Carbon transfer from 14C‐labelled needles to mineral soil, and 14C‐CO2 production, in a young Pinus radiata Don stand
Carbon transfer from 14C‐labelled needles to mineral soil, and 14C‐CO2 production, in a young Pinus radiata Don stand
复制标题
辐射松幼林中碳从 14C 标记的针叶到矿质土壤的转移以及 14C-CO2 的产生
DOI：
10.1111/j.1365-2389.2010.01316.x
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
J. Dando
中科院分区：
文献类型：
--
作者：
K. Tate;S. Lambie;D. J. Ross;J. Dando
在森林生态系统中，关于凋落物碳(C)向矿质土壤转移速率的数据很少。然而，预测林地利用变化和管理对土壤碳储量的影响需要这些数据。我们在这里报告了放射性松凋落物中碳在117周内向矿物土壤的转移，使用14C标记的针和未标记的针，在放置于5年生辐射松林分地上的渗血仪中进行。年平均气温约12.9℃，年平均降雨量约995 mm；土壤为排水良好的粉砂壤土。在39周、78周和117周时，对残余凋落物中的14C含量进行了测量，在深度为50 mm的矿质土中以10毫米增量进行了测量，在深度为50至100 mm的矿质土中以25毫米增量进行了测量。还测量了14C - CO2的产生，在前5周内频繁间隔，然后不那么频繁。不同暴露时间凋落物和矿质土中14C的回收率为51% ~ 66%。暴露时间分别为39周和117周后，累积呼吸14C‐CO2（以初始添加14C的百分比表示）从16%增加到19%。在三个测量周期内，添加的14C的总回收率随时间没有显著差异（P > 0.12），平均值为68%至84%。14C的表观损失量具有较大的重复变异性，变异系数在20% ~ 31%之间，并且与鸟类对凋落物的干扰有关。我们估计每年有1.0-2.2%的凋落物14C被转移到10-100 mm深的矿质土壤中。在微生物生物量- 14C测量的基础上，这种转移的C比矿物土壤中较老的总C按比例含有更多的微生物（不稳定）C。因此，研究结果与其他有机层发育良好的森林的研究结果一致，表明腐殖化有机质中的C，而不是新落的凋落物中的C，是向矿物土壤转移的主要地上来源。
In forest ecosystems, few data are available on transfer rates of litterfall carbon (C) to mineral soil. Such data are, nevertheless, needed for predicting the effects of forest land‐use change and management on soil C stocks. We here report the transfer of C from Pinus radiata litter to mineral soil over 117 weeks, using 14C‐labelled needles mixed with unlabelled needles in lysimeters placed on the forest floor of a 5‐year‐old P. radiata stand. Mean annual temperature was about 12.9°C and mean annual rainfall about 995 mm; the soil was a well‐drained silt loam. Measurements were made at 39, 78 and 117 weeks of 14C in residual litter and in 10‐mm increments of mineral soil to 50 mm depth and 25‐mm increments from 50 to 100 mm depth. Measurements were also made of 14C‐CO2 production, at frequent intervals over the first 5 weeks and then less frequently. Recovery of 14C in litter and mineral soil ranged from 51 to 66% at the different exposure times. Cumulative respired 14C‐CO2, expressed as a percentage of the initially added 14C, increased from 16 to 19% after exposure times of 39 and 117 weeks, respectively. Total recovery of the added 14C did not differ significantly (P > 0.12) with time over the three measurement periods, with means ranging from 68 to 84%. Apparent losses of 14C were associated with large replicate variability, with coefficients of variation ranging from 20 to 31%, and with some disturbance of litter in the lysimeters by birds. We estimate that 1.0–2.2% of the litter 14C was transferred annually to 10–100‐mm depth of mineral soil. On the basis of microbial biomass‐14C measurements, this transferred C contained proportionately more microbial (labile) C than did the older total C in mineral soil. Results therefore are consistent with other studies on forests with well‐developed organic horizons indicating that C in humified organic matter, rather than in newly fallen litter, is the main above‐ground source for transfer of C to the mineral soil.