| Spartina alterniflora which was one of the invaders spreading on coastal wetland in East Fujian and fierce competition with native species of Kandelia obovata,forming a mosaic distribution pattern.In this thesis,the macro distribution pattern and growth rate,the micro scale of S.alterniflora and mangroves mosaic distribution pattern,the relationship between population distribution pattern along tidal gradients and between population pattern and environment factors of S.alterniflora.4 aspects were used to study the invasive species on coastal wetlands in East Fujian by the methods of collecting data and combining with field investigation and indoor test.The results reveal that:(1)S.alterniflora growing mainly in the temperate zone in the mean tide level to the mean along and Estuarine Intertidal zone.Along the coast of China,S.alterniflora have been distributed,from north to Panshan County(40°53’N)in Liaoning Province,to South to Dianbai County(21°30’N)in Guangdong province,but the distribution was extremely uneven,mainly affected areas as Jiangsu Province(18711 hm2),Zhejiang Province(4812 hm2),Shanghai City(4812 hm2),and Fujian province(4812 hm2),this 4 areas occupy the national coastal S.alterniflora total distribution area 94.1 3%.In addition,from the growth rate on different latitudes,S.alterniflora.annual expansion speed size was in the order of Shanghai nine sand(31°03’-31°17’N)>Fujian Quanzhou estuary(24°27’-24°58’N)>Jiangsu Yancheng(32°51’-34°01’N)>Zhejiang Wenzhou(27°03’-28°36’N).Broad cloth of S.alterniflora and high resistance to adversity was the main cause of invasive plants become.(2)Fujian was the earliest province which field artificial planting of S.alterniflora around the country,it’s also one of the most serious invasion provinces by S.alterniflora.It’s concentrated in 13 main bays in Fujian province,from the aspect of spatial pattern,as the province affected 95.84%of the total area.From the aspect of administrative jurisdiction,the total area of S.alterniflora level ranking on the coastal cities of Fujian Province was:Ningde>Fuzhou>Quanzhou>Zhangzhou>Xiamen>Putian.If’s worth noting that the distribution was not suitable for the growth of S.alterniflora each bay has S.alterniflora,which Fujian province was the S.alterniflora.serious violations,while in the area of Fuqing Bay,Shenhu Bay and the Gulf of Zhaoan found no explanation of S.alterniflora.It illustrates the long distance communication ability of S.alterniflora was not strong and artificial cultivation was the main cause of S.alterniflora.rapid spread of large area.(3)S.alterniflora and K.obovata on the coastal wetland in East Fujian were showed that belonged to the aggregated distribution type,different water level aggregation degree was slightly different,and S.alterniflora gathering in different tidal levels that were higher than the population of K.obovata.From the the type index of spatial distribution in micro scale(1000m*100m)such as diffusion coefficient C,clumping index I,negative binomial K value,Cassie index Ca,mean crowding,and patchiness index.(4)At the micro-scale,the total of various types of patches was 102,a large number of plaques,the phenomenon with landscape fragmentation was serious,and mosaic distribution significantly between different plaque ecotone on the coastal wetlands in east Fujian.From the various types of plaque area,all plaque areas of S.alterniflora were 51435m2,the total area of the study area was more than 50%,area of bare flat plaques was 31321m2,the largest patch of K.candel plaque and grasses plaque area were 9015 m2 and 4838 m2.In short,a "large settlement,distribution pattern of small scattered" space were showed by S.alterniflora patches and K.candel plaques on the coastal wetlands in east Fujian.the patch area,perimeter and shape index of S.alterniflora were higher than other types of plaque,indicating its good connectivity and patch shape was called irregular which reflecting the state of spatial pattern of S.alterniflora invasion under natural conditions on the coastal wetlands in east Fujian.(5)The largest patch index of S.alterniflora patches at the 1000m*100m scale on the coastal wetlands in east Fujian was 51.42%which was the highest,and average patch area of S.alterniflora beyond the K.candel 4 times,while the degree of fragmentation of K.candel was stronger than S.alterniflora.Condensation degree of 4 different types plaque was more than 99%,which explained they had high degree of distribution aggregation and belonged to the aggregated distribution pattern.The higher index of Simpson diversity showed that rare types of plaque on the larger information contribution,has emerged the phenomenon of fragmentation,speculate that this was due to more finely plaque,different types of vegetation cover in mosaic distribution caused by the intersecting part.Together,a plurality of landscape index suggests that S.alterniflora was the dominant species which occupy the main living space.The order of plaques base on fragmentation degree of different types was grass patches>K.candel patches>bare flat plaques>S.alternilfora patches.(6)Tidal gradient make an effect on S.alterniflora patches on the coastal wetland in east Fujian,mainly through the influence of morphological characteristics and growth difference,which it only has less influence.The external resources environment differences showed high phenotypic plasticity,which may be an important reason for its successful invasion.Asexual reproduction indicators of invasive plant populations at different tidal differences were not significant(P>0.05)in addition to new shoot number,sexual reproduction indicators of different tidal levels were significant(P<0.05),sexual reproduction ability of S.alterniflora as the tide,high tide level>middle tidal level>low tide level.Tidal gradient in vivo number or population density did not show significant difference,illustrated that sexual reproduction was extremely low efficiency of S.alterniflora,which may be reasons to explain its slow intrusion and even tends to be stable during 10 years on the coastal wetlands in east Fujian.(7)Habitat environmental factors of S.alterniflora roughly 3 laws with tide rise,first kinds was that the soil moisture and the total phosphorus of soil decreasing regularly with tide rising;Second kinds was that soil pH and total nitrogen of soil were affected no significant by the changing of tide;Third kinds was that these environmental factors which were total salt of soil,total organic carbon of soil and soil organic matter,been the highest point in S3 and the lowest point in S6,which may be related to the soil deposition.The distance from shore based and kind of elevation was significantly negative correlation(r=-0.980,P<0.01),there was a significant positive correlation of soil moisture and distance from shore based(r=0.854,P<0.05),total phosphorus of soil and distance from shore based had a significant positive correlation(r=851,P<0.05),was negatively correlated with elevation(r=-0.922,P<0.05),total salt of soil was negatively correlated with total potassium of soil(r=-0.871,P<0.05),the correlation of total salt of soil and other environmental parameters reflecting the characteristics of salt marsh water I coupling effect.Total nitrogen of soil and total carbon of soil of S.alterniflora community habitat on the coastal wetlands in east Fujian were well coupled,and total nitrogen of soil and total organic carbon of soil showed significant positive correlation(r=983,P<0.01).(8)The distribution pattern and tidal gradient of S.alterniflora population on the coastal wetlands in east Fujian was closely related to population pattern,the two index of density of population pattern and the number of in vivo were significantly positive correlation with elevation,the correlation coefficients were 0.962 and 0.959(α=0.01);The density of S.alterniflora which has strong ability to absorb phosphorus and the number of in vivo were significant negative correlation with total phosphorus of soil,means of the higher S.alterniflora population density was,the greater phosphorus consumption was and the lower soil phosphorus content was.Influenced by the hydrological impact,root length of S.alterniflora and distance of shore based had significantly positive correlation,and was significantly negatively correlated with elevation.Asexual reproduction capacity of S.alterniflora and total salt of soil,total organic carbon of soil showed significant positive correlation,the correlation coefficients were 0.943 and 0.927(α=0.01),had positively correlated with total nitrogen of soil,was negatively correlated with total potassium of soil(r=-0.828,α=0.05),soil organic matter was an important environmental impact to sexual factor patterns of reproduction of S.alterniflora.Aboveground biomass and total biomass were significantly negative correlation with soil organic matter,illustrated that biomass index of S.alterniflora was mainly affected by soil organic matter. |
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