【作者】 高伟；

【导师】 游水生； 叶功富；

【作者基本信息】 福建农林大学 ， 自然地理学， 2011， 硕士

【摘要】 木麻黄（Casuarina equisetifolia）是我国滨海沙地的重要防护树种,在缓解沿海地区生态环境恶化,弥补海岸带生态脆弱性,抵御自然灾害方面发挥了重要的作用。但由于长期的纯林经营和严重的人为干扰,林带破碎、土壤养分失调和病虫害频发等问题逐渐出现,严重影响了防护林的稳定性,构建近自然的沿海防护林体系可使群落保持较高的物种多样性与稳定性,使种间关系更和谐,结构更健康,有助于沿海防护林的可持续经营。因此,本研究以东山岛沙质海岸带4种不同干扰方式（A:天然林,B:择伐天然林补植木麻黄,C:皆伐天然林种植木麻黄后实施保护,D:皆伐天然林种植木麻黄后对林下植被频繁干扰）影响下的植物群落为实验材料,系统研究了不同干扰方式对各群落物种组成、关键植物资源的种群动态、群落物种多样性和主要种群的生态位以及土壤理化性质的影响,揭示了各植物种群对不同干扰方式的响应和滨海沙地特定环境中植被的自然演替规律,为海岸带防护林的近自然恢复提供了基础资料,研究结果表明:1.随着干扰强度和频率的增大,群落的科、属、种数均表现出先升高后下降的趋势,说明适度干扰可增加物种多样性,支持中度干扰假说。不同干扰方式使植物群落处于不同的自然恢复演替阶段,群落受干扰强度越大,距离演替顶级就越远。随着时间的进行,植物群落在恢复演替上向着科、属、种组成更为丰富、复杂的方向发展;不同干扰方式下各林分的植物组成和重要值差别较大,天然次生林的乔木层和灌木层中,乡土植物潺槁木姜子（Litsea glutinosa）均是第一优势种,重要值分别为98和137,群落结构稳定;择伐干扰群落中,潺槁木姜子变为乔木层第三优势种,重要值为33,灌木层中仍为第一优势种,重要值为128;皆伐干扰后实施保护的群落,乔木层已无潺槁木姜子的分布,但灌木层中仍为第一优势种,重要值为64.12;皆伐干扰后频繁干扰的群落物种组成简单,各层次发育均较差;在植被的天然演替中,潺槁木姜子表现出较强的自然恢复能力,是对防护林进行近自然恢复的关键植物资源。2.不同干扰方式群落中潺槁木姜子种群的年龄结构均呈明显的反J型分布;样地A中潺槁木姜子种群各龄级间的个体数量变化动态指数V₁—V₆皆>0,V₇= V₈=0,整个种群年龄结构的数量变化动态指数V_pi=73.78%,考虑到种群的外部干扰时V_pi=8.18%>0;样地B中潺槁木姜子种群各龄级间的个体数量变化动态指数V₁—V₅皆>0,V₆= V₇=0,整个种群年龄结构的数量变化动态指数Vpi=86.93%,考虑到种群的外部干扰时V_pi=10.87%>0;样地C中潺槁木姜子种群各龄级间的个体数量变化动态指数V₁—V₂皆>0,V3=0,说明潺槁木姜子种群具有前期增长、后期稳定的特点,种群长远来看表现出增长与稳定的趋势。样地A中潺槁木姜子种群存活曲线拟合模型（N_X=N0e-0.7994x,R=0.952、N_X=N0x-3.3025,R=0.945）,属于DeeveyⅡ型,样地B中潺槁木姜子种群存活曲线拟合模型（N_X=N0e-0.851x,R=0.8812、N_X=N0x-3.1489,R=0.9854）和样地C中潺槁木姜子种群存活曲线拟合模型（N_X=N0e-1.798x,R=0.8995、N_X=N0x-3.9257,R=0.9295）属于DeeveyⅢ型;4种生存分析函数曲线都表明,潺槁木姜子种群具有前期增长、后期稳定的特点,与种群生命表的存活曲线、死亡率曲线和致死力曲线分析结果相一致。3.随着干扰强度和频率的增大,乔木层物种多样性和均匀度随着干扰强度和频率的增大逐渐降低,优势度逐渐上升,样地B的林下物种多样性都不同程度的高于样地A,说明择伐干扰增加了林分的物种多样性;样地C的灌木层和草本层物种多样性最高,说明皆伐干扰虽使乔木层物种多样性大大降低,但实施保护之后,灌木层和草本层的物种多样性逐步得到恢复,群落处于进展演替当中,另一方面也说干扰后自然恢复的初期,物种间的资源利用性竞争相对缓和,较多物种可在群落内共存;皆伐后持续干扰的群落各层次物种多样性均较低,人工种植的木麻黄成为群落的优势种,控制着群落的性质和结构,群落各方面指标与天然植被相差较远。4.随着人为干扰强度和频率的增大,群落间物种更替的速率逐渐升高,β多样性指数（CJ和Cs）越来越小,指数值均在50%以下,即随着干扰强度和频率的增大,植被的天然性程度越来越低,距离初始植被原来越远;βWS、βC、βR指数测度结果随着人为干扰强度和频率的增大,B级和C级群落间相异性指数（βWS、βC、βR）最大,说明皆伐干扰使群落物种更替速率最大,群落相似性最低;CN和CMH指数总体变化规律与βWS、βC、βR指数相反,随着人为干扰强度和频率的增大,其值变化规律是先减小后增大,人工纯林间物种组成和个体数最相似,其值最大。5.根据不同干扰方式各群落中的种群生态位特征,可将所有种群划分为生态位扩展型、衰退型、敏感型和稳定型4个类型;天然林中的演替优势种在木麻黄林的灌木种群中已有较大数量的分布,且具有较大的生态位宽度值,但由于人工林生态位分化不良,种间竞争相对激烈,群落组成不稳定;天然林中大部分乡土树种生态位宽度较之在木麻黄林中大为增加,但除敏感型种群和潺槁木姜子、雀梅藤以外,天然林中其他种群的生态位重叠值较之在木麻黄林中有所降低,说明经过长期的协同进化,天然林种间生态位分化程度高,竞争相对缓和。总体来看,以乡土树种为优势种的天然林比人工林生态位配置更优化,对维持群落的稳定更有意义,其群落结构可为沿海防护林的近自然恢复提供参考资料。6.对不同干扰方式下各群落土壤理化性质测定结果表明:天然次生林的土壤容重较低,孔隙度较高,有利于降水的下渗从而降低降水的径流系数,以减少土壤的侵蚀量,具有较强的水土保持能力,随着干扰强度和频率的增大,土壤的水土保持功能呈现逐渐下降的趋势,人工纯林的土壤孔隙度较低,不利于降水下渗,地表径流大,水土保持能力相对较低。天然林的PH值高于木麻黄林,除全氮外各种养分含量也不同程度的高于木麻黄林,因此,实现沿海防护林的近自然经营,对缓解纯林经营养分不足的缺陷,实现养分平衡,改善立地条件等有一定的启发意义。更多还原

【Abstract】 Casuarina equisetifolia was the important protective tree on sandy coast in China, played an important role in remedying the environmental deterioration, the ecological vulnerability and resisting the natural disaster of coastal areas. Because of the long-term suffering of pure forest management and serious human disturbance, frequent problems such as woodland crushing, soil nutrient disordering, diseases and pests of forest gradually appeared. The stability of protection forest was affected seriously. Constructing an near-nature coastal protection forest system can keep higher species diversity, community stability and more harmonious relationship between species, which was helpful in building the stable and efficient coastal protection forest system. Therefore, this paper took 4 communities （A: secondary forest, B: planting Casuarina after selective cutting the secondary forest, C: planting Casuarina after clear cutting the secondary forest then protect to now, D: planting Casuarina after clear cutting the secondary forest then disturb the undergrowth frequently）under different patterns of disturbance as material, studied the species composition and diversity of each community, the population dynamics of keystone plants and the main population niche, revealed the response of plants to different patterns of disturbance and the natural succession law of vegetation in coastal sandy environment, provided basic materials for building a neat-nature coastal protection forest system, the results showed that:1. The number of family and genera in community increased at first and then downward with the increase of intensity and frequency of disturbance, which means moderate disturbance can increase diversity, supporting intermediate disturbance hypothesis. Different ways of disturbance made communities in different stages of natural recovery, which means the succession will further from climax if the intensity of disturbance was greater. With time passed, the recovery towards a direction that the compose of families and genera in community become more abundant and complex. The species composition and importance value in each community were different under different patterns of disturbance, Litsea glutinosa was the first dominant specie in both tree layer and shrub layer of natural secondary forest, the importance value were 98 and 137, the community structure was stable. In selective cutting forest, Litsea glutinosa became the third dominant specie in tree layer which the importance value was 33 but still kept the first dominant position in shrub layer which the importance value was 128. However, the dominant position of Litsea glutinosa gradually decreased in clear cutting forest. There was no Litsea glutinosa existed in tree layer. The community structure was simple and the stability was weak. Litsea glutinosa represented strong ability of natural recovery in succession, which can be taken as the keystone species in the near-nature construction of protection forest2. The age structure of Litsea glutinosa under different patterns of disturbance appeared to be inversed J shape. Quantitative analysis showed that: the V₁—V₆ of Litsea glutinosa in sample A were all > 0, V₇ = V8 = 0, the whole dynamic index of quantity change of age structure V_pi = 73.78%, when considering external disturbance V_pi = 8.18%> 0; the V₁—V₅ of Litsea glutinosa in sample B were all > 0, V₆= V₇=0, the whole dynamic index of quantity change of age structure V_pi=86.93%, when considering external disturbance V_pi=10.87%>0; the V1—V2 of Litsea glutinosa in sample C were all > 0, V3=0, which indicated the population increased at the early stage, but kept stable at the late stage, the population showed a growth and stable trend.The survival curve of Litsea glutinosa in sample A（N_X=N0e-0.7994x,R=0.952、N_X=N0x-3.3025,R=0.945）belonged DeeveyⅡ, The survival curve of Litsea glutinosa in sample B（N_X=N0e-0.851x,R=0.8812、N_X=N0x-3.1489,R=0.9854）and sample C（N_X=N0e-1.798x,R=0.8995、N_X=N0x-3.9257,R=0.9295）belonged DeeveyⅢ, 4 functions all indicated the population increased at the early stage, but kept stable at the late stage, agreed the analysis of survival curve, date rate and lose rate in life table.3. With the increase of intensity and frequency of disturbance, the species diversity and evenness in tree layer gradually reduced, and the dominance rise gradually, the diversity of understorey in sample B were higher than sample A, which means selective cutting can increase the species diversity, the diversity of shrub and herb layer were highest in sample C, which means diversity was greatly reduced because of clear cutting in tree layer, but gradually recovered in shrub and herb layer when after protection, succession of community was in progress, it also said that, in the initial period of natural recovery after disturbance, the competition of resource utilize was more relax, more species can coexist in community. Species diversity in every layers were all low in sample D, Casuarina was the dominant species, controls properties and structure of community, the community was more different with natural vegetation.4. With the increase of intensity and frequency of disturbance, the speed of species replacement among communities had an increasing trend from low to high, the changes in species were greater and the common species decreased.βdiversity（CJ and Cs）trend from high to low, values were all bellow 50%. The natural degree of vegetation trend from high to low with the increase of intensity and frequency of disturbance, and became further from the initial vegetation.βdiversity（βWS、βC、βR）showed that the dissimilarly value between sample B and sample C was larger than others, which means the speed of species replacement among communities was largest under clear cutting disturbance, CN and CMH value downward at first and then increased with the increase of intensity and frequency of disturbance, the species composition and individual number in pure forest were most similar, the value was largest.5. According to the dynamics of niche breadth of each population, the main populations could be divided into 4 groups,niche invasive population,niche declining population,niche stable population and niche sensitive population;The dominant species of nature forest were wide distributing in shrub layer of Casuarina equisetifolia forest,and with wide niche breadth,but the niche differentiation of population were not sound,intersprcific competitions were severe,and community structure was not stable;Niche breadth of most native population in nature forest were wider than that of Casuarina equisetifolia forest,but the niche overlap of most population were lower except Litsea glutinosa,Sageretia thea and some niche sensitive population,which indicated that the niche differentiation of nature forest was greater,and the competitions among populations were not strong;On the whole,niche disposition in nature forest which composed by native species was more rational than that in Casuarina equisetifolia forest,and this was more meaningful on maintain the stability of community,so there was some reference value on the construction of stable coastal protection forest system if we can realize the rational disposition of native species and Casuarina equisetifolia.6. The density of soil in secondary forest was lower than other communities, but the porosity was higher, which was significant for the infiltration of rainfall and the reduce of surface water runoff,that can reduce the soil erosion with strong ability of soil and water conservation. With the increase of the intensity and frequency of disturbance, the function of water and soil conservation of community declined gradually, the porosity of soil in pure forest was lowest, and lacking in the function of water and soil conservation. PH value in secondary forest in higher than other communities, the nutrient was also higher except total N, so there was enlightening significance in reliving nutrient shortage, realizing nutrient balance and improving the site condition if we construct an near-nature coastal protection forest system.更多还原