Physical ecology of hypolithic communities in the central Namib Desert: The role of fog, rain, rock habitat, and light
Physical ecology of hypolithic communities in the central Namib Desert: The role of fog, rain, rock habitat, and light
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纳米布沙漠中部次生石群落的物理生态学：雾、雨、岩石栖息地和光的作用
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发表时间：
2013
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通讯作者：
K. Rhodes
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作者：
K. Warren;C. Mckay;L. Boyle;M. R. Wing;Elsita Kiekebusch;D. Cowan;F. Stomeo;S. Pointing;K. Kaseke;F. Eckardt;J. Henschel;Ari Anisfeld;M. Seely;K. Rhodes
在全世界的沙漠中，底栖微生物群落是生产性的生态位，但其基本生态的许多方面仍然未知。纳米布沙漠是一个重要的地下岩研究场所，因为它有丰富的石英岩适合殖民，并从西向东延伸，从雾到雨为主的水分来源过渡。结果表明，雾在几个方面维持和影响着底栖生态：（1）雾有效地替代了纳米布中部西部地区的降雨，使景观（1-10 km）和更大尺度上的底栖丰度高（≥95%）;和（2）高水的可用性，通过雾（西部区域）和/或降雨（东部区域），导致较小尺寸级的岩石以较高的比例被殖民（平均6.3 ± 1.2 cm）（例如，98%对约3%）比以前研究的超干旱沙漠。我们测量了0.1%的入射阳光的下限hypolithic生长在纳米布的石英岩，并发现，未殖民的腹部岩石表面的光，而不是水分的限制。原位监测表明，虽然降雨提供更多的液态水（36小时）每事件比雾（平均4小时），在同等的年度基础上，雾提供了近两倍的液态水降雨的hypolithic区。在年平均降水量（MAP）约为40-60 mm时，底栖生物丰度达到100%，但当雾中的水分可用时，MAP（约25 mm）要低得多。
Hypolithic microbial communities are productive niches in deserts worldwide, but many facets of their basic ecology remain unknown. The Namib Desert is an important site for hypolith study because it has abundant quartz rocks suitable for colonization and extends west to east across a transition from fog‐ to rain‐dominated moisture sources. We show that fog sustains and impacts hypolithic ecology in several ways, as follows: (1) fog effectively replaces rainfall in the western zone of the central Namib to enable high (≥95%) hypolithic abundance at landscape (1–10 km) and larger scales; and (2) high water availability, through fog (western zone) and/or rainfall (eastern zone), results in smaller size‐class rocks being colonized (mean 6.3 ± 1.2 cm) at higher proportions (e.g., 98% versus approximately 3%) than in previously studied hyperarid deserts. We measured 0.1% of incident sunlight as the lower limit for hypolithic growth on quartz rocks in the Namib and found that uncolonized ventral rock surfaces were limited by light rather than moisture. In situ monitoring showed that although rainfall supplied more liquid water (36 h) per event than fog (mean 4 h), on an equivalent annual basis, fog provided nearly twice as much liquid water as rainfall to the hypolithic zone. Hypolithic abundance reaches 100% at a mean annual precipitation (MAP) of approximately 40–60 mm, but at a much lower MAP (approximately 25 mm) when moisture from fog is available.