Desi Powell, a field botanist and restoration specialist with the Natural Resources Group (NRG), gave an in-depth overview of the multi-year work and progress of the study site at Bloodroot Valley in the Greenbelt at our fall semi-annual meeting. You may have become familiar with the site, as it is often mentioned in descriptions of our walks and was also covered in a talk Don Recklies gave at our winter 2024 semi-annual meeting.
Ms. Powell explained that serpentinite is a rare metamorphic green rock that is rich in iron and magnesium. Serpentine barrens habitat is an extremely rare ecological community in North America. It is classified both globally and critically imperiled by NatureServe and the New York Natural Heritage Program, two organizations which serve to collect data and provide information to organizations interested in conservation activities.
In all of New York State, this geographically limited habitat only occurs in Staten Island.
Serpentine barrens habitat can be found on Staten Island in the following areas, together with an assessment of their stage of succession, where the area transitions from meadow to shrubby habitat:
Serpentinite exposed in the Todt Hill region
Bloodroot Valley (later succession)
(early succession)
During the process of succession, shade from new trees will suppress the growth of shade-intolerant grasses and forbs while favoring the growth of more woody species. As new woody species decompose, a layer of organic material will develop on top of the serpentine soil, inhibiting the growth of unique species that thrive in the nutrient-poor substrate. According to the New York Natural Heritage Program, serpentine barrens are dominated by graminoid (grass-like) vegetation including yellow Indiangrass (Sorghastrum nutans) and little bluestem (Schizachyrium scoparium). Some trees, such as gray birch (Betula populifolia) and trembling aspen (Populus tremuloides) may also occur here.
The NRG outlined a 5-year management plan, with the goal being to increase the spatial extent of the globally imperiled serpentine grassland and increase available habitat for state-endangered plants, with a target of an increase of those plants to 85% by 2026. The site was prepared by tree removal, soil scraping, soil testing, and building deer exclosures.
Shockingly, though not unexpectedly, in the first year of monitoring the invasive stiltgrass roared in, requiring dedicated stiltgrass removal. Once stiltgrass removal became an ongoing part of the program, serpentine plants began to thrive. Seeds embedded in the soil took hold and began to fill in the space previously occupied by stiltgrass.
In the second study year, native species coverage increased from 40% to 89%. Stiltgrass cover decreased from 32% in 2022 to 19% in 2024, demonstrating the effectiveness of targeted removals of this species.
Rare green milkweed was replanted in 2024. The latest check shows a higher species diversity in the restoration area.
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