台灣南部多納針闊葉林土壤種子庫與森林更新

Soil Seed Bank and Forest Regeneration in a Broadleaf-Coniferous Forest of Dona, Southern Taiwan

林文智(Wen-Chih Lin) ； 郭耀綸(Yau-Lun Kuo) ； 陳永修(Yung-Hsin Chen) ； 張乃航(Nan-Hang Chang) ； 洪富文(Fu-Wen Horng) ； 馬復京(Fu-Ching Ma)

《台灣林業科學》 19卷1期 (2004/03) Pp. 33-42

https://doi.org/10.7075/TJFS.200403.0033

摘要

本研究調查多納森林之樹種及土壤種子庫組成，藉以了解土壤種子庫與森林更新的關係，並比較埋土種子在孔隙及林下兩環境發芽數量的差異。多納森林為針闊葉混生林，優勢種為長尾柯、威氏帝杉、錐果櫟及紅楠。除了威氏帝杉外，其它優勢種的徑級分布均呈反J型，在林下有數量眾多之稚樹庫，應可持續更新。多納森林種子庫共有23種組成植物，先驅種22種，非先驅種僅紅楠1種。種子庫中可發芽種子密度達5,924粒m^(-2)，先驅種即佔99%。以生長型區分，種子庫中以草本植物及灌木為主，發芽數分別達全部的31及68%。現存森林組成中僅有紅楠及光葉柃木也出現在土壤種子庫中。紅楠種子為當年所掉落，可發芽者密度為34粒m^(-2)，可成為林下苗木庫。光葉柃木為灌木，可發芽種子數量達3,418粒m^(-2)，佔發芽總數的57.8%，且由土表至30cm深均有出現。以上結果可推論多納森林現存非先驅性樹種並不是以土壤種子庫為主要更新來源。埋土種子在孔隙環境的發芽數量為林下環境的2.6倍，顯示林冠孔隙的形成有利於埋土種子的發芽。

關鍵字

生長型 ； 孔隙 ； 先驅種 ； 結構分布

並列摘要

We investigated the species composition of standing trees and the composition of the soil seed bank of a forest at Dona, southern Taiwan. Germination of buried seeds in a forest gap was compared to that in the forest understory. The forest at Dona is a broadleaf-coniferous forest dominated by Castanopsis carlesii, Pseudotsuga wilsoniana, Cyclobalanopsis longinux, and Machilus thunbergii. Except for P. wilsoniana, the stem diameter distributions of the dominant species were all anti-J shaped, indicating that there were abundant young trees for sustainable regeneration. The soil seed bank was composed of 23 species, including 22 pioneer and 1 non-pioneer species, M. thunbergii. The density of germinated seeds in the soil seed bank was 5,924 seeds m^(-2), 99% of which were pioneer species. If classified by their growth forms, the majority of the germinated seeds were herbaceous plants (31%) and shrubs (68%). Among all species compositions, only seeds of M. thunbergii and Eurya nitida var. nitida, which is a shrub, occurred in the soil seed bank. Seeds of M. thunbergii in the soil seed bank came from the seed rain of the current year, and the density of its germinated seeds was 34 seeds m^(-2). The density of germinated seeds of E. nitida was 3,418 seeds m^(-2), accounting for 57.8% of all germinated seeds in the soil seed bank. Its seeds occurred from the soil surface to 30 cm of depth. These results revealed that the soil seed bank was not the main source for the regeneration of existing non-pioneer tree species in the Dona Forest. In addition, germination of buried seeds in the forest gap was 2.6-fold higher than that in the forest understory, indicating that the formation of forest gaps is advantageous to the germination of buried seeds.

並列關鍵字

growth form ； gap ； pioneer species ； stem diameter distribution