Browsing by Author "Lin, Teng-Chiu"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Forests affected by frequent and intense typhoons challenge the intermediate disturbance hypothesis
    (Wiley, 2019-11) Wang, Lixin; Lin, Teng-Chiu; Earth Sciences, School of Science
    Tropical cyclones (hurricanes and typhoons) are extreme disturbances that have a significant impact on ecosystem structure and processes. The intermediate disturbance hypothesis (IDH) generalizes disturbance–diversity relationships but its validity is hotly debated. The IDH has been challenged both theoretically and with results from experimental studies; however, few studies have empirically tested the proposed mechanisms of IDH using results from the actual ecosystems. In this commentary, based on empirical observations from studies on the interactions between tropical cyclones and forest dynamics, we outlined seven possible outcomes of gap dynamics and tree diversity as a result of different frequency and intensity combinations. We argue that the lack of distinction and differentiation between disturbance intensity and severity, and the overlooked role of tree mortality, seedling recruitment, and tree adaptations limit the applicability of IDH in predicting the disturbance–diversity relationship. In the era of climate change characterized with more frequent climate extremes and natural disturbances, we should move beyond the generalizations and directly address the processes leading to the observed disturbance–diversity relationships to make reliable predictions.
  • Thumbnail Image
    Item
    Impacts of increasing typhoons on the structure and function of a subtropical forest: reflections of a changing climate
    (Nature Publishing Group, 2017-07-07) Lin, Kuo-Chuan; Hamburg, Steven P.; Wang, Lixin; Duh, Chin-Tzer; Huang, Chu-Mei; Chang, Chung-Te; Lin, Teng-Chiu; Earth Science, School of Science
    Due to their destructive and sporadic nature, it is often difficult to evaluate and predict the effects of typhoon on forest ecosystem patterns and processes. We used a 21-yr record of litterfall rates to explore the influence of typhoon frequency and intensity, along with other meteorological variables, on ecosystem dynamics in a subtropical rainforest. Over the past half century there has been an increasing frequency of strong typhoons (category 3; >49.6 m s-1; increase of 1.5 typhoons/decade) impacting the Fushan Experimental Forest, Taiwan. At Fushan strong typhoons drive total litterfall mass with an average of 1100 kg ha-1 litterfall typhoon-1. While mean typhoon season litterfall has been observed to vary by an order of magnitude, mean litterfall rates associated with annual leaf senescence vary by <20%. In response to increasing typhoon frequency, total annual litter mass increased gradually over the 21-year record following three major typhoons in 1994. Monthly maximum wind speed was predictive of monthly litterfall, yet the influence of precipitation and temperature was only evident in non-typhoon affected months. The response of this subtropical forest to strong typhoons suggests that increasing typhoon frequency has already shifted ecosystem structure and function (declining carbon sequestration and forest stature).
  • Thumbnail Image
    Item
    Large Ecosystem Service Benefits of Assisted Natural Regeneration
    (Wiley, 2018-02-01) Yang, Yusheng; Wang, Lixin; Yang, Zhijie; Xu, Chao; Xie, Jingsheng; Chen, Guangshui; Lin, Chengfang; Guo, Jianfen; Liu, Xiaofei; Xiong, Decheng; Lin, Weisheng; Chen, Shidong; He, Zongming; Lin, Kaimiao; Jiang, Miaohua; Lin, Teng-Chiu; Earth Sciences, School of Science
    China manages the largest monoculture plantations in the world, with 24% being Chinese fir plantations. Maximizing the ecosystem services of Chinese fir plantations has important implications in global carbon cycle and biodiversity protection. Assisted natural regeneration (ANR) is a practice to convert degraded lands into more productive forests with great ecosystems services. However, the quantitative understanding of ANR ecosystem service benefits is very limited. We conducted a comprehensive field manipulation experiment to evaluate the ANR potentials. We quantified and compared key ecosystem services including surface runoff, sediment yield, dissolved organic carbon export, plant diversity, and aboveground carbon accumulation of ANR of secondary forests dominated by Castanopsis carlesii to that of Chinese fir and C. carlesii plantations. Our results showed that ANR of C. carlesii forest reduced surface runoff and sediment yield up to 50% compared with other young plantations in the first 3 years and substantially increased plant diversity. ANR also reduced the export of dissolved organic carbon by 60–90% in the first 2 years. Aboveground biomass of the young ANR forest was approximately 3–4 times of that of other young plantations, while aboveground biomass of mature ANR forests was approximately 1.4 times of that of mature Chinese fir plantations of the same age. If all Chinese fir plantations in China were replaced by ANR forests, potentially 0.7 Pg more carbon will be stored in aboveground in one rotation (25 years). The results indicate that ANR triggers positive feedbacks among soil and water conservation, biodiversity protection, and biomass accumulation and thereby enhances ecosystem services.
  • Thumbnail Image
    Item
    On the seasonality of long-range transport of acidic pollutants in East Asia
    (IOP, 2022-08-07) Chang, Chung-Te; Wang, Lixin; Wang, Lih-Jih; Liu, Chiung-Pin; Yang, Ci-Jian; Huang, Jr-Chuan; Wang, Chiao-Ping; Lin, Neng-Huei; Lin, Teng-Chiu; Earth and Environmental Sciences, School of Science
    East Asia currently has the largest SO2 and NOx emissions in the world. The long-range transport (LRT) of acidic pollutants in this region is of great concern but the extent is not well understood. Here results from combined long-term (⩾20 years) atmospheric deposition monitoring and air trajectory analysis in East Asia were reported. The results showed that despite the large decrease of SO2 and NOx emissions in Taiwan, annual deposition of non-sea-salt sulfate (nss-SO2−4 ) in northern Taiwan showed no decreasing trend during 1994–2020. However, when divided seasonally, both nss-SO2−4 and nitrate (NO−3 ) deposition had a significant decreasing trend in the summer but not in the winter. Similar patterns were found for Japan and Korea. Air trajectory models in combination with a regional emission map indicate that LRT from eastern China contributed up to 70% of the winter deposition of nss-SO2−4 and NO−3 in Taiwan and up to 50% in Japan and Korea. The results indicate that LRT obscured the efficacy of local pollution control measures in East Asia and suggest that transboundary air pollution regulations are required to combat acid deposition.
  • Thumbnail Image
    Item
    Precipitation controls on nutrient budgets in subtropical and tropical forests and the implications under changing climate
    (Elsevier, 2017-05) Chang, Chung-Te; Wang, Lih-Jih; Huang, Jr-Chuan; Liu, Chiung-Pin; Wang, Chiao-Ping; Lin, Neng-Huei; Wang, Lixin; Lin, Teng-Chiu; Department of Earth Sciences, School of Science
    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.
  • Thumbnail Image
    Item
    Recent Photosynthates Are the Primary Carbon Source for Soil Microbial Respiration in Subtropical Forests
    (AGU, 2022-11-28) Yang, Zhijie; Lin, Teng-Chiu; Wang, Lixin; Chen, Shidong; Liu, Xiaofei; Xiong, Decheng; Xu, Chao; Arthur, Mary; McCulley, Rebecca; Shi, Sihong; Yang, Yusheng; Earth and Environmental Sciences, School of Science
    Tropical and subtropical forests represent the largest terrestrial carbon pool. Elucidating the carbon sources for soil microbial respiration (Rm) in tropical and subtropical forests is of fundamental importance to the global carbon cycle in a warming world. Based on hourly measurements, we quantified Rm of in situ forest soil and soil cores from a subtropical forest. We found recent photosynthates, not soil organic carbon (SOC), contributed 88% ± 12% of the carbon source fueling Rm. The control of recent photosynthates on Rm is also supported by the close relationship between Rm and photosynthetically active radiation as well as literature data synthesis results. These results challenge conventional models based on the tenet that Rm is mainly regulated by soil temperature in all forest ecosystems. The results imply that the widely observed warming-induced Rm increases are largely explained by the enhanced input of recent photosynthates in tropical forests, not SOC consumption.
  • Thumbnail Image
    Item
    Shifts in stream hydrochemistry in responses to typhoon and non-typhoon precipitation
    (European Geosciences Union, 2018-04-19) Chang, Chung-Te; Huang, Jr-Chuan; Wang, Lixin; Shih, Yu-Ting; Lin, Teng-Chiu; Earth Sciences, School of Science
    Climate change is projected to increase the intensity and frequency of extreme climatic events such as tropical cyclones. However, few studies have examined the responses of hydrochemical processes to climate extremes. To fill this knowledge gap, we compared the relationship between stream discharge and ion input–output budget during typhoon and non-typhoon periods in four subtropical mountain watersheds with different levels of agricultural land cover in northern Taiwan. The results indicated that the high predictability of ion input–output budgets using stream discharge during the non-typhoon period largely disappeared during the typhoon periods. For ions such as Na+, NH+4, and PO3−4, the typhoon period and non-typhoon period exhibited opposite discharge–budget relationships. In other cases, the discharge–budget relationship was driven by the typhoon period, which consisted of only 7 % of the total time period. The striking differences in the discharge–ion budget relationship between the two periods likely resulted from differences in the relative contributions of surface runoff, subsurface runoff and groundwater, which had different chemical compositions, to stream discharge between the two periods. Watersheds with a 17–22 % tea plantation cover showed large increases in NO−3 export with increases in stream discharge. In contrast, watersheds with 93–99 % forest cover showed very mild or no increases in NO−3 export with increases in discharge and very low levels of NO−3 export even during typhoon storms. The results suggest that even mild disruption of the natural vegetation could largely alter hydrochemical processes. Our study clearly illustrates significant shifts in hydrochemical responses between regular and typhoon precipitation. We propose that hydrological models should separate hydrochemical processes into regular and extreme conditions to better capture the whole spectrum of hydrochemical responses to a variety of climate conditions.