鲁中南山地黑松人工林土壤和林下植被的动态格局

林下植被和土壤演变过程与人工林生长发育和群落结构互为因果，共同影响人工林的群落稳定性和健康水平。以鲁中南山地黑松Pinus thunbergii人工林为研究对象，采用空间序列代替时间序列的研究方法，在调查不同发育阶段林分的群落结构、林下植被、林地土壤理化性质和微生物群落特征基础上，分析了人工林生态系统随林龄变化的演替规律。研究结果表明:①土壤有效磷质量分数以6年生黑松林最高、30年生黑松林最低，有效钾质量分数以30年生最高、6年生最低，不同林龄阶段之间差异显著（P < 0.05）；土壤全氮和有效氮质量分数均表现为30年生最高、50年生最低，其中50年生土壤全氮质量分数显著低于6年生和30年生，30年生土壤有效氮质量分数显著高于6年生和50年生（P < 0.05）。②土壤蔗糖酶、纤维素酶活性以30年生最高，50年生最低，不同林龄阶段之间差异显著（P < 0.05）；土壤脲酶活性随林龄增加而降低，50年生显著高于30年生和6年生（P < 0.05）。③土壤微生物多样性为6年生> 50年生> 30年生，土壤微生物丰度随林龄升高呈先降后升的趋势，其中变形菌门Proteobacteria，放线菌门Actinobacteria和酸杆菌门Acidobacteria为绝对优势菌群。④林下草本植物和灌木多样性随林龄升高呈递减趋势。

Understory vegetation patterns and soil characteristics of a Pinus thunbergii plantation in mountainous land of Shandong Province

Undergrowth vegetation and soil evolution are essential prerequisites of plantation growth and community structure, which then determine the stability and health of a plant community. To evaluate community succession patterns of plantation ecosystems along with stand age changes, plantation and soil ecosystem changes in forests were analyzed using a spatial sequence approach instead of a temporal sequence. Pinus thunbergii plants in the mid-southern mountainous lands of Shandong Province were the test materials, and plant community structure, understory vegetation, soil physicochemical properties, and microbial community characteristics were determined. Results showed that (1) Soil available P was significantly different for different stand ages (P < 0.05). For different stand ages, soil available K was also significantly different with 30 years being highest and 6 years lowest (P < 0.05). Total N at 50 years was significantly lower than at 6 and 30 years (P < 0.05); whereas, available N at 30 years was significantly higher than at 6 and 50 years (P < 0.05). (2) At different stand ages, soil invertase and cellulase activities were significantly different (P < 0.05) with 30 years being highest and 50 years lowest. Soil urease activity was significantly greater at age 50 than at 6 years and 30 years (P < 0.05) and decreased with the increasing stand age. (3) For soil microbial diversity, the order of change for stand age was 6 year-old > 50 year-old > 30 year-old with Proteobacteria, Actinobacteria, and Acidobacteria having the greatest abundance. (4) The diversity of undergrowth vegetation decreased as stand age increased. These results have theoretical significance in guiding the management of Pinus thunbergii plantation scientifically.