Climate change is resulting in a number of changes to precipitation and weather patterns. Between 1901 and 2014, total annual precipitation increased by 7% in the northeastern U.S. (Huang et al. 2017). Because of rising temperatures, a greater proportion of precipitation is arriving as rain rather than snow; heavy rainfall events, which have become substantially more frequent and severe across the region over the last century, are expected to continue increasing (Huang et al. 2017, Easterling & Kunkel et al. 2017, Spierre and Wake 2010). The Northeast in particular has seen a greater increase in heavy precipitation events than any other part of the country, with the amount of precipitation coming in extreme events increasing by 41% between 1901 and 2014 (Huang et al. 2017). The fall season has exhibited the largest increase in precipitation, followed by spring (Easterling et al. 2017).

Extreme precipitation and intense storm events can negatively impact forest ecosystems in a variety of ways, and the effects will depend on site-specific characteristics, such as the current health of the forest, its topography, and location within the landscape. Heavy rain events can lead to intense erosion—resulting in soil loss and sedimentation in nearby streams—as well as flooding, which can damage trees by breaking stems and limbs (Groffman et al. 2014, Furniss et al. 2010). The increased occurrence of these heavy rain events in fall and spring, when there is little to no vegetation to intercept excess precipitation, can lead to greater erosion in forests and riparian areas.

A variety of storm types occur in the region, including thunderstorms, ice storms, tropical cyclones and hurricanes, and nor’easters (Kunkel et al. 2013). Potential impacts from storms include tree damage and mortality, altered forest structure, and altered tree species composition and diversity (Xi and Peet 2011, Holzmueller et al. 2012). Winter ice storms can be particularly damaging, and are expected to become more severe (Klima & Morgan 2015, Campbell et al. 2020). The accumulation of ice on trees can lead to extensive damage to tree limbs, especially in oaks and other species with wide crowns and secondary trunks (Turcotte et al. 2012). High wind events in oak dominated forests within the midwest and central Appalachians have accelerated successional transition, where high levels of damage and mortality in the overstory oak allow for the abundance of shade-tolerant species in the understory, such as red maple and American beech, to dominate (Holzmueller et al. 2012). Fire exclusion from oak dominated forests due to suppression efforts has also contributed to this successional transition.

Forests stressed by other disturbances are likely to be more vulnerable to impacts from extreme precipitation and weather events. For instance, where vegetative cover is reduced by disturbance events such as pest infestations or wildfire, the forest is more susceptible to erosion during extreme precipitation. Likewise, forests impacted by extreme precipitation and weather are likely to be more vulnerable to other disturbances; physical damage to trees can leave them more susceptible to negative impacts from forest pests and diseases (Janowiak et al. 2018).

These conditions also make it more challenging to conduct forestry operations while minimizing impacts on soil and water resources. Decreased climate stability could lead to less predictable seasonal planning of harvesting activities, which could in turn increase logistical costs and enforcement considerations ( Giesler et al. 2016, Janowiak et al. 2018). These events can compromise stream crossings, which hinders operations and can negatively impact water quality and aquatic organisms (Gillespie et al. 2014, Boston 2016).