【作者】 胡楠；

【导师】 丁圣彦；

【作者基本信息】 河南大学 ， 植物学， 2008， 博士

【摘要】 植物功能群(Plant Functional Groups, PFGs)把植物的功能特性与环境变化明晰地联系在一起。目前,陆地生态系统植物功能群研究主要以草原生态系统为主,对森林生态系统的研究较为薄弱。植物功能群的提出和研究,为研究复杂的植物生态系统提供了一个良好的方法和途径。现在对植物功能群研究的广度和宽度已经远远超过了这个概念本身。植物功能群整合了功能及对环境响应相似的一类植物,但植物功能特征不是绝对的、单一的,所以对植物功能群就会有不同的理解,会有不同的定义及划分方法。许多研究者从不同的角度、尺度来对植物功能群进行研究,这些研究结果有不同的针对方向和目的,使我们可以从不同的角度更全面的理解复杂的陆地生态系统。学者们在研究生态系统时,或多或少地总要与植物功能群相联系,这大大拓宽了植物功能群的应用范围。所有前人的研究使植物功能群的概念、划分、方向和应用等诸方面越来越清晰。一个规范、统一和明确的植物功能群研究方案,能对植物功能群的研究更加深入,也能整合全球所有植物功能群的相关研究。森林生态系统结构复杂,植物种类丰富。对森林生态系统复杂多样的植被进行功能群划分可以深入了解森林生态系统的结构和功能。优势种左右着森林生态系统的结构与功能,以优势种为主体划分森林生态系统功能群,可以对森林生态系统的功能、框架结构及类群分布有一个明晰的认识。伏牛山国家级自然保护区是中国东部森林样带中的北亚热带和暖温带的结合点,具有南北气候过渡带的典型特征,在自然和人为双重因素的作用下,群落的优势种突出。随着环境梯度(海拔)的变化,优势种变化明显,能较好的反映出植被与环境的动态关系。采用群落生态学的调查方法,对伏牛山南北坡植被进行调查。根据调查结果,通过计算重要值等方法选择优势种,进而进行植物功能群划分。(1)确定37个乔木树种为研究对象,以X2(卡方)检验为基础,结合联结系数AC和共同出现百分率PC来测定乔木优势种间的联结性。根据优势种间的联结性及其在海拔梯度上的变化异同来划分植物功能群,结果表明,栓皮栎(Quercus variabilis)、短柄枹(Q. glandulifera)、锐齿栎(Q. acutidentata)、华山松(Pinus armandi)依海拔升高分别具有最大的优势性。以这四个优势种为主体将伏牛山自然保护区乔木层划分为四个植物功能群,第一组功能群为:栓皮栎,槲栎(Q. aliena),山槐(Aldizzia kalkora),茅栗(Castaneaseguinii()1100m以下);第二组功能群为:短柄枹，化香(Platycarya strobilacea),黄连木(Pistacia chinensis)(1100~1400m);第三组功能群为:锐齿栎,千金榆(Carpinus cordata),漆树(Toxicodendron vernicifluum)(1400~1800m);第四组功能群为:华山松,油松(P. tabulaeformis),六道木(Abelia biflora),白桦(Betula platyphylla),红桦(B. albo-sinensis)(1800m以上)。分析各功能群沿水热梯度的动态变化及其内在联系。可以十分清楚的发现在这四个植物功能群内有一些重要的形态特征是有相似之处的,功能群间的形态特征也有明显的区别,如叶片的大小、树干的栓皮等。它们在进化的过程中也有着某些关联与差异。(2)草本植物对环境的反应较为敏感,能较好的反映出植被与环境的动态关系。以同样的方法研究了林下草本植物,共划分七组草本植物功能群:Ⅰ“伴人型”,Ⅱ“高山型”,III“阴湿型”,Ⅳ“耐旱型”,Ⅴ“林隙型”,Ⅵ“基础型”,Ⅶ“原始型”。这七种草本植物功能群基本上反映了不同环境条件下不同结构与功能的草本植被的分布情况。优势种种群的分布格局在不同功能群中多呈集群分布,且空间分布指数沿海拔梯度呈规律性变化。重要值大生态位宽的种群与其它种群的生态位重叠程度较大,相反,重要值小生态位窄的种群与其它种群生态位重叠程度较小。少数种群间出现重要值大,生态位重叠小;重要值小生态位重叠大的特征。用Li-6400便携式光合作用测定系统在典型样地测定优势种的光合作用日变化及光响应特性,分析不同植物功能群优势种的光合特性,结果表明:在森林生态系统中,乔木和草本植物由于适应机制不一样,光合特性主要是受光合有效辐射的影响;同样的光强下,在短时间内草本与乔木物种光合速率相差不大;植物对光强的适应范围比人们想象的要大;受森林生态系统各种外界条件的影响,植物“光合午休”现象并不明显。森林土壤的pH值、有机质含量、有效氮含量、速效钾含量及有效磷含量基本代表了土壤的养分状况,这些因素与植物功能群关系也较密切。不同植物功能群(乔木、灌木、草本)的分布与数量与森林土壤有着一定相互关系:南坡的pH值、有机质含量、有效氮含量、速效钾含量及有效磷含量总体上高于北坡;pH值沿海拔梯度变化不大;有机质含量、有效氮含量、速效钾含量随海拔上升而上升;有效磷含量在中低海拔含量较高;土层越深,有机质含量、有效氮含量、速效钾含量及有效磷含量越低,pH值变化不明显。森林土壤特性变化的明显程度依次为:有机质>速效钾>有效氮。乔木和草本植物的种类、组成和多少对森林土壤养分含量具有决定作用,这是由于植被的归还作用引起的。更多还原

【Abstract】 Plant functional groups (PFGs) link plant functional traits and environmental variations with great clarity. Most of the studies on PFGs of terrestrial ecosystems to date have concentrated on grasslands and forests. The PFGs concept has facilitated studies on complex plant communities. It allows us to describe an entire terrestrial ecosystem in a very finite number of distinct plant functional types instead of thousands of plant species, thus vastly simplifying studies on highly complex plant communities by reducing variables that require investigation phenomenally. Currently, the extent and width of researches on PFGs have far exceeded the PFGs concept itself. Indeed, researches on PFGs have evolved and coalesced into a self-sustaining academic discipline. The PFGs concept groups plant species into distinct clusters according to similarities in their functions and responses to environmental conditions. Plants respond to environmental conditions in various ways that are subject to specific circumstances, however, and their functional characteristics are far from absolute and simple, therefore different definitions and classification methods of PFGs exist. Many researchers have studied Plant Functional Types from different perspectives and on varying scales. Focused on differing topics, these studies are designed to answer a wide range of scientific questions in relation with PFGs. The processes and results of these studies can provide much insight into plant functional groups, thus significantly facilitating our comprehension of complex terrestrial ecosystems. The PFGs concept has by now permeated the entire field of ecosystem ecology so thoroughly that researchers almost always use this concept while studying terrestrial ecosystems, either explicitly or implicitly. Consequently the application of the PFGs concept has been much broadened. Having conducted numerous studies on PFGs and thus accumulated large amounts of relevant data, researchers working on plant functional groups and related topics all over the world now need a universal, standardized, and unequivocal research protocol. Such a protocol will allow a comprehensive integration of research projects on PFGs globally, which in turn can provide a significant boost to future researches on PFGs and deepen our understanding of plant functional groups. Forest ecosystems are characterized by extraordinary structural complexity and phenomenal plant species richness. While making forest ecosystems fascinating, these characteristics complicate the task of understanding the interconnections and functions of forest plant species. Dividing the species rich and functionally complex vegetation of a forest ecosystem into plant functional groups can significantly facilitate studies on the structure and functioning of such an ecosystem by vastly reducing variables that require investigation. Dominant species control the structure and functioning of a forest ecosystem. Delimiting plant functional groups of a forest ecosystem according to dominant species, therefore, is a viable approach to gaining a clear understanding of the functions, structural framework, and species distributions of such an ecosystem. Straddling the subtropical and warm-temperate zones of East China, the FuNiu Mountain National Natural Reserve is representative of north-south climatic transition zones. Its ecosystem is composed mainly of a few dominant species whose abundances clearly vary along altitudinal gradients. Using community ecology techniques, we investigated plant assemblages on both the north and south slopes of the FuNiu Mountain. Results of this investigation were used to calculate species importance values, which in turn were used to identify dominant species. In all, thirty-seven tree species were studied. X2 test, together with association coefficient (AC) and percentage co-occurrence (PC), were used to measure interspecific associations of the dominant tree species. PFGs were defined according to interspecific associations and altitudinal distributions of the dominant species. Four dominant tree species are identified (Quercus variabilis, Q. glandulifera, Q. acutidentata, Pinus armandi), forming the basis of four PFGs. PFG1: Q. variabilis, Q. aliena, Aldizzia kalkora, Castanea seguinii (under 1000m); PFG2: Q. glandulifera, Platycarya strobilacea, Pistacia chinensis (1100m-1400m); PFG3: Q. acutidentata, Carpinus cordata, Toxicodendron vernicifluum (1400-1800m); PFG4: P. armandi, P. tabulaeformis, Abelia biflora, Betula platyphylla, B. albo-sinensis (above 1800m). By analyzing dynamics of these plant functional groups along the moisture and temperature gradients, we have discovered that while these PFGs have similarities in several important morphological characteristics, they differ in many other vital morphological traits such as leaf size and cork thickness. Some evolutionary connections and differentiations also appear to exist among these PFGs. Highly responsive to changes in environmental conditions, herbaceous plants are very useful to the study of vegetation-environment dynamics. Following the investigation protocol applied to the tree species, seven PFGs of herbaceous plants were identified: I. anthropophilic, II. montane, III. sciophilic, IV. drought-tolerant, V. forest gap,Ⅵ. foundational, and VII. primordial.The dominant species showed clumped distribution patterns. Species that scored high on importance value and niche width had relatively high levels of niche overlap with other species. Species that scored low on importance value and niche width had relatively low levels of niche overlap with other species. There were however a few exceptions to these general observations.Daily photosynthetic changes and light responses of the dominant species were measured using the Li-6400 system. Photosynthetic efficiency characteristics of these species were analyzed. The results showed that the photosynthetic characteristics were mainly influenced by PAR, the plant species were adapted to light intensity ranges that were greater than expected, and there was no obvious midday depression of photosynthesis.Soil fertility is determined primarily by pH value and fractions of organic matter, available nitrogen, phosphorus and potassium. In this study, the distribution of plant functional groups appeared to be closely correlated with attributes of the forest soil. Organic matter content, available nitrogen content and available potassium content all increased with elevation, while available phosphor content peaked at medium and low altitudes. Apparently nutrient content was determined by vegetation attributes, perhaps due to nutrient recycling by plants.更多还原