Habitat Modeling of Goldenseal (Hydrastis Canadensis L.) and Ramps (Allium Tricoccum Ait.) PDF Download

Author: Ezra Houston
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Languages : en
Pages : 0

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Book Description
The forest flora of the eastern U.S. includes a number of species which have long held cultural and economic importance. Two well-known species, goldenseal (Hydrastis canadensis) and ramps (Allium tricoccum) are both regarded as non-timber forest products (NTFPs) and harvested from the wild in Pennsylvania (PA) for commercial sale. Conservation concerns surround goldenseal because it is harvested from the wild for medicinal markets and has experienced habitat loss and change due to land conversion and the influence of non-native vegetation. Additionally, the species is uncommon in Pennsylvania--a state within the northeastern edge of the species range. Ramps are more common in Pennsylvania but trending culinary interests surrounding foraged seasonal and farm-to-table foods has driven growth in commercial harvesting from wild populations in recent years. A better understanding of habitat predilections of these plants could help guide in situ and proactive conservation efforts such as forest farming and assisted migration. In this study, GIS-based Maximum entropy (Maxent) modeling and field data collected from wild goldenseal and ramp populations were combined to determine abiotic habitat characteristics and identify site indicators for both species in Pennsylvania. Maxent modeling suggested that average winter temperatures below -5.0oC may exclude goldenseal northern PA and at high elevations elsewhere in the state, highlighting the importance of warmer micro-sites in this part of the species range. Base-rich bedrock types including limestone and diabase were identified as most suitable in models and confirmed by soil test results showing high calcium and pH levels in field plots. The influence of bedrock is complicated by overlapping land use legacy, particularly in the Piedmont and Ridge-and-Valley physiographic provinces. Both modeling and field data identified lower slope positions with wet to mesic soil as most associated with goldenseal. Community analysis identified 159 woody and herbaceous associates, including many indicators of the following supportive rich mesic forest types: "Tuliptree-Beech-Maple," "Red Oak-Mixed hardwood," and "Central Appalachian Rich Cove". Eighteen non-native exotic species were encountered, including 13 so called "invasive" taxa, of which at least one was present in 83% of plots. These results suggest that goldenseal habitat is widespread in the state (and region) and absences may be due to abiotic influences. While a projected warming climate may increase suitable habitat for goldenseal in PA, negative impacts to extant goldenseal populations might be anticipated resulting from competition and habitat modification associated with non-native taxa. Maxent modeling of ramps highlighted lower slope positions, high moisture index, low surface roughness, deep soil, base-rich bedrock, and high silt content as the most important characteristics of suitable habitat. Moist floodplains and north and east facing lower slopes were the most frequent conditions encountered in the field, confirming model results. Soil macronutrients varied substantially but were usually high in calcium and slightly acidic. Forest types included "Central Appalachian Rich Cove," "Sugar maple-Mixed Hardwood Floodplain," "Tuliptree-Beech-Maple," and "Sugar maple-Basswood". A total of 252 species were documented and sites shared 50% of floristic associates on average. Sugar maple (Acer saccharum) was the most important overstory species and was a significant indicator on north facing slopes. Bitternut hickory (Carya cordiformis) ranked fifth in importance but was an indicator on floodplains. Several regional differences in forest type stood out, as represented by indicator species: sugar maple and black cherry (Prunus serotina) were top indicators in northern PA, while tulip-poplar (Liriodendron tulipifera) and American beech (Fagus grandifolia) were significant in the south. Non-native multiflora rose (Rosa multiflora), and Japanese barberry (Berberis thunbergii) were found to be more common than native shrubs and provided little indicator value to this stratum due to their broad habitat requirements. Blue cohosh (Caulophyllum thalictroides), and yellow trout lily (Erythronium americanum) were the most common understory associates, further pointing to ramps preference for moist, base rich sites.