鲁中南山地黑松人工林土壤和林下植被的动态格局

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

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。

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.