Carbon Dynamics in a Human-Modified Tropical Forest: A Case Study Using Multi-Temporal LiDAR Data

Tropical forests hold significant amounts of carbon and play a critical role on Earth´s climate system. To date, carbon dynamics over tropical forests have been poorly assessed, especially over vast areas of the tropics that have been affected by some type of disturbance (e.g., selective logging, understory fires, and fragmentation). Understanding the multi-temporal dynamics of carbon stocks over human-modified tropical forests (HMTF) is crucial to close the carbon cycle balance in the tropics. Here, we used multi-temporal and high-spatial resolution airborne LiDAR data to quantify rates of carbon dynamics over a large patch of HMTF in eastern Amazon, Brazil. We described a robust approach to monitor changes in aboveground forest carbon stocks between 2012 and 2018. Our results showed that this particular HMTF lost 0.57 m·yr−1 in mean forest canopy height and 1.38 Mg·C·ha−1·yr−1 of forest carbon between 2012 and 2018. LiDAR-based estimates of Aboveground Carbon Density (ACD) showed progressive loss through the years, from 77.9 Mg·C·ha−1 in 2012 to 53.1 Mg·C·ha−1 in 2018, thus a decrease of 31.8%. Rates of carbon stock changes were negative for all time intervals analyzed, yielding average annual carbon loss rates of −1.34 Mg·C·ha−1·yr−1. This suggests that this HMTF is acting more as a source of carbon than a sink, having great negative implications for carbon emission scenarios in tropical forests. Although more studies of forest dynamics in HMTFs are necessary to reduce the current remaining uncertainties in the carbon cycle, our results highlight the persistent effects of carbon losses for the study area. HMTFs are likely to expand across the Amazon in the near future. The resultant carbon source conditions, directly associated with disturbances, may be essential when considering climate projections and carbon accounting methods.

Download Full-text

Estimating aboveground carbon density and its uncertainty in Borneo’s structurally complex tropical forests using airborne laser scanning

10.5194/bg-2018-74 ◽

2018 ◽

Cited By ~ 3

Author(s):

Tommaso Jucker ◽

Gregory P. Asner ◽

Michele Dalponte ◽

Philip Brodrick ◽

Christopher D. Philipson ◽

...

Keyword(s):

Tropical Forests ◽

Laser Scanning ◽

Canopy Cover ◽

Carbon Stocks ◽

Forest Carbon ◽

Airborne Laser Scanning ◽

Tropical Asia ◽

Airborne Laser ◽

Dipterocarp Forests ◽

The Tropics

Abstract. Borneo contains some of the world’s most biodiverse and carbon dense tropical forest, but this 750 000-km2 island has lost 62 % of its old-growth forests within the last 40 years. Efforts to protect and restore the remaining forests of Borneo hinge on recognising the ecosystem services they provide, including their ability to store and sequester carbon. Airborne Laser Scanning (ALS) is a remote sensing technology that allows forest structural properties to be captured in great detail across vast geographic areas. In recent years ALS has been integrated into state-wide assessment of forest carbon in Neotropical and African regions, but not yet in Asia. For this to happen, new regional models, need to be developed for estimating carbon stocks from ALS in tropical Asia, as the forests of this region are structurally and compositionally distinct from those found elsewhere in the tropics. By combining ALS imagery with data from 173 permanent forest plots spanning the lowland rain forests of Sabah, on the island of Borneo, we develop a simple-yet-general model for estimating forest carbon stocks using ALS-derived canopy height and canopy cover as input metrics. An advanced feature of this new model is the propagation of uncertainty in both ALS- and ground-based data, allowing uncertainty in hectare-scale estimates of carbon stocks to be quantified robustly. We show that the model effectively captures variation in aboveground carbons stocks across extreme disturbance gradients spanning tall dipterocarp forests and heavily logged regions, and clearly outperforms existing ALS-based models calibrated for the tropics, as well as currently available satellite-derived products. Our model provides a simple, generalised and effective approach for mapping forest carbon stocks in Borneo, and underpins ongoing efforts to safeguard and facilitate the restoration of its unique tropical forests.

Download Full-text

Characterizing forest carbon dynamics using multi-temporal lidar data

Remote Sensing of Environment ◽

10.1016/j.rse.2019.02.018 ◽

2019 ◽

Vol 224 ◽

pp. 412-420 ◽

Cited By ~ 8

Author(s):

Michele Dalponte ◽

Tommaso Jucker ◽

Sicong Liu ◽

Lorenzo Frizzera ◽

Damiano Gianelle

Keyword(s):

Carbon Dynamics ◽

Forest Carbon ◽

Lidar Data ◽

Multi Temporal

Download Full-text

Estimating aboveground carbon density and its uncertainty in Borneo's structurally complex tropical forests using airborne laser scanning

Biogeosciences ◽

10.5194/bg-15-3811-2018 ◽

2018 ◽

Vol 15 (12) ◽

pp. 3811-3830 ◽

Cited By ~ 17

Author(s):

Tommaso Jucker ◽

Gregory P. Asner ◽

Michele Dalponte ◽

Philip G. Brodrick ◽

Christopher D. Philipson ◽

...

Keyword(s):

Tropical Forests ◽

Laser Scanning ◽

Carbon Stocks ◽

Forest Carbon ◽

Airborne Laser Scanning ◽

Tropical Asia ◽

Aboveground Carbon ◽

Airborne Laser ◽

Dipterocarp Forests ◽

The Tropics

Abstract. Borneo contains some of the world's most biodiverse and carbon-dense tropical forest, but this 750 000 km2 island has lost 62 % of its old-growth forests within the last 40 years. Efforts to protect and restore the remaining forests of Borneo hinge on recognizing the ecosystem services they provide, including their ability to store and sequester carbon. Airborne laser scanning (ALS) is a remote sensing technology that allows forest structural properties to be captured in great detail across vast geographic areas. In recent years ALS has been integrated into statewide assessments of forest carbon in Neotropical and African regions, but not yet in Asia. For this to happen new regional models need to be developed for estimating carbon stocks from ALS in tropical Asia, as the forests of this region are structurally and compositionally distinct from those found elsewhere in the tropics. By combining ALS imagery with data from 173 permanent forest plots spanning the lowland rainforests of Sabah on the island of Borneo, we develop a simple yet general model for estimating forest carbon stocks using ALS-derived canopy height and canopy cover as input metrics. An advanced feature of this new model is the propagation of uncertainty in both ALS- and ground-based data, allowing uncertainty in hectare-scale estimates of carbon stocks to be quantified robustly. We show that the model effectively captures variation in aboveground carbon stocks across extreme disturbance gradients spanning tall dipterocarp forests and heavily logged regions and clearly outperforms existing ALS-based models calibrated for the tropics, as well as currently available satellite-derived products. Our model provides a simple, generalized and effective approach for mapping forest carbon stocks in Borneo and underpins ongoing efforts to safeguard and facilitate the restoration of its unique tropical forests.

Download Full-text

Modelling above-ground carbon dynamics using multi-temporal airborne lidar: insights from a Mediterranean woodland

Biogeosciences ◽

10.5194/bg-13-961-2016 ◽

2016 ◽

Vol 13 (4) ◽

pp. 961-973 ◽

Cited By ~ 17

Author(s):

W. Simonson ◽

P. Ruiz-Benito ◽

F. Valladares ◽

D. Coomes

Keyword(s):

Climate Change ◽

Large Scale ◽

Critical Role ◽

Carbon Fluxes ◽

Carbon Dynamics ◽

Airborne Lidar ◽

Lidar Data ◽

Low Carbon ◽

Data Set ◽

Multi Temporal

Abstract. Woodlands represent highly significant carbon sinks globally, though could lose this function under future climatic change. Effective large-scale monitoring of these woodlands has a critical role to play in mitigating for, and adapting to, climate change. Mediterranean woodlands have low carbon densities, but represent important global carbon stocks due to their extensiveness and are particularly vulnerable because the region is predicted to become much hotter and drier over the coming century. Airborne lidar is already recognized as an excellent approach for high-fidelity carbon mapping, but few studies have used multi-temporal lidar surveys to measure carbon fluxes in forests and none have worked with Mediterranean woodlands. We use a multi-temporal (5-year interval) airborne lidar data set for a region of central Spain to estimate above-ground biomass (AGB) and carbon dynamics in typical mixed broadleaved and/or coniferous Mediterranean woodlands. Field calibration of the lidar data enabled the generation of grid-based maps of AGB for 2006 and 2011, and the resulting AGB change was estimated. There was a close agreement between the lidar-based AGB growth estimate (1.22 Mg ha−1 yr−1) and those derived from two independent sources: the Spanish National Forest Inventory, and a tree-ring based analysis (1.19 and 1.13 Mg ha−1 yr−1, respectively). We parameterised a simple simulator of forest dynamics using the lidar carbon flux measurements, and used it to explore four scenarios of fire occurrence. Under undisturbed conditions (no fire) an accelerating accumulation of biomass and carbon is evident over the next 100 years with an average carbon sequestration rate of 1.95 Mg C ha−1 yr−1. This rate reduces by almost a third when fire probability is increased to 0.01 (fire return rate of 100 years), as has been predicted under climate change. Our work shows the power of multi-temporal lidar surveying to map woodland carbon fluxes and provide parameters for carbon dynamics models. Space deployment of lidar instruments in the near future could open the way for rolling out wide-scale forest carbon stock monitoring to inform management and governance responses to future environmental change.

Download Full-text

Degradation and forgone removals increase the carbon impact of intact forest loss by 626%

Science Advances ◽

10.1126/sciadv.aax2546 ◽

2019 ◽

Vol 5 (10) ◽

pp. eaax2546 ◽

Cited By ~ 19

Author(s):

Sean L. Maxwell ◽

Tom Evans ◽

James E. M. Watson ◽

Alexandra Morel ◽

Hedley Grantham ◽

...

Keyword(s):

Tropical Forest ◽

Tropical Forests ◽

Selective Logging ◽

Carbon Accounting ◽

Carbon Equivalent ◽

Forest Loss ◽

Climate Mitigation ◽

International Climate Policy ◽

Global Land ◽

International Climate

Intact tropical forests, free from substantial anthropogenic influence, store and sequester large amounts of atmospheric carbon but are currently neglected in international climate policy. We show that between 2000 and 2013, direct clearance of intact tropical forest areas accounted for 3.2% of gross carbon emissions from all deforestation across the pantropics. However, full carbon accounting requires the consideration of forgone carbon sequestration, selective logging, edge effects, and defaunation. When these factors were considered, the net carbon impact resulting from intact tropical forest loss between 2000 and 2013 increased by a factor of 6 (626%), from 0.34 (0.37 to 0.21) to 2.12 (2.85 to 1.00) petagrams of carbon (equivalent to approximately 2 years of global land use change emissions). The climate mitigation value of conserving the 549 million ha of tropical forest that remains intact is therefore significant but will soon dwindle if their rate of loss continues to accelerate.

Download Full-text

Modelling the impact of lianas on the biogeochemical cycles of tropical forests

10.5194/egusphere-egu2020-13740 ◽

2020 ◽

Author(s):

Félicien Meunier ◽

Michael Dietze ◽

Manfredo di Porcia e Brugnera ◽

Marcos Longo ◽

Hans Verbeeck

Keyword(s):

Carbon Storage ◽

Tropical Forests ◽

Tree Growth ◽

Model Uncertainty ◽

Negative Impact ◽

Carbon Dynamics ◽

Biogeochemical Cycles ◽

Forest Carbon ◽

Allometric Relationships ◽

Net Productivity

Despite their low contribution to forest carbon stocks, lianas (woody vines) play an important role in the carbon dynamics of tropical forests where they compete with free-standing plants for below- and above-ground resources. Doing so, they negatively impact individual tree growth, as well as the net productivity and the long-term carbon storage of the ecosystem.However, lianas remain largely ignored in field-scale studies as well as modelling forecasts. Therefore, their exact impact on tropical forest biogeochemical cycles is very uncertain. In particular, it is unclear which resource (light, water) is the most competed for between growth forms and so is is the future impact of lianas on forests in a global climate change context in which brighter, drier and CO2-enriched conditions are expected in the Tropics.To answer those burning questions, we incorporated for the very first time a plant functional type accounting for the lianescent growth form into a dynamic global vegetation model (ED2). We implemented several liana-specific processes in the modelling framework (climbing, resprouting, height limitation due to lack of self-supporting tissues etc.), and integrated liana-specific parameters according to data from multiple studies in order to account for significant differences of functional and structural traits between lianas and trees. These parameters included (but were not limited to) leaf biochemical and photosynthesis properties, stem hydraulic traits, root distribution, and allometric relationships.Baseline runs successfully reproduced ecosystem gas exchange fluxes (GPP and latent heat), forest structural features (LAI, AGB), and several other benchmarking observations in multiple tropical sites characterized by different rainfall regimes and levels of liana abundance. In those simulations, lianas negatively reduced forest productivity and total carbon storage, by increasing tree mortality (+ 30% on average) and decreasing tree growth (-35%). The inclusion of lianas in the simulations reduced the forest net productivity by up to 0.5 tC ha&#8722;1 year&#8722;1, which resulted in significantly reduced accumulated above&#8208;ground biomass by up to 20 tC/ha in regrowth forests. The negative impact of lianas on carbon storage almost disappeared in wetter, old-growth forest sites. Model uncertainty analyses also revealed that water limitation was the dominant factor driving competition between trees and lianas, even in sites with a short dry season.These two-key findings (higher impact in regrowth forests and water-dominated competition) are expected to lead to a reinforcement of the negative impact of lianas on forest productivity under future aggravated forest disturbance and warmer climate conditions. The modelling workflow also allowed to identify key liana traits (quantum efficiency, stomatal regulation parameters, allometric relationships) and processes (water use, respiration, climbing) driving the overall model uncertainty. They should be considered as priorities for future data acquisition and model development to improve predictions of liana-infested forest carbon dynamics.

Download Full-text

Using lidar data and a height-structured ecosystem model to estimate forest carbon stocks and fluxes over mountainous terrain

Canadian Journal of Remote Sensing ◽

10.5589/m08-036 ◽

2008 ◽

Vol 34 (sup2) ◽

pp. S351-S363 ◽

Cited By ~ 35

Author(s):

R. Quinn Thomas ◽

George C Hurtt ◽

Ralph Dubayah ◽

Mariya H Schilz

Keyword(s):

Ecosystem Model ◽

Carbon Stocks ◽

Forest Carbon ◽

Lidar Data ◽

Mountainous Terrain

Download Full-text

Droughts, Wildfires, and Forest Carbon Cycling: A Pantropical Synthesis

Annual Review of Earth and Planetary Sciences ◽

10.1146/annurev-earth-082517-010235 ◽

2019 ◽

Vol 47 (1) ◽

pp. 555-581 ◽

Cited By ~ 38

Author(s):

Paulo M. Brando ◽

Lucas Paolucci ◽

Caroline C. Ummenhofer ◽

Elsa M. Ordway ◽

Henrik Hartmann ◽

...

Keyword(s):

Tropical Forests ◽

Tree Mortality ◽

Scientific Evidence ◽

Alternative Stable States ◽

Forest Carbon ◽

Autotrophic Respiration ◽

Stable States ◽

Threshold Conditions ◽

The Tropics ◽

Forest C

Tropical woody plants store ∼230 petagrams of carbon (PgC) in their aboveground living biomass. This review suggests that these stocks are currently growing in primary forests at rates that have decreased in recent decades. Droughts are an important mechanism in reducing forest C uptake and stocks by decreasing photosynthesis, elevating tree mortality, increasing autotrophic respiration, and promoting wildfires. Tropical forests were a C source to the atmosphere during the 2015–2016 El Niño–related drought, with some estimates suggesting that up to 2.3 PgC were released. With continued climate change, the intensity and frequency of droughts and fires will likely increase. It is unclear at what point the impacts of severe, repeated disturbances by drought and fires could exceed tropical forests’ capacity to recover. Although specific threshold conditions beyond which ecosystem properties could lead to alternative stable states are largely unknown, the growing body of scientific evidence points to such threshold conditions becoming more likely as climate and land use change across the tropics. ▪ Droughts have reduced forest carbon uptake and stocks by elevating tree mortality, increasing autotrophic respiration, and promoting wildfires. ▪ Threshold conditions beyond which tropical forests are pushed into alternative stable states are becoming more likely as effects of droughts intensify.

Download Full-text