Influence of stand thinning and repeated fertilization on plant community abundance and diversity in young lodgepole pine stands: 15-year results

编号 010026004

推送时间 20201012

研究领域 森林生态 

年份 2020 

类型 期刊 

语种 英语

标题 Influence of stand thinning and repeated fertilization on plant community abundance and diversity in young lodgepole pine stands: 15-year results

来源期刊 Forest Ecology and Management

期 第260期

发表时间 20131115

关键词 Biodiversity;  British Columbia;  Fertilization;  Forest management;  Lodgepole pine;  Plant productivity; 

摘要 Enhanced forest productivity may provide the supply of wood fiber to keep pace with increasing global demand for wood products and the growing constraints on the harvestable land base imposed by measures to conserve biodiversity. Stand thinning and fertilization are silvicultural practices that increase forest productivity in many situations. Intensive management has debatable impacts on plant species diversity with no consistent predictions from existing models and a general lack of long-term responses to treatments. This 15-year study was designed to test four hypotheses (H), that (H1) the application of a range of pre-commercial thinning (PCT) intensities will increase plant abundance in herb and shrub layers, (H2) fertilization will increase abundance of all plant layers (herbs, shrubs, trees, and combined total), (H3) PCT and fertilization treatments will decrease species and structural diversity of all plant layers, and (H4) enhanced abundance of vegetation will result in a decline in total species diversity and structural diversity. Study areas were located in lodgepole pine (Pinus contorta var. latifolia) stands near Summerland, Kelowna, and Williams Lake in south-central British Columbia, Canada. Each study area had nine treatments: four pairs of stands thinned to densities of ～250 (very low), ～500 (low), ～1000 (medium), and ～2000 (high) stems/ha with one stand of each pair fertilized five times at 2-year intervals, and an unthinned stand.
Mean abundance (crown volume index) of herbs and shrubs were unaffected by stand density, and hence H1 was not supported. Mean abundance of herbs and mean total abundance of the plant community were significantly higher in fertilized than unfertilized stands, and hence H2 was only partially supported. Mean species richness of the herb, shrub, tree, and combined total layers were unaffected by density or fertilization. Mean species diversity of these layers were also unaffected by density, but fertilization reduced herb and shrub diversity, at least temporarily. Neither tree nor total species diversity were affected by fertilization. Mean structural diversity of herb and shrub layers were unaffected by stand density. Mean structural diversity of the tree layer was significantly greater in the most heavily thinned stands (250 stems/ha) than in the unthinned and lightly thinned stands (2000 stems/ha), and similar to that of the 500 and 1000 stems/ha stands. Mean structural diversity of the total plant community was significantly enhanced by fertilization. Thus, H3 was partially supported for the fertilization-induced reduction in herb and shrub diversity, but structural diversity was unaffected or enhanced. A trend of decreasing total species diversity with increasing productivity supported H4. The changing relationship between productivity and structural diversity indicated that structure was more related to succession than productivity, and therefore our results did not support H4.
PCT and fertilization clearly influence plant community abundance, diversity, and structure. This is one of the first studies to document the magnitude and longevity of these changes with a replicated, large-scale, and long-term study. PCT and repeated fertilization of young lodgepole pine stands appear to be management strategies compatible with wood production and biodiversity conservation.

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