Streamside forests store tons of carbon; restoration doubles carbon storage in first 10 years (new Point Blue publication)

  • Mature streamside forests store as much carbon as any other forest type in the world, helping to address climate change.
  • Planting trees to actively restore riparian forests can more than double the rate of carbon storage.
  • Carbon storage is an important and previously overlooked co-benefit of riparian forest restoration.
  • Increasing the pace and scale of riparian forest restoration is a valuable investment providing both immediate carbon sequestration value and long‐term ecosystem service benefits —including water quality, habitat for fish and wildlife, and recreational opportunities that support local economies.

by Kristen Dybala, PhD, kdybala@pointblue.org  Read ScienceDaily coverage here

Forest restoration is a strategy for addressing climate change because forests store tons of carbon, both in the trees and the soil. However, the carbon storage potential of streamside forests is relatively unknown, despite extensive efforts to restore these forests globally. We compiled data on carbon storage from 117 publications, reports, and other data sets on streamside forests around the world to determine how they compare to other forest types and estimate how much carbon storage can be expected from restoring them.

We found that the average amount of carbon stored in mature streamside forest rivals the highest estimates for any other forest type around the world. The estimates for streamside forest vary depending on whether it is located in a relatively wet or dry, and warm or cool climate, but the average values range 168 – 390 tons of carbon per acre in the trees alone. We also found that, on average, soil carbon can be expected to more than triple when converting from an unforested site to a mature streamside forest. However, as with other forest types, it can take decades for these changes to go into full effect, on the order of 40-90 years for the carbon stored in trees (depending on climate) and more than 115 years for soil carbon. We also found that planting trees to actively restore these forests gave them a head-start: over the first 10 years, they stored carbon in the trees at more than twice the rate of forests that were regenerating naturally.

Our results reflect patterns for streamside forests around the world, but we could not find suitable data from every continent, or for actively planted streamside forests more than 50 years old. There are also other potentially important factors that we could not examine, such as the frequency of flooding. We encourage additional data collection that will allow us to further refine these estimates and better document the long-term carbon storage benefits.

Streamside ecosystems around the world have been severely degraded, and their large-scale restoration is a priority in many places, including California’s Central Valley and Brazil. Restoring these ecosystems is known to benefit water quality, habitat for fish and wildlife, and recreational opportunities like fishing and wildlife watching that help support local economies. Our results demonstrate the substantial additional benefit of carbon storage, which should increase the priority of restoring and maintaining streamside forests.

Dybala KE, Matzek V, Gardali T, Seavy NE. (2018) Carbon sequestration in riparian forests: a global synthesis and meta-analysis. Global Change Biology. 10.1111/gcb.14475.

Abstract

  • Restoration of deforested and degraded landscapes is a globally recognized strategy to sequester carbon, improve ecological integrity, conserve biodiversity, and provide additional benefits to human health and well‐being. Investment in riparian forest restoration has received relatively little attention, in part due to their relatively small spatial extent. Yet, riparian forest restoration may be a particularly valuable strategy because riparian forests have the potential for rapid carbon sequestration, are hotspots of biodiversity, and provide numerous valuable ecosystem services. To inform this strategy, we conducted a global synthesis and meta‐analysis to identify general patterns of carbon stock accumulation in riparian forests. We compiled riparian biomass and soil carbon stock data from 117 publications, reports, and unpublished data sets. We then modeled the change in carbon stock as a function of vegetation age, considering effects of climate and whether or not the riparian forest had been actively planted. On average, our models predicted that the establishment of riparian forest will more than triple the baseline, unforested soil carbon stock, and that riparian forests hold on average 68–158 Mg C/ha in biomass at maturity, with the highest values in relatively warm and wet climates. We also found that actively planting riparian forest substantially jump‐starts the biomass carbon accumulation, with initial growth rates more than double those of naturally regenerating riparian forest. Our results demonstrate that carbon sequestration should be considered a strong co‐benefit of riparian restoration, and that increasing the pace and scale of riparian forest restoration may be a valuable investment providing both immediate carbon sequestration value and long‐term ecosystem service returns.