Eco-Economy And Eco-Safety Management Of Coastal Wetland Invasive Plants,with Special Reference To Spartina Alterniflora Lois In Fujian,China

This paper taking Spartina alternijlora Lois in the coastal wetland in Fujian as a case and adopting the methodology of combining literature survey and field experiments,explores the eco-economy and eco-safety management of invasive plants in the coastal wetland. The major results are as follows.1. State of Art of Invasive Plants in the Coastal FujianAmong about 60 species of indentified alien plants in China, 27 species of 11 families are found in Xiamen of Fujian. The most typical invasive plant in the coastal wetland of Fujian is smooth cordgrass(5partina alterniflora Lois).2. Eco-environmental Features of Coastal FujianThe marine eco-environments in Fujian are featured by complicated mairne hydrology,heavier winds and bigger waves,specific botton geology and geomorphology,more coastal and oceanic disasters, rich living resources,more complicated ecological types,rich and diverse marine ecosystems and more natural nurseries for commercial species. Coastal and oceanic economy has become a new economic growth point for Fujian province. Along 3 324km of zigzag mainland coastline of Fujian, there are 125 harbours or bays.Offshore 24 coastal coastal counties(cities),there are 205 919 hm~2 intertidal zone with an averae width of 619m, the total intertidal zone area being about 1.72% of the the land land. Altogether 1118 species of benthos have identified in the intertial zone and the sublittoral zone of 10 major harbours or bays, of which polychaetes are 200 species, molluscs 395 species,crustacean 230 spcecies,benthic fishes 107 species, alage 107 species and others 79 species. The coastal intertidal zone have comparatively higher ecological and economic values as it functions in degrading environment pollution,mitigating natural disasters, maintaining biodiversity, providing natural resources, water resources, land resources and tourism resources. However, the inrshore waters in several major harbours and bays are suffering from nutrient pollution dominated by inorganic nitrogen with a tendency of becoming more serious. In addition, the invasive plant of Spartina alterniflora is spreading in about 11 000 hm2 in the intertidal zone and there is rather serious problem of unplanned land-reclaimation from the sea.3. Biological and ecological features of Spartina alterniflora Smooth cordgrass is a vivacious member in the genus of Spartina of the grass family. A plant is l~3m high and and more than lcm in stem diamter, with alternate leaf blades. In the form of elongated lanceolation, a leaf is deep or light green with waxy glittering on it smooth back. Endowed with saline gland, the plant could exclude salts. With cone inflorescence, the plant flowers from July to October with bisexual flowers and 3 male buds. The anther cracks logitudianlly when ripen and the pollen is yellow. The seeds become mature in October and November and are easy to fall off. Every 1 000 seeds weigh 7.5~~7.7g. A seed will directly germinate into a young plant when falls off naturally as it is featured by postripeness. The seeds fail to germinate when dry. The germination will be inhibited if the seeds are processed with 5% ~7% sodium chloride solution.Smooth cordgrass, with highly developed rooting system composed generally of short and thin fibril and long and robust underground stalks (root stalks), expands rapidly. A sporadic plant cluster in a barren intertidal zone may radially expand one to several meters about.Smooth cordgrass highly tolerates saline and flooding and grows well in the intertidal zone from lower high water to upper mid-water zones. With lower requirements for soil quality, the height of a grass is mainly subject to ambient conditions. With various ecological types, the plant generally shows an increasefrom the north to the south in its seasons of blossoming and growth, stem height and leafblade broadth. 4. The distribution of Spartina alterniflora in coastal FujianBased on remote sensing data, about 11 000 hm2 of Spartina alterniflora has been mapped in coastal Fujian, mainly in coastal Ningde, where about 90% of the total distribution area is identified. In addtion, the grass is also distributed scatterly in the coastal wetland off Fuzhou, Quanzhou, Xiamen and Zhangzhou, with a further exapanding tendency.The expansion rate of smooth cordgrass displays three stages, the initial stage accounting for 30% and culminating stage for about 43%. With the complete occupation of the suitable niche in the intertidal zone, its expanding rate may decrease to 10% and expects to continue the decreasing until the rates suits to the growth rate of the intertidal zone. Smooth cordgrass, with high tolerance to saline and flooding, suits to growth in the intertidal zone between the lower high water and upper mid-water zones.5.Ecological and Economic function analysis of smooth cordgrass Smooth cordgrass plays a role in coastal protection as it functions in waterbreaking, flow-reduction, siltation promotion and land consolidation. Its cost of coastal protection is only 0.3% of riprapping. In addition, the grass promotes siltation and land reclaimation.Smooth cordgrass demonnstrates direct impact on the content and distribution of nitrogen, phospherous, potassium and organic matters in the intertidal zone and the transfer of more than 10 mineral elements in the saline marsh. The rooting system of the plant may concentrate heavy metal and radionuclides such as mercury, l37Cs,90Sr,ll5Cd and 65Zn. With distinct capability in sewage purification, the plant removes in an average 32.1% and 38.8% of total phospherous and ammonium nigtrogen.In addition to bearing chemical elements very similar to that in human blood, the grass contians sulfonate such as sulfonic amine and sulfonic flavone, 13 species of animo acids, higg density lipid proteins, agglutinin and various volatile composition. These secondary metabolites are bioactive materials good for human health. In addition, Spartina alterniflora has enriched anti-inversion genebank and can be used for the cultivation of new breed with anti-inversion new strains.Smooth cordgrass contains 10.75% crude protein, 2.04% crude fat, 26.01% crude fibre, aq certain amount of ash and vitamins and 10 necessary animo acids for animals. Its fresh leaves and undground roots are high quality and dainty food for domestic animals, who might graze or comsume the compound feed containing with the processed dry leave powder. The compound feed has been sucessuflly used in feeding sheep, swine, chicken, rabbit and fish. Moreover, the grass might be turned into organic fertilizer and made use of as firewood, grass fence and culture for edible musshrooms.6. The analysis of benefits and harms of smooth cordgrass and its riskassessmentAs it has dense and robust stems and developed underground rooting system which help promote rapid settlement and deposition of silt, as a result the growth of the grass changes the landform in the interdial zone and reduces the waterflow in the tidal creeks and channels ,or even induces flooding and hampers smooth ship operation. Moreover, it may may bring imapct to navigation and great threat to the normal functions of a navigation port.The expanding of Spartina alterniflora may change the habitat of benthos in the intertidal zone and cause the destruction of some benthic population with high commerical value, and the loss of beds for shellfish culture and nursery and normal growth of algae. In Fujian along, the expansion of the grass has casued an economic loss of RMB 300 million yuan per year in this regard. The grass by its invasion may compete with or replace the native plants and form a dense and unique community of smooth cordgrass by occupying the invaded area, so as causing the habitat loss for wading birds and the decrease of the population of wading birds. This is the major ecological aftermath from the invasion of smooth cordgrasses in the world. Fujian waters charaterizes the northern boundary for the distribution of natural mangroves. The impact of smooth cordgrass on mangrove trees, especially on the native species such as Avicennia marina has caused ecological destruction in the coastal wetland ofFujian Province.The integrated assessment of various indexes shows that smooth cordgrass is a species with high risk and its invasion and expanding in the coastal wetland of Fujian should be strictly controlled.7. Management and control of smooth cordgrass development The control and mitigation methodology for smooth cordgrass includes phsical methods by plant removal, burning and bulldozing for holding back its growth and shield coverage or water flooding of its distribution area for limiting its respiration or photosynthesis, the chemical methods by applying glyphosate,gallant (haloxyfop-ethoxyethyl) and smooth cordgrass herbicide BC-08, the biological control methods by Prokelisia marginata and ergot bacteria. In addition, the replacement of the cordgrass by mangrove plants is an alternative for biological control of the grass.The above-mentioned methods might be combined for the control and mitigation of smooth cordgrass.In order to control the further spawling of smooth cordgrass and mitigate its expansion rate, it is necessary to construct a decision-making system for its monitoring and removing and a technical supportive system and monitoring and supervision system for further strengthening the management of the grass invasion.The control and mitigation methodology for smooth cordgrass includes the phsical methods such as pulling , digging-out, covering ,flooding ,buring , cutting and bulldozing of the plants for holding back their growth or limiting their respiration or photosynthesis, with the aim to kill the plants. The chemical methods include the applying glyphosate, gallant and smooth cordgrass herbicide BC-08 and the biological control methods applying Prokelisia marginata and ergot bacteria(C7av/ce/w purpurea). In addition, the replacement of the cordgrass by mangrove plants is an alternative for biological control of the grass.The above-mentioned methods might be combined for the control and mitigation of the cord grass.The case study in Xiamen indicates that scientific approaches shoud be followed in the artificial removal of smooth cordgrass, otherwis, the results may go contrdict against the intention.The apply of of glyphosate, fusillade, gallant and...