Biomass Production and Wildlife

The topic, wildlife considerations in siting, establishment, management, and harvest of grass stands for biomass energy production was  included in several plant and soil science workshops held recently.  Interest in cellulosic energy production continues to grow as energy prices rise. Switchgrass and other native warm season grasses have good potential for this application as they reduce erosion, improve soil quality and percolation, and have lower input requirements than other plants used for energy production.  While there is a perception that low diversity grass stands are little used by wildlife, research results show that structure is more important than species composition. About one-third of the grassland nesting bird species (e.g., sedge wren, Henslow’s sparrow, bobolink, common yellowthroat, dickcissel, American goldfinch, and song sparrow) prefer tall, dense vegetation. Grasslands established and maintained for the production of biomass feedstock, when managed with consideration for avian wildlife and with awareness of the surrounding habitat matrix, have the potential to provide quality wildlife habitat.

Grasslands are disturbance-adapted systems.  In the absence of disturbances the attractiveness and productivity of fields for grassland-dependent wildlife declines. Late winter harvest of grasses for cellulosic energy is generally good timing for wildlife.

When planning with cooperators for biomass production the following points may help address wildlife needs:
• Harvest as late in the winter as possible, but before spring green-up.
• Leave about 20-33 percent of the acres unharvested on a rotational basis. This will help retain plant vigor and provide wildlife cover during storm events.
• Larger blocks are best (>125 acres) so maximize block size and area: perimeter ratios to reduce linear edges (i.e., circles and squares are better than rectangles or strips).
• Where large blocks (~ >50 acres) are not possible, establish several clustered patches at least 15-20 acres near each other.
• Minimize fragmentation – establish plots adjacent to other grasslands including pasture, hay, and rangeland.
• Locate plantings >100 yards from forested areas and activity centers (farmsteads, homes, etc.).  Immediately adjacent land uses should be structurally open.

Additional guidelines for managing forest and grassland bird habitat can be found in Herkert et al. 1993.
Your contact is NRCS wildlife biologist Steve Brady at 817-509-3285.