Development of a carbon calculator tool for riparian forest restoration

Abstract

Aim(s):Methods for estimating carbon sequestration in riparian forest biomass are needed to qualify riparian restoration and conservation projects for funding through carbon credits. As part of a proposed accounting methodology for California's capand-trade system, we described five riparian vegetation associations and created a tool to predict their rates of carbon accumulation under different restoration and land-use scenarios.Location: California, USA. Methods:We assembled a database of 654 forest inventory plots of known age (3-108 years) from replanted and naturally recruiting California riparian forests. We then used detrended correspondence analysis and agglomerative hierarchical clustering to detect vegetation structure in the plots and delineate distinct forest types.We used allometric equations to estimate biomass from individual trees' diameters and calculate total biomass for each plot. Next, we fitted sigmoid growth functions to the plot biomass data to generate expected values for live-tree biomass over a 100year period for each forest type. Finally, we created an algorithm to match userinputted data for an intended restoration project with a look-up table that predicts carbon accumulation appropriate to the user's scenario.Results: California riparian vegetation was divided into willow scrub, cottonwoodwillow, mixed riparian, upland riparian and riparian woodland types. Total carbon sequestration in riparian vegetation and soil varied from 75.7 to 137.4 Mg C/ha at 30 years post-restoration and from 95.1 to 175.8 Mg C/ha 100 years after stand initiation. Vegetation types dominated by taller, more shade-tolerant trees developed more slowly than scrubby and pioneer stands, but came to a higher maximum biomass. Our models put riparian biomass accumulation in the range of the few extant literature values for mediterranean systems, but uncertainties are high, and soil carbon may be underestimated. Conclusions:Our workflow and methods should be transferable to the development of carbon accounting tools for any other woody vegetation type. However, our difficulty in finding appropriate published data for the analysis suggests a critical need for field surveys appropriate to biomass estimation in woodland and forest | 585

Carbon Stock Estimations in a Mediterranean Riparian Forest: A Case Study Combining Field Data and UAV Imagery

“…In addition, it can be used to assess the economic value of the carbon ecosystem service provided by the riparian forest. Carbon storage can be seen as a co-benefit of riparian restoration, in addition to biodiversity improvement and conservation [5,20].…”

“…AGB is usually determined using a combination of allometric equations that establish the relationships among field plot inventory data (stem diameter, tree height, tree density,) and AGB. These allometric equations are, in turn, developed from trees that have been dissected, oven-dried and weighed [18] and mostly directed for commercial woody species [19,20]. Thus, field surveys are an urgent need to develop appropriate allometric biomass models across a wide range of riparian ecosystems, which may be important to assess the global significance of riparian systems on the overall carbon cycle.…”

Carbon sequestration in riparian forests: A global synthesis and meta‐analysis

“…Reference rates of carbon stock accumulation have been compiled for many forest types (e.g., IPCC, 2006), but these do not typically distinguish between riparian and upland forests. Despite their relatively small spatial footprint, riparian forests will usually have more favorable growing conditions (e.g., soil moisture), and they may accumulate carbon stocks at a greater rate than upland forests (Matzek, Stella, & Ropion, 2018;Naiman, Decamps, & McClain, 2010;Sutfin, Wohl, & Dwire, 2016), contributing more to rapid carbon sequestration in the short-term. Further, riparian ecosystems are widely recognized to provide numerous ecosystem services (Daigneault, Eppink, & Lee, 2017;Naiman et al, 2010;O'Brien et al, 2017), having the potential to mitigate the effects of climate change (Capon et al, 2013), and being biodiversity hotspots that provide critical habitat for fish and wildlife (Knopf, Johnson, Rich, Samson, & Szaro, 1988;Naiman et al, 2010).…”

Increases in soil and woody biomass carbon stocks as a result of rangeland riparian restoration

“…Modeled carbon stocks in mature riparian vegetation ranged from 188 to 279 Mg C per hectare, depending on landform. These estimates are very high compared to the 87.2 Mg C per hectare predicted for restored “willow scrub” riparian forests by CREEC (Carbon in Riparian Ecosystems Estimator for California), a statewide riparian forest carbon calculator [ 47 ]. They are higher than predictions for all other California riparian forest types in CREEC, the maximum for riparian woodlands being 245.1 Mg C per hectare.…”