環山火燒跡地植群變化之研究

Abstract

為瞭解火燒後對於森林生態系植群組成之影響程度，本研究乃針對環山地區之火燒跡地進行調查。本研究區之火燒跡地冠層植物以臺灣二葉松為優勢，地被則以高山芒、巒大蕨等陽性植物佔優勢，萌櫱植物在演替初期佔有相當重要的角色，而有益於植被之恢復；優勢草本植物進入乾季後枯萎的植物體累積所形成燃料庫，極易引起下次火燒之發生。火燒初期造成α歧異度下降，經過18個月後已有恢復之趨勢，而β歧異度則與海拔差呈正相關；環境因子中海拔高度與全天光空域影響其他環境因子，進而影響植物組成與分佈；臺灣二葉松、高山芒與細葉杜鵑因生態幅度大可廣泛分佈於本區。 臺灣二葉松之致死率隨火燒強度而增加，由於無萌櫱能力，其致死率高達76.71％；闊葉樹則因具有萌櫱能力，同時土壤對於植物生存芽之保護能力較佳，火燒後因此大多闊葉樹有地際萌櫱情形致死率僅3.6%。臺灣二葉松致死率雖高，可藉由毬果內宿存之種子大量下種，有助於其在火燒後族群之恢復。火燒後光度增加、溫差大及礦質土壤裸露，有利於植物下種與萌芽，因此火燒跡地天然更新苗數量高於對照區；光度越大苗木生長越佳，相對濕度對苗木死亡率之影響亦至鉅。就火燒後植被恢復與天然更新方面，顯示出火燒跡地已自然回復而趨於穩定之狀態，因此應任其自然演替恢復成林，而無重新造林之必要。

In order to comprehend the effect of vegetation composition in forest ecosystem after firing, many forest researchers plan to monitor the burned area in Huanshan area. Pinus taiwanensis is a dominant crowned specie on the burned area. Miscanthus transmorrisonensis, Pteridium aquilinum etc. are dominant pioneer plants in the burned area. Sprouted plants are helpful to recover the vegetation. The plants, above-mentioned, play very important roles in the primary stage of succession. Dominant herbaceous plants would fade and the plant remains would become fuel during the drought. Therefore, it is easy to occur another fire. It make α diversity decreased for the primary stage of the fire, but it has became better after 18months. β diversity is related to the difference of the altitude. The environment factor, the altitude and the WLS would affect the composition and distribution of the plants. Due to the large niche of the Pinus taiwanensis, Miscanthus transmorrisonensis and Rhododendron noriakianum, the distribution of the spices is very widespread in the area. The mortality of the Pinus taiwanensis would increase with the fire intensity. Because Pinus taiwanensis have no sprouted ability, the mortality after firing is about 76.71%. However, the hardwood species have sprouted ability, the mortality after firing is only 3.6%. Moreover, the soil could help the buds to suffer from other injures, so most of the hardwood species would based sprout. Although the mortality of Pinus taiwanensis is very high, Pinus taiwanensis could exist by regeneration which are stored into the cone. Increasing lightness, increasing temperature difference and uncovered soil after firing would be helpful for the plants to regenerate and sprout. Therefore, the number of the regeneration in the burned area is higher than checker area. The lightness is stronger, and the seedling grows better. However, the value of the relative humidity content would affect the mortality of the seedlings. In vegetation in the burned area, water quality, soil, and insect aspects, it reveals that the burned area has already been recovered naturally and tended to be a stable situation. Consequently, it should be reforested succession naturally, not reforested by hand.