Use of the water-level fluctuation analysis tool (Regcel) in hydrological status assessment of Finnish lakes

Regulation of water flow constitutes the most important hydromorphological burden to Finnish lakes. The total area of regulated lakes is nearly 11,000 km², equalling one-third of the total area of Finnish inland waters. Extensive research projects have been carried out since the end of the 1980s to find out opportunities to mitigate harmful effects of the regulation of watercourses. A water-level fluctuation analysis tool, known as Regcel, has been developed to study water level data and to identify the most significant impacts. Results of the Regcel analysis give an overall picture of the impact of lake regulation in northern climate. The model is based on relationships between the water-level fluctuation and factors related to environmental, social and economical effects. Regcel has been used in 12 Lake Regulation Development Projects in Finland. In this article, we show how the Regcel model was applied in two cases. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: K. M. Wantzen, K.-O. Rothhaupt, M. M?rtl, M. Cantonati, L. G.-Tóth & P. Fischer Ecological Effects of Water-Level Fluctuations in Lakes     

Reaction of forest soil microflora to environmental stress along a moderate pollution gradient next to an oil refinery

Twenty-five study sites were established along a 57-km-long transect in order to estimate the impact of an oil refinery, mainly emitting sulphur dioxide (24000 t yr⁻¹), on forest soil (F/H-horizon) chemistry and microbiology. The study demonstrated the existence of a pollution gradient which was best represented by the logarithm of the concentration of vanadium in the analyzed F/H soil layer. Of the soil microbial characteristics measured, including length of fungal hyphae, soil respiration, microbial biomass C and N, and percentage mass loss of Scots pine (Pinus sylvestris) needle litter, only fungal hyphal length was suppressed by the pollution load. No reduction in basic cations (Ca, Mg, K, and Na) in the F/H-horizon, or enrichment of soluble aluminum in the F/H-horizon of the Scots pine forest could be detected to result from the deposition.     

Ornithine Decarboxylase Activity in Brain Regulated by a Specific Macromolecul, the Antizyme

Mouse brain ornithine decarboxylase activity is about 70-fold higher at the time of birth compared with that of adult mice. Enzyme activity declines rapidly after birth and reaches the adult level by 3 weeks. Immunoreactive enzyme concentration parallels very closely the decrease of enzyme activity during the first postnatal week, remaining constant thereafter. The content of brain antizyme, the macromolecular inhibitor to ornithine decarboxylase, in turn is very low during the first 7 days and starts then to increase and at the age of 3 weeks it is about six times the level of that in newborn mice. This may explain the decrease in enzyme activity during brain maturation, and suggests the regulation of polyamine biosynthesis by an antizyme-mediated mechanism in adult brain.     

Restoration of managed pine fens: effect on hydrology and vegetation

Question: How does restoration affect the hydrology and the understorey vegetation of managed pine fens? Location: Oligotrophic pine fens in Natura 2000 areas in Kainuu, eastern Finland. Methods: Eleven managed pine fens and eight pristine reference pine fens were chosen for the study in 2005. The managed fens, which had been drained for forestry during the 1970s and 1980s, were restored in 2007. The water table was monitored in all fens over four growing seasons during 2006 to 2009, and vegetation was surveyed from permanent sample plots in 2006 and 2009. Results: Before restoration in 2006, the water table was at a significantly lower level in the managed fens compared with the pristine fens. Immediately after restoration, the water table rose to the same level as in the pristine fens, and this change was permanent. Forest drainage had had little impact on the understorey vegetation of the managed fens in the three decades before restoration, with species typical of pristine fens still dominating the sites. Forest dwarf shrubs and feather mosses had started to increase in cover, but mire dwarf shrubs and Sphagnum mosses still dominated the managed fens. Only the typical hollow species Sphagnum majus, Sphagnum balticum and Scheuzeria palustris were missing from the managed fens. Two years after restoration, the changes in species composition were also marginal, with increased cover of mire dwarf shrubs and sedges being the only significant change. Conclusions: The success of restoration of oligotrophic pine fens seems likely, given that changes in hydrological functioning occurred rapidly, and since little change has occurred in the vegetation composition after draining. Speeding up the regeneration process in these peatland types by restoration may, therefore, be recommended, especially if the drainage effect extends to nearby pristine mires and influences their biodiversity.     

Degradability, molecular weight and adsorption properties of dissolved organic carbon and nitrogen leached from different types of decomposing litter

Aims

We characterized dissolved organic matter (DOM) leached during decomposition of deciduous silver birch litter (Betula pendula Roth.), coniferous Norway spruce litter (Picea abies (L.) Karst.) and a mixture of these litters in order to find out whether the properties of DOM would explain the earlier observed signs for higher microbial activity in soil under birch than spruce.

Methods

DOM leached from decomposing litters was collected in a litter-column experiment in the laboratory. Adsorption properties (XAD-8 resin fractionation) and molecular weight as well as the degradability of dissolved organic carbon (DOC) and nitrogen (DON) were measured three times during decomposition: 1) in the early stages, 2) after the mass loss reached 20–30 % and 3) when the mass loss reached 30–40 %.

Results

The leaching of DOC hydrophilic neutrals and bases, regarded easily degradable, decreased during decomposition. The leaching of DOC in hydrophobic acids, regarded refractory, increased from spruce and especially from the mixture litter during decomposition and may be connected to the degree of litter decomposition that was highest for the mixture. Unexpectedly, the degradability of DOC differed only slightly between the litters but the degradability of DON was substantially higher for spruce than birch. Spruce DOM seemed to be more N-rich than birch DOM in the early stages of decomposition and it seemed that labile DON was mobilized earlier from spruce than birch litter.

Conclusions

We conclude that the decomposition degree of litter determines largely the properties of DOM. The observed differences in the properties of DOM sampled during the litter decomposition cannot explain differences in C and N cycling between birch and spruce.     

Restoration of Young Forests in Eastern Finland: Benefits for Saproxylic Beetles (Coleoptera)

Effective fire suppression in combination with intensive forestry has caused a large number of dead wood‐dependent (saproxylic) species to become threatened in Fennoscandia. In order to return the fire disturbance dynamics and to increase the amount of dead wood, restoration actions are urgently needed. We studied the effects of restoring young (under 30 years old) pine‐dominated (Pinus sylvestris L.) forest stands on saproxylic beetle assemblages in eastern Finland, focusing especially on rare, red‐listed, and pyrophilous (RRLP) species. Our experiment included a restoration treatment including two tree felling levels for fuel load (10 or 20 m³/ha) followed by burning, and an untreated control. We sampled beetles before restoration in 2005, during the year of restoration in 2006, and in two post‐treatment years in 2007 and 2011. Both restoration treatments increased the number of saproxylic and RRLP species. The species richness increased most in the year of restoration in 2006 and this trend continued in the following year 2007, but no differences in species assemblages were detected between the two fuel load levels. By 2011, however, the species richness and abundance had declined back to the pre‐treatment level. We suggest that restoration burning can also be directed to young forests where biodiversity values are initially low. On the basis of the observed decline in the species richness, we suggest that fire could be introduced in neighboring areas in approximately 5‐year intervals to maintain populations of the most demanding pyrophilous species .     

Temperature responses of photosynthetic capacity parameters were not affected by foliar nitrogen content in mature Pinus sylvestris

A key weakness in current Earth System Models is the representation of thermal acclimation of photosynthesis in response to changes in growth temperatures. Previous studies in boreal and temperate ecosystems have shown leaf‐scale photosynthetic capacity parameters, the maximum rates of carboxylation (V_cmax) and electron transport (J_max), to be positively correlated with foliar nitrogen (N) content at a given reference temperature. It is also known that V_cmax and J_max exhibit temperature optima that are affected by various environmental factors and, further, that N partitioning among the foliar photosynthetic pools is affected by N availability. However, despite the strong recent anthropogenic influence on atmospheric temperatures and N deposition to forests, little is known about the role of foliar N contents in controlling the photosynthetic temperature responses. In this study, we investigated the temperature dependencies of V_cmax and J_max in 1‐year‐old needles of mature boreal Pinus sylvestris (Scots pine) trees growing under low and high N availabilities in northern Sweden. We found that needle N status did not significantly affect the temperature responses of V_cmax or J_max when the responses were fitted to a peaked function. If such N insensitivity is a common tree trait it will simplify the interpretation of the results from gradient and multi‐species studies, which commonly use sites with differing N availabilities, on temperature acclimation of photosynthetic capacity. Moreover, it will simplify modeling efforts aimed at understanding future carbon uptake by precluding the need to adjust the shape of the temperature response curves to variation in N availability.     

The role of phosphorus release by roach [Rutilus rutilus (L.)] in the water quality changes of a biomanipulated lake

SUMMARY 1. Following fish removal, the water quality in biomanipulated lakes often improves concomitant with decreased phosphorus (P) levels. Because the decrease in P concentrations derives most probably either directly or indirectly from fish, which are the main target of biomanipulation, this study examined the P release of 0+, 1+ and 2+ roach [Rutilus rutilus (L.)] and changes in the P release during summer in a shallow eutrophic lake in Finland. 2. The P release was separated into P derived from benthic and littoral food items and into recycled P derived from feeding on zooplankton, to estimate the contribution of net P additions to the water column by the fish to the increase in P concentrations of the lake water (75–110 mg P m^?3) in summer 1991–96. 3. Individual P release of roach by both egestion and excretion was estimated with a bioenergetics model. The size of the roach population was estimated with a depletion method and the proportions of different age groups from catch samples, using a programme separating mixtures of normal distributions. The sensitivity of the release estimates to variation in the growth data was estimated with the jackknife technique. 4. The biomass‐specific P release by 0+ roach (0.36–0.54 mg P g^?1 day^?1) was higher than that by older roach (0.07–0.16 mg P g^?1 day^?1) throughout the summer. The P release by the whole roach population deriving from benthic and littoral food items (0.7–2.7 mg m^?3 during July to August, representing a net addition to the water column) was 5–19 times lower in 1991–96 than the recycled P release deriving from zooplankton (8.9–25.7 mg m^?3), and too low to explain the increase in the P concentration of the lake water during the summer. Because the biomass‐specific P release and roach diet composition vary with fish age, it is important to consider the age structure of fish populations to obtain correct estimates of P release and net additions to the water column. 5. The removal of roach by fishing diminished the roach stock greatly, but the fish‐mediated P release to the water column changed little. This effect was because of the high compensation capacity of the roach population, leading to high recruitment of young fish with higher biomass‐specific P release rates. 6. External loading is very low during summer months and therefore it cannot explain the increase in the P concentration of water during that time. Internal loading from the sediment might be as high as 10.2 mg P m^?2 day^?1, i.e. 50 times higher than the maximum net P addition by the total roach population.     

Charcoal as a habitat for microbes and its effect on the microbial community of the underlying humus

Wildfires produce a charcoal layer, which has an adsorbing capacity resembling activated carbon. After the fire a new litter layer starts to accumulate on top of the charcoal layer, which liberates water‐soluble compounds that percolate through the charcoal and the unburned humus layer. We first hypothesized that since charcoal has the capacity to adsorb organic compounds it may form a new habitat for microbes, which decompose the adsorbed compounds. Secondly, we hypothesized that the charcoal may cause depletion of decomposable organic carbon in the underlying humus and thus reduce the microbial biomass. To test our hypotheses we prepared microcosms, where we placed non‐heated humus and on top one of the adsorbents: non‐adsorptive pumice (Pum), charcoal from Empetrum nigrum (EmpCh), charcoal from humus (HuCh) or activated carbon (ActC). We watered them with birch leaf litter extract. The adsorbing capacity increased in the order Pumorg in the litter extract, respectively. After one month, all adsorbents harboured microbes, but their amount and basal respiration was largest in EmpCh and HuCh, and smallest in Pum. In addition, different kinds of microbial communities with respect to their phospholipid fatty acid and substrate utilization patterns were formed in the adsorbents. The amount of microbial biomass and number of bacteria did not differ between humus under different adsorbents, although different microbial communities developed in humus under EmpCh compared with Pum, which is obviously related to the increased pH of the humus under EmpCh, and also ActC. We suggest that charcoal from burning can support microbial communities, which are small in size but have a higher specific growth rate than those of the humus. Although the charcoal layer induces changes in the microbial community of the humus, it does not reduce the amount of humus microbes.     

THE EFFECT OF dl-ALLYLGLYCINE ON POLYAMINE AND GABA METABOLISM IN MOUSE BRAIN

Abstract— dl -Allylglycine, a potent inhibitor of glutamate decarboxylase in vivo when given intraperitoneally, causes a marked decrease in brain GABA concentration and at the same time a dramatic increase in l -ornithine decarboxylase activity and a simultaneous decrease in S -adenosyl- l -methionine decarboxylase activity followed by putrescine accumulation. It does not, however, alter the degree of GABA formation from putrescine. The timing of the recovery of glutamate decarboxylase activity after the injection of dl -allylglycine is concomitant with that of the GABA concentration, indicating that it is probably glutamate decarboxylase that is solely responsible for making up the GABA deficit caused by dl -allylglycine, and that the changes in polyamine metabolism are associated in some indirect way with the recovery process.