Transforming approaches to forest biomass estimations

Transforming approaches to forest biomass estimations

10 Oct 2024

Forest biomass is composed of above-ground and below-ground biomass. While the former refers to the total dry mass of living and dead organic material found above the soil in a forest, including trees, shrubs, and undergrowth, the latter includes roots but also soil carbon. From a remote sensing point of view only the above-ground biomass can be directly estimated, while the below-ground biomass have has to be deduced based on allometric equations specific for certain ecosystems.

Forest above-ground biomass is a critical indicator of forest health and productivity, providing valuable information on the amount of carbon stored in forest ecosystems. Biomass data is vital for assessing the role of forests in carbon cycling, understanding their contribution to climate regulation, and evaluating their capacity to support biodiversity and other ecosystem services. Accurate biomass data allows for ecosystem accounting, where environmental data is integrated with economic information, enabling the economic valuation of natural resources.

Research shows that forests are significant carbon sinks, absorbing approximately 2.6 billion tons of carbon dioxide annually, which is about one-third of the carbon dioxide released from fossil fuels. Thus, understanding and accurately estimating forest biomass is critical for climate models and carbon budgeting, informing strategies to combat climate change.

Who Uses Forest Biomass Data

Government bodies and ministries utilise biomass data to develop policies on sustainable forest management and climate change mitigation. For instance, biomass data informs core EU policies such as the Land Use, Land-Use Change, and Forestry (LULUCF) Regulation, the EU Forest Strategy, and the EU Biodiversity Strategy 2030. These policies rely on accurate biomass estimates to set targets, monitor progress, and implement measures to protect and sustainably manage forest resources.

International organisations, such as the United Nations Food and Agriculture Organization (FAO), use biomass data for global assessments and reporting. The FAO’s Global Forest Resources Assessment (FRA) depends on accurate biomass data to provide comprehensive information on the state of the world’s forests.

Additionally, other stakeholders such as forest managers, researchers, environmental NGOs, and various forest-based industries (e.g., timber, wood products, pulp and paper, biomass energy) rely on biomass data for operational planning, scientific research, conservation efforts, and commercial activities. Accurate biomass estimates are crucial for these stakeholders to make informed decisions and optimise their activities in alignment with sustainability goals.

Why Now is the Opportune Time

The urgency to address climate change, promote sustainable forest management, and conserve biodiversity drives the current emphasis on forest biomass information. Accurate biomass data can potentially support compliance with environmental policies, aids in the transition to renewable energy sources, and helps combat deforestation. When combined with ancillary data such as forest canopy height maps and natural vegetation type maps, biomass information might also help to mitigate biodiversity loss. Moreover, it allows for the precise valuation of ecosystem services, which is increasingly important for integrating natural capital into economic planning and decision-making.

EvoLand has forestry high upon its priorities as in total three of the prototypes are focused on improving the available information around that topic. We’ve previously detailed the work EvoLand is carrying out in relation to the continuous monitoring of forests as well as detecting forest disturbances.

Deciphering the EvoLand C3 prototype

Forests play a crucial role in sustainable development by conserving biodiversity and mitigating climate change. Vegetation height and above-ground biomass are high-priority biodiversity variables for space observation. The Copernicus Land Monitoring Service (CLMS) currently lacks timely information on these variables, which are essential for supporting EU policies on renewable resources, climate change, and biodiversity. To address this, a candidate service aims to provide consistent spatio-temporal estimates of above-ground woody biomass (AGB) and forest canopy height (FCH) across Europe (with study areas in Sweden and Spain) as well as in the tropics (French Guiana) at a yearly coverage and with a minimum mapping unit of 0.5 ha.

Method-wise, both parametric and non-parametric models are used. While parametric methods are based on a predetermined model describing the relationship between AGB, FCH and the remote sensing signal, non-parametric methods learn these relationships directly from the data. A possible combination of both models could allow for AGB and FCH to be estimated at the pixel level and aggregated based on stakeholder requirements.

The project’s first phase demonstrated the potential of using satellite time series and reference data from national forest inventories and from space-borne LiDAR to map AGB and FCH. The next phase will focus on multi-annual consistent estimates to assess forest ecosystem dynamics. Radar data, like L-band ALOS PALSAR, improves mapping quality due to better canopy penetration. Upcoming sensors like NISAR (L-band SAR) and BIOMASS (P-band SAR) are expected to further enhance biomass mapping.

Cover image credit: European Union, Copernicus Sentinel-2 imagery

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This article is part of a series providing more details on all 11 EvoLand candidate prototypes.

Previous article in the series: 

Innovative on-demand land cover services for customised spatial and temporal needs – EvoLand (evo-land.eu)

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