Although it lacks connectivity, isolated urban forest fragments can deliver similar amounts of ecosystem services as in protected areas

Abstract

Backgrounds: Urban forests can provide citizens with various types and quantities of ecosystem services. However, the contribution of isolated forest fragments to this process and its value are not well understood. Therefore, our main goal was to analyze the patterns of ecosystem service delivery by three forest fragments along an urban-to-rural gradient. Carbon storage was estimated using three different models (general and local), with input variables such as diameter at breast height (DBH), total height, and wood density. Rainfall interception was assessed using water collectors placed inside the forest fragment, at the border, and outside, throughout the four seasons. Data were collected from three forest fragments of different types (urban, periurban, and rural), each covering an area of 1.0 hectare.
Results: Isolated forest fragments did not significantly differ (p>0.01) in terms of carbon stocks compared to a protected area. The urban fragment had a carbon stock of 33.70 mg.ha-1, while the rural fragment had a carbon stock of 37.19 mg.ha-1. Regarding rainfall interception, there were no significant differences (p>0.01) among the forest fragments. The highest average rainfall interception
percentage (58.65%) was observed during the summer. The capacity for rainfall interception changed from the border (lower) to the center of the fragment (higher) in a similar manner for both isolated and connected forest fragments.
Conclusion: Isolated Forest fragments can provide ecosystem services (carbon storage and rainfall interception) in the same way as connected forest fragments in the periurban and rural places, like in protected areas. It highlights the importance of promoting the protection of forests fragments in cities.