Antarctica greening due to climate change

[OKIsItJustMe]

https://www.exeter.ac.uk/news/featurednews/title_583908_en.html

[font face=Serif][font size=5]Antarctica ‘greening’ due to climate change[/font]

[font size=4]Plant life on Antarctica is growing rapidly due to climate change, scientists have found.[/font]

[font size=3]Few plants live on the continent, but scientists studying moss have found a sharp increase in biological activity in the last 50 years.

A team including scientists from the University of Exeter used moss bank cores – which are well preserved in Antarctica’s cold conditions – from an area spanning about 400 miles.

They tested five cores from three sites and found major biological changes had occurred over the past 50 years right across the Antarctic Peninsula.

“Temperature increases over roughly the past half century on the Antarctic Peninsula have had a dramatic effect on moss banks growing in the region,” said Dr Matt Amesbury, of the University of Exeter.

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http://dx.doi.org/10.1016/j.cub.2017.04.034

[GreydeeThos]

1. How much of this is due to contamination from people traveling there?

With the ability to fly to Antarctica from warmer climates, how much non-native biological material is being brought in by people? I have read that there are tourist visits where they have to have the visitors clean their shoes before going ashore.

[OKIsItJustMe]

2. Very little

http://dx.doi.org/10.1016/j.cub.2017.04.034

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Moss banks are distributed sporadically along the western Antarctic Peninsula (AP) [21] from Alexander Island (69.4°S) [14] to Elephant Island (61.1°S) (Figure 1; Table S1) and northeast to Signy Island, South Orkney Islands (60.7°S) [15]. Mosses accumulate in small annual increments from new growth at the surface, and old moss growth is exceptionally well preserved [25] by year-round cold temperatures and relatively rapid incorporation into permafrost, leading to deep accumulations of moss over thousands of years. AP moss banks are often dominated by a single species (Polytrichum strictum or Chorisodontium aciphyllum) and are easily dated by radiocarbon due to their highly organic nature [13]. Relatively stable down-core bulk density and peat humification profiles (Figure S4; see also [14]) show that compaction or decomposition effects are not significant. Mass accumulation (r2 = 0.82, p = 0.013) and growth rates (r2 = 0.75, p = 0.026) are significantly positively related to latitude, but since latitudinal temperature variability over our study area is not significant (Figure 1; [23, 24]), these trends are likely driven by differences in the dominant moss species (Table S1). Therefore, moss bank proxies provide unique insights into the scale and rapidity of biological shifts over decadal to centennial timescales in the past and under future warming.

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The strong response of moss growth and microbial populations to increasing temperature, coupled with the ?¹³C results, suggest that these systems are driven primarily by temperature, strongly modified by more localized changes in water availability at both regional and local scales. Increasing temperature has likely driven a longer growing season and a greater number of days in the year where air temperature at the moss surface exceeds 0°C for at least part of the day. The largest increases in recorded temperature have occurred during the winter, spring, and autumn periods [35], which suggests that changing temperature has had the greatest impact on biological productivity during the shoulder periods of the growing season. Thus, while longer periods of growth have resulted in overall higher growth rates and increased microbial productivity, the changes in ?¹³C suggest that growing conditions at any point in time may actually have been worse, likely due to sub-optimal moisture availability. There is some suggestion (Figure 2) that very recent growth rates of moss and microbial populations may have been slower, and this could be the result of lack of moisture or a reversal in the direction of temperature change in some parts of the year [4].

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