Coarse Wood Debris #6: Urban Forests
Urban forests have become more prevalent in the 21st century (3.5% of U.S. land area is urban). Their importance in the functioning of our forest ecosystems, and the services they provide, is significant. The urban forest can no longer be treated and managed as simply an amenity. We must begin to incorporate the bits and pieces of complex forest diversity, such as coarse woody debris, to the extent that human safety and technological knowledge allow.
Urban forestry is emerging as a critical discipline in the conservation of biological diversity. To date it has avoided the incorporation of coarse woody debris (CWD) – standing dead snags and down and dead woody material – into the urban environment. The concern for human safety and aversion of dead wood of many residents and landscape designers has led to its almost complete removal from urban parks and natural areas.
Our understanding of the roles that CWD play in functioning of forest ecosystems is geographically uneven. The northwest U.S. has been studied and contributed greatly to our understanding of the vital role of CWD in basic nutrient cycling, soil dynamics, surface hydrology and habitat. In contrast, the southeastern U.S., has produced little usable knowledge to guide management. The practice of urban forestry has added little to our understanding of the roles of CWD. It is through the investigation of urban wildlife habitat that we are just now beginning to capture some knowledge useful in the development of urban CWD conservation strategies.
The following urban conservation management goals are suggested for west central Florida:
- Integrate coarse woody debris into management of all natural areas and parks.
- Establish coarse woody debris standards using existing knowledge of Florida forests.
- Conduct analysis of existing coarse woody debris in natural areas and parks.
- Manage coarse woody debris through balance of ecological health, public safety and aesthetics.
The following management guidelines are intended to provide general guidance until local analysis can provide specific management targets.
Snag Conservation and Management
- Leave all snags and dead and down logs within the riparian zones adjacent to water bodies.
- Retain snags of various sizes in streams and rivers.
- Maintain a minimum of 6-9 snags per acre;
- Avoid disturbing snags during the nesting season (March – June).
- If snags must be felled during a conservation or management practice, leave it on site.
Coarse Woody Debris Conservation and Management
- If snags must be felled during a conservation or management practice, leave the log on site.
- Leave root system in place after felling trees.
- Avoid damaging existing dead and down material during conservation practices.
- When possible, leave at least 4 decaying logs per acre; at least 2 of these logs should be >12 “dbh and >6 ‘long.
- Avoid disturbance to wood debris already in the stream.
Enhancement of Coarse Woody Debris
- Where absent, create cavities or partial openings in large and hard standing snags.
- Plant native vegetation around logs to modify aesthetics, while enhancing habitat value.
For a brief review of what we do know about coarse woody debris in forest ecosystems please see the following: