湖南省马尾松林生物总量的空间分布与动态变化

Spatial distribution and dynamic changes of total biomass quantity of Pinus massoniana forests in Hunan province

根据湖南省2006～2011年森林资源统计年报数据，分别采用相对生长方程和材积源法，估算湖南省马尾松林生物总量、各地市（州）的分布及动态变化。结果表明：相对生长方程估算的湖南省2006年的马尾松林的生物总量为66．87×10^6t，2011年为71．18×10^6t，上升了4．31×10^6t；材积源法估算的全省马尾松林生物总量由2006年45．15×10^6t下降到2011年39．12×10^6t，相对生长方程估算的平均值50．98t·hm^-2比材积源法的33．36t,hm-2高。2006～2011年间，全省幼龄林和中龄林的生物总量呈下降趋势，近熟林、成熟林和过熟林的生物总量呈上升趋势，西南部和南部马尾松林生物总量较高，北部和东部较小。14个地市（州）中，怀化市马尾松林的生物总量最高，2011年达7．86×10^6t；衡阳市最小，2011年仅0．92×10^6t。2011年湖南省马尾松林平均单位面积的生物量为31．61t·hm^-2，与2006年相比，下降了0．23t·hm^-2，低于我国森林生物量平均值（86．3t·hm^-2）。如何通过合理经营、调整马尾松的林分和林龄结构提高林分生物量是林业生产中需要解决的问题。

Pinus massoniana forests play an important role in carbon storage and sequestration of regional and national scale because of their large forest area in China. Both general allometric equation and volume conversion function were used to estimate total stand biomass and average stand biomass ofP massoniana forests in Hunan Province, based on the data from forest resource inventory during the period from 2006 to 2011. The results show that total stand biomass of P massoniana forests in Hunan estimated by allometric equation increased from 66.87 ×10^6 t in 2006 to 71.18 ×10^6t in 2011, but the values estimated by volume conversion function decreased from 45.15 ×10^6 t.hm2 in 2006 to 39.12 ×10^6 t·hm^-2 in 2011. Average total stand biomass estimated by allometric equation was higher than that estimated by volume conversion function. The differences in the values estimated by two methods could be attributed to the increase in area of mature and over-mature stands and the underestimated stand biomass by volume conversion function. Total stand biomass of young and immature age-class forests decreased while those of near-mature, mature, and over-mature age-class forests increased during the period from 2006 to 2011. Spatially, total stand biomass of P massoniana forests tended to decreased from southwest and south parts to north and east part. Among 14 cities at prefecture level in Hunan province, Hualhua had the largest total forest biomass （7.86 ×10^6 t·hm^-2） ofP massoniana forests in 2011, and Hengyang had the smallest total forest biomass （0.92 ×10^6 t·hm^-2） of P massoniana forests in 2011. Average stand biomass ofP massoniana forests （31.61 t·hm^-2） in Hunan in 2011 was lower than the average stand biomass of the forests （86.3 t·hm^-2） in the whole country. To raise stand biomass ofP massoniana forests through forest structure adjustment and appropriate management is of fundamental for the forestry practices in Hunan Province.