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Abstract Invasive forest pests can affect the composition and physical structure of forest canopies that may facilitate invasion by non‐native plants. However, it remains unclear whether this process is generalizable across invasive plant species at broad spatial scales, and how other landscape characteristics may simultaneously facilitate non‐native plant invasion. Here, we assembled a dataset of over 3000 repeatedly measured forest plots and quantified the impact of emerald ash borer (EAB,Agrilus planipennis) residence time, land cover, and forest structure on the accumulation and coverage of invasive plants. We show plots in counties with longer EAB residences tended to accumulate more invasive plants than plots with shorter EAB residences. On average, nearly half of the plots with ash (Fraxinusspp.) in counties with EAB accumulated an additional 0.48 invasive plant species over the 5‐ to 6‐year resample interval compared to plots with ash in counties without EAB at the time of sampling. Increases in invasive species coverage were also evident in counties with EAB—although residence time did not have a strong effect, while forest gap fraction and vertical complexity were each negatively associated with increased coverage. This work has implications for understanding how invasive forest pests can facilitate the spread of non‐native plants.
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Changing litter composition following the dual invasion of Amur honeysuckle and the emerald ash borer alters fungal driven decomposition in Midwestern forests
Midwestern forests are currently impacted by two prominent invaders, the emerald ash borer (EAB; Agrilus planipennis) and Amur honeysuckle (AHS; Lonicera maackii). The loss of ash (Fraxinus spp.) trees due to EAB invasion can further facilitate AHS invasion, driving changes in the composition of forest leaf litter to reflect a greater portion of labile, more easily decomposed litter. To evaluate the extent to which these changes alter ecosystem function, we conducted litter bag and culture-based decomposition experiments using leaf litter from sugar maple (Acer saccharum), oak (Quercus spp.), black ash (Fraxinus nigra), green ash (Fraxinus pennsylvanica), spicebush (Lindera benzoin) and AHS. To further understand the mechanism driving differences in decay rates, we inoculated six species of decomposing fungi separately onto both single species and multispecies (half AHS and half native species) leaf litter and measured decomposition rate, fungal growth and enzymatic activity in laboratory-based cultures. AHS leaf litter decomposed faster, had increased fungal growth, and had higher activity for carbon degrading enzymes compared to native species leaf litter. Furthermore, multispecies mixtures followed the same patterns as AHS, suggesting that the addition of AHS to leaf litter to native litter will accelerate ecosystem functions related to carbon breakdown. Consequently, forests that experience the invasion of AHS and EAB induced loss of ash are likely to have faster rates of decomposition, potentially resulting in an influx of available nutrients.
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- Award ID(s):
- 2227331
- PAR ID:
- 10418327
- Date Published:
- Journal Name:
- Biological Invasions
- ISSN:
- 1387-3547
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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In northern hardwood forests, litter decomposition might be affected by nutrient availability, species composition, stand age, or access by decomposers. We investigated these factors at the Bartlett Experimental Forest in New Hampshire. Leaf litter of early and late successional species was collected from four stands that had full factorial nitrogen and phosphorus additions to the soil and were deployed in bags of two mesh sizes (63 µm and 2 mm) in two young and two mature stands. Litter bags were collected three times over the next 2 years, and mass loss was described as an exponential function of time represented by a thermal sum. Litter from young stands had higher initial N and P concentrations and decomposed more quickly than litter from mature stands (p = 0.005), regardless of where it was deployed. Litter decomposed more quickly in fine mesh bags that excluded mesofauna (p < 0.001), which might be explained by the greater rigidity of the large mesh material making poor contact with the soil. Neither nutrient addition (p = 0.94 for N, p = 0.26 for P) nor the age of the stand in which bags were deployed (p = 0.36) had a detectable effect on rates of litter decomposition.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s10530-023-03084-6
