摘要 【目的】研究华北落叶松人工林天然更新的主要限制因素,探索寻找促进天然更新的实用技术,为改善华北落叶松林天然更新和林分结构提供技术支撑。【方法】在宁夏六盘山选择5个试验点,每个试验点按林冠郁闭度不同选择华北落叶松人工林5类生境(近熟林的林冠下、林隙、林中空地、林缘和退耕幼龄林地),每类生境各设1块12 m×20 m样地,2018年10月中旬在每块样地设置割草、除落、开沟、挖穴和对照5种处理,采用完全随机区组设计,每个区组平行于等高线排列,地表处理后撒播华北落叶松种子(100粒·m-2)。整个试验共设置25块样地,每块样地5种处理,每种处理3次重复。在近熟林林冠下和退耕幼龄林生境设置防止鸟鼠采食种子的尼龙网覆盖和不覆盖2种措施。2019年6月计数存活幼苗,并进行统计分析。【结果】不覆网时,退耕幼龄林、林缘、林隙、林冠下和林中空地5类生境的幼苗密度均值依次为2.7、1.8、1.4、1.3和0.8株·m-2;开沟、挖穴、清枯、割草和对照5种处理幼苗密度均值依次为2.1、1.9、1.8、1.3和1.1株·m-2;每类生境的5种处理之间,最高的平均幼苗密度依次为林缘样地开沟4.1株·m-2、退耕幼龄林样地割草3.6株·m-2、林隙样地开沟2.4株·m-2、林冠下样地挖穴2.1株·m-2、林中空地挖穴1.3株·m-2。林地覆网能极显著提高所有处理的幼苗密度。近熟林内林冠下样地的幼苗密度均值提高幅度依次为清除枯落物2.3株·m-2、开沟1.0株·m-2、对照0.5株·m-2、挖穴0.5株·m-2、割草0.5株·m-2,即可提高0.5~2.3株·m-2;退耕幼林样地的幼苗密度均值提高幅度依次为清枯2.3株·m-2、开沟1.7株·m-2、挖穴1.3株·m-2、割草0.6株·m-2、对照0.3株·m-2,即可提高0.3~2.3株·m-2,与近熟林内林冠下样地基本一致。【结论】限制华北落叶松人工林天然更新的主要 【Objective】Larix principis-rupprechtii is one of the main tree species for plantations in north China,but its natural regeneration is generally poor.It is therefore important to identify the main limiting factors and explore practical techniques to promote the natural regeneration.【Method】In the mid October of 2018,five sites in Liupan Mountains of Ningxia,China,were selected,each of which 5 habitat types were chosen according to canopy closure(near-mature forests,forest gaps,forest glades,forest edges,and young forests grown by farmland conversion program).A sample plot with a size of 12 m×12 m was set up for each habitat type,and within each sample plot 5 treatments,i.e.,cutting grasses,completely removing humus layer after grass cutting,digging holes to expose mineral soil after humus removal,opening ditches into mineral soil after humus removal,and the control(without any treatment).The completely randomized block design was used,and each block was arranged parallel to the contour line.A total of 25 plots,each containing 5 treatments with 3 replications.Larch seeds were sowed by broadcasting(100 seeds·m-2)after the plantation floor was treated,and two treatments of covering the ground with nylon mesh and not covering as control were employed to evaluate the effect of nylon mesh-covering on seedling density by preventing birds and rats from eating seeds.We counted the number of remaining seedlings in June of 2019 for statistical analyses.【Result】In the case of no mesh-covering,the mean seedling density was 2.7 plants·m-2for the young forests,1.8 plants·m-2for the forest edges,1.4 plants·m-2for the forest gaps,1.3 plants·m-2for the near-mature forest,and 0.8 plants·m-2for the forest glades;the mean seedling density was 2.1 plants·m-2for the opening ditches,1.9 plants·m-2for the digging holes,1.8 plants·m-2for the humus removal,1.3 plants·m-2for the grass cutting,and 1.1 plants·m-2for the control.The highest mean seedling density among the 5 treatments in
出处 《林业科学》 EI CAS CSCD 北大核心 2021年第3期18-28,共11页 Scientia Silvae Sinicae
基金 宁夏回族自治区农业科技自主创新全产业链项目(YES-16-12) 国家重点研发计划项目(2017YFC0504602)。
关键词 六盘山 华北落叶松 天然更新 地表处理 幼苗密度 Liupan Mountains Larix principis-rupprechtii natural regeneration forest floor treatments seedling density
