晋西北丘陵风沙区柠条林下草本植物群落组成和种群生态位变化特征

Changes of herbaceous plant composition and niche characteristics in different-aged artificial Caragana korshinskii forest in sandy-hilly region of northwest Shanxi Province,China

晋西北丘陵风沙区生态环境脆弱,是我国风沙活动危害最为严重的地区之一。为探究晋西北丘陵风沙区人工柠条林林下草本植物群落组成和种群生态位变化规律,以不同种植年限(撂荒地CK、6、12、18、40、50 a)人工柠条林林下天然草本植物群落作为研究对象,对其群落组成、重要值及种群生态位变化特征进行分析。研究结果表明:(1)不同年限柠条林下天然草本植物组成共记录到22科41属52种,其中,种植前期(0-6 a)林下草本植物以一年生草本植物为优势类群,伴有少数多年生草本植物(3种);种植中期(12-18 a)林下草本植物主要由多年生草本植物(12种)为主,伴生有一年生草本植物(6种)及天然灌木(2种)组成;在种植后期(40-50 a),林下草本植物依然以多年生草本植物(12种)为主。(2)在不同年限柠条林下,草本植物生态位宽度和生态位重叠发生明显变化,种植前期(0-12 a)的优势类群为一年生先锋物种(米蒿和野燕麦),其生态位宽度最宽(9.46、9.34),且与其他物种的生态位重叠程度最大(0.3、0.29);而种植中后期(18-50 a)优势类群变为多年生草本植物,优势种披碱草与其他物种的生态位重叠程度最大(0.42),说明其为林下植物群落主要的优势种和泛化种。(3)柠条林种植后期(50 a),多数草本植物主要集中分布在生态位重叠系数DCA排序图的中心位置,说明在种植后期草本植物对相同环境的资源竞争激烈,林下草本植物群落处于演替过渡阶段。综上,人工种植柠条林相较于天然恢复(CK),更有利于增加草本植物群落的多样性,但林下植物群落对资源的竞争更为激烈。这些研究结果对干旱半干旱地区风沙区植被恢复和生态重建具有重要的参考价值,对人工林生态恢复具有重要意义。

The ecological environment of sand-blown hilly area in northwest Shanxi is fragile and it is one of the most serious areas in China.This study investigated the community composition and niche change of herbaceous plants in artificial Caragana korshinskii forest in sandy-hilly region of northwest Shanxi Province.The natural herb community under artificial Caragana korshinskii forest with different planting years(CK,6,12,18,40,50 a)was taken as the research object,and its community composition,important value and population niche change characteristics were analyzed.The results showed that:(1)A total of 52 species,41 genera and 22 families were recorded in the composition of the natural herbaceous plants in the understory of Caragana korshinskii forest with different ages.In the early plantation period(0-6 a),the annual herbaceous plants were the dominant group,accompanied by a few perennial herbaceous plants(3 species).In the middle period(12-18 a),the understory herbaceous plants were mainly composed of perennial herbaceous plants(12 species),accompanied by annual herbaceous plants(6 species)and natural shrubs(2 species).In the later period(40-50 a),the understory vegetation was still dominated by perennial herbaceous plants(12 species).(2)Under Caragana korshinskii forest,the niche width and niche overlap of herbaces changed significantly.The dominant species in the early planting period(0-12 a)were the pioneer species(Artemisia dalai-lamaeand and Avena fatua),which had the widest niche width(9.46 and 9.34),and the largest niche overlap with other species(0.3 and 0.29).In the middle and late planting period(18-50 a),the dominant species changed into perennial herbaceous plants,and the niche overlap between Elymus dahuricus and other species was the largest(0.42),indicating that Elymus dahuricus was the dominant and generalized species in the understory plant community.(3)In the late planting period(50 a),most herbaceous plants mainly distributed in the center of the system clustering sequence diagram of niche overlap coefficient,indicating that herbaceous plants competed fiercely for resources in the same environment in the late planting period,and the understory herbaceous plant community was in the transition stage of succession.In conclusion,artificial planting of Caragana korshinskii forest is more effective to increase the diversity of herbaceous plant community than natural restoration(CK),but the competition of understory plant community for resources is more intense.These results have important reference value for vegetation restoration and ecological reconstruction in arid and semi-arid sandstorm areas,and have important significance for ecological restoration of artificial forest.