【作者】 蒋智林；

【导师】 万方浩；

【作者基本信息】 中国农业科学院 ， 生物安全， 2007， 博士

【摘要】 入侵我国西南地区的恶性杂草紫茎泽兰（Ageratina adenophora（Sprengel））对农业、林业、草场牧场以及自然生态系统带来了严重的危害，常导致入侵生境生态系统结构和功能发生改变，降低生物多样性且造成巨大的经济损失。为控制这一恶性杂草，人们尝试了多种方法，“以草制草”和恢复本地植物群落多样性控制紫茎泽兰入侵扩张为最有潜力的途径。本文围绕紫茎泽兰的竞争替代控制这一科学问题，采用植物竞争的现代生态学理论和方法，重点研究了紫茎泽兰与几种非入侵草本植物的竞争效应及其竞争策略，阐明了紫茎泽兰与几种非入侵草本植物的竞争替代效应及资源利用的生理生态机理，对揭示紫茎泽兰的种群扩张和实施紫茎泽兰入侵生境的植物替代控制策略具有重要的理论指导意义与实践价值。主要研究结果如下：1．在温室采用取代系列试验研究了紫茎泽兰与三种非入侵草本植物（马唐、牛膝菊和非洲狗尾草）幼苗的基本生物学特征及其竞争效应，以及施氮对其生长和竞争的影响。结果表明，四种植物同期播种，与紫茎泽兰相比三种非入侵草本植物植株高大、分蘖数多且生物量大，但不同物种植株叶片数关系各异；施氮对植物生长发育均具有促进作用，但非入侵草本植物增长能力更强；在种间竞争中，紫茎泽兰植株株高、分蘖数、叶片数和生物量均随其相对密度的下降而显著降低或呈降低趋势，但非入侵草本植物则随其相对密度的下降而显著升高或无显著变化。进而表明，紫茎泽兰幼苗期的竞争能力较非入侵草本植物马唐、牛膝菊和非洲狗尾草弱；施氮更有利于非入侵草本植物幼苗的生长和竞争；紫茎泽兰相对密度越低，在竞争中受到的抑制作用越大。2．在温室比较研究了非洲狗尾草和紫茎泽兰在不同氮磷肥力条件下的竞争效应及其光合生理。结果表明，非洲狗尾草根生物量和总生物量较紫茎泽兰的高，施肥显著提高了非洲根狗尾草的相对生物量，其中施氮作用更为明显。未施肥时，紫茎泽兰的光合养分（氮素、磷素、水分）利用效率均比非洲狗尾草的高，施肥时非洲狗尾草的光合养分利用效率、相对生长速率和净同化速率均显著升高，而紫茎泽兰的降低或无显著变化，这些生理变化在施用氮肥时比施用磷肥时更为明显。说明非洲狗尾草的相对竞争能力较紫茎泽兰强，施氮比施磷更有利于非洲狗尾草对紫茎泽兰的竞争。3．在野外建立不同密度非洲狗尾草和紫茎泽兰单种及两物种1：1混种种群，比较研究了两物种2年期间的生长特征及其竞争效应。结果表明：非洲狗尾草植株生物量、相对产量和竞争平衡指数均较紫茎泽兰的高，相对产量总和小于1，且均随种群密度增大而更加明显。紫茎泽兰在混种密度为20株·m^-2、45株·m^-2和175株·m^-2时植株生物量较其在单种对应密度时分别降低了33.0％、38.5％和70.1％，而非洲狗尾草植株生物量在单混种时无明显变化。两物种混种时，非洲狗尾草的根茎比比其在单种时降低，但紫茎泽兰的根茎比比其在单种时升高。说明在2年期间非洲狗尾草具有较强的竞争能力，其地上竞争作用更为明显，在密度较高时对紫茎泽兰的控制效果较好。4．对上述种群中非洲狗尾草和紫茎泽兰植株氮、磷、钾养分含量和养分利用效率，以及植株养分生产力和养分平均滞留时间的研究表明：（1）非洲狗尾草植株氮和钾含量均显著比紫茎泽兰的高，而其磷含量显著比紫茎泽兰的低；两物种植株氮和钾含量均随密度增大均显著降低，而其磷含量则均显著升高。（2）非洲狗尾草植株氮素利用效率显著比紫茎泽兰的高，但其磷素利用效率和钾素利用效率均显著比紫茎泽兰的低；非洲狗尾草植株养分利用效率均随种群密度增大显著升高，紫茎泽兰则显著降低。与在单种时相比，在混种竞争中非洲狗尾草植株养分利用效率均降低；紫茎泽兰在密度为20株·m^-2和45株·m^-2时植株养分利用效率均显著升高，但在密度为175株·m^-2时急剧降低低。（3）两物种植株养分生产力和养分平均滞留时间均显著负相关，但对密度变化和竞争的反应策略不同。说明非洲狗尾草氮素利用能力比紫茎泽兰强，而磷素和钾素利用能力比紫茎泽兰弱；在密度较低时紫茎泽兰对养分的竞争能力较强，而在高密度时对养分的竞争能力较弱。5．对紫茎泽兰和非洲狗尾草单种及两物种1：1混种种群根际土壤中4种土壤酶活性和土壤有效养分的研究表明：（1）非洲狗尾草种群根际土壤NH₄⁺-N和NO₃^--N含量均显著比在紫茎泽兰种群的高，而与在混种种群的无显著差异；非洲狗尾草种群根际土壤有效磷和有效钾含量均显著比在紫茎泽兰种群的低，但显著比在混种种群的高。（2）非洲狗尾草种群根际土壤蛋白酶和脲酶活性均显著比在紫茎泽兰种群的高，但其磷酸酶和蔗糖酶活性均显著比在紫茎泽兰种群的低，在单种和混种种群中不同酶活性高低关系不一致。（3）不同种群根际土壤有效养分与土壤酶活性具有较一致的相关性。这说明非洲狗尾草对土壤含氮化合物的活化能力比紫茎泽兰强，且在种间竞争中能够抑制紫茎泽兰对土壤含磷和含钾化合物的活化能力，这可能是其竞争取胜的原因之一；土壤酶活性对根际土壤有效养分的变化可能具有重要作用。6．不同植物功能型群落对紫茎泽兰种子发芽存活率和幼苗生长影响的研究表明：（1）紫茎泽兰种子在非洲狗尾草种群和非洲狗尾草与牛膝菊混种种群中均不能发芽存活，在禾本科植物群落中的发芽存活率比在非禾本科植物群落低，而在混种群落的发芽存活率比在单种种群的低；（2）紫茎泽兰在非洲狗尾草和野艾蒿种群的生产力最小，而在大狗尾草种群的生产力最大；两种植物功能型混合群落的生产力介于单一植物功能型种群的生产力之间；与单一植物功能型和紫茎泽兰混种比较，两种植物功能型植物与紫茎泽兰混种时的相对产量与相对产量总和均呈降低趋势。这说明不同植物功能型对紫茎泽兰入侵抵御能力不同，植物功能型多样性越高的群落对紫茎泽兰的抵御能力越强。更多还原

【Abstract】 Ageratina adenophora （Sprengel） is a worldwide noxious weed and has caused tremendous detrimental effects on agriculture, forestry, rangeland and natural ecosystem since it invaded in Southwesten China in last century. It is replacing native species and leading to alteration of ecosystem structure and function and causing enormous economic losses. Management actions that control the spread and impacts of the weed become very stringent, and controlling the weed by other competitive and economic grasses or by restoring native species biodiversity was thought to be most hopeful ways. In this study, the morphological characteristics, resource use physiological strategies, competition effect and competition response of A. adenophora and non-invasives were studied comparatively and the resistance of different plant functional type communities on A. adenophora invasion were explored. The main contents and results were as follows:1. Three comparative competition experiments between A. adenophora and non-invasives （i.e. Setaria viridis, Digitaria sanguinalis, and Galinsoga parviflora） with a replacement series design were studied in greenhouses at seedling stage with N supply or without N supply. The results showed that the plant shoot height, tiller number and biomass of A. adenophora were significant lower than those of non-invasives and there was no consistent relations in leaf number between A. adenophora and non-invasives. Comparad to in no N supply treatment, the plant shoot height, tiller and biomass of two species increased significantly in N supply treatments, and the non-invasives showed greater increasing response to N supply than A. adenophora. With the relative density decreasing, the plant shoot height, tiller and leaf numbers and biomass of A. adenophora decreased significantly or had a trend of decreasing, but those of non-invasives showed significant increasing or no obvious changes. Those indicated that the competitive ability of A. adenophora was less than that of non-invasives at seedling stage. N supply had greater effect on facilitating growth and competition of non-invasives seedling compared to A. adenophora, and the negative effects of non-invasive on growth of A. adenophora were heavier with the decreasing of A. adenophora density.2. The effects of N and P supply on root biomass, total biomass, relative growth rate （RGR）, net assimilation rate （NAR）, relative biomass ratio （RBR）, photosynthetic nitrogen-use efficiency （PNUE）, photosynthetic phosphorus-use efficiency （PPUE） and photosynthetic water-use efficiency （PWUE） of A. adenophora and S. sphacelata were studied in the greenhouse using a pair comparative design. The results showed that the root biomass and total biomass of S. sphacelata were higher than those of A. adenophora, RBR of S. sphacelata increased significantly when nutrient provided and this become more obvious with the increasing of N supply. The PNUE, PPUE and PWUE of A. adenophora were higher than those of 5. sphacelata when no nutrient supplied, but nutrient supply increased the PNUE, PPUE, PWUE, RGR and NAR of S. sphacelata significantly, and those of A. adenophora decreased or no obvious changes were observed. N supply had greater effect on these changes than P supply. Those indicated that the relative competitive ability of S. sphacelata was greater than that of A. adenophora, N supply had greater effect on improving the relative competitive ability of S.sphacelata compared to the effect of P supply.3. The monoculture and mixture communities of A. adenophora and S. sphacelata were established for 2 yr on three experimental densities in the field, the above- and blow-ground biomass of the two species were measured, and the growth response and relative competitive ability were evaluated. The results showed that the total biomass, relative yield and competitive balance index of 5. sphacelata were significant higher than those of A. adenophora, the relative yield total was significant lower than 1. The relationships mentioned above become more obvious with the increasing of density. The total biomass of A. adenophora at the densities of 20, 45 and 175 plants.m^-2 in mixture decreased by 33.0%、38.5% and 70.1% compared to those in monoculture, respectively. However, the total biomass of S. sphacelata at the same density between monoculture and mixture showed no significant difference. The ratios of root mass vs shoot mass of S. sphacelata in mixture were significant lower than those in monoculture. However, the ratios of root mass vs shoot mass of A. adenophora in the mixture were significant higher than those in monoculture. Those indicated that the relative competitive ability of S. sphacelata was higher than that of A. adenophora, which decreased the growth of A. adenophora mainly by aboveground competition. It will be a good strategy for replacement control of A. adenophora by using S. sphacelata as a competitor at higher density condition.4. The contents of nutrients （N, P and K） in plant, plant nutrient use efficiency and its two components （nutrient productivity and means residence time） of A. adenophora and S. sphacelata were studied in the monoculture and mixture communities of A. adenophora and S. sphacelata in the field. The results showed as follows: （1） The N and K contents in plant of S. sphacelata were higher than those of A. adenophora, but the plant P content of S. sphacelata was lower than that of A. adenophora. With the increasing of density, the N and K contents in plants of two species decreased sharply, but the P content in plant of them increased greatly. （2） The plant N nutrient use efficiency of S. sphacelata was significant higher than that of A. adenophora, but the plant P and K nutrient use efficiencies of S. sphacelata were significant lower than those of A. adenophora. The plant N, P and K nutrient use efficiency of S. sphacelata increased significantly with the density increasing, but those of A. adenophora decreased significantly. Compared to in the monoculture, the plant nutrient use efficiency of S. sphacelata decreased significantly in the mixture, similar with that of A. adenophora at the densitiy of 175 plant·m^-2 in the mixture, but contrary to that of A. adenophor at densities of 20 and 45 plant.m^-2 in the mixture. （3） There were significant different nutrient use strategies for A. adenophora and S. sphacelata, and there appeared to be a trade-off between nutrient productivity and means residence time, since both components of nutrient use efficiency could not be maximised together.5. Four kinds of soil enzymatic activities and soil available nutrients in communities of A. adenophora monoculture （A）, S. sphacelata monoculture （S） and two species mixture （A+S） at the rhizosphere zones were studied at different development stages, and the correlations of soil enzymatic activities and soil nutrients were analyzed. The results showed as follows: （1） The rhizosphere soil NH₄⁺-N and soil NO₃^--N contents in S. sphacelata monoculture community were higher significantly than these in community A, but there weren’t different compared to these in communities A+S. The contents of soil available P or available K in community A were highest followed in community S, and these in community A+S were least. （2） The soil protease and soil urease activities in three kinds of plant communities decreased as protease: S＞A+S＞A, urease: A+S＞S＞A. And the soil phosphate and invertase activities increased as phosphate: A+S＜S＜A, invertase: S＜A＜A+S. （3） There were consistent relationships between soil enzymatic activities and soil available nutrients contents in the three kinds of plant communities. Our results indicated that S. sphacelata has higher net ammonification and nitrification rates compared to those of A. adenophora and could decrease the available P and available K in mixture communities of A. adenophora and S. sphacelata, which may be potential reasons for S. sphacelata out-competed A. adenophora. The soil enzymatic activities should play an important action on the changes of the soil available nutrients at the rhizosphere zones.6. The effects of different plant functional type communities on seed germination livability and seedling growth of A. adenophora were studied. The results showed that the seed germination livability of A. adenophora in the community of Setaria faberii was lower than those in the communities of Galinsoga parviflora and Artemisia lavandulaefolia, and the seed germination liabilities of A. adenophora in mixture community of S. faberii and G. parviflora was lower than those in their monoculture communities, respectively. However, the seed germination liabilities of A. adenophora were zero in the community of Setaria sphacelata and in mixture community of S. sphacelata and G parviflor. The productivity of A. adenophora was the lowest in mixture communities of A. adenophora with S. sphacelata and A. lavandulaefolia, but it was the highest in the community of S. faberii. The productivity in mixture communities of two kinds of plant functional types was higher than that in one plant functional type community, but it was lower than that in the other plant functional types community. Compared to one plant functional type community, the relative yield and relative yield total of mixture community of A. adenophora and two plant functional types had a trend of decreasing, indicating that different plant functional types had different resistance ability to the invasion of A. adenophora. The communities with various plant functional types had greater resistance ability to A. adenophora invasion. Restoring and protecting the native plant biodiversity will play an important role for control and prevention of further invasion of A. adenophora.更多还原