SePPCon 2024: Granite Outcrop Species Conservation
SePPCon 2024: Granite Outcrop Species Conservation
Restoration, Creation, and Enhancement of Rare Plant Habitats and Populations: The Case of Three Federally-listed, Highly-specialized Inhabitants of Granite Rock Outcrop Pools
J. Mincy Moffett, Jr.*, U.S. Fish & Wildlife Service – Georgia Ecological Services
Granite rock outcrops are exposed areas of granitoid rock found across the Piedmont ecoregion of the Southeastern United States, epi-centered in Georgia. Sizes range from large prominent monadnocks to small roadside flatrocks. They are considered among the crown jewels of Georgia’s natural communities and support a variety of endemic or nearly endemic plant species. Most remarkable is a suite of three federally-protected species inhabiting small pool depressions: Pool Sprite (Gratiola amphiantha); Black-spored Quillwort (Isoetes melanospora); and Mat-forming Quillwort (Isoetes tegetiformans). Pools are ephemeral in nature and fill with rainwater and seepage/sheet flow between December and May. A natural limiting factor of the habitat is the availability of ‘quality’ pools; those capable of holding water for a sufficient period and having adequate soil development with little graminoid/herbaceous competition. In 1988, plant conservationists in Georgia began experimenting with pool creation, enhancement, and repair. Techniques and approaches were refined through the 2010s and included deepening pools with concrete saws and jack hammers, repairing lips with concrete, excavating and/or adding soil to achieve appropriate depth, removing competing vegetation, adding graminoid buffers to slow runoff and reduce scour, and/or inoculating pools with target conservation species. Recent surveys determined that 22 created/established pools are still supporting quillworts, ranging from eight to 36 years post-creation. Natural pools of quillworts have also been enhanced through graminoid management. Serendipitously, 11 of the created/enhanced quillwort pools now contain pool sprite recruited from nearby pools. Plans are underway to expand this program to other protected granite rock outcrops in Georgia.
Occupancy patterns of the federally threatened, granite outcrop endemic, Gratiola amphiantha
Anna Wyngaarden*, Megan DeMarche, University of Georgia
Video start time: 10:20
Estimates of a species’ area of occupancy is critical for understanding population trends and prioritizing conservation efforts. For the federally threatened Gratiola amphiantha (syn: Amphianthus pusillus), or pool sprite, which is endemic to pool habitats on granite outcrops, the number of pools occupied with the species is key for assessing the species’ recovery and ranking sites. However, pool occupancy varies within a single season, complicating annual estimates of the number of occupied pools. Here we ask, when surveyed multiple times in a season, how often is the species detected present in a pool? Based on three repeat surveys in a single season, we quantified how frequently pool sprite was detected present in individual pools at two granite outcrops. We found that when the species was detected present in a pool in the season, it was detected present at all three surveys only 77.7% of the time, thus 22.3% of the time it was detected present in only one or two surveys. This discrepancy in detectability within a season can lead to incomplete counts of the total number of pools occupied with pool-sprite. We conclude that repeated surveys of the species within a season can enhance our estimates of its total area of occupancy and should be incorporated into management practices.
Testing the effects of a naturally patchy habitat on reproduction in Helianthus porteri, a Piedmont granite outcrop endemic
Riley D. Thoen*, Megan L. DeMarche, University of Georgia, Department of Plant Biology
Video start time:19:06
Successful reproduction is necessary to ensure the persistence of plant populations into future generations. This is especially true for short-lived species, as reproduction contributes disproportionately to their population growth. Habitat patchiness is hypothesized to affect plant reproduction by physically separating individuals, leading to mate limitation, and by increasing habitat variability, which may affect flowering phenology. We performed a pollen supplementation experiment on Helianthus porteri, an annual Piedmont granite outcrop endemic, to identify the factors that most strongly affect reproduction in the soil patches of granite outcrops. We hypothesize that 1) plants in more isolated patches are more mate limited, and 2) environmental variation among patches increases variability in flowering phenology, reducing flowering synchrony and reproductive success. Characterizing whether these factors drive reproduction in patchy environments allows conservation practitioners to alleviate negative consequences of patchiness for sexual reproduction – for example, through assisted colonization of unoccupied patches. This is especially true for the insular ecosystems of the southeastern United States (e.g., granitic outcrops) and as historically contiguous habitats are broken into patches by anthropogenic habitat fragmentation.