# Deciduous afforestation as a natural climate solution: impacts on biomass and carbon sequestration in boreal forests of Canada

## TL;DR

This paper explores how planting deciduous trees in Canadian boreal forests can increase carbon storage and reduce water stress compared to coniferous trees under future climate scenarios.

## Contribution

The study introduces a process-based modeling approach to compare carbon sequestration and water stress in deciduous versus coniferous afforestation in boreal regions.

## Key findings

- Deciduous afforestation sequestered significantly more carbon than coniferous species under all climate scenarios.
- Coniferous species experienced higher water stress compared to deciduous species, especially in warmer conditions.
- Deciduous afforestation could help mitigate wildfire risk and support northern boreal forest adaptation.

## Abstract

Rising temperatures and altered precipitation patterns are expected to have profound impacts on the composition and condition of boreal forests. As a result there are growing needs for climate adaptation strategies in boreal forest management; one potential solution to achieve these goals is the utilization of nature-based climate-informed adaption solutions including afforestation using deciduous species which can help offset carbon emissions and sequester carbon at an increased rate. Deciduous afforestation has the potential to allow mangers to adapt fire-risk, while increasing carbon storage. Here, we investigated the impact of deciduous compared to coniferous afforestation on biomass accumulation in the Canadian boreal using a process-based model (3-PG). 3-PG utilises physiological principals to predict the growth of individual species across a variety of climate scenarios. This approach is valuable for projecting forest growth under changing climate, as it can account for plant responses to environmental factors which may not be captured by empirical models based on historical data. We simulated forest growth under three future climate scenarios to 2080, and compared the aboveground biomass (AGB, tons of Dry Matter per hectare; tDM ha−1) accumulated to baseline estimates using locally adapted coniferous species. In addition, we investigated the modelled effects of converting from conifer to deciduous species on stand level soil water and vapor pressure deficit responses to climate.

We found that deciduous simulations sequester more carbon under all climate scenarios, with the greatest difference occurring in the warmest scenario (171 tDM ha−1 for coniferous species compared to 347.1 tDM ha−1 for deciduous species). Coniferous species were generally more water stressed than deciduous species; conifers were generally 65.6% more stressed compared to deciduous species in August under the warmest climate scenario, while northern sites were less stressed than southern sites.

Simulations such as these highlight the importance of modelling and consideration of different planting scenarios in decision-making to ensure successful resource allocation. They also demonstrate the potential of nature-based adaptation solutions projects, and the role deciduous afforestation can play in provision of habitat, modifying wildfire risk and northern boreal biomass and timber supply.

The online version contains supplementary material available at 10.1186/s13021-025-00385-2.