| What is the Plant Stewardship Index? |
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A new analytical tool for land conservationists, land managers and property owners
What is the principle of stewardship? It is grounded in the notion of caring for the earth for future generations and recognizing that we are not truly masters of the land we own but merely stewards.
Bowman’s Hill Wildflower Preserve’s mission is to lead people to a greater appreciation of native plants, to an understanding of their importance to all life and to a commitment to a healthy and diverse natural world. As such, the Preserve focuses on the stewardship of our landscapes, both natural and cultivated, from the perspective of the plants growing there. What do plants tell us about how we are caring for, restoring or degrading our landscapes? What can they tell us in aggregate, not just as a single species of endangered or threatened plant, about what is changing in the landscape?
We hope that by using the Plant Stewardship Index (PSI), which is a tool for conducting an ecological assessment of your properties, you will begin to look differently at those sites and develop a delight and an intimacy with its plants and habitats.
The Index is designed to assist in answering two questions: What is the naturalness of any site? How have land management practices (or their absence) affected that naturalness over time?
The Index is based on the observation that plants may act as “generalists,” which are not particular about where they grow and might grow very well on roadside ditches or in dooryards, as opposed to “conservative” species, which may grow only in specialized habitats, such as serpentine barrens or the pine barrens of New Jersey. The PSI methodology was created in the 1970’s in the Chicago region by Floyd Swink and Dr. Gerould Wilhelm and has been developed in many other states as the Floristic Quality Assessment Index (FQAI).
Now, for all of New Jersey and the Piedmont region of Pennsylvania, over 2000 plants have been catalogued and assigned a number from zero to ten by local experts and botanists. Zero represents the most generalist species, tolerant of disturbance and includes invasive or introduced nonnative species such as multiflora rose. Ten represents the most conservative species and includes many rare and endangered state-listed native plants that require special habitats and do not regrow after disturbance.
This database of plants and associated numerical values are available to users through Bowman’s Hill Wildflower Preserve’s PSI Calculator located on this website. Once a user inputs a list of plants found on a particular site, the Calculator automatically computes: 1. the Mean C, which is the average of all the assigned numbers of plants found on a site, and 2. the Index number, which is the Mean C multiplied by the square root of the total number of plant species.
For more information about the Plant Stewardship Index, sign up for the “Introduction to the Plant Stewardship Index” or request a customized group presentation. To do either, please contact the PSI Coordinator at (215) 862-2924 or email psi@bhwp.org.
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