桫欏科植物為孓遺植物,廣泛分布在熱帶與亞熱帶地區,為一見證地球演變的物種,具有保存與保育價值。影響桫欏科植物生長之主要因子包括溫度、濕度、光度等。近年來因筆筒樹有大量死亡現象,顯示該物種已面臨生存威脅。為瞭解南部地區筆筒樹之生長狀態,以達仁林場為調查範圍,建立筆筒樹健康度調查指標,監測筆筒樹生長情況,並配合筆筒樹生育環境,探討筆筒樹之保育策略。本研究利用林木健康指標項目進行樣木健康狀態評估,利用現地214株樣木健康調查資料,以因素分析建構筆筒樹的健康指標,由五種健康指標中萃取出三種共同因素,利用判別分析增加筆筒樹健康度之客觀性,結果顯示在調查樣區內筆筒樹健康等級所占株數比例最多,約占總調查株樹的38.8%,其次為枯死等級,所佔總調查株數總計有22.7%。利用筆筒樹健康程度探討與植群歧異度及光量之關係,結果顯示植群歧異度和筆筒樹健康度具有正相關性,當物種歧異度越高,林分較具異質性且林下幼苗更新多,並可有效減緩病蟲害傳播。在光度方面,強光環境不利於小苗更新,弱光環境導致資源競爭大,筆筒樹適合生長於光度中度偏高之環境,以利植株生長及小苗更新。筆筒樹最適生態區域為偏好酸性土pH介於4.4-6.8、海拔高500-800 m、坡度20-30゚、坡向為90-135゚屬於東向坡、全天光空域(Whole Light Sky Space, WLS) 20-80%,生育地明顯生長於兩種棲地,林內潮濕的溪谷地形及坡度陡峭的開闊地,而溪谷之筆筒樹健康度較佳。在半年監測下,經過成對檢定顯示筆筒樹在半年內健康狀況有顯著的衰退趨勢,筆筒樹不健康原因可能為罹病,未來除了藥劑施打之外,應依筆筒樹生育之適宜環境劃設物種保育區,並運用適切之森林經營方式才能達成就地保育之目標。
Cyatheaceae (tree ferns) is a relic plant, which is widely distributed in tropical and subtropical regions, as a witness to the evolution of the Earth's species therefore that has a value of preservation and conservation. The effect factors of tree ferns growth are included temperature, moisture and light, etc. In recent years, Taiwan have occurred mass mortalities on Cyathea lepifera. This species had been facing the threat of surviving. In order to understanding the growth situation of tree ferns in sourth of Taiwn, we were used the Tajen Experimental Forest Station (TEFS) as a study area and suervey 214 samples trees of C. lepifera for developing a system of health index to monitor the growth situation. We also establish the spatial information of C. lepifera site that could be provided the information for conservation strategy. This research uses factor analysis to establish C.lepifera health indictors in order to assess and to classify the tree fern health condition. It has extracted three common factors from five health-related variables. We used the stepwise discriminate analysis to increase the degree of objectivity for C. lepifera healthy. Results showed that C. lepifera occupied the largest proportion of health level; there are 38.8% on total 214 sample trees. Secondly, total number of dead level trees has occupied 22.7% on total 214 sample trees. Using the health of the tree fern explore the vegetation diversity and understory light. Results show that the vegetation diversity is positively with the health of the tree fern. When the stand has high diversity, they will have more heterogeneous. Hence, the seeding has more chance to regenerate. It can effectively reduce the spread of pests and diseases. The high light environment is not conducive seedlings regeneration and low light conditions lead to compete for resources. Therefore, C. lepifera is suitable for growing in the medium-high photometric of the environment, it will promote plant growth and seedlings regeneration. The ecological optimum are pH value from 4.4 to 6.8, elevation 500-800 m, slope 20-30゚, aspect 90-135゚ (Eastern), whole light sky space (WLS) 20-80%;Most of tree ferns grow in open areas and valley areas. Moreover, the healthy of C. lepifera is best in the valley areas. After six months monitored, the C. lepifera health status via paired t-test have a significant declining trend. The reason causing tree ferns unhealthy probability is C. lepifera wilt. In future, we not only taking drug to treat the pest but also using the optimal habitat to define the conservation area and using the technology of forest management to protect this species.
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