When forests hold their breath: Will increasing drought further disrupt carbon sequestration? This study, which meticulously combines in-situ data, advanced satellite observations, and ecological data analysis, reveals the drastic effects of severe drought on wildfire and the carbon sequestration capacity of Taiwan's subtropical forests. Drought events have the potential to disrupt the functionality of forest ecosystems, shifting them from carbon sinks to carbon sources. Satellite monitoring of groundwater levels can offer a predictive lead time of 1 to 2 months to anticipate emissions. It is recommended to choose drought-resistant tree species for future forest management strategies, plan firebreaks, and simultaneously monitor forest net ecosystem exchanges as action plans to adapt to climate warming. The results have been published in the February issue of Environmental Research Letters in 2024. Link

Tropical cyclones facilitate recovery of forest leaf area from dry spells in East Asia: The view that tropical cyclones disturb forests by breaking and uprooting trees is widely supported by studies focusing on the effects of a few exceptionally strong cyclones. Such a viewpoint may however limit our understanding of the impact of tropical cyclones in general. Changes in forest leaf area in East Asia were estimated by jointly analyzing the cyclone tracks, climate reanalysis and satellite-based leaf area of tropical cyclones. Sixty days following their passage ~15% of the cyclones resulted in a decrease in leaf area and ~50 % showed no change in leaf area. Surprisingly, in nearly one-third of the cyclones, an increase (or a reduced decrease)  in leaf area was observed. Further analysis revealed that cyclones bringing abundant precipitation towards the end of the summer could relieve water stress for the vegetation within the cyclone track whereas the vegetation outside the track might continue to suffer until the start of the next wet season. The finding that a third of the tropical cyclones in East Asia facilitate recovery of forest leaf area from dry spells urges refining the present-day bias of cyclones as agents of destruction toward a more nuanced vision that recognizes that cyclones could also have little or even positive effects on forest growth. Link

Reconstructing Taiwan's land cover changes: A new reconstitution of Taiwan’s land cover changes and its uncertainty between 1904 and 2015 is presented. The reconstruction which integrates geographical information from historical maps and satellite images from SPOT is spatially explicit with a 500 x 500 m resolution and distinguishes six land cover classes: forests, grasslands, agriculture land, inland water, built-up, and bare soil. This type of information is essential to quantifying the contribution of climate warming from land cover changes by making use of a modeling approach, which is also in line with the large-scale land cover reconstruction in Europe. The new land cover reconstruction is thus expected to contribute to future revisions of global land cover reconstructions as well as to studies of (gross) land cover changes, the carbon budget, regional climate, urban heat islands, and air and water pollution at the national level. Download Dataset 

Simulating the impact of environmental disturbances on the forest biomass in Taiwan: The results from numerical experiments were used to attribute the impact of tropical cyclones, land-use and -cover changes (LULCC), and CO₂ fertilization on the biomass accumulation in Taiwanese forests. Simulation experiments rely on a long-term land cover reconstruction in Taiwan and a new model feature, wind-throw development, to attribute changes of the forest biomass. Possibly this research is the first model experiment quantifying the long-term impact of wind storms on Taiwanese forests biomass and is also the first application of a century-long land cover reconstruction informed by local sources to study the dynamics of forest biomass in Taiwan. The model simulated above-ground woody volume was increased from 197 ±5 m³ ha^-1 in 1979 to 217 ±4 m³ ha^-1 in 2017 and its dynamics were consistent with the national inventories. The annual carbon sequestration rate is 0.5 ±0.1 m³ ha^-1 yr^-1 averaging from 2.4 Mha forest area over the past 39 years. The wind disturbance contributed a surprising wood loss which is almost at the same level of the annual carbon sequestration rate. LULCC between afforestation and deforestation resulted in a trade-off in forest biomass sequestration, which shows an increase of forest biomass in lowland areas and a decrease of forest biomass in the mountainous area due to the agricultural expansion or local deforestation. The CO₂ fertilization effect contributed to the enhancement of forest biomass stock by almost 40%, while the CO₂ concentration increased from 300 ppm to 400 ppm over the past 40 years. Link