Effect Of Cutting-based Control On Smooth Cord Grass, Spartina Alterniflora

Since its introduction into the Fujian province in the 1980s, Spartina alterniflora (cordgrass) has rapidly expanded its range and invaded many areas. This has caused serious damage to the structure and function of tidal ecosystems. Our study group seeks an efficient cutting regime that will help control cordgrass in the Ningde tidal flats. Additional field experiments are necessary to determine the most effective period during which to cut Spartina. We are also conducting research on the soluble sugars, respiratory metabolism and root activity of this species. The main results were as follows:1. Effects of cutting on the efficiency of Spartina controlWe conducted a field experiment that included three treatments (cutting above the ground level, cutting at the ground level and cutting below the ground level) applied during three growth periods (15th May, 15th July and 15th September). In this mowing experiment, the plant density, height, diameter and coverage rates were significantly different between treatments at the end of the growing season. Each treatment inhibited the regrowth of Spartina in each of the three periods. Cutting below the ground was the most effective because it eliminated the regrowth during all of the growth periods. The optimal control period was determined to be May–June because there was no regrowth after any of the treatments applied at this time.2. Effects of cutting on the soluble sugar concentration in the rootsIn this study, the soluble sugar concentration in the roots of Spartina was tested. The soluble sugar concentration decreased significantly for all of the cutting treatments done in May. The soluble sugar concentrations in the roots of Spartina plants that were cut below the ground were lower than that of plants mown at the ground level or above the ground level. Cutting below the ground level in July significantly reduced the soluble sugar concentrations in the roots. However, sugar concentrations decreased slowly and then increased slightly after plants were cut at or above the ground level. The results show that the depth of cutting influences the concentration of soluble sugar in the roots and thus the plant's capacity for regrowth.3. Effects of cutting on root respiratory metabolism and root activityCutting below the ground caused anoxia tolerance in the roots of Spartina, which led in turn to reductions in the activity of the enzyme SDH until it was completely inactivated. The enzyme SDH is involved in aerobic respiration. The other two treatments caused initial reductions in the activity of SDH and root activity. These initial reductions were followed by slow increases. The activities of ADH and LDH and the ethanol concentrations in the roots exhibited different trends. The results show that cutting leads to a shift from aerobic respiration to anaerobic respiration, which means that the roots are unable to acquire enough energy and accumulate a large number of harmful metabolites. Cutting below the ground level caused the greatest damage, and the plants were unable to regrow.