Annual variation in soil respiration and its components in a coppice oak forest in Central Italy
Annual variation in soil respiration and its components in a coppice oak forest in Central Italy
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DOI：
10.1046/j.1365-2486.2002.00521.x
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发表时间：
2002-09-01
影响因子：
11.6
通讯作者：
Valentini, R
中科院分区：
文献类型：
--
作者：
Rey, A;Pegoraro, E;Valentini, R
为了研究地中海混合橡树林生态系统土壤呼吸及其组分与土壤温度和土壤水分季节变化的关系，我们于1999年5月设置了一系列实验处理，其中4 m（2）的地块不包括凋落物（无凋落物）、根（无根，通过挖沟）或两者。随后，我们测量了土壤呼吸，土壤温度和土壤水分在每个地块超过一年后，森林被矮林。各处理对土壤温度和0-10 cm土壤水分的影响不显著，土壤呼吸年内变化明显，春季和秋季呼吸速率较高，夏季呼吸速率较低，夏季干旱时呼吸速率较高，冬季气温最低。非常高的呼吸速率，但是，观察到在夏季降雨事件后立即。土壤呼吸年平均速率为2.9 μ mol·m ~（-2）·s ~（-1），变化范围为1.35 ~ 7.03 μ mol·m ~（-2）·s ~（-1）.在此阈值以下，土壤呼吸与土壤温度之间没有相关性，但土壤湿度是土壤呼吸的一个很好的预测。利用土壤温度和土壤湿度预测土壤呼吸的经验模型可解释土壤呼吸年变化的91%以上，土壤呼吸各分量具有相似的季节变化趋势，并受夏季干旱的影响。土壤呼吸的Q（10）值为2.32，这与森林生态系统的其他研究结果一致。然而，我们发现根呼吸的Q（10）值为2.20，低于森林站点最近报道的值。地中海生态系统根生长随温度的季节变化不同于温带地区，这一事实可以解释这种差异。在温带地区，在生长季节的根种群的大小增加，符合高温，可能会产生较高的表观Q（10）值比在地中海地区，根系生长受到抑制的夏季干旱。有机质和地下凋落物的分解是土壤呼吸的主要组成部分，约占总土壤呼吸通量的55%。这一比例高于已报道的成熟的寒带和温带森林，可能是一个短期的C损失的结果，最近在site.The土壤呼吸与土壤温度和土壤湿度的关系，建议是有用的理解和预测地中海森林生态系统的潜在变化，以响应森林管理和气候变化。
In order to investigate the annual variation of soil respiration and its components in relation to seasonal changes in soil temperature and soil moisture in a Mediterranean mixed oak forest ecosystem, we set up a series of experimental treatments in May 1999 where litter (no litter), roots (no roots, by trenching) or both were excluded from plots of 4 m(2) . Subsequently, we measured soil respiration, soil temperature and soil moisture in each plot over a year after the forest was coppiced. The treatments did not significantly affect soil temperature or soil moisture measured over 0-10 cm depth.Soil respiration varied markedly during the year with high rates in spring and autumn and low rates in summer, coinciding with summer drought, and in winter, with the lowest temperatures. Very high respiration rates, however, were observed during the summer immediately after rainfall events. The mean annual rate of soil respiration was 2.9 mu mol m(-2) s(-1) , ranging from 1.35 to 7.03 mumol m(-2) s(-1) .Soil respiration was highly correlated with temperature during winter and during spring and autumn whenever volumetric soil water content was above 20%. Below this threshold value, there was no correlation between soil respiration and soil temperature, but soil moisture was a good predictor of soil respiration. A simple empirical model that predicted soil respiration during the year, using both soil temperature and soil moisture accounted for more than 91% of the observed annual variation in soil respiration.All the components of soil respiration followed a similar seasonal trend and were affected by summer drought. The Q (10) value for soil respiration was 2.32, which is in agreement with other studies in forest ecosystems. However, we found a Q (10) value for root respiration of 2.20, which is lower than recent values reported for forest sites. The fact that the seasonal variation in root growth with temperature in Mediterranean ecosystems differs from that in temperate regions may explain this difference. In temperate regions, increases in size of root populations during the growing season, coinciding with high temperatures, may yield higher apparent Q (10) values than in Mediterranean regions where root growth is suppressed by summer drought.The decomposition of organic matter and belowground litter were the major components of soil respiration, accounting for almost 55% of the total soil respiration flux. This proportion is higher than has been reported for mature boreal and temperate forest and is probably the result of a short-term C loss following recent logging at the site.The relationship proposed for soil respiration with soil temperature and soil moisture is useful for understanding and predicting potential changes in Mediterranean forest ecosystems in response to forest management and climate change.