Question

During Ecological sucession, why is air temperature, soil temperature, wind speed and light meter reading higher in a community of rock outcrop? (Detail please)

Answer 1

The plant taxa of rock outcrops include primarily species capable of withstanding environmental extremes. Rock outcrops are characterized by high solar irradiance and highly fluctuating temperatures. The combination of high insulation, heat absorption of the rock surface and limited evaporative cooling can produce rock surface temperatures of 50-55^oC. Water availability is also less because of rapid runoff from the rock surface and low water holding capacity of shallow sandy soils in the shed of depressions.Rapid transpiration during high temperatures intensifies moisture stress producing a microenvironmental desert.

Trees cannot establish in the shallow outcrop soils and thus light meter reading is high contributing to high temperatures in air and winds.The shallow soils can be very dry seasonally but are saturated following precipitation due to impermeability of the underlying rock which causes moisture to pool in the depressions.

In rock outcrops, soil is initially very shallow, nutrient poor and have low water holding capacity.hence warmest and driest environment containing lowest organic matter resulting in higher soil temperature.Indeed rock outcrop is described as desert like.