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Vegetation Structure
and Diversity
and Diversity
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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
- Loss of plant species
- Changes in/loss of native ecosystems
- Loss of canopy
- Changes in midcanopy openness
- Changes in views
- Carbon sequestration
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- Ailanthus appears to suppress native vegetation by competition and allelopathic effects and the establishment of pure stands implies strong effects on community structure (Kawarik 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)_v090_post.html_files/ilink.png)
- 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)
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- 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)._v090_post.html_files/ilink.png)
- Upland pine forests (Georgia) had about half the plant species richness as those invaded by woody tree species (Klaus and Keys, 2007).
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- 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). _v090_post.html_files/ilink.png)
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Bird Diversity and Abundance
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- 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). _v090_post.html_files/ilink.png)
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Historic Structures
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- 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).
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