Canadian Forest Service Publications

Shifts in biomass and productivity for a subtropical dry forest in response to simulated elevated hurricane disturbances. 2017. Holm, J.A.; Van Bloem, S.J.; Larocque, G.R.; Shugart, H.H. Environ. Res. Lett. 12: 025007.

Year: 2017

Available from: Laurentian Forestry Centre

Catalog ID: 38713

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1088/1748-9326/aa583c

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Abstract

Caribbean tropical forests are subject to hurricane disturbances of great variability. In addition to natural storm incongruity, climate change can alter storm formation, duration, frequency, and intensity. This model-based investigation assessed the impacts of multiple storms of different intensities and occurrence frequencies on the long-term dynamics of subtropical dry forests in Puerto Rico. Using the previously validated individual-based gap model ZELIG-TROP, we developed a new hurricane damage routine and parameterized it with site- and species-specific hurricane effects. A baseline case with the reconstructed historical hurricane regime represented the control condition. Ten treatment cases, reflecting plausible shifts in hurricane regimes, manipulated both hurricane return time (i.e. frequency) and hurricane intensity. The treatment related change in carbon storage and fluxes were reported as changes in aboveground forest biomass (AGB), net primary productivity (NPP), and in the aboveground carbon partitioning components, or annual carbon accumulation (ACA). Increasing the frequency of hurricanes decreased aboveground biomass by between 5% and 39%, and increased NPP between 32% and 50%. Decadal-scale biomass fluctuations were damped relative to the control. In contrast, increasing hurricane intensity did not create a large shift in the long-term average forest structure, NPP, or ACA from that of historical hurricane regimes, but produced large fluctuations in biomass. Decreasing both the hurricane intensity and frequency by 50% produced the highest values of biomass and NPP. For the control scenario and with increased hurricane intensity, ACA was negative, which indicated that the aboveground forest components acted as a carbon source. However, with an increase in the frequency of storms or decreased storms, the total ACA was positive due to shifts in leaf production, annual litterfall, and coarse woody debris inputs, indicating a carbon sink into the forest over the long-term. The carbon loss from each hurricane event, in all scenarios, always recovered over sufficient time. Our results suggest that subtropical dry forests will remain resilient to hurricane disturbance. However carbon stocks will decrease if future climates increase hurricane frequency by 50% or more.

Plain Language Summary

In this article, the researchers present a model of the dynamics of Puerto Rico’s subtropical dry forests.

By reconstituting the hurricane history and integrating case studies, the researchers obtained the following results:

  • The increase in hurricane frequency leads to a 5 to 39% reduction in aboveground biomass and a 32 to 50% increase in net primary productivity.

  • An increase in hurricane intensity would not have any long-term effects on forest structure and stored carbon levels.

  • A decrease in both hurricane intensity and frequency results in the highest biomass values.

Therefore, subtropical forests are resistant to such disturbances. However, carbon stocks would decrease if the frequency of hurricanes increased by 50% or more.

Caribbean tropical forests are subject to hurricanes which formation, duration, frequency and intensity are influenced by climate change.

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