Our Goals1. Understand the mechanisms and key drivers of forest resilience, including degradation and alternative stable states, at various scales.
2. Quantify to what extent to which anthropogenic disturbances, such as climate change, defaunation and deforestation, impact forest ecosystems functioning and relevant ecosystem services. 3. Explore the roles of biotic interactions in maintain biodiversity and resilience in tropical forest. 4. Provide scientific guidance and offer evidence-based policy recommendations to decision-makers. |
Forest resilience and ecosystem functioning
Tropical forests are biodiversity hotspots on earth. Unfortunately, deforestation has been widespread in pan-tropical forests for many decades. Some areas that were once deforested have since been abandoned and have been regenerating into second-growth forests. However, there is limited knowledge and data available to generalize mechanisms and processes of forest resilience, particularly regarding community dynamics and ecosystem functioning. Additionally, there have been relatively fewer studies conducted in Southeast Asian tropical forest. Our site is located in Khao Yai National Park, Thailand, which is known as one of the most pristine forests in the region. This park is home to several endangered wildlife such as elephants, hornbills and gibbons, which are commonly observed here. The geographic location of Thailand makes it a central hub for biodiversity in Southeast Asia, as it shares two major biogeographical zones and covers nearly all forest types in Southeast Asia. Our site is located in the central part of Thailand, representing for biodiversity that spans a vast region encompassing Southeast China, Laos, Cambodia and Thailand. The landscape consists a succession gradient, with the majority of the area covered by old-growth or intact forests. Within this context, the long-term 30.2-ha plots namely “Mo Singto (the hill of lion in Thai)” was established in 2001. The plot is located in the intact forest, and has been part of to the network of Forest Global Observation (https://forestgeo.si.edu/) since 2005. All trees with DBH ≥1 cm has been fully mapped, tagged and monitored since 2001. The plot was initially found by Professor Warren Brockelman, who also initiated the world’s longest study of gibbon in this area. An important on-going research topic on this plot includes not only forest dynamics but also animal seed dispersal, particularly focusing on gibbons. In addition to tree community, the entire 30.2-ha plot is subject to a long-term liana census (DBH ≥2-3 cm). Currently, this plot has affiliated with the National Biobank of Thailand.
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In 2013, we established small permanent plots (0.48-ha, 60m×80 m) to capture distinct stages of forest succession stages—specifically, stand initiation, stem exclusion and old-growth—in the same forest landscape of the Mo Singto plot (totaling approximately 2.9 ha in size, for more detail see Chanthorn et al., (2017). Associate Professor Wirong Chanthorn is the founder of this plot. The ensure future comparison with data from the Mo Singto plot or other ForestGEO plots, we applied the same census protocol as ForestGEO. Since 2018, all lianas with DBH ≥1 cm have been long-term monitored on these plots. Furthermore, we established two new plots (2 ha and 1 ha) aiming to capture early stages of succession. Both types of plots have been funded by National Science and Technology Development of Thailand (NSTDA) of Thailand. The combination of these permanent plots serve as an essential research facility, supporting not only community ecology but also other studies focusing on tropical forests. The combination of these permanent plots serves as an essential research facility, supporting not only community ecology but also other studies that focus on tropical forests.
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Ecosystem functioning across succession stages
The carbon cycle of tropical forest is globally essential in climate change mitigation. Here we investigate above- and below-ground productivity i.e. litterfall and fine-root dynamics across all succession stages. These studies are parts of two collaborative projects supported by EU-ASEAN jointed funding and Chinese-Thai jointed funding, which Dr. Pantana Tor-ngern, (Chulalongkorn University) is the principal investigator. |
Functional traits:
Intraspecific variability: A current project has created an original dataset of wood density (wood specific gravity) and wood carbon in our forest landscape to understand drivers of intraspecific variability in wood density and carbon content, and its consequence for above-ground biomass and carbon estimates. Seed size of lianas and trees: This project aims to explain what ecological and evolutionary factors determine seed size in a tropical forest and to disseminate seed size dataset of trees and lianas from our study area. Leaf functional traits of lianas on the Mo Singto plot: We have the field campaign aiming to create the rare important dataset for other relevant studies. Here we target to have about 80-100 species (of 150 species) on the plot. This campaign is supported by the Humboldt foundation. |
Remote sensing
Here our aims of applying remote sensing are to examine forest resilience, carbon cycle and biodiversity. The LiDAR data, which has the footprint covering all plots described above, is a main core analysis combining with other coarser-scale products of remote sensing, but have a very longer temporal scale (see an example in Jha et al. 2020). This project is a collaboration with the Institute of Research Development of France and Asian Institute of Technology in Thailand. We also apply remote sensing to predict ecosystem functioning such as litterfall dynamics, which has monitored across succession stages as previously described. Currently we have a project applying a product of Sentinel satellite to examine this topic. |
Biotic interactions
Seed dispersal,
The Mo Singto plot has the long-term study of seed dispersal. We have a database of seed dispersal covering nearly all species of trees (~250 species) categorized with respect to a size of frugivore (see Chanthorn et al. 2019). Based on this data, we have linked this information to the forest census data. For example, we apply an advanced spatial statistic developed by Dr. Thorsten Wiegand, which is capable to reveal each species properties. Surprisingly, we found that primates (gibbons and macaques) are an underlying mechanism of the accumulator—species assist to increase species diversity in their neighborhood (Chanthorn et. al. 2018). We have also linked this data to ecosystem functioning and services such as a long-term carbon sink. Our collaboration with Dr. Florian Hartig demonstrated that defaunation of large-bodied frugivores also affects carbon storage in Southeast Asian tropical forest, contradicting to a prior belief of no effect (Chanthorn et. al. 2019). Liana-tree interaction, This is an on-going project. We are interested to know what extent lianas contribute to tropical forest in community and ecosystem functioning in the following perspectives: 1) ecosystem functioning such as above-ground biomass, 2) non-spatial and spatial interactions between trees and lianas. We apply both species and functional traits perspectives to answer questions. This project is collaborative with Dr. Wiegand supported by Humboldt foundation. We also have partners from, Xishuanbanna tropical botanical garden in China (Dr. Zhenhua Sun), University of Regensburg in Germany and Institute of Research Development in France (Dr. Maxime Rechou-Mechain). |
Plant-microbe interaction: a parasitic fungus
In Khao Yai National Park, there are reports of some specific fungi that infected on top-ranked tree species. For example, Laurobasidium hachijoense (Family Laurobasidiaceae), the new-recorded species in Thailand, infects the Cinnamomum subavenium tree. We demonstrate that this fungus species is an example of a cause of conspecific negative density dependence that may regulate dominant species and stabilize diversity in this tropical forest (Chanthorn et al. 2013).