Maciej Maryański

THE DYNAMICS OF CHEMICAL ELEMENTS IN FOREST LITTER

Litter bags with natural mixed litter were incubated until =60-70% mass loss in two oak-hornbeam and two pine-beech forest stands in southern Poland. At the same stands the input of chemical elements with throughfall was followed. Decomposition con- stants k for the oak-hornbeam litters were -0.57 and -0.55, and for the pine-beech litters -0.30 and -0.27. Chemical elements (except for Cu and Mn) revealed similar relative mobility in the four litters. On average the elements could be ordered by decreasing mobility as follows: K > Mg > Ca > S > Cu > Na > Mn = N > Cd > Pb = Zn > Fe. Instead of the two presupposed factors controlling litter decomposition, biological and chemical, three factors were specified: (1) biological, dominating the decay of organic matter and the dynamics of N, Ca, Mg, Mn, and S; (2) physical, dominated by leaching and atmospheric deposition, and controlling the dynamics of organic matter, K, Na, Pb, Cd, and Zn; and (3) chemical, determining the dynamics of Fe, Zn, Pb, and Cd through the fixation of metal ions to humic substances. Potassium was the only element that decreased in concentration in all litters, while the concentrations of N, Na, Fe, Zn, Pb, and Cd increased in all litters. S, Ca, Mg, and Mn concentrations revealed different patterns in different litters, presumably due to the differences in initial concentrations and soil acidity. No clear trend was found for Cu. In all litter types, Fe, Zn, Pb, and Cd significantly increased in absolute amounts at the end of litter-bag incubation. In all four stands the input with throughfall was high enough to explain the increases in amount of elements, with the exception of Fe in the oak-hornbeam litters.

Effect of temperature on humus respiration rate and nitrogen mineralization: Implications for global climate change

Respiration and nitrogen mineralization rates of humus samples from 7 Scots pine stands located along a climatic transect across the European continent from the Pyrenees (42°40′) to northern Sweden (66°08′) were measured for 14 weeks under laboratory conditions at temperatures from 5 °C to 25 °C. The average Q10 values for the respiration rate ranged from about 1.0 at the highest temperature to more than 5 at 10 °C to 15 °C in the northernmost samples. In samples from more northern sites, respiration rates remained approximately constant during the whole incubation period; in the southern end of the transect, rates decreased over time. Respiration rate was positively correlated with incubation temperature, soil pH and C∶N ratio, and negatively with soil total N. Regressions using all these variables explained approximately 71% of the total variability in the respiration rate. There was no clear relation between the nitrogen mineralization rate and incubation temperature. Below 15 °C the N-mineralization rate did not respond to increasing temperature; at higher temperatures, significant increases were found for samples from some sites. A regression model including incubation temperature, pH, Ntot and C∶N explained 73% of the total variability in N mineralization. The estimated increase in annual soil respiration rates due to predicted global warming at the high latitudes of the Northern Hemisphere ranged from approximately 0.07×1015 to 0.13×1015 g CO2 at 2 °C and 4 °C temperature increase scenarios, respectively. Both values are greater than the current annual net carbon storage in northern forests, suggesting a switch of these ecosystems from net sinks to net sources of carbon with global warming.

Decreased Energetic Reserves, Morphological Changes and Accumulation of Metals in Carabid Beetles (Poecilus cupreus L.) Exposed to Zinc- or Cadmium-contaminated Food

The prime objective of the study was to find out whether contamination of food with metals affects body size, energetic reserves and developmental instability in ground beetles (Poecilus cupreus L.: Carabidae). The transfer of Cadmium (Cd) and Zinc (Zn) from medium (nominal concentrations in the medium: 0, 40, 160, 640 or 800 mg kg−1 for Cd and 0, 400, 1600 or 6400 mg kg−1 for Zn) to housefly larvae to beetles was also studied. Feeding the beetles throughout their entire lifetime with Cd-contaminated housefly pupae resulted in a significant decrease in body caloric value and the size of the elytrae, tibiae and rear femora. Although body mass also decreased with increasing Cd concentration, this effect was non-significant due to large variance in all treatments. Similar trends were also found in beetles fed pupae contaminated with Zn, but the effect on body mass and caloric value was non-significant. Zn exerted significant effects only on the size of the elytrae, middle and rear tibiae, and front and rear femora. No effect on fluctuating asymmetry (FA) was found in Cd- or Zn-treated beetles. The results indicate that ground beetles exposed to metal-contaminated food have lower amounts of energy available, which may be reflected in lower energetic reserves and changed body growth. However, the metals do not cause developmental instability in the carabids studied, at least not in the first generation. The concentrations of Zn were efficiently regulated in carabids, resulting in only minor differences between the beetles exposed to different Zn treatments. In contrast, Cd accumulated both in the housefly and the beetles, and the concentrations increased significantly with increasing medium contamination level.

Effect of heavy metals and mineral nutrients on forest litter respiration rate.

Two hypotheses were tested: (1) heavy metals such as Zn, Pb and Cd can suppress the respiration rate of forest litter at low-moderate pollution levels, and (2) mineral nutrients such as K, Ca and Mg can counteract the toxicity of heavy metals when applied onto the polluted litter. In a completely randomised design, three doses of heavy metals were used: Cd-10, 50, 250; Pb-100, 500, 2500; Zn-200, 1000, 5000 microg/g dwt litter, respectively. For Ca, Mg and K, the doses corresponded to 100, 500 and 2500 microg/g. A significant decrease in cumulated CO2 evolution after 4 weeks of incubation was found for the litter samples treated with medium doses of Zn, Cd/Ca, Cd/Mg, Pb/Ca, Pb/Mg, Pb/K, Zn/Mg, Zn/Ca, Zn/K and for all the highest-dose treatments. The largest drop in respiration rate in both the medium and the highest doses was caused by additions of Zn either alone or in combination with K, Ca or Mg. The additions of mineral nutrients were found to decrease the litter respiration rate below the value measured for the respective heavy metal alone in the case of Cd/Ca, Cd/Mg, Pb/Ca, Pb/Mg and Pb/K in the medium-dose treatments, and for Cd/Ca, Cd/Mg, Cd/K, Pb/Ca and Pb/Mg in the highest-dose treatments. In all other cases, additions of the mineral nutrients did not influence the respiration rate significantly when compared to the effect of the respective heavy metal.

Body mass and caloric value of the ground beetle (Pterostichus oblongopunctatus) (Coleoptera, Carabidae) along a gradient of heavy metal pollution

At five sites located along a metal-pollution gradient in southern Poland, we collected, during the spring and summer of 2000, more than 1,200 individuals of the ground beetle (Pterostichus oblongopunctatus) to examine the relationship between pollution level and body mass. Animals from one additional sampling in May 2001 were used to measure body caloric value to verify whether metal pollution has an effect on the energy content of the body. The study sites were located in an area with a history of zinc and lead mining and smelting dating back to medieval times. Metal concentrations in the humus layer ranged from 200 to 9,600 mg/kg of zinc, 120 to 1,600 mg/kg of lead, and 3 to 82 mg/kg of cadmium. We found a significant increase in body mass with increasing pollution level. The beetles from all sites collected near the end of the season were lighter. However, no statistically significant trend in body caloric value was detected. We suggest that the high metal tolerance of the species, combined with altered interspecies competition at the polluted sites, is responsible for the positive correlation between soil metal concentration and body mass.

Effect of the chemical composition of industrial dusts on forest floor organic matter accumulation

The influence of dusts from aluminium (AP), zinc and lead (ZP1, ZP2), sintering (SP) and power (PP) plants on organic matter accumulation on the forest floor of a mixed oak-pine forest was studied in Niepołomice Forest near Kraków, Poland. An artificial application of the dusts on experimental plots was used corresponding to 100, 500, 1000, 2000, and 5000 t km−2. Increased organic matter accumulation was observed 5 yr following the addition of AP, ZP1 and ZP2 dusts, while SP and PP dusts at levels > 100 t km−2 caused a slight decrease in litter accumulation. Statistical analysis indicated that Cd, Mn, Pb and Zn present in industrial dusts were responsible for the increase in litter accumulation, while some nutrients (e.g. K, Mg, Na) contained in the dusts might decrease organic matter storage to some extent.

Chemical input/output balance for a moderately polluted forest catchment in southern Poland

A four-year study in a forest catchment exposed to a moderate level of anthropogenic pollution indicated heavy accumulation of hydrogen (H+), manganese (Mn), zinc (Zn), copper (Cu) and lead (Pb) in the ecosystem and phosphorous (P), potassium (K) and cadmium (Cd) to a lesser extent. Nitrogen, which is also accumulated, is leached mainly as NO3−, even though the input is dominated by NH4+. Magnesium (Mg), calcium (Ca) and sodium (Na) are leached from the catchment, presumably due to intensive weathering processes in deeper layers of mineral soil. Chloride ion (Cl−) is also lost from the ecosystem. The output of sulphate (SO42−) with stream water exceeds its input only slightly. Although it appears that the catchment as a whole has a large buffering capacity (average stream water pH=7.43, rainfall pH=4.33), the upper biologically active soil layers are probably more susceptible to acidification and pollution. With constant accumulation of H+ and heavy metal ions this may lead to degradation of forest health.