Forest Analysis Techniques: Comparing fixed- and variable-width riparian buffers

Introduction

Does better protecting streams mean harvesting less timber?

Forest managers often delineate buffers around water features, such as streams, to protect aquatic organisms and to preserve travel corridors for land-based animals. The riparian buffers commonly established in managed forests are of fixed widths between 30 and 50 m. Some argue, however, that better protection could be achieved with variable-width buffers. With this approach, smaller buffers could adequately protect flat areas, while buffers of greater width could protect the steeply sloped areas that require them.

The question is, Will buffering streams as a function of slope exclude more timber from harvest compared to the status quo? How would you make the comparison, to find out the trade-off between harvesting enough timber in the woodlot and establishing better protection of streams?

Location

A small 1,400 ha woodlot in the Acadian-New England forest region of North America

Time to complete the lab

3 hours

Prerequisites

Students should have a basic working knowledge of ArcGIS and GIS data, including use of a geodatabase. Familiarity with forest inventory data is also helpful, but not essential.

Data used in this lab

Feature classes and rasters for a forest woodlot (personal geodatabase)

Geographic coordinate system : NAD 1983 CSRS New Brunswick Stereographic

Datum: NAD83

Projection: New Brunswick Double Stereographic Grid (unless otherwise stated)