부산대학교 도서관

Tropical Dry Forest are an important global carbon sink, with fundamental ecologicalfunctions of capture, regulation, and supply of water resources. However, due to theseasonality with prolonged dry season water is the most limiting resource for growth. Eventhough Tropical Dry Forest represents 42% of all tropical forests, studies dealing with theircarbon and greenhouse gas (GHG) exchange are still scarce. The aim of this study was toevaluate the seasonal variations of soil CO2, N2O and CH4 fluxes in a Tropical Dry Forest.We evaluated three different land covers in the Tropical Dry Forest Santa Rosa National Parkin Costa Rica i.e. advanced forest succession, early succession, and pasture: At each site soilGHG exchange was measured by replicated (n=6) dark static chamber technique.Measurements were taken between 8:00 and 9:00 am twice a week at each siteduring the period of dry/wet transition season (May-June) and monthly during therainy season (July-December) in the year 2018. Over the same period, the NEE(net ecosystem exchange) at the late stage forest site was measured using an Eddycovariance flux tower. Our results show that in the dry season soil fluxes remainlow and with the start of the first rain events, we see large pulse emissions at allsites caused by the "Birch effect." Moreover, these high pulses were lower in thepasture (CO2 24.50 ± 18.29 mg C m−2 h−1, N2O1.58 ± 1.88 μg N m−2 h−1, andCH4-4.86 ± 8.10 μg C m−2 h−1), followed by the late forest succession (CO2 38.38± 21.78 mg C m−2 h−1, N2O17.39 ± 21.48 μg N m−2 h−1, and CH4-24.57 ±10.52 μg C m−2 h−1) and the early succession (CO2 50.67 ± 20.7 mg C m−2 h−1,N2O21.37 ± 34.02 μg N m−2 h−1, and CH4-3.23 ± 16.77 μg C m−2 h−1). The earlystage forest had the highest soil fluxes, probably due to the higher accumulation oforganic matter and dieback of microbial biomass in the soil during the dry season.The ecosystem NEE measured with the eddy covariance tower at the beginning ofthe rainy season was of 4154.01 ± 2782.68 mg C m−2 d−1reaching maximumvalues of 8184.98 mg C m−2 d−1. The total GHG exchange from the soil varies forall sites going from ∼2 kg CO2-C equiv ha−1d−1 in the dry season, to >15 kgCO2-C equiv ha−1d−1 in the transition season and >5 kg CO2-C equiv ha−1d−1in the rainy season. Soil moisture is the main driver for soil respiration and soilgreenhouse gasses in this ecosystem, however, the current and historic land useand stage of forest succession also affects differently the accumulation and releasedynamics of soil greenhouse gasses to the atmosphere in tropical dry forest soils. [ABSTRACT FROM AUTHOR]