【作者】 李贺鹏；

【导师】 张利权；

【作者基本信息】 华东师范大学 ， 生态学， 2007， 博士

【摘要】 生物入侵对全球农业和自然生态系统完整性所造成的巨大危害已成为生态学家关注的焦点。生物入侵不仅导致生态系统功能丧失,而且致使本地物种灭绝和降低生物多样性,最终影响到全球的生态环境和经济发展。自20世纪90年代中期以来,随着外来植物互花米草在崇明东滩保护区内迅速扩散和大面积入侵,东滩生态系统的结构和功能正受到严重威胁,因此治理和控制互花米草对维护和保护东滩保护区的生物多样性具有非常重要的意义和必要性。作者于2005～2006年间,在东滩互花米草入侵区域进行了翻耕、碎根、刈割和以及生物(芦苇)替代实验,得出了如下结果:1)互花米草根茎的克隆生长是其在崇明东滩进行大面积扩散的重要方式。通过对互花米草地下根茎进行处理,研究其在不同程度处理下的再生生长特点。不同深度(20 cm、40 cm和60 cm)的处理结果表明:翻耕处理后互花米草植株密度于当年7月份开始迅速增加,但在第一个生长季末期,其植株密度、平均高度、盖度、地上生物量、结穗数都显著低于对照(P<0.05),而结穗率和种穗长度都不同程度的低于对照,但是没有显著性差异(P>0.05);在不同翻耕深度处理之间,互花米草的生长特征都不存在显著性的差异(P>0.05)。在第二年生长季,互花米草的植株密度、结穗数和结穗率都迅速增加,至生长季末期,除了结穗数和结穗率显著高于对照,以及60 cm深度处理的在盖度和地上生物量显著低于对照外(P<0.05),其他各处理的各参数都与对照无显著性差异(P>0.05)。在碎根实验中,碎根处理后的第一个生长季,不同深度的处理都显著抑制了互花米草的无性生长和有性繁殖特征,其抑制作用随处理深度增加而明显提高(P<0.05);经过两个生长季后,互花米草基本恢复到与对照相同的水平(P>0.05),而其结穗数和结穗率都显著高于对照(P<0.05)。在对互花米草进行根部处理后的第一个生长季内,动物种类和密度都显著增加,同时海三棱藨草也出现短暂生长;但是在第二个生长季内随着互花米草的迅速生长,动物种类和密度都显著下降。2)在互花米草的控制研究中,掌握实施处理的最佳时期是控制入侵物种的关键因素之一。本实验在互花米草的整个生长季内对其进行单次刈割和多次刈割处理,比较了不同时期的刈割以及多频率刈割处理下互花米草地上部分的生长特征,结果表明:在第一个生长季,早期刈割(3月)显著提高了的互花米草群落盖度、植株密度、地上生物量、结穗数和结穗率等(P<0.05);5～9月间和多频率的处理都显著抑制了互花米草的无性生长和有性繁殖生长(P<0.05)。在第二个生长季,各处理中互花米草的生长都得到一定程度的恢复,其中单次刈割中的6～9月的处理,以及两次和三次刈割处理都显著降低了互花米草的无性生长(P<0.05),但是其有性繁殖特征都接近或超过了对照(除8月的处理在结穗数上显著较低外)。综合两个生长季末期互花米草生长的调查结果,单次刈割中8月的处理对互花米草生长的影响最大,然后分别是7月和9月;两次刈割和三次刈割的处理对互花米草生长的抑制效果不如单次刈割中8月的处理。3)生物替代是根据群落演替的规律利用本地物种替代外来物种的生态学方法。本实验在对互花米草进行不同深度翻耕处理和碎根处理的基础上,进行了芦苇替代实验,结果表明:移栽的芦苇保持了较高的存活率,并占据一定的空间;在第一个生长季,芦苇存活率率最大值出现在处理深度为40 cm的处理,分别为66.7%(翻耕)和77.8%(碎根);在第二个生长季,由于受到迅速再生互花米草的影响,移栽芦苇的平均成活率稍有降低,但仍维持在53.7%,植株高度和结穗率也明显增加。综上所述,互花米草具有较强的抗干扰能力和恢复能力。若利用翻耕和碎根处理防治互花米草,必须考虑处理的强度和时间;利用芦苇替代实现控制互花米草的目的,需要注意及时去除再生的互花米草,促进移栽芦苇得到较快恢复,同时还要注意移栽的最佳时间和移栽密度,以及需要考虑其他影响芦苇生长的环境因子等。更多还原

【Abstract】 Biological invasion has received considerable attention recently due to their increasing impacts on local ecosystems and is becoming one of the six most serious environmental problems that may influence the future economical and social development. Since introduced into the Chongming Dongtan Nature Reserve in 1995, Spartina alterniflora has rapidly expanded and seriously threatened the biodiversity there. During 2005 and 2006, a field experiment of controls, including digging tillage, breaking rhizome, mowing, and biological substitute, on S. alterniflora was conducted to search effective measures for controlling this invasive plant. The growth parameters of plant density, height, cover, leaf area index (LAI), stem diameter, aboveground biomass, fruiting number, fruiting rate and inflorescence length were used to evaluate the efficiency of different treatments. The major findings are summarized as follows.1) S. alterniflora has invaded rapidly into the intertidal zones mainly via asexually spreasing at Chongming Dongtan in recent years. It was hypothesized that the different treatments on the vegetative rhizomes would have different effects on the re-growth of S. alterniflora.The results from the treatment of digging tillage (20 cm, 40 cm and 60 cm) showed that the density of S. alterniflora began to increase from July for the treatment of digging tillage, while the plant density, mean height, cover, aboveground biomass and fruiting number were still significantly lower than those of the control (P<0.05), but fruiting rate and inflorescence length met those of the control. There were no significant differences between the different treatments of the three depths (P>0.05). In the second growing season, the differences between the treatment and the control were not as significant as in the first growing season and there were no significant differences in the end of the second growing season, except that the fruiting number and fruiting rate of S. alterniflora were significant higher than those of the control, and the cover and aboveground biomass of 60 cm depth treatment were much lower than that of the control (P<0.05).The treatment of breaking rhizome significantly inhibited the growth of S. alterniflora in the first growing season and the inhibition increased with the depth of the treatment. However, the inhibition on S. alternijlora’s growth disappeared after two growing seasons and there were no significant differences among the treatments and the control (P>0.05).The treatments on the rhizomes of S. alternijlora in this study resulted in many native species occurring in the first year, including Assiminea violacea, Cerithiidea largillierli, Sesarma denaani, Ilyrplax deschampsi, Boleophthalmus Pectinirostris L., and one native species of plant: Scirpus mariqueter, suggesting that it may facilitate the establishment of the native community. However, the aboundance and density of benthic macroinvertebrates decreased significantly with the rapid enhancement in cover of S. alterniflora in the second year.2) The optimal period of controlling invasive species is a key factor to succeed in removing the invaders. The treatment of mowing on control of S. alterniflora occurred in every month throughout one growing season (except April), and included repeated mowing: two and three times. The results showed that the treatment of mowing significantly inhibited both vegetative growth and sexual reproduction of S. alterniflora in the first growing season (P<0.05), while the treatment of mowing in March significantly promoted the growth of S. alterniflora, including higher cover, density, aboveground biomass, fruiting number and fruiting rate compared to those of the control (P<0.05).In the end of second growing season, both vegetative growth and sexual reproduction of S. alterniflora recovered in some extent. The treatments occurred in June, July, August, September, and repeated mowing (two and three times) significantly inhibited its vegetative growth (P<0.05). However, the sexual reproduction of S. alterniflora under all the treatments met or exceeded that of the control, only the fruiting number recorded in the treatment of mowing in August was significantly lower than that of the control (P<0.05). The treatment of mowing in August had proven to be the most effective, so it might be the suitable time for controlling.3) Biological substitute is to use native species, economically or ecologically benefit to the native ecosystems, as a biological control agent to replace the invasive species. In the experiment of biological substitute, S. alterniflora was first removed by the treatments of both digging tillage and breaking rhizome, and then Phragmites australis was transplanted into the treated plots. The results showed that the transplanted P. australis kept a relatively high survival and occupied certain room among the population of re-grown S. alterniflora during the two growing seasons. Both plant height and fruiting rate of P. australis increased considerably in the second growing season.The results from this study indicated that S. alterniflora has a strong capacity to withstand physical stresses or disturbances and regrow rapidly. It is necessary to take into account of frequency, intensity and season of these measures to achieve a feasible strategy for controlling the invasion of S. alterniflora in the nature reserve.更多还原