西南亚高山次生灌丛促进建群树种更新恢复技术

Regeneration and growth-promoting constructive species in the subalpine secondary shrub ecosystem of southwestern China

针对西南亚高山区大量退化灌丛恢复技术缺乏的问题,在浓密灌丛抑制建群树种幼苗更新的生态系统,采用调控灌丛冠幅和适当去除地被物层技术,以改善灌丛生态系统中限制建群树种更新和生长的环境因子,促进幼苗生长和更新;在缺乏种源的灌丛生态系统,利用灌丛微环境的直播和栽植技术补充种源.对调控处理后的幼苗存活、生长及微环境的变化进行了动态监测(2018-2020),发现:(1)水平或垂直去除部分灌丛冠幅增加了粗枝云杉(Picea asperata)建群种幼苗的基径和株高,其中水平去除处理使得幼苗基径和株高分别增加了51.5%和61.6%;(2)仅凋落物去除和地被物全部去除后,灌丛空地移栽的云杉幼苗死亡率从20.8%下降到7.1%,且株高和基径增长率为24.6%-35.8%,均高于地被物保留时的对照幼苗(4.0%-20.7%);(3)野外原位播种四川红杉(Larix mastersiana)和粗枝云杉种子的萌发率为密灌>疏灌>草地(P<0.05),抚育方式对种子萌发和保存的影响均为微肥>CK>微肥+保水剂>保水剂(P<0.05);(4)未添加有机底肥条件下,栽植在灌丛根围区域和非根围区域的云杉幼苗存活率分别为56.9%和30.0%,其中栽植在灌丛坡位上方位更有利于幼苗存活,添加底肥促进了栽植在无灌丛植被区域的云杉的存活,存活率达到100%.可见,在有建群树种幼苗的浓密灌丛区,通过改善抑制幼苗生长的微环境,建群树种的生长得到明显改善;在次生灌丛无建群树种种源区,通过引入建群树种种源,能促进建群树种幼苗定居;上述研究结果为亚高山退化森林生态系统的恢复提供了新的思路和技术途径.

To address the lack of restoration techniques for a large number of degraded shrubs in subalpine areas,in this study,we proposed removing the restrictive environmental factors that affected the regeneration and growth of constructive tree species in the shrub ecosystem and supplementing their provenance.For ecosystems where dense shrubs inhibited the seedlings of constructive tree species,we designed a technology to improve growing conditions by appropriately adjusting the shrub crown width and removing the ground floor layer.For shrub ecosystems lacking provenance,we directly added seeds and planted seedlings on the sides of the shrubs.By monitoring the survival,growth,and microenvironment changes in the seedlings after the treatment,the following results were obtained:(1)horizontal and vertical removal of part of the shrub crown increased the basal diameter and height of spruce(Picea asperata)seedlings.Horizontal removal increased the basal diameter and height of seedlings by 51.5%and 61.6%,respectively.The increase in base diameter and height of seedlings was positively correlated with temperature after treatment.(2)After only the litter and ground cover were completely removed,the height and basal diameter of spruce seedlings transplanted in the shrub open area were 24.6%-35.8%higher than those of the control,respectively.(3)The seed germination rates of Sichuan redwood(Larix mastersiana)and spruce in the field were closed shrubland>open shrubland>grassland(P<0.05),and the effects of nurturing methods on seed germination and preservation were micro-fertilizer>CK>micro-fertilizer+water-retaining agent>water-retaining agent(P<0.05).(4)Without the addition of organic fertilizer,the survival rates of spruce seedlings planted in the shrub rhizosphere and non-rhizosphere areas were 56.9%and 30%,respectively.Planting at the upward side of shrubs is more favorable for seedling survival.Adding fertilizer increased the survival rate of spruce seedlings planted in non-shrub vegetation areas to 100%.These results suggest that the introduction of constructive tree species in secondary shrub ecosystems can promote the survival and preservation of seedlings.In the dense shrub area with constructive tree seedlings,the growth of seedlings was significantly improved by regulating the microenvironment that inhibited their growth.These results provide new ideas and technical approaches for the restoration of subalpine degraded forest ecosystems.