Biological activity and amount of FDA mycelium in mor humus of Scots pine stands (Pinus sylvestris L.) in relation to soil properties and degree of pollution

Abstract

Abstract. The biological activity and the amount of living fungal mycelium in the mor humus of pine forests around an industrialized city were studied. The activities were lower in the more polluted zone than in a cleaner one but varied between sites within the zones. The relationship of these activities to the microbial environment was determined in both the total data and in the various zones separately. Soil respiration rate was positively related to ammonium nitrogen concentration of the humus in the less polluted zone but negatively in the more polluted zone, while it related negatively to total nitrogen concentration of the humus in the entire data set. DHA was partly accounted for by the variation in acidity parameters, and best by pH(CaCl,), with a positive relation. The length of FDA active fungal mycelium showed no significant variation between the zones or sites, and was thus poorly explained by the environmental variables. The weather conditions prevailing at two seasons did not explain any variation of the activities or the length of FDA mycelium, though the biological variables were in general positively related to the moisture of the humus.

Accumulation of organic matter along a pollution gradient: Application of odum's theory of ecosystem energetics

“…The tendency for the S content of pine needles to increase towards the city center, and a quite narrow pH range of the mor humus were criteria when selecting the sites. The sites were located along the S and N concentration gradient in the mor humus ranging from 1.6 to 3.9 mg S g-1OM [27] and from 14 to 23 mg N g-IOM, respectively [26]. The pH of the sites Organic Matter Accumulation Along a Pollution Gradient 45 varied from 3.79 to 4.28 [25].…”

“…The pH of the sites Organic Matter Accumulation Along a Pollution Gradient 45 varied from 3.79 to 4.28 [25]. Ten of the sites were considered to belong to the less polluted zone situated 5--40 km from the city center, and ten to the more polluted one situated close to the city center [26].…”

“…Soil samples were taken from the complete humus layer, which varied in thickness from 2.3 to 8.9 cm [26,28], in September 1991. Approximately 500 g of fresh humus was taken for each bulk sample, which consisted, on average, of 25 suhsamples, taken randomly with a stainless steel soil auger 30 mm in diameter.…”

“…The forest sites lie along a sulphur and nitrogen concentration gradient in the mor humus ranging from 1.6 to 3.9 mg S g-1 organic matter (OM) and from 14 to 23 mg N g-~OM. A number of biological parameters have decreased along this gradient, e.g., soil respiration rate [25,26,28] and cellulolytic activity [31], mycorrhizal infection of pine roots, diversity and sporophore production of mycorrhizal fungi [25,28], and the number of enchytraeids and acarics [30]. The activity of peroxidase enzymes in pine roots has correspondingly increased, presumably indicating pollution stress [17].…”

“…The activity of peroxidase enzymes in pine roots has correspondingly increased, presumably indicating pollution stress [17]. A hypothesis about the increased soil organic C (Corg) content at the S and N polluted sites (accumulation of organic matter in the humus layer) due to decreased biological activity, changes in the microbial community, and altered quality and quantity of the organic matter has been presented by Ohtonen and Markkola [26]. The type of vegetation strongly influences Corg contents owing to the different amounts and quality of the C input [14].…”