惠蓀林場土壤種子庫組成

Soil Seed Bank Composition of Hui-Sun Experimental Forest Station

被干擾和劣化的森林生育地恢復是生態復育的重要工作之一，而土壤種子庫和人工造林是有效重建和加速修復退化生育地的方法。土壤種子庫被視為植群潛在更新的重要組成，在自然復育過程中扮演重要的角色。本研究即以種子發芽法調查惠蓀林場第三林班集水區內臺灣杉、香杉及臺灣肖楠等3種人工林，以及火燒跡地和次生林等5種植物社會之土壤種子庫組成與空間分布，並探討植被復育過程中，歸化植物對土壤種子庫影響。本試驗共發芽出14,752株種子苗，計有36科82屬97 種，平均種子密度達10,927粒/ m2 ；其中，菊科（16種）、禾本科（11種）及莎草科（10種）是本研究種子庫出現物種數最優勢的前三科。種子密度最高的為臺灣杉人工林（23,411粒/ m2 ），其次依序為臺灣肖楠人工林（11,293粒/ m2 ）、火燒跡地（10,563粒/ m2 ）、杉木人工林（6,467粒/ m2 ）、次生林（2,904 粒/ m2 ）；種子庫組成物種數以臺灣肖楠人工林（63種）最高，依次為臺灣杉人工林（57種）、火燒跡地（51種）、杉木人工林（49種）及次生林（47種）。儲量前三名物種依序為母丁香、倒地蜈蚣和揚波，合計占種子庫種子儲量一半以上。人工林種子庫組成主要以草本為主，而火燒跡地和次生林則以灌木為優勢，各植物社會之土壤種子庫種子優勢組成不儘相同。山黃麻是土壤種子庫前十名中唯一的喬木植物，且在各植物社會均有分布，可能反映出其鳥類傳播的特性。土壤種子庫分布在空間上有顯著差異，土壤深度和植物社會影響種子庫儲量，除枯枝落葉層外，愈深的土層含愈少的種子。植物社會內的土壤種子庫儲量相近，但植物社會間則有顯著差異。火燒跡地歸化植物種類及種子儲量最高，而人工林土壤種子庫尚未受到歸化植物入侵。不同人工林之間土壤種子庫組成相似性相對較高，人工林與火燒跡地、次生林的相似性較低。本研究結果顯示，土壤種子庫之種子組成與儲量受前期植群、造林樹種、撫育措施、過去及現生地上部植群、植群演替過程，以及種子傳播等影響。 Restricting disturbance and degraded forest habitat recovery has been one of the important ecology resilience tasks. Soil seed bank and forest plantation are the effective rebuilding methods to speed up the degraded forest habitat recovery. As the potential population in plant regeneration, soil seed bank plays a significant role for the vegetation restoration. This study used seed germination to investigate the seed banks in one burned areas, one secondary forest and three types of forest plantation, Taiwania cryptomerioides, Calocedrus formosana and Cunninghamia lanceolata, at the watershed of the third forest compartment in Hui-Sun Experimental Forest Station, and explored the influence of naturalized plants on the soil seed bank. There were 14,752 seeds sprouted in total. There were 36 families, 82 genera and 97 species with average density 10,927 seeds/ m2 . Among these, Asteraceae (16 species), Poaceae (11 species), and Cyperaceae (10 species) were the top three families whth more species numbers in the soil seed bank. The forest plantation of Taiwania cryptomerioides had the highest density (23,411 seeds/m2 ) followed by Calocedrus formosana forest plantation (11,293 seeds/m2 ), burned area (10,563 seeds/m2 ), Cunninghamia lanceolata forest plantation (6,467 seeds/m2 ), and secondary forest (2,904 seeds/m2 ). Calocedrus formosana forest plantation had the highest species number (63 species) of the soil seed bank composition, and then Taiwania cryptomerioides (57 species), burned area (51 species), Cunninghamia lanceolata forest plantation (49 species), and secondary forest (47 species). The soil seed bank of forest plantation was mainly composed of herbaceous species while burned area and secondary forest had more shrubs. The top three quantity in the soil seed bank were Torenia fl ava, Torenia concolor, and Buddleja asiatica, occupied over 50% of the total quantity in soil seed bank. And the main quantities of soil seed bank composition between five vegetation communities were different. However, Trema orientalis is the only tree species of the top ten quantities in the soil seed bank. There was a significant difference in the space distribution of seed bank, and the soil depth and vegetation community influenced the remaining quantity in the soil seed bank. Other than the litter layer, the deeper the soil layer was, the fewer the seeds. Even though the soil seed bank remaining quantity was similar within the vegetation communities, there were still significant differences among the vegetation communities. Burned area had the highest amount of naturalized plants and seed remaining quantity while the soil seed bank in forest plantation hadn't been invaded by naturalized plants. The similarity of the soil seed bank compositions among different forest plantation was comparatively higher, but the similarity of the soil seed bank was lower among forest plantation, burned area and secondary forest. The results showed that the composition of soil seed bank was affected by early-stage vegetation, forest plantation, nurture measures, past and current aboveground vegetation, vegetation succession process, and seed dispersal, etc.