Invasive Species Across Kingdoms: Mapping, Monitoring, and Quantifying Impacts on Forest Biogeochemical Cycles

Author

• Kelsey Parker, CUNY Graduate CenterFollow

Date of Degree

9-2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Earth & Environmental Sciences

Advisor

Andrew Reinmann

Committee Members

Peter Groffman

Theodore Muth

Richard Hallet

Subject Categories

Biodiversity | Forest Biology | Forest Management | Other Ecology and Evolutionary Biology | Terrestrial and Aquatic Ecology

Keywords

Invasive Species, Urban Forestry, Soil Biogeochemistry, Earthworms, Practitioner-Researcher Collaboration

Abstract

Forests provide a wide range of important ecosystem services like carbon sequestration and nutrient cycling. Invasive species threaten forests’ ability to carry out these ecosystem services. Forest managers and ecologists are both tasked with mapping, monitoring, and mitigating the effects of invasive species, which includes advancing our understanding of the biology, invasion dynamics, and ecosystem impacts of novel invasive species. Through my dissertation research I sought to advance our knowledge and monitoring capabilities of invasive species in forests through application and practice. I specifically aimed to provide a framework to facilitate collaborations between practitioners and researchers using remote sensing and quantify earthworm phenology, community structure in relation to forest type, and impacts on soil biogeochemistry.

One area where researcher-practitioner collaboration could be particularly beneficial is in mapping the distribution and impacts of invasive species. While practitioners utilize field surveys to record species presence and impacts, researchers are developing remote sensing products to detect vegetation changes caused by invasive species. Despite working towards similar goals, and remote sensing products requiring field data for validation and training, collaboration is infrequent. In chapter 2, I led a collaborative study spanning researchers and practitioners to discuss lessons learned from experiences collaborating to advance detection, monitoring, and management of the invasive pest Hemlock Woolly Adelgid (Adelges tsugae; HWA) and summarize the literature to discuss bridging the gap between researchers and practitioners. In this chapter, I highlight the synergies of researcher-practitioner collaborations and suggest field variables, community science apps, and provide a framework for facilitating research-practitioner collaborations.

Another group of invasive species of concern to foresters and ecologists in the Northeastern U.S. is earthworms. Currently in the northeastern U.S. there are two dominant families of invasive earthworms: Lumbricidae from Europe and Megascolecidae from Asia, referred to as ‘Lumbricid’ and ‘Amynthas’ hereafter. As ecosystem engineers, invasive earthworms can alter soil biogeochemistry and biodiversity, posing a significant threat to forest function. In chapters 3 and 4, I assess relationships among invasive earthworms, invasive tree species, and soil biogeochemistry. From 2021 through 2023, I quantified earthworm communities in three forest types: Native oak (Quercus spp.), non-native black locust (Robinia pseudoacacia), and invasive Norway maple (Acer platanoides) in New York City, New York. In 2023, I also assessed soil biogeochemistry throughout the growing season with a paired mesocosm experiment. I found stratification of earthworm communities by forest types with highest Amynthas abundances in black locust forest and Lumbricid only consistently sampled in Norway maple forest, suggesting earthworm groups may not co-exist well in the same soil niche. I also observed declines from 2021 to 2022 from which only Lumbricid rebounded in 2023 and quantified phenological differences between groups with Amynthas peaking in August and Lumbricid June, highlighting the importance of sample timing in future studies. In the field, I found positive correlations between Amynthas biomass and both seasonal variation and surface enrichment in total inorganic nitrogen, peaking in August and October as Amynthas biomass peaks and worms senesce. Mesocosm results suggested that Amynthas shaped microbial communities after invasion. Despite shaping microbial communities, my research results suggest Amynthas continue to increase inorganic N pools after prolonged invasion, but high litter C:N likely increases organic N more than low litter C:N.

In my dissertation work, I highlighted synergies between researchers and practitioners utilizing remote sensing, suggested standardized sample timing twice per season when assessing invasive earthworms to allow for better comparisons between studies, identified black locusts as potential target species when assessing Amynthas invasions, and found that earthworm legacy and litter chemistry alter the biogeochemical impacts of invasive Amynthas earthworms. Invasive species will continue to threaten forest health for the foreseeable future; thus, it is essential to advance our knowledge of how they have and will continue to shape our forests.

Recommended Citation

Parker, Kelsey, "Invasive Species Across Kingdoms: Mapping, Monitoring, and Quantifying Impacts on Forest Biogeochemical Cycles" (2026). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/6869