广东省天然林资源近35年动态变化分析

依据广东省1978-2012年8次森林资源连续清查资料，以天然林面积、蓄积、公顷蓄积量为指标，从总体、林种、优势树种（组）、龄组结构等方面研究了广东省天然林资源近35a间动态变化，并分析了其原因。结果表明：全省天然林面积、蓄积总体呈增加趋势，年均增长率分别为0．73％、1．55％，其中天然林面积呈“降一升一降”的三阶段波动变化，天然林蓄积量保持增长；天然林林种由过去以商品林为主的结构逐步改善，生态公益林面积和蓄积比例稳步提高，到2012年分别达到45．94％和50．45％；优势树种（组）方面，阔叶林面积、蓄积比例由1978年的37．68％和45．17％。持续增加到目前的70．69％和75．03％，逐渐成为主要优势树种（组）；龄组结构方面，近、成过熟林的面积和蓄积比例由1978年的3．22％、8．98％大幅增加到2012年的20．31％、30．90％，但仍未改变以中幼龄林为主的格局；天然林分公顷蓄积量较1978年增加了47．26％，达到2012年的64．34m^3／hm^2，林地生产力不断提高。1983年和2002年是多个指标变化的拐点，表明导致天然林资源变化的主要因素为经济形势和政策。

Analysis on Dynamic Change of Natural Forest Resources in \=Guangdong Province in Recent 35 Years

The dynamic changes of natural forest resources from 1978 to 2012 in Guangdong province and its causes were analyzed and studied according to total status, forest category, dominate tree species group, and age structure. The data of area, volume and volume per hectare of natural forest were based on 8 periods continuous forest inventory data from 1978 to 2012. In general, natural forest increased with the average annual growth rate of 0.73% for area and 1.55% for volume. The results showed that area varied with a drop rise drop curve of three stages, while volume maintained steady growth. The forest category structure of natural forest with priority of commercial forests was gradually improved, meanwhile, area and volume proportion of ecological forest increased steadily to 45.94% and 50.45%, respectively, by 2012. The broad leaf forest gradually turned to be domain forest with a steady increase in its area and volume proportion from 37.68% and 45.17% in 1978 to 70.69% and 75.03% in 2012, respectively. It has been the main position of young and middle aged forests, although the area and volume proportion of near mature, mature and over mature significantly increased from 3.22% and 8.98% in 1978 to 20.31% and 30.90% by 2012, respectively. Volume per hectare increased by 47.26% since 1978, reached 64.34 m3hm-2 by 2012, which indicated that the forest land productivity was gradually improved. 1983 and 2002 were the changing inflection points of many indicators, indicated that economic situation and policy was the priory reason for varieties of natural forest resources.