Ecosystem services loss due to impacts of hurricanes Irma and María in San Juan residential trees

Methods

Summary

We will re-visit the plots where we have conducted complete i-Tree Eco inventories. i-Tree Eco is a tool that helps evaluate the provision of ecosystem services by trees and estimates their monetary value based on data on their volume. For example, for an individual tree, i-Tree Eco can estimate the reduction in air temperature it can reduce and depending on where is located, how much money can be saved in a household energy consumption. We will conduct a rapid assessment to record the types of damage experienced by yard trees (crown damage and bole damage), cause of damage (wind, insects, poor planting, damage by infrastructure), their fate (loss, pruning), state of recovery (re-foliation) one month after hurricanes Irma and Maria and whether or not they represent a hazard in their current state. This information is valuable to evaluate the resilience of individual tree species to these large-scale events and provides preliminary data on the potential loss of ecosystem services after hurricanes.

Challenges

The biggest challenge in censing yard vegetation in the past has been access to private yards.  We believe that access may be easier this time around provided that some residents are still on their houses for several reasons. Lack of power in the city has prevented many residents from going back to work, so many more residents might be home in the aftermath of the hurricane. The hurricane crisis, has opened up communities and bonded neighbors in times of need. Sine households are being revisited and some degree of trust has been established from prior work, we hope to be granted access.

Pre Analysis Plan

We now ask: What where the ecosystem services of residential trees in San Juan before the hurricane and what types of damage were sustained by recorded species following hurricanes Irma and Maria?  We will finish entering and validating tree data collected prior to the hurricane events and will submit i-Tree Eco projects for two communities to evaluate ecosystem services (carbon sequestration, run-off reduction, air quality, energy savings) that were provided at that time. With the rapid assessment we hope to use contingency analyses to evaluate differences among species in the relative frequency of 1) different types of damage (broken branches, uprooting, tip-off, split), 2) management type after the hurricane (cut, pruned, none), 3) causes of damage (natural vs anthropogenic), 4) state of recovery (re-foliating vs not re-foliating), 5) mortality (through presence and absence of trees). We will also use general linear models to evaluate site and species differences in crown damage and loss of crown cover (using pre-post hurricane values of %crown missing records). By looking at at the qualitative changes on residential trees we will be able to make recommendation on the types of trees that may be more resilient to hurricane events and those that may provide more stability to the provision of ecosystem services.