Warren G. Gold

The effects of the spatial pattern of defoliation on regrowth of a tussock grass. III. Photosynthesis, canopy structure and light interception.

SummaryThe spatial pattern of foliage removal from a tussock grass can influence regrowth through effects on daily carbon gain (CERd). This field study examined the extent to which tussock photosynthetic responses to different defoliation patterns were associated with changes in whole-canopy attributes (e.g., foliage age structure, canopy light microclimate). During the spring growing season, 60% of the green foliage area was removed from individual Agropyron desertorum tussocks with scissors in different spatial patterns. These patterns represented extremes of defoliation patterns that might be inflicted by natural herbivores. Tussock photosynthesis (per unit foliage area) at high light (2000 μmol photons m−2 s−1 between 400 and 700 nm; P2000) increased following clipping with all defoliation patterns. The increases in P2000 were greater when leaves were removed from low in the tussock (older leaves) than if leaves high in the canopy (younger leaves) were removed. These relative changes of P2000 among clipping patterns paralleled the responses of CERd and regrowth from an earlier study. Furthermore, the changes in P2000 corresponded with increases in the proportion of foliage within the tussocks that was directly illuminated at midday. The greater photosynthesis of tussocks after lower-leaf removal was directly related to a higher proportion of younger foliage and a smaller fraction of foliage shaded within the tussock. In a dense canopy, such as these grass tussocks, the influence of defoliation on whole-canopy attributes may be of primary importance to whole-plant photosynthetic responses.

An Analysis of Factors Driving Success in Ecological Restoration Projects by a University-Community Partnership

Every year since 2000, five to ten ecological restoration projects have been implemented on public and private lands in the Puget Sound region of Washington State by the University of Washington Restoration Ecology Network (UW-REN) capstone program. Students, faculty, and community partners have collaborated to implement these restoration projects, improve ecological function at the sites, and build site stewardship. Approximately twenty-nine, 2,000 m2 projects from the first ten years of the capstone projects were retrospectively evaluated using a variety of response variables that could reflect ecological “success”, including native species cover, richness, and diversity in the restoration plant community. We hypothesized that certain elements of restoration design and implementation, such as selected techniques for invasive vegetation management and the resulting degree of site stewardship, would strongly contribute to the success of these restoration projects. Stewardship was found to contribute to native species cover, richness, and diversity. Native plant species richness and diversity responded to initial invasive control techniques; stem-only removal did not work as well as root system removal for native species richness or diversity. The use of wood chip and cardboard-with-wood chip sheet mulches had less clear effects on species richness. An interaction between mulch and control technique was found to contribute to species diversity evenness. Overall, this study of restoration projects led by university students in cooperation with community partners highlights the importance of specific elements of restoration design and implementation and due diligence in the form of long-term stewardship.

Realizing the Educational Potential of Ecological Restoration

As individuals it is easy to feel overwhelmed by the continuing media coverage of environmental problems, such as climate change, species loss, and overpopulation. As a result it is often profoundly difficult to imagine ways to contribute meaningfully to environmental solutions. Ecological restoration, however, provides hands-on opportunities for everyone, from the general populace to experts, to come together, forging solutions, and making a difference. Ecological restoration empowers people.