Effects Of Simulated Warming And Nitrogen Deposition On Growth And Morphological Characteristics Of Several Species Of Invasive Asteraceae Plants

Global change, climate warming and nitrogen deposition as its characters, hasbeen changing the ecological environment that human beings survived on, whichcaused increasing attentions and researches. Relative studies indicated that theincreasing of temperature and nitrogen deposition may influence plants’ growth andmorphological character, either promoting or restraining their growth. The change ofenvironment also may change the interspecific competition of plants, and affectthe invasive process and results of exotic species into a new habitat. The interactionsbetween plant invasion and global change factors have become a hot issue inGlobal Ecology. With methods of simulated warming by infrared radiant heaterand simulated nitrogen deposition by adding ammonium nitrate solution, thisexperiment studied the interspecific competition of several invasive plants and nativeplants, and their competitive growth response under the condition of global change.The main results were as follows:1The increasing of temperature had influence on the growth and morphologicalfeatures of Centaurea maculosa in different areas. When the temperature raised by2℃, it was propitious to the growth of local species in some areas while wentagainst that in other areas, and the influence may be related to their geographicallocation and climate condition. The concrete influence was that the response of areasin low latitude and high latitude was greater than those in middle latitude, and theresponse of mountainous area was greater than that of coastal area. After nitrogendeposition of4.0g.m^-2, the height and aboveground biomass of C. maculosa in eachteam （except Maryland group） increased, while the root biomass and root-shoot ratiodecreased. The response degree of C. maculosa in different areas varied, and theconcrete degree was Vermont group> Montana group> Maryland group, which hadsimilarity with the result of temperature increasing disposal. These indicated addingnitrogen promoted the growing ability of C. maculosa, but it went against the growthof plant root by persistent adding nitrogen in long term or adding nitrogen of high concentration.2When the Poa annua suffered no competition from C. maculosa, temperatureincreasing could promote the growth of P. annua. When suffered competition from C.maculosa, the growth of P. annua suffered got strong interference, and indexes likeleaf area and biomass decreased evidently, with the concrete influence ordered asUkraine group> Arkansas group> Romania group> Vermont group> Montanagroup> Maryland group> Canada group. Under increased temperature, the growth ofmost C. maculosa and P. annua in competition got acceleration, and the growth of P.annua aboveground accelerated more markedly while that of C. maculosa root wasmore sensitive. When the P. annua didn’t suffer competition from C. maculosa,nitrogen deposition of4.0g.m^-2could observably boost the growth of P. annua. WhenC. maculosa competed with P. annua, the response of the former was more sensitivewith its growth status and competitive power stronger than P. annua. The competitiveadvantage of C. maculosa in different areas was Vermont group> Maryland group>Montana group. The growth of C. maculosa was dominant in competition, andnitrogen deposition made such dominance more prominent.3Different warming models had various influence on the growth of plant. Theresponse of Bidens pilosa to warming from strong to was weak all-day warming, nightwarming, day warming; that of Eupatorium chinense and Eupatorium adenophorumwas day warming, night warming, all-day warming; that of Solidago canadensis wasday warming, all-day warming, night warming. Such three warming models hadpromotion on the aboveground growth of native species （B. pilosa and E. chinense）,but went against the growth of their root. Except all-day warming had no accelerationon the growth of E. adenophorum, all warming models speeded the aboveground androot growth of the invasive species （E. adenophorum and S. canadensis）. Throughadding nitrogen of1.0g.m^-2and4.0g.m^-2to4plant species, it found that nitrogen oftwo concentrations had acceleration on the growth of plant. The acceleration of nativespecies under nitrogen disposal of1.0g.m^-2was greater than that under nitrogendisposal of4.0g.m^-2, while that of invasive species was reverse. This indicated that,compared with native species, the invasive species had stronger endurance to nitrogenof higher concentration or persistent nitrogen deposition, and their growth was moredominant.