Status of Lichens and Bryophytes on Middle Island: Declining Carolinian Habitat at Canada's Southernmost Point

Double-Crested Cormorant Disturbance: Restoration Potential for a Forested Urban Park

“…The high levels of nitrate are a result of strong nitrification of the ornithogenicallydeposited ammonium in the soil (Boutin et al, 2011;Doubt and McMullin, 2016;Hobara et al, 2005;Ishida, 1996). Additionally, the clearly evidenced high nitrification occurring here means that more hydrogen ions are being release from ammonium particles during the formation of nitrates, and the soils are becoming more acidic, which was shown earlier in the results.…”

“…DCC guano contains large amounts of nitrogen and phosphorus, resulting in higher rates of nitrification in the soil and therefore acidification (Boutin et al, 2011;Doubt and McMullin, 2016;Hobara et al, 2005;Ishida, 1996). Soil pH within cormorant colonies can be up to 10 times more acidic than adjacent reference sites (Ayers et al, 2015).…”

“…Nitrogen in the forms of nitrate and ammonium are readily taken up by plant roots, and lead to increased plant productivity when at moderate levels, which is why these forms of nitrogen are key components in nutrient fertilizers (Boutin et al, 2011;Rush et al, 2011;Wright et al, 2011). In most non-human dominated ecosystems, initial nitrogen fixation in soils occurs by nitrogen fixing bacteria that remove nitrogen gas from the atmosphere, however, nitrogen-rich soils also form in avian-colonized environments due to the birds' nitrogen-rich piscivorous diets and resulting deposition of ammonium-rich excrement (Boutin et al, 2011;Breuning-Madsen et al, 2010;Doubt and McMullin, 2016;Hobara et al, 2005;Ishida, 1996;Rush et al, 2011). In DCC colonies, ammonium concentrations are typically twice as high as non-DCC colonies (Hobara et al, 2005).…”

“…The distribution and species diversity of terrestrial plants can also become limited based on the threshold of phosphorous that is reached in soils (Ellis et al, 2006;Hobara et al, 2005). In soils within cormorant colonies, phosphorus has been measured at 80 times higher than control environments; if soil phosphorus accumulates above 330 ppm, reforestation studies have shown that soil remediation is required prior to any re-vegetation (Ayers et al, 2015;Breuning-Madsen et al, 2010;Doubt and McMullin, 2016).…”

“…The soil chemical factors that include nutrient content (phosphorus, nitrate, and ammonium), can all be altered with increased DCC guano deposition (Boutin et al, 2011;Breuning-Madsen et al, 2010;Doubt and McMullin, 2016;Hebert et al, 2005;Hobara et al, 2005;Ishida, 1996;Rush et al, 2011). Each of these three nutrients were given a weighting of 5% due to the influence they have on plant growth as macronutrients, while also maintaining the ability to become phytotoxic when present in high concentrations in the soil (Bobbink et al, 2016;Hobara et al, 2005;Natusch et al, 2017;Rush et al, 2011).…”