The relationships between litterfall and soil dynamics on Kenting Uplifted Coral Reef Nature Reserve Forest Ecosystem

• Main Authors: Jiung-Hao Liao, 廖駿豪
• Other Authors: Zeng-Yei Hseu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/61193690817752553639

碩士 === 國立屏東科技大學 === 環境工程與科學系 === 94 === The Kengting Nature Reserve of Uplifted Coral Reef (KNROUCR) is the largest in area and well protected area for tropic evergreen broad-leaved rain forest in Taiwan. The long-term plot of 10 ha was divided into four habitat types with different species compositions: the autum maple tree (Bischofia javanica)- Taiwan nato tree (Palaquium formosanum) type on the flat terrace whereas was designed as habitat A in this study; the sappan wood (Aglaia formosana) – pouteria (Pouteria abovata) type on the ridge of exposed coral reef, designed as habitat B; the eleplant’s ear (Macar tanarius) – konishi cryptocarya (Cryptocarya concinna) type on the sedimentary basin, designed as habitat C; the pisonia tree (Pisonia umbellifera) type at the bottom of valley, designed as habitat D. Litter productions, and leaf litter decomposition , soil microbial biomass C and N(MBC and MBN), carbon and nitrogen mineralization, and the compositions of soil solution were monitored for 2-year period (Feb. 2004-Feb. 2006) in the four habitats . The aims of this study in the KNROUCR were conducted: (1) to investigate the litter inputs and leaf litter decomposition process in relation to plant habitat types and seasons, (2) to explore the soil organic matter mineralization, (3) to illustrate the influence of soil microbial biomass on the litter decomposition dynamics, and (4) to explore the bioavailability, seasonal dynamics, and flux of soil nutrients. Experimental results indicated that litterfall in all habitats shows a marked seasonal pattern, with the lowest amounts in spring (0.34-0.54 ton/ha/month) and the highest amounts in the summer (0.81-1.32 ton/ha/month) and winter (0.49-0.69 ton/ha/month) seasons because of typhoon and monsoon. In addition, the litterfall production in habitats A and D was significantly (p<0.05) greater than in habitats B and C. It is probably because the dominant tree species of habitat B are relatively adapted to strong wind, and the leaves survived long on the exposed rock; habitat C was secondary forest which dominated by early succession tree species with lower leaf area index. The litter remaining mass percentage in the first year was from 50% to 45.6%, however in the second year was from 25.8% to 18.2%. The litter remaining mass percentage in the 2nd year was lower than 1st year, because of the larger rainfall from frerquent typhoon events in the 2nd year. Nevertheless, the Olson’s decomposition parameters (k and t50) between the leaf littes of four habitats were not significant. Overall, the leaf litter decomposition rate followed the order by Ca > Mg >N> Na > K > P > mass > C. Additionally, the annual return of nutrient followed the order by C (221-4483 kg/ha) > Ca (160-324 kg/ha) > N (58.6-123 kg/ha) > K (24.7-41.7 kg/ha) > Mg (16.2-30.6 kg/ha) > Na (5.35-25.0 kg/ha) > P (0.16-1.95 kg/ha). The surface soil (0-15 cm) MBC ranged in 477-1135 mg/kg in each habitat, whereas is higher than those in general tropical forests (149-667 mg/kg), however, the MBN ranged in 65.7-81.0 mg/kg, whereas is similar to those in general tropical forest (38.0-78.0 mg/kg). The rate of C mineralization (the amount of CO2-C production) ranged in 25.0-36.0 g CO2-C/kg/yr, which is not different from tropical and subtropical forests, however, the rate of C mineralization C in the 2nd year was 4-5 folds than that in the 1st year, because of the dramastic change in soil hydrology in altering doiminant microbes. The NO3--N/NH4+-N ratios ranged in 3-4, and N mineralization, ammonification, and nitrification ranged in (-0.12)-(0.09), (-0.04)-(-0.02), and (-0.27)-(0.08) mg/kg/d. The order of cation concentration in the soil solution is Ca > Si > K > Na > Al > Mg> Fe > NH4 > Mn > Zn > Cu, and it of anion is Cl > SO4 > NO3, respectively. Overall, the input of C and N was much more than the within the study area, so that the forest ecosystem keeps in dynamic balance.