碩士 / 國立中興大學 / 森林學系 / 90 / The purposes of this study were to explicate how did Casuarina adapt to a mineral deficient site. Litterfall, decomposition, soil nutrient, nodule biomass and N2 fixation in the 25-year-old Casuarina stand at Taichung Harbor were studied during October 2000 to April 2002.
The results showed that the amount, one yearly basis, of litterfall in the Casuarina stand was 16.25 t/ha and indicated that litterfall varied significantly with month. Maximum litterfall occurred in October (4.44 t/ha); the main reason may cause by typhoons and northeast monsoon in winter. The litterfall of which 59.6-87.1% was composed of branchlet, 2.49-23% was branch, 2.66-30.33% was reproduction, and the remainder (0.11-12.06%) was comprised of other materials. Annual amounts of these nutrients included 8.15 t/ha C, 288.99 kg/ha N, 5.75 kg/ha P, 51.78 kg/ha K, 75.67 kg/ha Na, 119.31 kg/ha Ca and 19.86 kg/ha Mg, respectively.
With respect to the decomposition by litterbag showed the highest rate during the initial stage (0-2 months). However the decomposition became slow down in 4 months later, which remaining mass ranged from 64.34% to 61.54%. During the period, the C concentration was decreased until the study end, the N, K and Na concentration were decreased initially but than increased, and the Ca, Mg and P concentration were increased until the study end.
The results showed that the litter layer nutrient contents were N 462.02 kg/ha, P 5.62 kg/ha, K 43.47 kg/ha, Na 27.59 kg/ha, Ca 196.56 kg/ha and Mg 28.15 kg/ha, respectively. It indicated the major nutrient pool in the soil was in the 0-5 cm depth. The soil layer nutrient concentration showed that total C and N were 2.6% and 0.13%; available P, NO3--N and NH4+-N were 5.43, 54.2 and 10.7 mg/kg; extractable K, Na, Ca, Mg and CEC were 0.62, 1.17, 1.78, 0.57 and 7.62 cmol/kg. Soil N concentrations didn’t fluctuate seasonally, but the others were higher in October or January.
Active nodule biomass of Casuarina varied significantly with month. The nodule biomass was highest in July (16.06±25.49 g/m2) and nodule formation occurred in summer. Nitrogen fixation was monitored using the acetylence reduction assay. Maximum rate of N2 fixation occurred in March (10.81±6.14 μmol/g/hr) and the minimum occurred in November (5.94±2.05 μmol/g/hr). It explicated that nitrogen fixation activation was vigorous in spring. Annual average of nodule biomass was 6.06 g/m2, the rates of N2 fixation was 7.8 μmol/g/hr. From this estimations, it can be calculated that 25-year-old Casuarina stand would fix about 38.65 kg N2 per ha per year.
| Identifer | oai:union.ndltd.org:TW/090NCHU0360029 |
| Date | January 2002 |
| Creators | Fung-Ting Lee, 李芳婷 |
| Contributors | Chiang-Her Yen, 顏江河 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 61 |
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