使用小兴安岭温带森林机载遥感-地面观测同步试验获取的机载激光雷达(light detection and ranging,Lidar)点云数据和地面实测样地数据,估测了典型森林类型的树叶、树枝、树干、地上、树根和总生物量等组分的生物量。从激光雷达数据中...使用小兴安岭温带森林机载遥感-地面观测同步试验获取的机载激光雷达(light detection and ranging,Lidar)点云数据和地面实测样地数据,估测了典型森林类型的树叶、树枝、树干、地上、树根和总生物量等组分的生物量。从激光雷达数据中提取了两组变量(树冠高度变量组和植被密度变量组)作为自变量,并采用逐步回归方法进行自变量选择。结果表明:激光雷达数据得到的变量与森林各组分生物量有很强的相关性;对于针叶林、阔叶林和针阔叶混交林三种不同森林类型生物量的估测结果是:针叶林优于阔叶林,阔叶林优于针阔叶混交林;不区分森林类型的各组分生物量估测与地面实测值显著相关,模型决定系数在0.6以上;区分森林类型进行建模可以进一步提高生物量的估测精度。展开更多
Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosys...Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.展开更多
文摘使用小兴安岭温带森林机载遥感-地面观测同步试验获取的机载激光雷达(light detection and ranging,Lidar)点云数据和地面实测样地数据,估测了典型森林类型的树叶、树枝、树干、地上、树根和总生物量等组分的生物量。从激光雷达数据中提取了两组变量(树冠高度变量组和植被密度变量组)作为自变量,并采用逐步回归方法进行自变量选择。结果表明:激光雷达数据得到的变量与森林各组分生物量有很强的相关性;对于针叶林、阔叶林和针阔叶混交林三种不同森林类型生物量的估测结果是:针叶林优于阔叶林,阔叶林优于针阔叶混交林;不区分森林类型的各组分生物量估测与地面实测值显著相关,模型决定系数在0.6以上;区分森林类型进行建模可以进一步提高生物量的估测精度。
基金supported by the National Natural Science Foundation of China (Grant No. 30870381)the Key Project of Scientific and Technical Supporting Programs Funded by the Ministry of Science & Technology of China (Grant No. 2007BAC06B01)
文摘Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.
