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標題: | 探討棲蘭雲霧森林在低土壤濕度期間的植物生長與降水變化的關係 Unique Responses of Vegetation During the Low Soil Water Periods under the Change of Precipitation in Chi-Lan Montane Cloud Forest |
其他標題: | Unique Responses of Vegetation During the Low Soil Water Periods under the Change of Precipitation in Chi-Lan Montane Cloud Forest |
作者: | 林思穎 Szu-Ying Lin |
指導教授: | 羅敏輝 Min-Hui Lo |
關鍵字: | 雲霧森林,降水,植生指數,光合作用,蒸散作用, cloud forest,precipitation,vegetation index,photosynthesis,transpiration, |
出版年 : | 2022 |
學位: | 碩士 |
摘要: | 降雨是熱帶森林中影響植物生長年際變化的重要因子之一。舉例來說,年降雨量大於2000mm/yr的地區在乾季具有充足的可用水,使植物在乾季更有效率地進行光合作用。相比之下,年降雨量小於這個門檻值的地區,則受到水分的限制。前人研究發現,雲霧森林具有比一般森林更充沛的水分來源,但蒸散作用和植被初級生產量卻低於一般熱帶森林,這之間的差異可能與能量的限制有關係。
本研究比較了台灣的兩個森林地區,棲蘭(雲霧森林)和蓮華池(典型一般森林),並分析其通量塔的降水資料與衛星觀測的植生指數,觀察兩者在土讓較乾的季節下是否具有相關性。觀測資料的結果顯示,在較乾燥的環境中(1月至4月),兩個森林對水分的需求表現不同。前一年年底的累積降水,藉由傳送至土壤再供給至植物,使蓮華池地區在隔年春季的光合作用更有效率;而棲蘭雲霧森林的植生指標在降水變化下則沒有顯著相關。 我們進一步利用陸地模式,在不變動其他天氣因子的理想化條件下,對降水的量值進行了測試,並分析所模擬的蒸散和光合作用變化。我們發現當地微氣候(降水、溫度等)在水文循環過程比地表特性和植物種類更影響光合作用的進行,同時在典型森林的降雨與植被的生長能力之間存在非線性的關係,其來自於土壤水分變化和植物大氣之間的蒸氣壓差。相反的,棲蘭由於土壤含水量相對偏高,植物生長狀態在乾季較不受影響,這也是雲霧森林獨有的特徵,在未來氣候變遷,乾季越乾以及水分減少的狀況下,有機會繼續維持植物的生長,並在碳吸收過程中扮演著相當重要的角色。 Rainfall is one of the essential factors in affecting the inter-annual variability of vegetation productivity over tropical forests. However, it was reported that transpiration and productivity in tropical montane cloud forests with sufficient water are lower than in non-cloud tropical forests. By comparing the observational precipitation and vegetation indexes from satellite datasets, different water demand was found between Chi-Lan (CL) montane cloud forest and LienHuaChih (LHC) typical forest from January to April. More precipitation accumulation in November and December causes higher photosynthetic activities in LHC, while there is no significant change in CL. We further conducted idealized sensitivity tests on precipitation in atmospheric forcing by using the land surface model to explore the critical factors affecting vegetation growth. The result shows that local microclimate dominates transpiration and photosynthesis, and a nonlinear response between the rainfall and gas exchange process in LHC corresponds to the soil water variation and vapor pressure deficit. No significant change in CL was found because of the stable and higher soil water content. Our study reveals that in non-cloud forests, vegetation photosynthetic activities in lower soil water periods could be affected by rainfall in the preceding months, while montane cloud forests are less susceptible because of sufficient water availability and less available solar energy. It could also indicate that in the future, with dry-get-drier climate conditions, montane cloud forests may be less influenced due to their relatively stable hydro-climatic conditions, especially from the water availability perspective. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/83085 |
DOI: | 10.6342/NTU202210168 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 生物科技研究所 |
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