Overview
An “invasive” plant is generally characterized as any nonnative, fast-growing, and aggressive species that out-competes native vegetation, causing ecological (or economic) harm. In the case of bog turtles, invasive plants have been demonstrated to block sunlight critical for thermoregulation and egg incubation, displace native flora that provide nesting habitat and foraging resources for preferred prey, alter the architecture and penetrability of the substrate, and reduce water levels from high levels of evapotranspiration. Invasive plants occur in nearly all bog turtle habitats but vary in degree of abundance. Bog turtles tolerate low to moderate densities of invasive flora often very well and will readily use some invasive plants for cover and as basking substrates. At sites where invasive flora is dominant, adult bog turtles may survive, but very little reproduction occurs—rendering populations functionally extinct.
Invasive plants common to bog turtle habitats in the Northeast include purple loosestrife Lythrum salicaria (Eurasia), Japanese stiltgrass Microstegium vimineum (Asia), small carpetgrass Arthraxon hispidus (Asia, Africa), mile-a-minute Persicaria perfoliata (Asia), common reed Phragmites australis (North America x Europe), multiflora rose Rosa multiflora (Asia), glossy buckthorn Frangula alnus (Africa, Eurasia), common buckthorn Rhamnus cathartica (Eurasia), and European alder Alnus glutinosa (Africa, Eurasia). There are several native wetland plants that can be as ecologically deleterious as nonnatives, including reed canary grass Phalaris arundinacea, cattail Typha, and lake sedge Carex lacustris. These plants (as with many invasive wetland plants) exhibit accelerated growth in response to nutrient enrichment, soil disturbance, and altered hydrology and can rapidly transform a bog turtle habitat into a dense mat of thatch.
Managing invasive plants in bog turtle habitats can be very challenging and requires a long-term commitment to keep levels of encroachment at tolerable thresholds. Most methods of control involve the application of herbicides, but because of the occurrence of many rare plants in bog turtle habitats, alternatives are often used, including biocontrol, prescribed grazing, and manual and/or mechanical removal. Because many floristic invasions of bog turtle habitats are a consequence of poor nutrient management and hydrological impairment, the most effective invasive plant control efforts are those that comprehensively address the target vegetation and incompatible land use practices. - Jason Tesauro, February 2021
