Local Alteration of Alpine Calcicolous Vegetation by Birds: Do the Birds Create Hummocks?

Between ice and ocean; soil development along an age chronosequence formed by the retreating Breiðamerkurjökull glacier, SE-Iceland

“…The highest SOC and N concentrations were attained in the 67 yr-old moraine (18.1% SOC, 1.1% N), perhaps reflecting more level topography, less input of eolian material or longer distance from the main road, which runs close by the terminal moraine, and therefore a quieter environment favored by the birds compared to the 82 and 112 yr-old moraines. Verbeek and Boasson (1984) studied bird hummocks in the Pyrenees, France, and similarly reported significantly more N compared to the soils of their surroundings. As did Tomassen et al (2005) for bird dropping sites in Irish bogs but those had significantly higher influxes of nutrients and showed more vegetation vigor than at reference sites without droppings.…”

Changes in vegetation and nutrient pools during riparian succession

“…1983), it is unlikely that these sources account for much of the nitrogen enrichment in the riparian system. Import of nitrogen by river water at 0.17 mg/L (USGS 1910(USGS -1981, precipitation (Likens et al t977, Schlesinger 1978), or birds and mammals (Verbeek and Boasson 1984) is too low to account for the majority of the increase. Import of nitrogen by river water at 0.17 mg/L (USGS 1910(USGS -1981, precipitation (Likens et al t977, Schlesinger 1978), or birds and mammals (Verbeek and Boasson 1984) is too low to account for the majority of the increase.…”