| Urban forest is one of the most important parts of urban ecosystem, and plays an important role in ecosystem services function. This research is mainly focused on Wuhan's urban forest pattern and predicting its landscape pattern by using TM image of 1996 and 2007, DEM data of 2009 provided by SRTM, and road data of Wuhan city. Using Fragstats software to analysis landscape indices and its variation, using CA-MARKOV model to compute Wuhan's landscape pattern of 2018. By evaluating the suitability of 2018's Wuhan urban forest expansion area, we verified whether the prediction is reasonable. The results demonstrated:(1) The main landscape type of Wuhan city is farmland, while water and urban forest also have a big proportion, that is according with Wuhan city's ecological developing idea. As far as forest distribution is concerned, large scale urban forest mostly gathering in suburbs, such as Huangpi, Jiangxia, Xinzhou districts, while Huangpi district has the largest forest proportion of 27.6%; however, in the area of Jianghan and Qiaokou district, because of high density of population and frequently human activities, this two districts has a quite small proportion of urban forest, less than 2% in all, and with serious fragmentation.(2) During 11 years from 1996 to 2007, there are evident changes occur in Wuhan landscape pattern, the area of farmland and water has declined, while other landscape types area has risen up. This is mainly because lots of farmland transferred to other landscape types. In 1996,60% urban forest remained, and 24% urban forest transferred to 2007's farmland, with a fraction transferred to grassland and city. From 1996 to 2007, the area of urban forest has added 82790.82hm2, and mainly gathering Huangpi, Jiangxia, Xinzhou, Caidian districts where urban forest is originally plentiful.(3) Results of urban forest landscape indices indicate, patch number and landscape shape index has decreased, largest patch index has increased, while The average perimeter area ratio has dramatic decreased, from 714.38 to 492.07. This indicates the fragmentation of urban forest has alleviated, and the landscape pattern has improved after 11 years' forest construction. (4) By using DEM, slope, NDVI, landscape type, road and railway factor as resistance, we computed suitability image of urban forest construction. Result indicates that resistance of urban forest expansion is lesser from the city center to outside, from road center to outside, and from water center to outside, and large urban forest areas generally have less resistance. The order of area proportion of each resistance level is, 32.03% of level 2,29.07% of level 3,22.79% of level 4,10.8% of level 1, and 5.31% of level 5, this data indicates Wuhan has great potential to build urban forest.(5) The prediction of Wuhan 2018's landscape pattern shows, all landscape type will keep the variation tendency as 1996 to 2007, the area of farmland and water will decrease while other types of landscape will increase. Furthermore, the distributions of the spreading area are basically expanded from the original landscape area.(6) Urban forest area has increased 25603.2hm2, from 2007 to 2018. More than 65% expansion area concentrates in level 1 and level 2 where has lowest resistance, while in high resistance region of level 4 and level 5, expansion area has a very small proportion of 6.13% and 0.25% respectively. This result indicates that the prediction of CA-MARKOV model is reasonable. However, different suitable level has different contribution to urban forest expansion, in general, contribution proportion decrease as the suitable level goes down, with 5.40% of suitable level 1,4.87% of level 2,3.15% of level 3, only 0.88% and 0.16% in the level 4 and level 5. Result shows that the prediction of Wuhan 2018's urban forest pattern is creditable, and in line with the principle of urban forest construction. |
PDF Full Text Request