桂北喀斯特石漠化地区不同植物群落土壤种子库特征及其与土壤养分关系

Characteristics of soil seed banks of different plant communities and their relationships with soil nutrients in karst desertification area, North Guangxi, China

关键词:  石漠化, 土壤种子库, 土壤元素, 土地利用类型, 植被恢复

Key words:  rocky desertification, soil seed bank, soil elements, land use types, vegetation restoration

摘要:

土壤种子库作为地上植被遗传信息库,对植被自然演替更新以及生态修复建设具有重要作用。为探明桂北喀斯特石漠化地区植被自然恢复潜力和恢复策略,该文选取恭城瑶族自治县喀斯特石漠化地区3种典型植物群落为研究对象,分析不同群落的土壤种子库结构、多样性及其对土壤养分特征的响应,以期为该地区石漠化治理和植被恢复提供理论依据。结果表明:(1)共计监测到幼苗3 648株,隶属于33科51属55种,其中1年生和2年生草本幼苗共20种,多年生草本幼苗21种,藤本幼苗5种、灌木幼苗3种、乔木幼苗6种; 不同植物群落土壤种子库平均密度为三华李经济林(22 493 grain·m^-2)>青冈次生林(1 033 grain·m^-2)>金竹灌丛(793 grain·m^-2)。(2)土壤种子库植物生活型方面,三华李经济林主要分布1年生恶性杂草,青冈次生林和金竹灌丛则以多年生草本为主,木本植物占比较少; 不同植被类型中土壤种子库物种多样性和相似性总体较低,同时与地上群落物种组成的相似性也较低。(3)研究区域的土壤元素存在高氮低磷的现象,其中磷元素为金竹灌丛和青冈次生林植物生长的限制因子。综上表明,恭城县石漠化地区植物群落虽然具备一定乡土种质资源,但其总体表现出的物种多样性较低,因此,亟须在自然封育的基础上人工引入乡土树种以加速植被正向演替,同时要注重养分管理特别是磷元素的调节。该研究结果为恭城的石漠化管理和植被修复提供了理论参考。

Abstract:

As a repository of genetic information of above-ground vegetation, the soil seed bank plays an important role in the natural succession and renewal of vegetation and the construction of ecological restoration. In this paper, three typical plant communities in the rocky desertification area of Gongcheng Yao Autonomous County were selected for the study, and soil seed bank structure and diversity in different communities and their response to soil nutrient characteristics were analyzed. The results were as follows:(1)A total of 3 648 seedlings belonging to 55 species in 51 genera and 33 families were detected, which included 20 species of 1, 2-year-old herbs, 21 species of perennial herbs, 5 species of vines, 3 species of shrubs and 6 species of trees; the average density of soil seed bank of different plant communities in karstic desertification areas of Gongcheng was Prunus salicina economic forest(22 493 grain·m^-2)> Cyclobalanopsis glauca secondary forest(1 033 grain·m^-2)> Phyllostachys sulphurea shrub(793 grain·m^-2).(2)As for the plant life type of the soil seed bank, the soil seed bank life type of Prunus salicina economic forest was mainly annual malignant weeds, the plant life type of the soil seed banks in the Cyclobalanopsis glauca secondary forest and Phyllostachys sulphurea shrub was dominated by perennial herbs, while woody plants account for a relatively small proportion; the species diversity and similarity of the soil seed banks of different vegetation types were generally low, while the species composition of the soil seed banks also had low similarity with the aboveground communities.(3)The soil elements in the study area had higher nitrogen content and lower phosphorus content, and phosphorus was a limiting factor for plant growth in Phyllostachys sulphurea shrub and Quercus glauca secondary forest. In conclusion, the plant community in the stone desertification area of Gongcheng has some native germplasm resources, but overall shows a low species diversity, and it is urgent to introduce native tree species artificially to accelerate the positive vegetation succession on the basis of natural sequestration, and pay attention to nutrient management, especially the regulation of phosphorus elements. The results provide a theoretical reference for karst stone desertification management and vegetation restoration in Gongcheng.