Comparative Studies on the Microbiology of Four Moorland Soils in the Northern Pennines

Abstract

The microbiology of 4 soils in Westmorland, England (Festuca-Agrostis grassland on limestone, Juncus squarrosus moor, mixed Calluna-Eriophorum moor and an area of bare eroded peat) was studied. The length of stained fungal mycelium, estimated by the Jones and Mollison (1948) method, decreased over the series limestone grassland (160-580 m/cm3), Juncus moor (50-160 m/cm3), mixed moor (15-180 m/cm3) to bare peat (5-44 m/cm3). As a percentage of the total mycelium, the stained decreased from 56 to 7% over the same series. The quantity of unstained mycelium varied from 100 to 600 m/cm3. Over the same series, slide traps, Warcup plates, cellulose films and cotton strips showed a general decrease in the variety of fungi and in their ability to colonize fresh substrates and to decompose cellulose. Numbers of bacteria estimated by direct counts were: limestone grassland 16-79 x 108/cm3 Juncus moor 18-39 x 108/cm3; mixed moor 14-35 x 108/cm3; bare peat 1-9 x 108/cm3. Estimated by dilution culture counts, numbers decreased from 13 x 106/cm3 in the limestone grassland to 8 x 103/cm3 in the bare peat. The ratio of dilution; direct count increased over the series from 1 : 360 in limestone grassland to 1:47,000 in bare peat. Estimates of the numbers of bacteria in particular physiological groups decreased over the series. The ratio, dilution count of bacteria: length of stained mycelium showed an increase from 1:300 in limestone grassland, 1:4000 in Juncus moor to 1:13000 in mixed moor and bare peat. Respiration showed a decrease over the series with a range of 26-0.2 [mu]l O2/cm3/hr. Many common soil forms were not recorded in the 4 soils and in general the flora contained relatively few species. This agrees with published information on the tolerance of the different fungi and bacteria to temperature, moisture and pH conditions of this area. The studies establish the existence of an activity gradient with its highest values in the grassland site and its lowest in bare peat. This gradient can be related to a change from mineral-rich, relatively basic and well-drained conditions to mineral poor, acid, waterlogged conditions.