58 research outputs found
Astrocyte elevated gene-1 is associated with metastasis in head and neck squamous cell carcinoma through p65 phosphorylation and upregulation of MMP1
Effects of physical exercise in older adults with reduced physical capacity: meta-analysis of resistance exercise and multimodal exercise
Older adults with reduced physical capacity are at greater risk of progression to care dependency. Progressive resistance strength exercise and multimodal exercise have been studied to restore reduced physical capacity. To summarize the best evidence of the two exercise regimes, this meta-analysis study appraised randomized-controlled trials from published systematic reviews. Medline, Embase, and the Cochrane Database of Systematic Review and Cochrane Central Register of Controlled Clinical Trials were searched for relevant systematic reviews. Two reviewers independently screened the relevant systematic reviews to identify eligible trials, assessed trial methodological quality, and extracted data. RevMan 5.3 software was used to analyze data on muscle strength, physical functioning, activities of daily living, and falls. Twenty-three eligible trials were identified from 22 systematic reviews. The mean age of the trial participants was 75 years or older. Almost all multimodal exercise trials included muscle strengthening exercise and balance exercise. Progressive resistance exercise is effective in improving muscle strength of the lower extremity and static standing balance. Multimodal exercise is effective in improving muscle strength of the lower extremity, dynamic standing balance, gait speed, and chair stand. In addition, multimodal exercise is effective in reducing falls. Neither type of exercise was effective in improving activities of daily living. For older adults with reduced physical capacity, multimodal exercise appears to have a broad effect on improving muscle strength, balance, and physical functioning of the lower extremity, and reducing falls relative to progressive resistance exercise alone
Precipitation controls on nutrient budgets in subtropical and tropical forests and the implications under changing climate
Biological, geological and hydrological drivers collectively control forest biogeochemical cycling. However, based on a close examination of recent literature, we argue that the role of hydrological control particularly precipitation on nutrient budgets is significantly underestimated in subtropical and tropical forests, hindering our predictions of future forest nutrient status under a changing climate in these systems. To test this hypothesis, we analyzed two decades of monthly nutrient input and output data in precipitation and streamwater from a subtropical forested watershed in Taiwan, one of the few sites that has long-term nutrient input-output data in the tropics and subtropics. The results showed that monthly input and output of all ions and budgets (output – input) of most ions were positively correlated with precipitation quantity and there was a surprisingly greater net ion export during the wet growing season, indicating strong precipitation control on the nutrient budget. The strong precipitation control is also supported by the divergence of acidic precipitation and near neutral acidity of streamwater, with the former being independent from precipitation quantity but the latter being positively related to precipitation quantity. An additional synthesis of annual precipitation quantity and nutrient budgets of 32 forests across the globe showed a strong correlation between precipitation quantity and nutrient output-input budget, indicating that strong precipitation control is ubiquitous at the global scale and is particularly important in the humid tropical and subtropical forests. Our results imply that climate change could directly affect ecosystem nutrient cycling in the tropics through changes in precipitation pattern and amount
雨水流經關刀溪三種林分水化學的變化
The study objectives were to compare the changes of water chemistry of bulk precipitation, throughfall and stemflow for 3 types of forest stands, China-fir (Cunninghamia lanceolata) plantation, secondary hardwood stand, and natural hardwood stand in Guandaushi Forest, in central Taiwan from January 1996 to December 1998.
Annual bulk precipitation had an average pH of 4.05 and stemflow of China-fir plantation was little more acidic than bulk precipitation, but throughfall of China-fir plantation almost maintain the same pH as in bulk precipitation. The pH values in throughfall and stemflow of secondary hardwood and natural hardwood were significantly higher than in bulk precipitation. It indicated that canopies and stems of hardwoods showed a high capacity to buffer the acidity of precipitation by accompanied with leaching and washing large amounts base cations. The conductivity in throughfall and stemflow of three stands were higher than in bulk precipitation. Most ion concentrations in throughfall and stemflow also showed higher values than in bulk precipitation except for H, F, Na and HCO3 in stemflow of China-fir plantation. The enrichment factors were from 1.50 to 64.49 in different ions, especially K, Ca, Mg, and HCO3 substantially increased in throughfall and stemflow of secondary and natural hardwood.
Under three stands, H had a negative net canopy exchange (NCE) attributable to acid neutralization in the canopies and stems, especially in secondary and natural hardwood. K, Ca, and Mg had a positive NCE due to canopy and stem leaching and washing, especially K. A comparison of NCE of inorganic anions in three stands showed that Cl, NO3-N, and SO4-S had higher positive values in China-fir plantation than in secondary and natural hardwoods, while HCO3 had a highest positive value in natural hardwood.
Regression analysis of single-event data showed that the most important factor regulating the event-to-event variation in net throughfall fluxes was the amount of precipitation, suggesting that canopy exchange (leaching and uptake) regulated the net throughfall fluxes for most ions. Duration of the interevent dry periods (dry deposition) was highly siginificant in most base cation fluxes for throughfall, especially in China-fir plantation, suggesting a higher scavenging efficiency of the needles for dry deposition.
The mean DOC concentration in bulk precipitation was 4.7 mg/L. However the rain passing through the tree canopies and barks as throughfall and stemflow, the mean concentrations were 7.0 and 30.8, 9.9 and 10.0, and 8.3 and 7.2 mg/L in China-fir plantation, secondary hardwood, and natural hardwood, respectively. Significant correlation between DOC and charge balance deficit was observed, indicating that organic ions would contribute to the charge balance in the three stands.
Hydrophilic and hydrophobic acids were the dominant fractions in bulk precipitation, throughfall and stemflow of three stands, accounting for ~ 90% of total DOC. However, differences in DOC fractions were found between bulk precipitation and throughfall or stemflow. In bulk precipitation, hydrophilic DOC were the dominant fraction but hydrophobic DOC were rich in throughfall and stemflow, indicating that these DOC fractions were altered when bulk precipitation were through canopies and stems. The elemental compositions of both humic polymers (MW>1000) and FAs (MW>1000), which were isolated from the water samples of throughfall and stemflow, were in the ranges typical for humic substances from other origin. Fourier transform infrared (FTIR) pectra also were close to the characteristics of reported humic substances. The results showed that the humic polymers (MW>1000) and FAs (MW>1000) in the water samples of throughfall and stemflow, which were above ground and soil mediation free environments, and in canopies and stems, may be a new pathway of formation as well as humification of humic substances. The occurrence and function of the humic substances in the water samples from various origins in forest ecosystem thus can not be overlooked.本試驗的目的主要在探討雨水及比較雨水流經不同林分後水質之變化。樣區設於惠蓀林場關刀溪支流之一小集水區,在此集水區內除收集林外雨外,並於相鄰的杉木林、次生闊葉樹林及天然闊葉樹林三種不同林分內收集穿落水和幹流水,以比較雨水及雨水流經此三種不同林分後水化學的變化。資料採用時間為1996年1月至1998年12月。
三年試驗期間,林外雨的pH平均為4.05,杉木林幹流水的pH比林外雨低,穿落水則略高,而天然林和次生林則不論穿落水或幹流水皆比林外雨顯著高出甚多,顯示闊葉樹林對林外雨具有較高之中和能力,但卻會增加除H外之其他鹽基陽離子(Na, K, Ca, Mg)的濃度及輸入量。當雨水通過林冠及樹幹到達林地後,電導度值明顯增加,尤其是杉木林的幹流水增加最多。此三種林分的穿落水及幹流水的無機離子濃度除H, F, Na及杉木林幹流水的HCO3外,皆顯著增加,其增多係數(enrichment)由1.50到65.49不等,其中以K, Ca, Mg及HCO3增加較為明顯。
若以淨林冠交換量(net canopy exchange, NCE)而言,H在三種林分皆有被林冠保留現象,其保留情形以次生林及天然林較杉木林明顯。K, Ca, Mg皆是釋出,尤其是K的釋出為最大量。陰離子方面,Cl, NO3-N及SO4-S釋出都是以杉木林最多,次生林次之,天然林最少。HCO3的釋出則剛好相反。
以穿落水淨輸入量當應變數,雨量、降雨間隔日數(乾沉降)、林外雨氫離子濃度和林外雨成份離子濃度當作自變數,以每場雨的資料推導迴歸方程式,分析的結果顯示與各成分離子輸入量顯著關係最高的是雨量,因此,雨量是影響雨水穿過此三種林分冠層後,離子輸入量的最重要因子。降雨間隔日數和大部分穿落水陽離子的淨輸入量,也都存有高度相關,尤其是杉木林,此結果證明杉木林對乾沉降的攔截能力。
林外雨之可溶性有機碳(dissolved organic carbon, DOC)平均濃度為4.7 mg/L,而杉木林、次生林及天然林的穿落水濃度分別為7.0, 9.9及8.3 mg/L,幹流水則分別提高到30.8, 10.0及7.2 mg/L,以杉木林增加最為顯著,顯示雨水流經此三種不同林分冠層後,DOC和上述的養分離子一樣,濃度皆增加。DOC的測定結果與水樣陰離子缺乏所作的迴歸分析,顯示陰離子的缺乏主要來自DOC。
DOC的特性方面,林外雨以親水性酸佔大部分,但穿落水及幹流水則以疏水性酸佔大部分。表示雨水經過冠層後,所含的有機酸成分已有明顯改變。另由羧酸濃度、元素分析百分比及FTIR圖譜等之DOC的特性分析顯示,雨水及通過林冠之穿落水或幹流水皆有腐植化現象,惟林外雨腐植化程度低,但三種林分的穿落水及幹流水已有明顯腐植化現象,證實腐植化物質的形成及腐植化過程在林分冠層或樹體中亦進行著。封面
摘要
Summary
目錄
表目次
圖目次
壹、前言
貳、前人研究
一、雨水的分配
二、無機養分離子
(一)雨水水化學
(二)穿落水水化學
(三)幹流水水的化學
三、可溶性有機碳(DOC)
參、材料與方法
一、樣區位置
二、水樣種類與收集
(一)降水的收集
(二)穿落水的收集
(三)幹流水的收集
三、水樣化學分析
(一)pH、電導度、懸浮質、無機陰陽離子及有機陰離子
(二)DOC的測定
(三)DOC分離與特性分析
1.中和酸的能力的測定
2.親水性與疏水性物質的測定
3.羶羧含量的測定
4.灰分測定及元素分析
5.傅立葉轉換紅外線光譜分析
(四)腐植化聚合物
四、資料的處理與分析
肆、結果
一、養分濃度的變化
二、水量及無機養份的輸入量
(一)降水量、穿落水量及幹流水量
(二)離子的輸入量
(三)離子輸入亮的季節變化
(四)離子的淨輸入量
三、可溶性有機碳(DOC)
(一)陰離子缺乏和DOC的關係
(二)DOC濃度的變化與輸入量
(三)DOC濃度的季節變化
(四)DOC的特性
伍、討論
一、離子濃度及輸入亮
(一)降水
(二)穿落水
(三)幹流水
(四)離子的淨輸入量
(五)影響穿落水離子淨輸入變異的原因
二、水中溶解碳(DOC)的化學
(一)DOC對水樣離子平衡的貢獻
(二)DOC在三種林分的差異及季節變化
(三)DOC在分離與特性分析
陸、結論
柒、引用文
Accessing the nursing behaviour of Moso bamboo (Phyllostachys edilus) on carbohydrates dynamics and photosystems
Nursing behaviour, also known as breastfeeding behaviour, is the feeding of juvenile individuals with
nutrients or proteins from matures especially in mammals. As a hypothetical phenomenon in bamboo
forests, mature bamboos have transferred photoassimilates to young bamboos for recovering and
rebuilding their photosystems especially in winter. This process is accompanied by changes in the
ability of photosystems and the mass fraction of non-structural carbohydrates (NSCs), structural
carbohydrates (SCs), and lignin. We analysed carbohydrates and chlorophyll fluorescence to compare
the physiological traits in mature (age 2, 3, 4) and immature (age 1) Moso bamboos (Phyllostachys
edilus) during a year using the Portable Chlorophyll Fluorometer (PCF) and the Liquid Chromatographic
(LC) method. The results showed that the mass fraction of total soluble carbohydrates (TSCs) and starch
in the bottom of bamboo at age 1 was higher than other parts and ages in spring, whereas the mass
fraction of TSCs, starch, and sucrose at age 3 was higher than other parts and ages in winter. The Fv/
Fm, an indicator to reveal photosystems were functional or not, at age 1 dramatically dropped when
the cold current attacked first time in October, and then quickly recovered in November. Our findings
indicate that mature bamboos very possibly provide carbohydrates to immature bamboos and help
them rebuild their photosystems when a bamboo forest resists cold stress.
Moso bamboo (Phyllostachys edilus) is a kind of broadly distributed bamboo species wit
Study on the Natural Regeneration by Self-Sown Seeds in Mature Casuarina spp. Stands
試驗主要目的是探討衰老之木麻黃林分實施天然下種更新的可行性。試驗地設在雲林縣四湖海岸木麻黃純林,試驗方法除在現場設置樣區外,部分試驗則於實驗室完成。試驗結果(1)清除地表枯落物的樣區,可發現萌發大量小苗,二年後還是可以保留部分幼苗的生長;(2)林地不同光照強度會影響小苗的生長,以相對光度約40%最適宜更新小苗的生長;(3)林地土壤雖不會影響種子的發芽率,但會延長發芽時間。經本試驗結果,我們認為利用天然下種更新以維持林分是絕對可行的,惟適時移除林地枯落物,以提高成苗率,是天然下種更新成功的關鍵。Casuarina spp. is an important tree species of coastal forest in Taiwan. This species is more quickly senescent under the most stressful environment. The aim of this experiment is to focus on how to regeneration those aging stands by self-sown seeds. During two years study, we not only established plots in the field but also designed control treatment in the laboratory. The results we got (1) there are many seedlings in the plots where the litter was moved, and still having some healthful seedlings after two years; (2) the survival rate and growth of seedlings were affected by light. In the stand, the seedlings grown under 40% of relative light intensity can get the best height growth; (3) although the seed germination rate was not affected by soil, but the germination speed was lagged. Our results provide evidence that future Casuarina spp. regeneration could use natural regeneration by self-sown seeds, but the key point is to move ground litter in time
Effects+of+Pretreating+Calcium+on+Acacia+confusa+Seedlings+under+Simulated+Acid+Rain+Stress
本研究探討相思樹(Acacia confusa)苗木在模擬酸雨逆境下的生長和生理活性表現,並比較外源添加鈣苗木抵抗酸雨之反應。相思樹苗木先預處理不同濃度(0 mM、0.15 mM、10 mM)的CaCl2,再噴灑以SO4^(2-):NO3^-當量濃度比2.5:1混合後並用蒸餾水調至pH 3.0的模擬酸雨,且以蒸餾水(pH 5.6)作為對照組,於酸雨噴灑2週後進行取樣分析。經過酸雨處理後,苗木的過氧化酵素(peroxidase, POD)活性顯著上升,而抗壞血酸過氧化酵素(ascorbate peroxidase, APx)活性則顯著降低,使得膜脂質過氧化程度顯著提高,葉綠素螢光參數Fv/Fm值顯著降低,造成細胞膜滲漏率提高。經由0.15 mM CaCl2預處理則能幫助苗木抵抗酸雨逆境,苗木的APx活性相較於酸雨處理組顯著上升,使得膜脂質過氧化程度明顯降低,而葉綠素螢光參數Fv/Fm值顯著提高,導致細胞膜滲漏率降低。然而,處理高濃度的CaCl2(10 mM),反而使得苗木在酸雨逆境下,其細胞膜脂質過氧化程度和細胞膜滲漏率相對提高,而抗氧化酵素APx活性和葉綠素螢光參數Fv/Fm值顯著低於0.15 mM CaCl2處理者。The study was to examine the effects of simulated acid rain on growth and physiological performance of Acacia confusa seedlings, and to compare with the responses of seedling to exogenous calcium before simulated acid rain treatment. Seedlings were pretreated with different concentrations of CaCl2 (0 mM, 0.15 mM, 10 mM, respectively), and then were sparyed with simulated acid rain, which was a mixture solution of 2.5:1 equivalent concentration ratio of SO4^(2-):NO3^-and was adjusted to pH 3 with distilled water, and distilled water (pH 5.6) as control treatment. After 2 weeks, The leaves of seedlings developed a distinct calcium deficiency symptoms under simulated acid rain treatment, peroxidase (POD) activity increased but ascorbate peroxidase (APx) activity decreased, resulted in membrane lipid peroxidation increased. Additionally, chlorophyll fluorescence parameter (Fv/Fm) decreased significantly under simulated acid rain treatment, resulted in membrane leakage increased. Application of 0.15 mM CaCl2 solution to seedlings, APx activity increased but membrane lipid peroxidation decreased, resulted in membrane leakage decreased. The Fv/Fm of seedlings also increased. Furthermore, application of 10 mM CaCl2 solution, resulted in APx activity decreased as well as membrane lipid peroxidation increased. Additionally, Fv/Fm reduced and membrane leakage increased compared to 0.15 mM CaCl2 solution treatment under simulated acid rain stress
Dry deposition of particulate matter and its associated soluble ions on five broadleaved species in Taichung, central Taiwan
Many studies have estimated particulate matter (PM) removal by urban trees using dry deposition models; however, few studies have quantified the accuracy of their results. Thus, this study investigated the dry deposition of PM and its associated soluble ions in five broadleaved species in three districts of Taichung, central Taiwan, through field experiments. The total suspended particulate (TSP) dry deposition flux on leaf surfaces varied with sampling time, site, and tree species. By contrast, single-factor effects were observed for PM10 and PM2.5. The average dry deposition velocities of TSPs, PM10, and PM2.5 were 0.63, 0.062, and 0.028 cm s−1, respectively. Moreover, the dry deposition velocities of sulfate and nitrate were estimated to be 0.186 and 0.194 cm s−1, respectively. A significant relationship was observed between the ambient concentration and the dry deposition flux for all size fractions of PM. By contrast, weak and negative correlations were found between particle deposition velocity and wind speed. The measured PM2.5 dry deposition velocity was approximately equal to the dry deposition velocity obtained with the i-Tree model (0.03 cm s−1), which indicated the promising application potential of i-Tree in Taiwan. Compound and rough leaves, such as leaves of the Taiwan golden-rain tree, intercepted a high amount of PM2.5, whereas the pongam tree, which has thin leaves and wax surfaces, exhibited the lowest TSP interception. Species difference mostly occurred in the dry deposition flux of nitrate rather than sulfate; however, the interception of sulfate by trees revealed the possibility of the long-range transport of air pollutants. The results of this study elucidate the dry deposition of PM and its associated soluble ions in real-world situations
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