作 者 ：刘爽,王传宽*
期 刊 ：生态学报 2010年 30卷 12期 页码：3135~3143
Keywords:soil microbe, seasonal dynamics, spatial pattern, forest type,
摘 要 ：土壤微生物是森林生态系统中的重要分解者，在碳和氮循环中起着重要作用，同时也是对环境变化的敏感指示者。采用氯仿熏蒸浸提法测定了我国东北地区5种温带森林土壤微生物生物量碳（Cmic）和氮（Nmic）的季节动态及其在土壤中的垂直变化。结果表明：林型之间Cmic和Nmic差异显著（P <0.01）。落叶松林、红松林、蒙古栎林、杨桦林、硬阔叶林的Cmic的变化范围依次为：278-937 mg kg-1、218-1020 mg kg-1、313-891 mg kg-1、510-1092 mg kg-1、440-1911 mg kg-1；其Nmic的变化范围依次为：18-72 mg kg-1、18-103 mg kg-1、24-95 mg kg-1、43-125 mg kg-1、40-208 mg kg-1。所有林型的Cmic和Nmic均随土壤深度的增加而下降。Cmic和Nmic基本上呈现出生长季开始之前下降、生长季结束时上升、其中出现1-2个峰值的季节变化格局，但峰值大小和出现时间随林型和土壤层次而变。0-10cm土层的Cmic和Nmic季节变化较大。Cmic和Nmic与凋落叶量、土壤有机碳含量和土壤总氮含量呈显著正相关。Cmic与土壤含水量呈正相关，而与土壤温度呈负相关。不同林型凋落物数量和组成、土壤理化性质的差异是导致其土壤微生物生物量时空格局差异的主要因素。
Abstract:Soil microbe is the most important decomposer in forest ecosystems and sensitive indicator to environmental changes. It plays a crucial role in forest carbon and nitrogen cycles. However, few studies on soil microbial biomass carbon (Cmic) and nitrogen (Nmic) have been conducted in the temperate forests of northeastern China. In this study, we used a fumigation-extraction method (FE) to examine seasonal dynamics of Cmic and Nmic and vertical changes along soil profiles in representative temperate forests in this region. The experimental design included five forest types, three 20 m×30 m plots in each forest type. The forest types were Dahurian larch (Larix gmelinii) plantation, Korean pine (Pinus Koraiensis) plantation, Mongolian oak (Quercus mongolica) forest, aspen-birch forest (dominated by Populus davidiana and Betula platyphylla), and hardwood forest (dominated by Fraxinus mandshurica, Juglans mandshurica and Phellodendron amurense). In each plot, we randomly took soil samples by two soil layers (0-10 cm and 10-20 cm) from five spots every month from March to November of 2008. The samples in each plot were mixed as one sample for Cmic and Nmic determination. All soil samples were stored at 2 ℃ before analyzed within one week from sampling. The Cmic and Nmic were significantly different (P < 0.01) among the forest types. The Cmic in the Dahurian larch, Korean pine, Mongolian oak, aspen-birch, and hardwood forests varied from 278-937, 218-1020, 313-891, 510-1092, and 440-1911 mg kg-1, respectively, while the Nmic varied from 18-72, 18-103, 24-95, 43-125, and 40-208 mg kg-1, respectively. Both Cmic and Nmic decreased with the soil depth increasing for all forests. Overall, the Cmic and Nmic showed similar seasonal patterns for all forests, in which they decreased before the growing season commenced, increased in the end of the growing season, and had 1-2 in-between peaks. However, the values and occurring times of the peaks varied with forest types and soil layers. The seasonal variations in the Cmic and Nmic were greater at the 0-10 cm soil layer than those at 10-20 cm. The Cmic and Nmic were significantly positively correlated with the leaf litterfall, soil organic carbon content and total soil nitrogen content. The Cmic was positively correlated with soil water content, but negatively with soil temperature. We concluded that the variations in litterfall amount and composition, soil physical and chemical properties among the forest types mainly contributed to the differences in spatio-temporal patterns of the soil microbial biomass in the five forests.
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