the value is>20-<40t/hm2;more, the value is>40-<60t/hm2; mast, the value is>60-<84.951t/hm2. Each grade in proportion to the entire study area is1.18%>22.70%>17.71%>27.03%and31.38%respectively in2010. The proportion of the land area with>0-<20t/hm2decreased from77.83%in1989to25.02%in1995; that with biomass of>20～<40t/hm2increased from17.60%in1989to48.19%in1995, increased by1.7times. That having>40～<60t/hm2of biomass increased from0.30%in1989to25.33%in1995, increased84times. The other with>40～<60t/hm2of biomass increased from0.07%in1995to31.38%in2010, increased447times. The still other with>20-<40t/hm2of biomass dropped down from48.19%in1995to17.71%in2010, down1.56times. |
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