The Senior Seminar in Ecology last semester at Bryn Mawr College made use of Crow’s Nest Preserve for fieldwork and as a case study. The focus of the class was the value of ecosystem services—those functions that support human life and well-being but are not usually commodities bought and sold: clean air and water, erosion control, climate regulation, and pollination.
The work brought up the importance of collecting raw data from the preserve: it would be difficult to know too much about a place!
Daniela Miteva wrote a study entitled How to Conserve Native Plants More Effectively that included an effort to estimate the monetary value of the native plants at the preserve as well as predictions—using flower and bee abundance data—of the impact of habitat disturbance and fragmentation on the native plant communities in Crow’s Nest’s meadows.
The benefit of the native plant habitat includes intrinsic values of its ability to support wildlife, manifest biodiversity, and contribute to the relative stability of an ecosystem. The report also estimated the value to Natural Lands Trust of the native habitat as a place to host environmental education and research projects, and to promote hiking and walking, bird and wildlife watching and nature photography. The study also estimated the value visitors place on the preserve (how much are they willing to pay to travel to get here) and the increase in market value of homes located near protected open space.
The study also accounts for management costs to maintain natural areas: that minimum intervention to keep a meadow open and free of invasive plants. It doesn’t, however, make an attempt to quantify future benefits (with inflation) of open space protected today.
The part of the study that most affects our land management is the flower and bee abundance surveys. One of the conclusions is that the factor that most affected native bee abundance is the presence of forested sites within 2,300 meters; these provide the bees’ nesting sites.
Fortunately Crow’s Nest’s meadows are embedded in a matrix of forested areas; the study also suggests that loss of surrounding continuous forest habitat could increase management costs here long-term.
The study also concluded that bee species diversity is most affected by frequency of mowing. Most of our meadows are mowed once per year to control invasives and keep them open. But sites that had the greatest number of different bee species were sites that had not been mowed for 2 – 3 years, so it may make sense for us to have more "reserves" of less-frequently-mowed areas, something I have begun to experiment with this winter.