【作者】 覃盈盈；

【导师】 梁士楚；

【作者基本信息】 广西师范大学 ， 野生动植物保护与利用， 2009， 硕士

【摘要】 互花米草(Spartina alterniflora Loisel)为禾本科米草属(Spartina Schreb)多年生草本植物。由于互花米草具有耐盐、耐潮汐淹没、根系发达、繁殖力强等特点,被许多沿海国家引种,用于保滩护堤、改良土壤、绿化海滩以及改善海滩生态环境。然而,由于互花米草特殊的生物学特性,其生长的速度远超过人们的控制能力,致使潮间带的生态系统遭受严重破坏。红树林是海岸潮间带重要的初级生产者,有较大的生物量和较多的凋落物产生,具有高度开放和高度复杂的能量流动和物质循环特征,是河口海岸重要的食物源和能量源。广西于1979年在合浦山口红树林保护区引种互花米草,当时对当地海域曾起到一定的防风消浪、保滩促淤等积极作用。但是,近年来互花米草在山口红树林保护区迅速扩散和蔓延,已经对该区生态系统的结构造成了一定程度的破坏。为了分析互花米草在红树林生境中的生长规律和繁殖特性,正确评估互花米草对红树林入侵的生态后果及在红树林区域开展合理防控措施,本文通过野外动态监测和室内栽培试验,对生长在该区红树林不同生境(淤泥质、泥沙质、沙质)中的互花米草的形态因子、生物量动态、光合作用、繁殖期的生物量动态和繁殖器官的特征进行了较为系统研究。结果如下:1、生境条件对互花米草的形态因子和生物量的生长有显著影响。如在生长旺盛期6月,淤泥质、泥沙质和沙质三种生境中互花米草的密度分别为95株/m2、87株/m2和63株/m2,生物量分别为578.823g/m2、475.316g/ m2和219.541g/ m2,以淤泥质中生长的互花米草的单位面积株数和生物量最高;对比单株的形态因子,则以泥沙质中的互花米草长势最佳,并与淤泥质、沙质相差显著;在淤泥质与沙质中,除地下生物量外,其它形态因子与生物量之间没有显著差异;在不同的生境中互花米草生物量的分配存在一定的差异。结合其它各月的实验结果发现,土壤透气性及养分含量可能是影响互花米草形态因子和生物量差异的主要因素。2、有性繁殖期(6~11月)的生物量动态变化初步研究表明:在繁殖初期,不同营养器官间的生物量随时间的增加均有不同程度的增加;但在繁殖后期,根、茎、叶的生物量的增长率均出现负值,其中,根生物量和叶生物量的负增长共同导致茎生物量出现负增长;除6月份外,生物量分配模式在各器官的顺序均为:茎>叶>根>繁殖器官;根生物量占总生物量比率有下降趋势,从6月份的28.9%下降到11月份的14.0%;茎生物量占总生物量比率随年龄增加呈上升趋势,由6月份的21.7%上升到11月份的44.0%;叶生物量随时间增长由于生理老化缓慢下降;小穗在7月和9月的时候占的比例分别为6.4%和7.0%,到了种子成熟期,种子占总生物量的比例分别为3.0%和9.7%。总的来说,繁殖器官生物量占总生物量的比例不大。3、互花米草净光合速率日变化呈双峰型,具有明显的午休现象,气孔导度和蒸腾速率的日变化均呈单峰曲线,胞间CO2浓度与光合速率呈极显著负相关,光合午休现象主要由非气孔因素影响。光强、温度、气孔导度和蒸腾速率的峰值均出现在12:00时,各种环境因素均影响互花米草的光合速率,互花米草光合作用受气孔因素与非气孔因素的共同影响。对其午间退潮到天黑前这一特定时间段互花米草叶片气孔导度及相应环境因子的变化测定和分析表明:互花米草不同叶位的叶片气孔导度是不同的,在垂直方向上,其排序大致呈现中上部>顶部>中下部>下部的趋势;叶片气孔导度与光强、叶温呈幂函数关系,与时间、相对湿度呈负指数函数关系;在相对湿度为50%~60%时,气孔导度最大,随着湿度的增加,气孔有关闭的趋势,气孔导度也变小;互花米草植株中部的叶片对整个植株光合产物积累的贡献较大。各种环境因子对互花米草气孔的开闭存在交互作用,因此,互花米草叶片的气孔导度是对环境因子的综合反应。4、经统计不同生境条件(淤泥质、泥沙质、沙质)下互花米草种子成熟期结实器官的形态、数量特征及饱满种子的百粒重发现:单株互花米草形态因子以泥沙质中的长势最好,沙质中生长的互花米草结实器官各形态因子均大于淤泥质和泥沙质,其中穗前总长达到了53.59cm,穗颈长为26.50cm,穗长为27.09cm,平均每穗长13.35cm,除了穗长和淤泥质无差异外,其余各形态因子均与其它两个生境中的有显著差异,三种生境中第二小穗的长度均大于第一小穗;在淤泥质中的小穗数最大值为13枝.泥沙质的为12枝,沙质中的最少,只有9枝;淤泥质、泥沙质、沙质中平均每穗种子数分布范围分别为14~42粒、15~35粒、21~43粒;第一小穗种子数的分别为4~48粒、3~34粒、8~46粒;第二小穗种子数分别为8~50粒、6~38粒、18~48粒。三种生境中小穗顶端的种子饱满程度远高于小穗底部。5、互花米草已经对山口国家级红树林保护区生态系统的结构造成了一定程度的破坏,必须高度重视互花米草对广西近岸海域及红树林国家级自然保护区的生物入侵问题,建议采取多种方法对互花米草入侵进行综合防治。更多还原

【Abstract】 Spartina alterniflora Loisel., a perennial grass, belongs to Spartina Schreb. in Gramineae. The originally purpose of introducing this species to many ocean countries and regions was to protect the beach environment, to improve soil properties and to make beach green due to its high tolerate ability to salinity and flooding, strong reproductive capacity and developmental root system. But now it is growing out of control and causes serious damages to the intertidal zone system.Mangroves are one of the most important primary producer in intertidal marine system, they have high biomass, litter production and high rate of energy flow and material circulation,and thus mangroves are an important food and energy sources in the estuarine and coastal systems. In Guangxi, S. alterniflora was first introduced in National Shankou Mangrove Nature Reserve in 1979, and has played an important role in preventing wind and wave, protecting beach erosion and promoting siltation. But in the last few years, S. alterniflora has gradually spread into neighboring mangrove communities and caused a large quantity of damage to the ecological system in the National Shankou Mangrove Nature Reserve. In this paper, the growth rules and reproductive characteristics of S. alterniflora in mangrove habitat were studied in order to provide some strategies to control its invasion. For this purpose, field dynamic monitoring investigation and indoor cultivation experiment were employed to make a systematic research on the morphological factor, biomass dynamics, photosynthesis, biomass dynamics in reproductive period and characteristics of reproductive organs of S. altemiflora in different mangrove habitats (clay, loam, and sand). The results obtained are as follows:1. Mangrove habitat has a significant effect on the biomass and morphological characteristics of S. alterniflora. Among the three habitats, individuals of S. alterniflora growing in clay habitat had the highest density and biomass. But in terms of morphological factors, the individuals of S. alterniflora grows best in the loam habitat than that of other two habitats. There was no significant difference between clay and sand habitats except for the under-ground biomass. Difference was exsited in biomass allocation among the three habitats. Soil porosity and nutrient content might be account to the difference of biomass and other morphological factos of S. alterniflora in three habitats.2. The biomass dynamics of S. alterniflora during the sexual propagation period were also studied in this paper. The results showed that: at the beginning of reproduction,the biomass of different organs increased respectively in various degrees with the time; but in the late of reproductive stage,the growth rates of root、stem and leaf biomass are negative, the negative biomass of stem was induced by the negative biomass growth rate of root and stem. The order of organs biomass is: stem> leaf>root>reproductive organ except in june; With the time goes by, the rate of root biomass decreased from 28.9% in June to 14.0% in November, while the ratio of stem biomass : total biomass was increased with the time goes by. The leaf biomass decrease slowly due to the physiologic aging. In a word, the biomass of reproductive organs only take a few part in the total biomass.3. The diurnal variation of net photosynthetic rate of S. alterniflora was a double peak curves and had a significant depression in the midday. Stomatal conductance(Gs) and transpiration rate (E) of S. alterniflora displayed single-apex curves. An significant negative correlation was exsited between intercellular CO2 concentration(Ci) and net photosynthetic rate. It was suggested that non-stomatal factors were the major causes of midday depression. The peak value of light intensity, temperature, stomatal conductance and transpiration rate appeared at 12:00, all environment factors could influence the net photosynthetic rate of S. alterniflora, and photosynthesis was controlled by stomatal factor and non - stomatal factor. The stomatal conductance dynamics of S. alterniflora growing in loamy mangrove habitat, was studied from noon to evening (ebb tide), and meanwhile, the relevant environmental factors were measured and analyzed. The results showed that: the stomatal conductance in different part of the plant varied vertically, i.e., the opening of leaf stomatal conductance was upper part>top>lower-middle part>under part. The leaf stomatal conductance had a relationship of power function to the light intensity and leaf temperature, but a negative exponential function with the time and relative humidity (RH). The stomatal conductance opening was biggest with humidity at 50%~60%, but with the increase of humidity the stomatal conductance became smaller. The leaves located at the middle part had the largest contribution to accumulation of photosynthate in the whole plant. The interaction of diverse environmental factors affected the stomatal opening and closure, and thus, its dynamic change can be viewed as a comprehensive response to environmental parameters.4. The morphological and quantitative characteristics, as well as the weight of 100 full seeds at maturity stage of S. alterniflora in three different habitats were studied in this paper. The results showed that: S. alterniflora had the best grow patterns in the loam habitat,the morphological factors of fructification of S. alterniflora grown in sand were larger than other habitats;The order of quantitative characteristics of fructification in the three habitats were clay>sand>loam; The variance analysis results showed that: In sand habitats, except length there were significant difference in all morphological factors to the other two habitats; length of second spikelet were longer than length of first spikelet in three habitats; the plumpness of seed at spikelet apical were higher than the button.5. The invation of S. alterniflora has caused large quantity of damage to the ecology system in the National Shankou Mangrove Nature Reserve. It’s necessary to pay high attention to the problems caused by the invasion of S. alterniflora in this area and comprehensive preventing methods should be applied to prohibiting its invasion.更多还原