Dissertation > Agricultural Sciences > Plant Protection > Harmful plants and their removal > Weeds

The Adaptability of Invasion Alien Species of Composite in Response to Different Environmental Gradients in Henan Section of the Yellow River Watershed

Author YuanXiaoZuo
Tutor DingShengYan
School Henan University
Course Ecology
Keywords Yellow River Basin Henan Section Asteraceae alien species Morphological changes Environmental gradients
CLC S451
Type Master's thesis
Year 2011
Downloads 73
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Flows through 21 counties in Henan Province, Henan section of the Yellow River Basin, it is important for some of the middle and lower reaches of the Yellow River, the cradle of Chinese civilization, is also an important grain-producing areas. The region from east to west by hills from the plains to the mountains to form the gradient of a continuously changing environment, and provide a variety of habitat conditions for the invasion of exotic species. 188 kinds of alien invasive plants in the Compositae only there 49. Research in Henan Section of Yellow River Basin, Asteraceae alien species Conyza canadensis (as Conyza canadensis), subulate Aster (the Aster subulatus) Bidens pilosa, Bidens pilosa the the Su-door liquor grass (as Conyza sumatrensis) , the Hong maackianus (Conyza bonariensis) and year pont (Erigeron annuus) 6. In the Yellow River Basin in Henan to set up 29 representative samples, each sample point selection flood land, farmland edge, plantations and abandoned land four common types of habitats, each habitat set up a large (20m × 20m), within a large plot with a five-point sampling method set quadrats (1m × 1m) of each quadrats Asteraceae alien species were observed. The observations include: leaf-storey, inflorescence, stem diameter, blade length and width (leaf area), leaf thickness, number of leaves, flowers and fruits number. In the spring of 2010, the summer and autumn, the regional survey, the survey results show that: Conyza canadensis are widely distributed in the Yellow River Basin in Henan, a large number; subulate Aster, of Sumen liquor grass and Hong wire grass mostly distributed in flood The places and plantation; Bidenspilosa basic distribution in flood land. Area, the most serious potential hazards of Conyza canadensis, followed subulate Aster, a potentially harmful Bidenspilosa flood land. According to the surveys, as well as access to relevant information in the experiment can be roughly estimated Conyza canadensis and Aster subulate spread diffusion path in the region as well as the mode of transmission. Conyza canadensis in Yantai in 1860, and then in 1886 and 1887, respectively, in Yichang, Hubei and Sichuan Nanxi taken to Thus Conyza canadensis may from Yantai after Shandong Province is transmitted to the Henan section of the Yellow River Basin, or incoming from Sichuan, Shaanxi by Shaanxi spread to the region; then spreading to the two sides in various habitats of vertical transmission. Subulate Aster at the earliest in 1947 in Hubei Wuchang reports, After subulate Aster generated a lot of seed may be spread by the Wuhan to Zhengzhou spread by sea or by land, and then in the Yellow River Basin in Henan. Conyza canadensis subulate Aster seeds are small and light, has crested, mainly spread by the wind, but accelerated the spread of human disturbance. Conyza canadensis is widely distributed in the lower reaches of the Yellow River plain areas and in larger quantities and plain areas conducive to its spread diffusion. Downward trend with increasing elevation, the landscape changes and heat conditions reduce flood land Conyza canadensis indicators performance; Conyza canadensis side of the farmland in the spring of each index is increased and then decreased trend in no significant variation in the summer its indicators, which is related to the strong side farmland human interference; plantation and fallow Conyza canadensis indicators peaked in the hilly areas, which may due to the hilly areas of high biological diversity within communities The competition is more intense, resulting in larger individual plants of Conyza canadensis. From changes in the summer and autumn Conyza canadensis floral number, come to the hilly and mountainous regions Conyza canadensis early entry into the breeding season. Described above Conyza canadensis strong resilience landscape changes in the region. Different seasons, Conyza canadensis morphological differences. Conyza canadensis height and stem diameter changes with the seasons and increased leaf area in order to meet the summer temperatures reduce transpiration decreases, leaf thickness thickening, and thus the allocation and utilization of resources is reflected in the number of blades, Conyza canadensis reached the maximum number of leaves in the summer. Conyza canadensis, a small part of the summer into the breeding season, most of the small bottle grows in the autumn into the peak of breeding, fall leaves, vegetative growth slows to stop into fecundity. The above description of Conyza canadensis to adapt to climate change in the region can be self-regulating the distribution of growth, especially leaf traits and floral number changes, has strong adaptability. Combination of local villagers asked the four habitats interference based on the observation of the surrounding environment and research plots broadly Sort: farmland edge gt; abandoned land gt; plantation gt; flood land. Conyza canadensis, farmland edges and fallow in four habitats due to human fertilization and irrigation morphological index is greater than the flood land and plantations, and plant more tall and stout, leaf area, number of leaves relatively dense the season; flood land and plantation morphological index size differences, and lighting conditions and moisture conditions. Due to plantation canopy density, resulting in a small bottle grows higher, but smaller stems, leaf area, leaves more sparse. Four habitat types, the stronger the interference, Conyza canadensis higher morphological index, Conyza canadensis can adapt to disturbed habitats. The subulate Aster basically the same rules for the adaptation of the different landscape types Conyza canadensis, in line with its seasonal changes Conyza canadensis. Which the aster leaf area subulate in the summer than in the spring large, with drill-shaped Aster itself blades structure can effectively prevent transpiration effects. Four habitat types (except plantation outside), interfere with the stronger, the higher the subulate Aster morphological index, indicating that it can adapt to the strong interference. Plantation subulate Aster indicators than in other habitats are low, indicating plenty of light to play an important role in the growth of the diamond-shaped Aster. The Henan section of the Yellow River Basin, from the East to the West formed a continuously changing environment gradient, Conyza canadensis, subulate Aster Asteraceae alien plants can regulate their own growth and nutrient distribution in various organs, to adapt to the complexity of the region environmental gradient, indicating its strong adaptability. The Henan section of the Yellow River basin, mainly in the context of the agricultural ecosystem quadrats research provides research basis for the future to find out the relationship between the invasion of alien species and agricultural development balance; and also later on a larger scale for invasive species a comprehensive analysis of the study provide a reference. In addition, in the Yellow River Basin in Henan Asteraceae potentially harmful invasive species research, prevent its outbreak as well as controlling the research foundation, has important significance for later.

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