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Highly disturbed forests are commonplace throughout the eastern United States and their residing composition and structure is reflective of their past land use. Management and restoration efforts are complicated by diverse and abundant nonnative invasive plants, including Ailanthus altissima. Verticillium nonalfalfae has been identified as a potential native mycoherbicide option for Ailanthus. To test the efficacy of Verticillium on Ailanthus we designed a study in highly disturbed forests of southern Ohio. At each of five sites, we monitored symptomology, mortality, and rate of spread of stem-inoculated Verticillium on Ailanthus in four inoculated plots and compared it to a control plot. We also monitored native plants for Verticillium symptomology and community responses to Ailanthus control. Our results suggest that Verticillium is an effective tool for controlling Ailanthus with no observed effect on native flora. Further, Verticillium naturally spreads through stands and mortality is slow enough that other resident nonnative invasive plants do not rapidly increase. Study Implications: Managing problematic invasive plants is a costly and time-consuming endeavor that quickly overwhelms resources. The identification and development of native biocontrols will help to suppress invasive plants, especially when considered in conjunction with other control options. Native biocontrols are pests or diseases that are typically nonlethal residents of the local environment but have significant and detrimental impact on nonnative plants. The native fungus Verticillium nonalfalfae along with several other Verticillium species has been identified to kill the invasive Ailanthus altissima. Verticillium can be applied to a subset of Ailanthus stems, and through time, will spread naturally with minimal impact to native species.

No abstract

Nitrogen (N) enrichment from excessive fertilization in managed forests affects biogeochemical cycles on multiple scales, but our knowledge on how N availability shifts multi-nutrient stoichiometries (including macronutrients: N, P, K, Ca, Mg and micronutrients: Mn, Fe, Zn) within and among organs (root, stem and leaf) remains limited. To understand the difference among organs in terms of multi-nutrient stoichiometric homeostasis responding to N fertilization, a six-level N supply experiment was conducted through a hydroponic system to examine stem growth, multi-nutrient concentrations and stoichiometric ratios in roots, stems and leaves of two-year-old Chinese hickory (Carya cathayensis) saplings. Results showed that N supply significantly enhanced leaf length, width, basal diameter and sapling height. Increasing rates of N also significantly altered multi-nutrient concentrations in roots, stems and leaves. Macronutrients generally responded more positively than micronutrients within organs. Among organs, leaves and stems generally responded more actively to N supply than roots. The stoichiometric ratios of nutrients within different organs changed significantly with N supply but their direction and degree of change varied by organ. Specifically, increased N supply reduced the ratios of both macronutrients and micronutrients to N in plant organs while increased N supply elevated the ratios of P to other nutrients. With N fertilization, ratios of micronutrients decreased in leaves and stems and increased in roots. In particular, leaf N and stem Mn stoichiometries responded strongly to N availability, indicating stimulated N uptake but decreased risk of Mn2+ accumulation to excessive N. Overall, Chinese hickory saplings responded positively to increasing N availability in terms of stem growth, but the multi-nutrient stoichiometric homeostasis were distinctively organ-dependent. These results are expected to enhance our understanding of N-induced changes in nutrient homeostasis of multiple nutrients at the organ level and may offer new insights into how plants adapt to increasing N fertilization.