雪山東峰亞高山草生地火燒後植群之回復

Fire is one of the most critical factors affecting plant growth and vegetation succession. This study established 10 plots on the east peak of Mt. Shei, which burned in 2001 and investigated the post-fire vegetation recovery of ＂Yushania niitakayamensis＂ grassland at four stages. A total of 43 vascular plant species were recorded at four stages with 27, 33, 32, and 33 species. The results revealed that after 6 months, most species of ＂Y. niitakayamensis＂ grassland occurred in the burned area, and the species diversity increased with the post-fire time. All of the species were perennial plants, among which 36.36% were evergreen plants and 63.64% were winter-withered plants. The coverage of the grassland was rehabilitated within approximately 2 years after the fire, whereas the recovery of the original height and appearance of the grassland required 3 years. A detrended correspondence analysis revealed that sequential changes in vegetation succession occurred after the fire. The composition of plant differences resulted from a decrease in species at an early stage after the fire and an increase in species at a later stage after the fire. The aboveground part of ＂Salix fulvopubescens＂ was burned after the grassland fire, and caespitosa shoots then sprouted from the surface. The saplings of ＂Abies kawakamii＂ were not resistant to fire, and the growth of adult A. kawakamii after the fire declined. At the marginal zone of fire, ＂A. kawakamii＂ saplings grew well. These phenomena confirmed that ＂Y. niitakayamensis＂ grasslands subject to periodic fire remain the grassland community, whereas grasslands transform into potential natural vegetation, an ＂A. kawakamii＂ forest, if no fire disturbance blocks succession.火燒是影響植物生長與植群演替的主要因子之一。雪山東峰玉山箭竹草生地於2001年發生火燒，本研究在火燒後設置10個樣區於4個不同時期進行植群調查。植物社會恢復過程中，共計調查到25科41屬43種維管束植物，蕨類商數為2.56；火燒後4個時期調查之物種數分別為27、33、32及33種，顯示火燒後6個月，大部分的草生地植物種類即出現，而物種多樣性則隨著火燒後植群恢復時間的增加而有增加趨勢。植物種類全部為多年生植物，其中36.36%為常綠植物，63.64%植物屬於冬枯。雪山東峰草生地在火燒後約2年可回復至火燒前的植被覆蓋狀態，但植群高度回復則約須3年後才能接近火燒前之原有高度。由DCA分析結果顯示，火燒後植群演替具時序的變化，物種組成差異來自火燒干擾初期的物種消失，以及火燒後期非萌蘖種類的新增。雪山東峰玉山箭竹草生地火燒後，玉山箭竹、褐毛柳等木本植物之地上部死亡，但在火後地際再度萌蘖；臺灣冷杉稚樹不耐火燒而死亡，成株亦因樹皮燒傷而剝落，並導致生長勢逐漸衰退，然在火燒跡地邊緣未受火燒傷害的臺灣冷杉稚樹生長良好。本研究發現，玉山箭竹草生地若發生火燒則將維持其原有形相，但長期無火燒的情況下，雪山東峰草生地將緩慢恢復至本地的潛在自然植群—臺灣冷杉林

雪山山脈臺灣冷杉林（Abies kawakamii (Hayayta) Ito）地被植群多樣性

Abies kawakamii (Hayata) Ito (Taiwan fir) is an endemic of glacial relic species. It is one of the species which composed the forest line. They are usually gregarious pure forest type at the subalpine ecology in Taiwan, and then became the important one of subalpine vegetation. The object of this study is to investigate the understory vegetation of Taiwan fir forest and classify, discussing the correlation with the environmental factors at the subalpine in Taiwan. Totally we set up 39 plots (10 m � 25 m), in the floristic surveys of vascular plant, 145 species (including under taxa species) belonging to 99 genera in 50 families. We found 62 species are endemic in Taiwan (endemic ratio is 42.8%). According the plant life form spectrum, there are 77 understory species classified into hemicryptophytes. Analyses the results of cluster and detrended correspondence analysis (DCA), the understory vegetation can be classified into 5 types: (1)Abies kawakamii-Ainsliaea latifolia type; (2)Ainsliaea latifolia-Polystichum morii type; (3)Angelica morrisonicola-Spiraea formosana type; (4)Yushania niitakayamensis-Ainsliaea latifolia type; (5)Yushania niitakayamensis-Rhododendron pseudochrysanthum type. Adding the environmental factors and diversity indexes to do CCA analysis, the diversity indexes are negative correlation with whole light sky (WLS). It means the species composition of understory vegetation in Abies forest would effected by solar radiation based on the topography shelter. Furthermore, because of the dense rhizomeand extremely high stem of Yushania niitakayamensis is an important role to affect the understory diversity and regeneration of Abies kawakwmii.臺灣冷杉（Abies kawakamii (Hayata) Ito）是臺灣特有之冰河孑遺針葉樹種，為森林界限樹種組成之一。本研究針對雪山山脈臺灣冷杉林地被植物組成多樣性、地被植物與環境因子相關分析和物種多樣性探討，以期瞭解臺灣亞高山生態系臺灣冷杉林型地被環境對於臺灣冷杉之相關性。本研究設置39個樣區（10 m×25 m），調查計得維管束植物50科、99屬、145種（含種以下分類群）植物，其中為臺灣特有種62種，特有種比例約42.8%。分析生活型譜以半地中植物77種最多，依序是挺空植物、地表植物、地中植物、一年生植物。依據群團分析及降趨對應分析結果，臺灣冷杉林下地被植群型可分為5型：1.臺灣冷杉－臺灣鬼督郵型；2.臺灣鬼督郵－玉山耳蕨型；3.玉山當歸－臺灣繡線菊型；4.玉山箭竹－臺灣鬼督郵型；5.玉山箭竹－玉山杜鵑型。加入環境因子及多樣性指數進行典型對應分析結果，雪山山脈臺灣冷杉林型地被植物多樣性指數與全天光空域呈負相關，顯示臺灣冷杉林下地被植物組成與樣區受到地形遮蔽後光照範圍所影響。此外，由於林下玉山箭竹具有緻密的地下莖及密度極高的莖稈，是影響臺灣冷杉林下地被物種多樣性及臺灣冷杉天然更新的重要因素

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies