Introduction Within the Knersvlakte, cyanobacteria occur hypolithically underneath translucent quartz stones in areas with quartz pavement and, outside pavement areas, they are soil-inhabiting within the uppermost millimeters of the soil. Both habitats were characterized in terms of biomass and growth patterns of cyanobacteria. Long-term microclimatic conditions were determined. Methods Biomass of organisms within both habitats was determined by means of chlorophyll analyses. A transect approach was used to determine the frequency of hypolithic growth depending on the size, weight, and embedding depth of the quartz pebbles. Organisms were identified by means of microscopic analyses of the samples. Microclimatic conditions within both habitats, i.e., temperature, light intensity, air humidity, and soil moisture, were recorded bi-hourly from September 23, 2004 through September 7, 2006. Results The biomass of hypolithic and soil-inhabiting crusts was almost identical, 88 vs. 86 mg Chla/m2 and 136 vs. 134 mg Chla+b/m2. Within the quartz fields, 46.8% of the surface area was covered by quartz stones with 69% of translucent quartz stones colonized by hypolithic cyanobacteria and algae. Colonized quartz stones were significantly thicker, heavier, and more deeply embedded in the soil than uncolonized ones. Whereas the annual mean temperature on top of quartz stones was nearly identical to that underneath thin and thick quartz stones, daily temperature amplitudes were largest on the stone surface (up to 48.1K), compared to the hypolithic habitats (up to 39.4K). Light intensity in the hypolithic habitat was between 15 and 30% of the ambient light intensity during daytime. Water condensation in the absence of rain occurred during 50% of the nights on the quartz stone surface, but only during 34% of the nights on the soil surface during winter months within 1 year. Soil moisture beneath quartz layers was greater and less variable than beneath soil-inhabiting crusts. Conclusions In spite of the large differences in the microclimatic conditions, both habitats seem to be similarly well suited for cyanobacterial growth, resulting in equal biomass values but some differences in taxonomic composition.
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机译：简介在Knersvlakte内，蓝藻发生在半透明石英石下面，在半透明的石英石下面，该石块位于石英铺装区，而在铺装区以外，它们居住在土壤的最高毫米内。两种生境均以蓝细菌的生物量和生长方式为特征。确定了长期的微气候条件。方法采用叶绿素分析法测定两个生境中生物的生物量。横断面方法用于确定次石生长的频率，具体取决于石英卵石的大小，重量和包埋深度。通过对样品进行显微镜分析来鉴定生物。从2004年9月23日至2006年9月7日，每两个小时记录一次这两个生境中的小气候条件，即温度，光照强度，空气湿度和土壤湿度。结果下部岩石和居住于土壤的地壳的生物量几乎相同， 88 vs. 86 mg Chl a / m 2 和136 vs. 134 mg Chl < sub class =“ a-plus-plus”> a + b / m 2 。在石英场内，46.8％的表面积被石英石覆盖，69％的半透明石英石被次石器时代的蓝细菌和藻类所占据。与未定殖的石英石相比，定殖的石英石明显更厚，更重且更深地嵌入土壤中。石英石顶上的年平均温度与薄而厚的石英石下的年平均温度几乎相同，而与石器时代的生境相比，日表面上的日温度振幅最大（最高48.1K），而在石器时代则最高（39.4K）。白天，石器时代栖息地的光强度为环境光强度的15％至30％。在无雨的情况下，水的凝结发生在石英石表面的50％的夜晚，但在一年之内的冬季，仅发生在土壤表面的34％的夜晚。石英层下的土壤水分比土壤下地壳更大，变化较小。结论尽管小气候条件存在很大差异，但两个生境似乎都非常适合蓝细菌的生长，导致生物量值相等，但生物分类组成方面存在一些差异。
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