External nutrient inputs into terrestrial ecosystems of the Falkland Islands and the Maritime Antarctic region

Abstract

Antarctic terrestrial ecosystems are nutrientpoor and depend for their functioning in part on external nutrients. However, little is known about the relative importance of various sources. We measured external mineral nutrient sources (wind blown material, precipitation and guano) at three locations, the cold temperate oceanic Falkland Islands (51°76¢S), and the Maritime Antarctic Signy (60°71¢S) and Anchorage Islands (67°61¢S). These islands differ in the level of vegetation development through different environmental constraints and historical factors. Total mineral nitrogen input differed considerably between the islands. During the 3 month summer period it amounted to 18 mg N m -2 on the Falkland Islands and 6 and 102 mg N m -2 at Signy and Anchorage Islands, respectively. The high value for Anchorage was a result of guano deposition. By measuring stable isotopic composition (d 15 N) of the different nitrogen sources and the dominant plant species, we investigated the relative utilisation of each source by the vegetation at each island. We conclude that external mineral nitrogen inputs to Antarctic terrestrial ecosystems show great spatial variability, with the local presence of bird (or other vertebrate) colonies being particularly significant.

Influence of allochtonous nutrients delivered by colonial seabirds on soil collembolan communities on Spitsbergen

“…In comparison, over the three month austral summer period on Anchorage Island, maritime Antarctic, guano input contributed ca. 100 mg N m -2 , the vast majority of the external nitrogen input at this location (Bokhorst et al 2007a). Smith and Froneman (2008, Tables 7.1 and 7.2) provide a detailed description of vertebrate (and other marine-derived) nutrient inputs into the terrestrial ecosystems of sub-Antarctic Marion Island.…”

Guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in Spitsbergen

“…This large-scale transport of organic and inorganic matter from sea to land is crucial for many Arctic and Antarctic terrestrial ecosystems, which otherwise are characterized by chronic deficiency of certain nutrients such as nitrogen, phosphorus, potassium, and calcium (Ryan and Watkins 1989;Cocks et al 1998;Stempniewicz 2005;Bokhorst et al 2007;Smith and Froneman 2008).…”

“…Highest levels are seen close to the colony, with levels decreasing with distance. This decreasing gradient is often oriented toward the coast, where fertilization through sea spray may become an additional or superimposed factor modifying soil characteristics (Gilham 1956;Ryan and Watkins 1989;Wainright et al 1998;Bokhorst et al 2007). Deposited guano is decomposed by microorganisms, and the proportion of biogenic nutrients made available to plants is therefore a balance between decomposition and leaching or outwash rates (Heal and French 1974;Stempniewicz 2005).…”

Variability of polar scurvygrass Cochlearia groenlandica individual traits along a seabird influenced gradient across Spitsbergen tundra

“…They feed at sea and breed on land, often in very large colonies. During the summer reproductive season, seabirds deposit considerable amounts of guano, as well as dead birds, chicks, feathers, egg shells and food remnants such as fish and/or crustaceans (Polis et al 1997;Bokhorst et al 2007). Stempniewicz (1990Stempniewicz ( , 1992 reports that during one breeding season in Hornsund (south-west Spitsbergen), little auks (Alle alle) deliver *60 t of guano dry mass per km 2 of colony area and *25 t around the colony.…”