水曲柳、落葉松人工林土壤無脊椎動物群落結構及對凋落物分解的影響1)

何瑞雪 謝旭強 馬雙嬌 王慶成 朱凱月 鞏瑞 剡麗梅 段嘉靖

(東北林業大學，哈爾濱，150040)

As an important decomposer of the ecosystem, soil invertebrate community structure has an impact on litter decomposition at different stages of litter decomposition. The soil invertebrate community structure of Larix gmelinii and Fraxinus mandshurica artificial pure forests at different periods (before soil freezing, during soil freezing, and during growth) and its impact on litter decomposition rate and nutrient dynamics were studied by using litter decomposition bag method with different apertures (0.01, 2.00 and 4.00 mm). The composition of soil invertebrate community was affected by litter type during litter decomposition. The dominant groups of soil invertebrates in the litter bag of F. mandshurica forest are Oribatida, Enchytraeidae, Onychiuridae, and the dominant groups of L. gmelinii forest are Oribatida, Onychiuridae. The individual number and diversity of invertebrates in F. mandshurica forest are higher than those in L. gmelini forest. The structure of functional groups of soil invertebrates changed with the decomposition process of litter, and the functional groups of soil invertebrates were significantly correlated with the decomposition rate of litter (P<0.05). The litter decomposition rate of F. mandshurica forest is higher than that of L. gmelini forest. Soil invertebrates have an obvious promoting effect on litter decomposition, which is shown as follows: the joint action of large, small and medium-sized invertebrates and microorganisms is greater than that of small and medium-sized invertebrates and microorganisms alone. The number of individuals and groups of soil invertebrates were significantly correlated with total N and organic C contents (P<0.05). The contribution rate of soil invertebrates to litter decomposition of L. gmelini forest is greater than that of Manchurian ash forest. The contribution of different types of soil animals to litter decomposition is different at different stages of litter decomposition. The community characteristics of soil invertebrates are significantly different in the litter of coniferous and broad-leaved forests, and their contribution to the litter decomposition of larch plantation is large.

凋落物是在生態系統內維持系統功能所有有機質的總稱[1]。凋落物分解過程中養分釋放對維持土壤養分和元素循環具有重要意義[2]。

氣候和基質質量是影響凋落物分解的主要非生物因素，解釋了全球尺度上陸地生態系統多達65%～77%分解率的變異，而土壤生物群落(動物和微生物)構成剩余分解率變異(23%～35%)[3-5]。在特定氣候區內，研究土壤生物群落對凋落物分解的貢獻有助于了解凋落物分解過程及機制。近年來，土壤無脊椎動物在凋落物分解中的作用已成為國際土壤生態學研究領域的熱點之一[6]。

土壤無脊椎動物主要涉及原生動物、扁形動物、線形動物、輪蟲動物、環節動物、緩步動物、軟體動物和節肢動物8個動物門[7-8]。土壤無脊椎動物通過掘穴、破碎、遷移、搬運、取食凋落物等直接改變土壤理化特性[9]。此外，土壤無脊椎動物通過選擇性捕食控制微生物數量、結構和活性，間接影響凋落物分解過程[10]。在一定程度上，土壤無脊椎動物與凋落物初始質量在分解過程中作用相當[11]。因此，了解凋落物中無脊椎動物的群落結構及其對凋落物分解過程的貢獻對全面了解凋落物分解具有重要意義。

我國自本世紀初開始進行森林土壤無脊椎動物對凋落物分解及養分釋放作用的研究，研究對象以闊葉林居多[12-14]，關于針葉林凋落物分解的相關研究相對較少[15]。部分研究結果表明，森林凋落物分解過程中土壤無脊椎動物的群落組成、結構、多樣性均受凋落物類型影響[16-17]?！?br>