四湖海岸木麻黃林分土壤養分量調查

Investigation on Soil Nutrient Contents of Casuarina Stands in the Suhu Coastal Area

陳財輝(Tsai-Huei Chen) ； 許博行(Bor-Hung Sheu) ； 張峻德(Chun-Te Chang)

《台灣林業科學》 13卷3期 (1998/09) Pp. 225-235

https://doi.org/10.7075/TJFS.199809.0225

摘要

調查雲林四湖4、10年生木麻黃純林及10年生木麻黃與黃槿混合林之0-2、2-10、10-20cm層林地之土壤化學性質及養分聚集量，微生物氮生物量、主要土壤微生物種類分布量及硝化細菌數，分析不同木麻黃林分間的差異。調查林地土壞一般屬微鹼性，下層土壤明顯受含鹽量高之地下水影響。木麻黃各林分土層碳／氮均在15以下，顯示土壤內有機物的分解速度很快。四湖林地之銨態氮、硝酸態氮及可交換性鉀、鎂、鈉養分濃度，在10年生林分明顯較高；可交換性鈣在三林分皆以0-2cm表層較其下層高，而以10年生混合林10-20cm最低，4年生林分20cm土壤可交換性鉀、鈣、鎂、鈉養分聚集量為35.5、991、458、11.5kg/ha，10年生純林及混合林則各為78.8、1033、781、113.9kg/ha 與40.4、630、635、107.8kg/ha。四湖木麻黃之微生物氮生物量主要均分布在表層，隨著土壤深度增加而減少，而且土壤微生物氮生物量與碳、氮及可交換性鉀、鈣、鎂、鈉間皆有極顯著的相關。四湖10年生混合林之異營營養細菌、亞硝酸菌及硝酸菌數均較10年生純林多，此顯示木麻黃與黃槿之混合林20cm土層中硝化作用較旺盛，此對林地有效養分提供上極有助益。

關鍵字

海岸防風林 ； 木麻黃 ； 養分 ； 土壤微生物

並列摘要

Soils of the Suhu coastal area that were composed of 3 stands, viz, pure stands of causuarina aged 4 and 10 yr old and a mixed stand of causuarina and hibiscus both aged 10 yr old, were divided into 3 layers which ranged 0-2, 2-10, and 10-20cm in depth. Chemical characteristics, nutrient accumulation, microbial biomass N, and the number of colonies of nitrifying bacteria of layered soils were investigated. The results indicate that the soil of the 3 stands was slightly alkaline. However, pH of the surface soil decreased due to the decomposition of litter-fall in both 10-yr-old pure casuarina and mixed stands. The soil at depth was maintained as alkaline as influenced by salty ground water. The ratios of carbon and nitrogen of soil in all layers were less than 15 indicating that the decomposition rate of organic matter in the casuarina stands was rapid. Concentrations of nitrogen sources, NH4(superscript +) and NO3(superscript -) and exchangeable K, Mg, and Na obviously increased in the 10-yr-old stands; exchangeable Ca at 0-2cm soil depths in the 3 stands was higher than in the other lower layers, and the lowest exchangeable Ca was in the 10-20cm layer of the mixed stand. Accumulations of exchangeable K, Ca, Mg, and Na at 20-cm soil depth were 35.5, 991, 458 and 11.5kg/ha in the 4-yr-old stand; 78.8, 1033, 781 and 113.9kg/ha in the 10-yr-old pure stand; and 40.4, 630, 635, and 107.8kg/ha in the 10-yr-old mixed stand, respectively. Microbial biomass N was mainly distributed in surface soil and decreased with increasing soil depth. Microbial biomass N was significantly correlated with total organic C, total N, and exchangeable K, Ca, Mg, and Na. Heterotrophic bacteria and nitrifying bacteria were abundant in the mixed casuarina stand, which indicates that vigorous nitrification was progressing. In general, nutrient accumulations of the 10-yr-old casuarina stands at the Suhu coastal areas had increased, except for Ca. The mixed casuarina stands maintain vigorous nitrification which helps available nutrients to return to the forest soil.

並列關鍵字

coastal windbreaks ； casuarinas ； nutrient ； soil microorganism