Trees Tree of Heaven (Ailanthus altissima)

Loss of structure and diversity may lead to:
- Loss of plant species
- Changes in/loss of native ecosystems
- Loss of canopy
- Changes in midcanopy openness
- Changes in views
- Carbon sequestration

- Presence of Ailanthus has been shown to reduce species diversity on average (Mediterranean sites) (Vila et al., 2006).;

- Ailanthus appears to suppress native vegetation by competition and allelopathic effects and the establishment of pure stands implies strong effects on community structure (Kowarik and Saumel 2007). Specific studies relevant to mid-Atlantic region include:
- Allelopathic compounds appear to reduce extension growth and biomass of seedlings of sugar maple (A. saccharum) and northern red oak (Q. rubra) but proximity to ailanthus enhanced growth of red maple seedlings (A. rubrum) possibly due to ailanthus-induced increase in soil nitrogen (Gomez-Aparicio and Canham, 2007)
- Ailanthus outcompetes black locust (R. psuedoacacia) (Call & Nilsen, 2005) User Link

- Pine barrens invaded by hardwood trees had "more vegetation layers, twice as much closed canopy, and higher tree stem densities in all but the largest (> 25 cm dia) size classes." (Beachy and Robinson, 2008)
- Upland pine forests (Georgia) had about half the plant species richness as those invaded by woody tree species (Klaus and Keys, 2007).

- Ailanthus would be expected to have lower long-term carbon sequestration compared to native trees, on a per-tree basis (but net community effects have not been estimated) (Nowak et al., 2002; Table 4, Pinus banksiana representative of category of medium-sized, short-lived, fast growth rate trees that includes Ailanthus).

Bird Diversity and Abundance

- Rather than being a direct cause of bird community changes, the presence of invasive woody trees in pine barrens or upland pine forests appears to be an indicator that natural disturbance dynamics have been disrupted. Specifically, fire suppression reduces the presence of early successional vegetation (pine-shrub), which shifts the bird community from birds preferring scrub-shrub vegetation to birds preferring closed canopy forests (Beachy and Robinson, 2008). Evidence from Georgia suggests that bird richness can decline with such changes and lost species are often species of conservation concern (Klaus and Keys, 2007).

- "...nests of the Willow Flycatcher (Empidonax traillii) were significantly more likely to be parasitized by Brown-headed Cowbirds (Molothrus ater) when placed in Russian olive than in native species, although nest success was not significantly different." (Stoleson and Finch 2001).

Insect Diversity

- Ecological theory suggests that invasive plants will be inadequate hosts for native insects that have co-evolved with specific plant hosts (Tallamy 2004). However, at least one insect, the ailanthus webworm, reproduces on Ailanthus (Tallamy & Shropshire 2009).

Historic Structures

- Ailanthus was shown to spread aggressively on both ancient and modern buildings in Mediterranean Italy and wind dispersal of seeds means trees are capable of reaching high spots that are difficult to treat (Celesti-Grapow & Blasi, 2004). The ability to colonize cracks and crevices, combined with rapid growth and vigorous roots can damage stone structures and accelerate weathering (Almeida et al., 1994).

- Anecdotal evidence is abundant that ailanthus roots, similar to many tree roots, break asphalt, enter sewers, and have other deleterious effects on built structures (Hu 1979, Danin 2000).

Historic Landscape

- Ailanthus would not have been present within the historic landscape of NPS parks (Hu 1979).

Direct Effects on People

- Pollen of ailanthus is a demonstrated allergen (Ballero et al., 2003)
- Contact with plant may cause dermatitis (Derrick and Darley, 1994) and myocarditis (Bisognano et al., 2005)