【作者】 张国斌；

【导师】 刘世荣；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2008， 博士

【摘要】 森林是地球上重要的陆地生态系统之一,森林在全球碳平衡和减缓全球气候变化方面发挥着不可替代的作用。在森林碳循环与碳储量的计算方法上,材积源-生物量法具有广泛的应用基础并能满足估算精度要求,利用森林资源清查数据和优势树种（组）材积源-生物量关系进行碳储量估算,也是政府间气候变化专门委员会（IPCC）推荐的国家和区域碳计量计算较好方法。岷江上游是典型的亚高山区,该区域的森林碳储量大小、组成及动态变化状况具有北半球中高纬度和亚高山的森林特点,在地理区域和森林类型方面有较强的代表性。本文通过研究该区域森林乔木层碳储量的组成、动态变化及优势树种组（暗针叶林）的生物量碳密度变化及老龄林生物量动态特征,分析了碳储量动态变化的影响因素,目的是揭示岷江上游亚高山区森林地上碳储量分配特征及其动态变化的影响因子,可为利用森林资源清查数据进行区域碳储量研究提供范例。主要内容包括以下几个方面:（1）研究表明岷江上游现有森林面积8.39×10⁵hm2,碳储量5.87×10⁷Mg·C,其中针叶林碳储量占84.73%,阔叶林碳储量占15.27%,岷江上游森林平均生物量碳密度为69.97 Mg·C·hm^-2,冷杉林所占面积和碳储量最高,碳密度最大。防护林面积和碳储量最大,特用林碳密度最高。人工林面积和碳储量分别占天然林面积和碳储量的20.3%、7.95%,人工林碳密度为天然林的37.80%。人工林面积所占比例相对较高,而碳储量与碳密度却较小。岷江上游碳储量主要集中在成、过熟林当中,占林分总碳储量的72.21%,碳密度随龄组的增大而增加。岷江上游林业用地和有林面积所占比例较高,但各县分配不均,森林平均覆盖率为34.50%。（2）岷江上游森林在1992-2006年期间,碳储量增加了10^.32×10⁶Mg·C,平均年增长率为1.52%,年固碳量为0.1².0×10⁶Mg·C·a^-1,森林面积增加了38.82%,碳密度从80.06Mg·C·hm^-2降低到69.97Mg·C·hm^-2,平均年降低0.9%。冷杉面积和碳储量所占比例不断下降,云杉面积和碳储量所占比例不断增加。用材林面积和碳储量减少,防护林面积和碳储量不断增加,特用林面积、碳储量及碳密度呈现增加,其他森林类型碳密度呈现下降。岷江上游碳储量在成、过熟林中所占比例不断下降,幼龄林、中龄林和近熟林所占比例呈不断增加的趋势,但目前仍然是成、过熟林碳储量所占比例高;中龄林和近熟林生物量碳密度呈现增加趋势,幼龄林、成、过熟林碳密度呈现下降趋势。在此期间林业用地面积和有林地面积不断增长,森林覆盖率增加了9.66%。（3）岷江上游暗针叶林中的成熟林、过熟林生物量碳密较高,中龄林、幼龄林生物量碳密度较低,成熟林、过熟林生物量碳密度高于全国平均水平,而中龄林和近熟林低于全国平均水平,幼龄林与全国平均水平相近;中龄林生物量碳密度年增长率最大,为1.3%,其次过熟林生物量碳密度年增长率为0.8%,幼龄林生物量碳密度年增长率最小,为0.7%;海拔3600～3800 m的生物量碳密度最大,明显高于其他海拔区段;海拔3000～3400m处的生物量碳密度年增长率最高,为1.03%;半阴坡和半阳坡的生物量碳密度高且年增长率大,阳坡生物量碳密度低,年增长率小,阴坡界于两者之间;过去20多年,岷江上游暗针叶林生物量碳密度呈现逐年增加的趋势,1997-2002年,生物量碳密度年平均增长率为1.15%,高于其他调查期间碳密度年增长率。（4）1988-2002年期间,老龄林地上生物量密度净增量为27.311±15.58Mg·hm^-2,平均每年增长率为1.930±1.091Mg·hm^-2·year-1 ,平均每年枯损率为2.271±1.424Mg·hm^-2·year-1;地上生物量变化受各径级保留木生长量、枯损量及进界生长量影响,其中20～40cm径级保留木生长量与生物量净增量最大,>80cm径级生物量增量最小,40～60和60～80cm径级生物量在调查期间净增量出现负增长;岷江上游老龄林地上生物量动态变化具有时空间异质性,同一样地在不同调查间隔期或同一调查期间不同样地间生物量变化不同,不仅是增量数值大小差异,还表现为生物量增量的正负差异。（5）通过因子分析等方法分析气候因子、海拔、人口、森林年龄、面积和碳密度等要素对岷江上游森林碳储量的影响。表明温度和降水与碳储量呈正向关系,降水影响更大,海拔与碳储量呈负向关系;人口密度与区域碳密度呈对数下降关系,随着人口密度增大碳密度呈下降趋势;森林年龄是影响碳储量的内在因子,区域整体各龄组碳储量增加而碳密度在幼龄林、成、过熟林呈现下降,固定连续调查样地各龄组碳储量与碳密度呈现增加;森林储量变化主要受森林面积和碳密度影响,岷江上游碳储量积累主要来自于森林面积的增加,森林碳密度在研究后期呈现增长。更多还原

【Abstract】 As one of the most important terrestrial ecosystems, forest ecosystem plays an irreplaceable role in balancing the global carbon budget and mitigating negative impact of global climate change. Among different approaches of measuring forest carbon cycling and carbon storage, the volume-derived method using forest resources inventory data （FID） and the relationship between dominant tree species （or species association） and its biomass have been widely applied with high accuracy. Therefore this method was recommended by the Intergovernmental Panel on Climate Change （IPCC） to calculate carbon storage at the national and regional scales. With the typical forest type, forest composition, dynamics and carbon storage size in the Valley of the Upper Minjiang River （UMR）, the local at the sub-alpine area, is similar to those in the middle-high latitude of the Northern Hemisphere and sub-alpine mountainous area. By studying the dynamics and composition of carbon storage in tree layer, biomass density change of dominant tree species and biomass dynamics in old-growth forests, the factors influencing carbon dynamics in the UMR were determined and the carbon allocation features were addressed. The results provide useful information for regional carbon estimating. The major results are summarized as follows:The total forest carbon storage has increased by 0.32×10⁶ Mg·C in the UMR from 1992 to 2006 [check whether this is your original meaning] with the average annual forest growth rate of 1.52 %, which converted to the annual increment of 0.1².0×10⁶ Mg·C·a^-1, forest area increasing of 38.82 % while biomass carbon density（BCD） reducing from 80.06 Mg·C·hm^-2 to 69.97 Mg·C·hm^-2 resulting from an average annual reduction rate of -0.9 %. The proportions of area and carbon storage of fir （Abies spp.） forest were declined,and the proportions for Picea spp. forest were increased. Timber forest area and its carbon storage were reduced, and the protected forest area and its carbon were increased. In the special purposed forest area, the carbon storage and BCD have observed an increase. BCD in the other forest types showed a reduction under the natural forest protection and forest classification management. Along with age, the proportion of carbon storage in the mature and over mature forest was declining, while it was increasing in young, middle-age and pre-mature forests. Currently, the mature and over-mature forest carbon storage still dominant in the UMR and the forest coverage rate has increased by 9.66 %. BCD of the middle-age and pre-mature forests showed an upward trend, while the young, mature and over-mature forests showed a downward trend.The higher BCD was found in the mature and over-mature dark coniferous forests （DCF） and the lower BCD in the young and middle aged DCF; For the same age class, the BCD values of the mature and over-mature DCF were higher than that of the national average level, while the BCD values of the middle age and pre-mature DCF were lower than that of the national average level. The BCD value of the young forests was similar to the national average. The annual increment rates of BCD in the middle-age, young and over-mature DCF were 1.3%, 0.8% and 0.7%, respectively. The higher BCD values occurred at the sites where the elevations range from 3600 to 3800 m. The annual increment rate of BCD was found to be the highest （1.03%） at the site with the elevation between 3 200 and 3 600 m. The higher BCD and the annual increment rate of BCD occurred on both north facing aspects and south-west and south-east aspects, while the lower values occurred on south facing aspects; The BCDs of DCF in the UMR have been increasing over the past 20 years, and the annual increment rate of BCD was 1.15% from 1997 to 2002, which was the highest among the five inventory periods.The net increase in the above-ground biomass density （AGBD） was 27.311±15.580 Mg·hm^-2 while the mean annual growth rate and the mean annual mortality rate were 1.930±1.091 Mg·hm^-2·a^-1 and 2.271±1.424 Mg·hm^-2·a^-1 during 1988-2002, respectively. The above-ground biomass （AGB） depended largely on the growth and mortality rate of the remaining trees of different diameter at breast height （DBH） classes and recruitment rate from one DBH class to another as well. The largest increment component of AGB came from DBH class at 20 to 40 cm, whereas the minimum increment component of AGB was above 80 cm. The net negative increment of AGB occurred at DBH ranging from 40 60 to 60～80 cm. There were temporal and spatial variations of AGB in the alpine old-growth forests as AGB changed over time for the same sampling plot and AGB varied with location or sites for the same period. The variations not only reflected in numerical value but also in positive or negative biomass increment.Based on factor analysis and other analysis methods, we analyzed relative contribution of the biotic and abiotic factors which include climate （annual precipitation, mean annual temperature）, elevation, population density, mean forest age and BCD to forest carbon storage in the UMR. Our results indicated that forest carbon storage was sensitive to changes in annual precipitation and mean annual temperature, with annual precipitation more sensitive than mean annual temperature. There was significant logarithmic relationship between population density and BCD, and BCD decreased along with the increase of population density. Forest age was the internal factors to forest carbon storages, and the total forest carbon storage of all age groups were increased; however, BCD in the young, mature and over-matures forest were decreased in the whole region. The forest carbon storage and BCD in every age group were increased in the permanent sampling plots. Forest area and BCD were major factors influencing forest carbon storage, and the increased forest carbon storage was resulted mainly from the contribution of increased forest area, and the BCD showed an increasing trend in the later period of this study.更多还原