Pastures as natural climate solutions: a socioecological study of tree carbon and beef production trade-offs
Faculty Advisor Name
Dr. Heather Griscom
Department
Department of Biology
Description
Forest restoration is the most effective natural climate solution, with the potential to sequester 37% of the carbon dioxide (CO2) needed to reach the Paris climate mitigation goal. Cattle pastures offer an underutilized opportunity to increase global forest restoration efforts, improve biodiversity, and maximize carbon storage through the adoption of management strategies that prioritize the incorporation of trees into pasturelands. However, remote estimations of tree carbon storage in pastoral systems have never been field-verified and their accuracy is unclear. Furthermore, the effect of increased trees on cattle production is understudied across biomes. Lastly, the restoration potential of these landscapes as a byproduct of tree carbon also remains to be studied. Therefore, the aims of this study were (i) compare past remote tree carbon estimations in pastureland systems to current field estimates to assess their accuracy, (ii) evaluate the effect of increasing tree carbon (MgC/ha) on the pastoral stocking density (AU/ha), (iii) quantify the woody species diversity (H’) within pastures, and (iv) compare findings between farms in temperate (n = 26) and tropical (n = 16) ecosystems. To accomplish these goals, two remote datasets of global tree carbon from Harris et al., 2021 and Chapman et al., 2020 were first acquired, while the current pastoral carbon storage in temperate forest ecosystems of Virginia, USA and dry tropical forest ecosystems of Los Santos, Panama was estimated with in-situ plots. Woody plant species were also quantified to determine diversity as a metric of ecological restoration potential within these systems. We also conducted IRB-approved interviews with landowners to better understand their motivations for tree incorporation in their systems. We found that Chapman et al., 2020 significantly overestimated the carbon storage of pasturelands in Los Santos, Panama, while underestimating carbon in Virginia (p < 0.001). There was no difference in MgC/ha between tropical farms and temperate farms, but H’ (p < 0.001) and stocking density (AU/ha) were significantly higher in Los Santos, Panama (p = 0.003). Additionally, farms enrolled in conservation programs had lower stocking densities than those that practiced traditional management (p = 0.026), but no significant differences in H’ or MgC/ha. There was also no effect of MgC/ha on stocking density, which suggests that pastures with more trees did not result in a decrease in beef production. Woody species diversity (H’) was positively associated with increasing MgC/ha (p < 0.001), in Los Santos, but not in Virginia. Landowners had overall positive perceptions of trees in their systems, but some struggled to incorporate them due to financial and labor-related hurdles. These findings demonstrate the potential for pastures to increase above ground tree carbon and potentially woody species diversity without decreasing beef production. Moreover, such efforts support landscape restoration and offer potentially novel revenue streams for farmers through carbon credit programs. Lastly, we demonstrate the importance of taking a socio-ecological approach to restoration of human-dominated systems.
Pastures as natural climate solutions: a socioecological study of tree carbon and beef production trade-offs
Forest restoration is the most effective natural climate solution, with the potential to sequester 37% of the carbon dioxide (CO2) needed to reach the Paris climate mitigation goal. Cattle pastures offer an underutilized opportunity to increase global forest restoration efforts, improve biodiversity, and maximize carbon storage through the adoption of management strategies that prioritize the incorporation of trees into pasturelands. However, remote estimations of tree carbon storage in pastoral systems have never been field-verified and their accuracy is unclear. Furthermore, the effect of increased trees on cattle production is understudied across biomes. Lastly, the restoration potential of these landscapes as a byproduct of tree carbon also remains to be studied. Therefore, the aims of this study were (i) compare past remote tree carbon estimations in pastureland systems to current field estimates to assess their accuracy, (ii) evaluate the effect of increasing tree carbon (MgC/ha) on the pastoral stocking density (AU/ha), (iii) quantify the woody species diversity (H’) within pastures, and (iv) compare findings between farms in temperate (n = 26) and tropical (n = 16) ecosystems. To accomplish these goals, two remote datasets of global tree carbon from Harris et al., 2021 and Chapman et al., 2020 were first acquired, while the current pastoral carbon storage in temperate forest ecosystems of Virginia, USA and dry tropical forest ecosystems of Los Santos, Panama was estimated with in-situ plots. Woody plant species were also quantified to determine diversity as a metric of ecological restoration potential within these systems. We also conducted IRB-approved interviews with landowners to better understand their motivations for tree incorporation in their systems. We found that Chapman et al., 2020 significantly overestimated the carbon storage of pasturelands in Los Santos, Panama, while underestimating carbon in Virginia (p < 0.001). There was no difference in MgC/ha between tropical farms and temperate farms, but H’ (p < 0.001) and stocking density (AU/ha) were significantly higher in Los Santos, Panama (p = 0.003). Additionally, farms enrolled in conservation programs had lower stocking densities than those that practiced traditional management (p = 0.026), but no significant differences in H’ or MgC/ha. There was also no effect of MgC/ha on stocking density, which suggests that pastures with more trees did not result in a decrease in beef production. Woody species diversity (H’) was positively associated with increasing MgC/ha (p < 0.001), in Los Santos, but not in Virginia. Landowners had overall positive perceptions of trees in their systems, but some struggled to incorporate them due to financial and labor-related hurdles. These findings demonstrate the potential for pastures to increase above ground tree carbon and potentially woody species diversity without decreasing beef production. Moreover, such efforts support landscape restoration and offer potentially novel revenue streams for farmers through carbon credit programs. Lastly, we demonstrate the importance of taking a socio-ecological approach to restoration of human-dominated systems.
