| In terrestrial ecosystems,litter degradation is a crucial process in carbon cycling.More than 50% of primary production is returned to the soil through litterfall.In many ecosystems around the world,fire is considered to be an important ecological factor and plays an essential role in the historical development and succession of plant communities.Previous research on subtropical grassland focused mostly on chemical elements,large soil animals,and soil erosion.This study attempts to explore the degradation mechanism of litter in subtropical grassland as influenced by fire disturbance.Duing 2017 September,hurrican Maria and hurrican Irma attack Puerto Rico,which left great opportunity for us to study the hurrican effecitons on litter degression,We conducted a litter degradation study using litterbags that vary in mesh sizes to study their effects of macro-,meso-,and micro-fauna on litter degradation in tropical grassland.We use 2 mm mesh screen to isolate soil macro-fauna,0.006 mm mesh cloth to isolate soil meso-fauna and micro-fauna,and 6 mm grid of litter bags allow all size soil fauna to enter litterbags.This research study found that(1)fire disturbance can inhibit the degradation of grass litter,and hurricane can promote the degradation of litter.The effect of microorganisms on litter is linear with time,and is less vulnerable to fire disturb.(2)Fire disturbance increase the total carbon and total nitrogen content of the soil in the short term.The average total carbon content of the soil: experimental group 17.43g/Kg,control group12.97 g/Kg.The average soil total nitrogen content: 0.41 g/Kg for experimental group and 0.32 g/Kg for the control group.(3)The synergy of meso-fauna and macro-fauna in the litter degradation process together guarantees the orderliness of the litter degradation and the stability of degradation rate.Compared with the control group,the decomposition rate of the experimental group was higher than that of the control group in the first week.During 3 to 15 weeks after burning,meso-fauna contributed significantly to litter degradation;the inhibitory effect of large soil animals on the predation of micro-arthropods led to the negative contribution of large soil animals to the litter degradation rate.At the bagining of the decoposition,macro-fauna contribute more on Megathyrsus Maximus,and soil arthropod controbute more on Dichanthium Annulatum decomposition. |
