Within a successional context, the vegetation associated with the cedar gladeecosystem in middle Tennessee develops from bare limestone bedrock to subclimax redcedar,preclimax oak-hickory, and climax mixed hardwood forests. Studies on the composition andstructure of forests associated with cedar glade–forming limestones (Lebanon, Ridley) are rare.We sampled the canopy and understory of six forest stands in middle Tennessee on theselimestones. Observed number of canopy species was 14–24 across stands; estimated richnesswas greater by 1–3 species (bootstrap) or 3–6 species (first-order jackknife) than observedrichness. With the exception of Ailanthus altissima in one stand, all other canopy species werenative. Juniperus virginiana, Fraxinus americana, Carya ovata, and Quercus muehlenbergii wereprimary canopy components in 4 or 6 stands, and C. glabra, Q. shumardii, Ulmus alata, F.quadrangulata, Q. alba, and Q. velutina in 2–3 stands. When we included stands from apreviously published study (most on the non-glade Carters Limestone) with our data, aprincipal components analysis identified three groups with the axes approximating a moisturebedrockgradient and a time-successional gradient. An examination of regeneration in ourstands predicts that (1) mesophytes and/or fire-sensitive species (Acer saccharum, Fraxinus spp.,Celtis spp.) will increase and (2) xerophytes and/or fire-adapted species (Quercus spp., Caryaspp.) will decrease. Altogether, our results strongly suggest that the oak-hickory stage shown insuccessional outlines of vegetation development associated with the cedar glade ecosystem maynot occur in its current state in the future.

Predation is one of the important selective factors that regulate the species composition of benthic invertebrate communities. The study objective was to investigate the invertebrate distribution in two contrasting habitats in Lake Takern, southern Sweden, submerged Chara vegetation and emergent Phragmites australis vegetation, and to investigate the influence of predation from fish on certain invertebrates. Laboratory studies were used to estimate handling time and the intake rate (mg/sec) by the fish based on the optimal foraging model. In the field, fish and invertebrates were collected with gill nets and hand nets respectively and the fish gut content was analyzed. In total, sixteen invertebrates’ taxa were collected from the two habitats. The proportion of the invertebrate’s overlaps from each of the habitat was calculated by Renkonen index and with Sorensen diversity index. Both indices showed a similarity larger than 65%, indicating that there was no significant difference in the invertebrates’ distribution in the P. australis and the Chara habitat. The fish caught with the gill nets were: roach (Rutilus rutilus), perch (Perca fluviatilis), tench (Tinca tinca), and rudd (Scardinius erythrophthalmus). The caught perch had eaten: Asellus aquaticus, Gammarus lacustris, Corixidae, and the larvae of Chironomidae and Zygoptera.A comparison was made on the invertebrates found in the field and the ones observed from the gut of the perch, and the findings were that the invertebrates that had more occurrence in the gut were less in proportion in the benthic samples. In the laboratory experiment perch ( Perca fluviatilis) was used as the predator fish and the prey organisms were Asellus aquaticus,Gammarus pulex, and Corixidae of three size categories. The results showed that perch handling time for A.aquaticus of the different size categories, was not significantly different (p>0.05); and the same results were valid for Corixidae and G. pulex. However, the intake rate of perch across the prey and their size categories were significantly different. The handling time was not significantly different which means that the predator fish will gain more in terms of intake rate as it prey on larger size prey items, thus harmonizing with the optimum foraging theory.

Two species of emergent macrophytes, Typha latifolia (common cattail) and Phalaris arundinacea (reed canary grass) were evaluated as substrates for biogas production. The specific methane yield for each plant was obtained by batch wise anaerobic digestion in 300-mL bottles. Three different pretreatments were evaluated for increased biogas production; mechanical milling, alkaline treatment with lime and fungal degradation with Pleurotus ostreatus (oyseter mushroom).The methane yield for Typha latifolia and Phalaris arundinacea was determined to 300 and 323mL methane per g VS, respectively. There was no statistical difference in methane yield between the two species. Milling pretreatment increased the biogas yield with 16 % by average compared to untreated plant. Alkaline pretreatment with lime increased the biogas yield with 27 % at roomtemp. and 22 % at 55 °C. The fungal pretreatment decreased the biogas production by 20 % and is probably not suitable for this kind of substrate.The results showed that emergent macrophytes have a biogas yield similar to other plants already tested (grasses) and commonly used (pasture crops) in large scale reactors. However, emergent macrophytes and grasses cause mechanical problems in a reactor due to their structure. Probably some kind of milling must be done to decrease the fiber length of the emergent macrophytes. The costs for harvest, transport, handling and possible pretreatment of the emergent macrophytes have to be estimated and included in the overall cost calculations. This can tell if emergent macrophytes should be used as a substrate for biogas production.

A constructed wetland (0.08 ha) receiving drainage water from a small agricultural catchment (22 ha) with clay soil, was investigated with respect to phosphorus dynamics and retention. The aim was to evaluate the function of the wetland with respect to phosphorus retention, and relate that to gross sedimentation as measured with sediment traps. Hydraulic load and phosphorus retention were estimated for 2003-2010 based on monitoring data. Furthermore, water quality dynamics was studied during three intensive sampling periods of 3-5 days during 2010. For each period, phosphorus retention was calculated and the relationship between flow and phosphorus concentrations analysed. Additionally, the gross sedimentation rate was estimated using sediment traps, and the phosphorus, carbon and nitrogen content analysed. The results suggested that there was no net retention of phosphorus during 2003-2010, except for 04/05. During the intensive sampling periods, release of phosphorus from the wetland mainly occurred during high flow. Sediment analyses showed that settling of inflow particles mostly occurred in the inlet pond, while the sediment found in a shallow vegetated area and outlet pond likely originated from internal processes rather than from the catchment. In fact, the gross sedimentation of phosphorus during April-July and July-August, respectively, exceeded the measured phosphorus inflow. The results showed that short periods with rapid flow increases were crucial for the wetlands function and thus high frequency sampling must be done during these periods. Furthermore, it seems that the particles lost from the catchment during high flows are too small to settle in the wetland.

In South Sweden, free water surface wetlands have been built to treat wastewater from municipal wastewater treatment plants. Commonly, nitrogen removal has been the prime aim, though a significant removal of tot-P and BOD7 has been observed. In this study, performance data for 3-8 years from four large (20-28 ha) FWS wetlands have been evaluated. Two of them receive effluent from WWTP with only mechanical and chemical treatment. At the other two, the wastewater has also been treated biologically resulting in lower concentrations of BOD7 and NH4+-N. The wetlands performed satisfactorily and removed 0.7-1.5 ton N ha-1 yr-1 as an average for the time period investigated, with loads between 1.7 and 6.3 ton N ha-1 yr-1. Treatment capacity depended on the pre-treatment of the water, as reflected in the k20-values for N removal (first order area based mode). In the wetlands with no biological pre-treatment, the k20-values were 0.61 and 1.1 m month-1, whereas for the other two they were 1.7 and 2.5 m month-1. P removal varied between 10 and 41 kg ha-1 yr-1, and was related to differences in loads, P speciation and to the internal cycling of P in the wetlands. © IWA Publishing 2005.

The rare beetle Elater ferrugineus was sampled at 47 sites in the county of Östergötland, Sweden by meansof pheromone-baited traps to assess its value as an indicator species for hollow oak stands rich in raresaproxylic beetle species. In addition, Osmoderma eremita was also sampled with pheromone baits. Thesedata were then compared against species survey data collected at the same sites by pitfall and windowtraps. Both species co-occur with many Red Listed saproxylic beetles, with E. ferrugineus being a somewhatbetter indicator for the rarest species. The conservation value of a site (measured as Red List pointsor number of Red Listed species) increased with the number of specimens of E. ferrugineus and O. eremitacaught. Accuracy of sampling by means of pheromone trapping turned out to be radically different for thetwo model species. E. ferrugineus traps put out during July obtained full accuracy after only 6 days,whereas O. eremita traps needed to be out from early July to mid-August in order to obtain full accuracywith one trap per site. By using E. ferrugineus, or preferably both species, as indicator species, accuracywould increase and costs decrease for saproxylic biodiversity sampling, monitoring and identificationof hotspots.

Recent studies show that populations of the freshwater isopod Asellus aquaticus L. can rapidly become locally differentiated when submerged stonewort (Chara spp.) vegetation expands in lakes. In the novel Chara habitat, isopods become lighter pigmented and smaller than in the ancestral reed stands. In this study, I used laboratory experiments to investigate if selective predation by fish could be a possible explanation for these phenotypic changes. Predation from fish is generally considered to be a strong selective force on macroinvertebrate traits. In the first experiment I measured perch (Perca fluviatilis L.) handling time for three size classes of Asellus to see which size of those that would be the most profitable to feed upon. No difference in handling time was detected between prey sizes, hence the largest size would be the most beneficial to feed upon. In a second experiment I let perch feed on a mixture of Asellus phenotypes in aquaria manipulated to mimic the substrates in either the Chara or the reed habitats. Remaining isopods were significantly smaller and lighter pigmented in the fish aquaria than in the controls, showing that the perch preferred to feed on large and dark individuals. In the Chara habitat, selection on isopod pigmentation was according to what could be expected from background matching, but in the reed habitat selection was quite the opposite. These results support the hypothesis that predation from fish is a strong selective force behind the rapid local adaptation seen in Asellus populations in the novel Chara habitat.

The complex interplay between biotic and abiotic factors, believed to be responsible for several oak declines in European oak stands during the last three decades, remains poorly understood. Hence, this study aims at clarifying the temporal process of oak declines, as well as identifying individual tree and environmental variables that increase the risk of oak mortality. The study was performed in one of the few areas in northern Europe still holding high densities of old oaks (Quercus robur L.). Cross dating revealed that most trees had died during the last decade. Averaged chronologies and multiple chronological clustering suggested that the onset of the oak decline happened in 1992, when a severe drought took place. Two of the sites showed a rather short time period of heavily reduced growth prior to death, most likely caused by an insect defoliation in combination with a mildew infection of the replacement shoots. Environmental variables presented a rather weak influence on oak mortality. The results support the idea of attributing oak mortality to a combination of long- and short-term stresses, and emphasize the importance of including present as well as past factors when analysing the causes of oak declines.

Background and purpose A complex interplay between biotic and abiotic factors is believed to be responsible for several oak declines in pedunculate oak (Quercus robur L.). This study aims to clarify the temporal process of oak declines, as well as identifying individual tree and environmental variables that affects growth rate and that may increase the risk of mortality. The study was performed in southern Sweden at three sites. Findings Cross-dating revealed that most trees had died during the last decade and that the growth rates of the dead oaks were affected long before death. Averaged growth chronologies of dead and control trees reaching 150 years back in time illustrated an excellent match up until around 1992, when a severe drought occurred after which the dead trees started to express reduced growth. Precipitation the previous year during August-September and during March-June this current year was of significant importance for oak growth. Site-specific results that showed that dead trees: included fewer small-sized trees, grew on non-clay soils, were more likely to have shelf fungus and cavities and were exposed to less sunshine. Conclusion The results support the theories that oak mortality is a long process that may be induced decades before the actual death.

The use of Mueller matrices for studies of polarizing properties and cuticle structure of scarab beetles are partly reviewed. Specifically we show how the polarization of the reflected light can be quantified in terms of degree of polarization and ellipticity. It is also shown that sum decomposition of Mueller matrices reveals cuticle reflection characteristics in different spectral regions, e.g. in terms of mirrors and circular polarizers. With a differential decomposition of cuticle transmission Mueller matrices, we determine the spectral variation in the fundamental optical properties circular birefringence and dichroism. (C) 2017 Elsevier Ltd. All rights reserved.

A Mueller matrix of a sample can be used to determine the polarization of  reflected light  for  incident light with arbitrary polarization. The polarization can be quantified  in terms of ellipticity, polarization azimuth and degree of polarization. We apply spectroscopic Mueller-matrix ellipsometry at multiple angles of incidence  to study the cuticle of beetles and derive  polarization features for incident unpolarized light.  In particular we address chiral phenomena in scarab beetles,  the origin of their structural colors and the observed high degree of circular polarization is discussed. Results from beetles in the Scarabaeidae subfamilies Cetoniinae and Rutelinae are presented including specimens with broad-band silver- or gold-like colors with metallic shine as well as specimens with narrow-band green or red reflectors. The variation of polarization with angle of incidence and occurrence of both left-handed and right-handed polarization from a single species are presented. We also use Mueller-matrix spectra in electromagnetic modeling and show how to determine structural parameters including cuticle layer thicknesses and optical properties. Interference oscillations in the observed spectra are due to allowed optical modes and we show how to develop a structural model of a cuticle based on this effect. Sum decomposition of  Mueller matrices measured on a depolarizing cuticle of a beetle is briefly discussed.

One hundred years ago Michelson discovered circular polarization in reflection from beetles. Today a novel Mueller-matrix ellipsometry setup allows unprecedented detailed characterization of the beetles polarization properties. A formalism based on elliptical polarization for description of reflection from scarab beetles is here proposed and examples are given on four beetles of different character: Coptomia laevis - a simple dielectric mirror; Cetonia aurata - a left-hand narrow- band elliptical polarizer; Anoplognathus aureus - a broad-band elliptical polarizer; and Chrysina argenteola - a left-hand polarizer for visible light at small angles, whereas for larger angles, red reflected light is right-handed polarized. We confirm the conclusion of previous studies which showed that a detailed quantification of ellipticity and degree of polarization of cuticle reflection can be performed instead of only determining whether reflections are circularly polarized or not. We additionally investigate reflection as a function of incidence angle. This provides much richer information for understanding the behaviour of beetles and for structural analysis.

Transmission Mueller-matrix spectroscopic ellipsometry is applied to the cuticle of the beetle Cetonia aurata in the spectral range 300-1000 nm. The cuticle is optically reciprocal and exhibits circular Bragg filter features for green light. By using differential decomposition of the Mueller matrix, the circular and linear birefringence as well as dichroism of the beetle cuticle are quantified. A maximum value of structural optical activity of 560 degrees/mm is found. (C) 2016 Optical Society of America

 Föreliggande rapport är slutrapporten inom projektet ”Landskapsekologiska effekter av vägar och järnvägar på ryggradslösa djur” som pågått 2001-2003. En övervägande majoritet av alla studier av vägars/järnvägars effekter på djur har tidigare gjorts på större däggdjur och fåglar, men även groddjur och smådäggdjur fanns relativt väl representerade. För ryggradslösa djur fanns dock få studier och kunskapen var dålig om effekterna på denna grupp som är den absolut artrikaste. Projektet har fokuserat på dagfjärilar och odlingslandskap. En av de bäst kända grupperna av ryggradslösa djur är dagfjärilar. Odlingslandskapet som de framförallt finns i är också ett intressant landskap gällande infrastrukturproblematik. Det här projektet ligger under paraplyprojektet EKLIPS (ekologisk infrastrukturplanering med fjärranalys). Målet med EKLIPS är att utveckla och förbättra trafikverkens hantering av natur- och kulturvärden i de olika delarna av planeringsprocessen.

Projektet bestod av två delar: 1) att undersöka arealkrav på landskapsnivå hos en grupp ryggradslösa djur (dagfjärilar) för att i förlängningen kunna identifiera värdefulla odlingslandskap. 2) att studera den eventuella barriäreffekt en väg kan ha på flygande ryggradslösa djur. Även här är det dagfjärilar som studerats.

De huvudsakliga slutsatserna av den här studien av dagfjärilar som verktyg i infrastrukturplanering är att:

• Dagfjärilar kan användas för att identifiera biologiskt rika odlingslandskap. Totalt undersöktes 62 områden och 12 170 individer av 57 fjärilsarter identifierades.
• Landskapet ska studeras i relativt stor skala. Den skala som påverkar fjärilssamhällets sammansättning handlar om kilometrar snarare än hundratals meter. Mängden hagmarker och lövskogar inom 500 m och 2000 m kunde inte förklara fjärilsfaunans sammansättning, däremot mängden inom 5000 m.
• Det finns kritiska tröskelvärden för mängden av habitat i landskapet och infrastruktur har troligen sin största negativa påverkan kring dessa värden. Tröskelvärdet för att ett artrikt område (>20 arter dagfjärilar) med >50% sannolikhet ska kunna finnas i ett område var i denna studie 570 ha (7,3%) hagmarker/lövskog inom en radie av 5000 m.
• Tröskelvärdena för enskilda arter varierade mellan 130-950 ha, det vill säga 1,6-12.1% av landskapet ska bestå av passande habitat.
• Indikatorarter kan användas för att identifiera rika landskap. Våra studier pekar på att flera arter och två artgrupper kan vara användbara. De två artgrupperna är pärlemorfjärilar och bastardsvärmare. Totalt 13 arter eller artgrupper påträffades främst i rika landskap, t ex skogsnätfjäril, vitgräsfjäril, midsommarblåvinge, brunfläckig pärlemorfjäril och silverstreckad pärlemorfjäril.
• Vägar kan fungera som barriärer för vissa arter. För två av arterna hade vägen en signifikant barriäreffekt. För luktgräsfjäril minskade flödet med 74% och för slåttergräsfjäril med 43%.
• Potentiellt rika landskap ska gå att identifiera från flygbilder och satellitdata utan att göra omfattande fältinventeringar i framtiden baserat på våra resultat. Fortfarande är dock resultaten för osäkra (ej upprepade i andra landskap) för att appliceras i större skala.
• När vägplaneringsprocessen kommit fram till vägutredningen kan indikatorarterna användas för att identifiera för artrikedomen viktiga områden och för att precisera målsättningarna för vilken naturhänsyn som skall tas i arbetet. Indikatorarterna kan också användas i uppföljningsarbete för att uppskatta om projektmålen uppnåtts.

Seeds of Drosera anglica collected in Sweden were dormant at maturity in late summer, and dormancy break occurred during cold stratification. Stratified seeds required light for germination, but light had to be given after temperatures were high enough to be favorable for germination. Seeds stratified in darkness at 5/1 ░C and incubated in light at 12/12 h daily temperature regimes of 15/6, 20/10 and 25/15 ░C germinated slower and to a significantly lower percentage at each temperature regime than those stratified in light and incubated in light. Length of the stratification period required before seeds would germinate to high percentages depended on (1) whether seeds were in light or in darkness during stratification and during the subsequent incubation period, and (2) the temperature regime during incubation. Seeds collected in 1999 germinated to 4, 24 and 92 % in light at 15/6, 20/10 and 25/15 ░C, respectively, after 2 weeks of stratification in light. Seeds stratified in light for 18 weeks and incubated in light at 15/6, 20/10 and 25/15 ░C germinated to 87, 95 and 100 %, respectively, while those stratified in darkness for 18 weeks and incubated in light germinated to 6, 82 and 91 %, respectively. Seeds collected from the same site in 1998 and 1999, stratified in light at 5/1 ░C and incubated in light at 15/6 ░C germinated to 22 and 87 %, respectively, indicating year-to-year variation in degree of dormancy. As dormancy break occurred, the minimum temperature for germination decreased. Thus, seed dormancy is broken in nature by cold stratification during winter, and by spring, seeds are capable of germinating at low habitat temperatures, if they are exposed to light. ⌐ 2001 ╔ditions scientifiques et mΘdicales Elsevier SAS.

Phenological changes within a growth season were investigated in two grazed, semi-natural grasslands in southern Sweden. On four occasions during the growth season, two independent observers recorded plant frequency and percentage cover. The vegetation data sets were analysed with ordination methods. The temporal changes were highly significant, but accounted for only a small part of the total variation in the data. Most species had early maxima, regarding both cover and frequency. There were differences in temporal pattern between the two grasslands. In a xeric area, the vegetation underwent a major change sometime in August, between survey-visit three and four. In a mesic area, the vegetation changed throughout the study period but least so during August. Therefore, phenological changes can be manifested in different ways, even within the same geographic region. Species-wise ordination scores highlighted those species whose records might be most affected by phenological patterns, information which is valuable when evaluating data collected in Scandinavian grasslands.

1. Like many butterflies, the woodland brown Lopinga achine has disappeared from many locations in western Europe due to habitat loss. The population dynamics and the effects of tree and bush cover on population size were studied experimentally south of Link÷ping, Sweden. 2. Most populations in the study area were small (< 500 individuals) and fluctuated synchronously between years. Long-term population dynamics and occurrence were closely correlated with tree and bush cover. Populations occurred only at sites with = 60% canopy cover, but population density decreased sharply where cover exceeded 90%. Survival from egg to adult was highest at the edges of glades (2.3 adults per female) and lowest in the deepest shade (0.7 adults) or open sun (0.6 adults). The annual rate of canopy closure at unmanaged sites decreased linearly with tree and bush cover, approximately 1% closure at 60% cover and 0.3% at 85% cover, making it possible to predict the impact of habitat changes for L. achine. 3. In 1992-95, vegetation was cleared experimentally to create new glade edges at six unmanaged sites where the risk of extinction was high because few glades remained. On average, population size at five of the managed sites increased by > 90%. The population at the sixth site, managed in 1995, decreased by 30%. 4. Cover of the host-plant Carex montana increased significantly at edges of new glades and decreased in closed unaffected woods. Successful restoration probably requires the presence of C. montana along edges of new glades from the onset of management because this plant was slow to colonize plots where it was initially absent. 5. Currently, 86% of the sites in southern Sweden occupied by L. achine are unmanaged. If this situation continues, the metapopulation in this study will probably collapse within 20-40 years. Recovery programmes for L. achine should emphasize metapopulation dynamics, host-plant cover and vegetation dynamics over time. As with many butterflies, successful conservation requires a blend of detailed autoecology and active site management to produce the required successional conditions.

One of the key aspects in conservation management and in understanding species distributions is how they respond to habitat factors at different scales. Old-growth deciduous forests is severely fragmented in Europe and the most important substrates for saproxylic beetles in this habitat is hollow veteran trees. In this study, we used an extensive field survey data, mapping all large and/or hollow oaks (ca 33,000) in an area of 10,000 km² in south-eastern Sweden. With beetle occurrence data from 38 sites we did a multi-scale analysis of how different beetle species responded to oak density. A total of 16 species responded significant to substrate density from 52 m to 5200 m showing that conclusions made from data measured on a single scale may lead to wrong conclusions. We hypothesized that larger species should respond to larger scales and that both local and landscape scales should be important for several species. We found no evidence for that larger species responded to substrate density at larger scales. However, several species as e.g. Tenebrio opacus, responded to oak density at both small a scale (92 m) and a large scale (859 m). The reason for the importance of two scales is probably that several processes are acting on different time scales and therefore over different spatial scales. Individual oaks may act as static patches in the short term and the small-scale response may reflect the scale of metapopulation dynamics. However, as changes in the densities of old oaks over larger landscapes over several centuries occurs, long-term substrate dynamics are expected to act over larger areas, reflecting the larger scale. The variation in species response to substrate density at different scales means that habitat loss and fragmentation will have different effects upon different species.

A key aspect for understanding species distributions is how they respond to habitat factors at different spatial scales. In this study we used a dataset mapping 33,000 large/hollow oaks, habitat for a guild of saproxylic beetles specialised on oaks at an extent of 10,000 km². A total of 16 oak-dependent saproxylic species, out of 35, showed a clear relationship with substrate density at scales ranging from 52 m to ⩾5200 m. The characteristic scale of response for species richness of oak specialist species was 2284 m. At this scale, there was a tendency for richness to plateau at about 0.15 oaks ha⁻¹, in which case about 250 hollow or large (circumference 310 cm) oaks would be needed in an area of 1600 ha to ensure a rich saproxylic oak fauna.

The main general conclusions were: (i) a multi-scale approach is especially valuable to identify the characteristic scale of response; and that assuming a joint, single scale for all species may result in very poor decision support. (ii) The variation in species’ responses to substrate density at different scales means that habitat loss and fragmentation as well as management and restoration may have very different effects upon different species. (iii) Some species respond both to local and landscape scales, indicating that species occurrences in fragmented oak landscapes are affected both by short-term dynamics of the beetles and long term dynamics of the oak substrate. (iv) Maps, useful as decision support, can be constructed based on resource availability (in our case oak density) and characteristic scales.

Metapopulation theory has generally focused only on the stochastic turn-over rate among populations and assumed that the number and location of suitable habitat patches will remain constant through time. This study combines in a PVA both the deterministic landscape dynamics and the stochastic colonisations and extinctions of populations for the butterfly Lopinga achine in Sweden. With data on occupancy pattern and the rate of habitat change, we built a simulation model and examined five different scenarios with different assumptions of landscape changes for L. achine. If no landscape changes would be expected, around 80 populations are predicted to persist during the next 100 yr. Adding the knowledge that many of the sites are unmanaged and that the host plant will slowly deteriorate as canopies close over, and adding environmental variation and synchrony, showed that the number of populations will decrease to around of 4.3 and 2.8 respectively, with an extinction risk of 34% - quite different from the first scenario based only on the metapopulation model. This study has shown the importance of incorporating both deterministic and stochastic events when making a reliable population viability analysis. Even though one can not expect that the long-term predictions of either occupied patches or extinction risks will be accurate quantitatively, the qualitative implications are correct. The extinction risk will be high if grazing is not applied to more patches than is the case today. The simulations indicate that an absolute minimum of 10-30 top-ranked patches needs to be managed for the persistence of the metapopulation of L. achine in the long term. The same problem of abandoned and overgrowing habitats affects many other threatened species in the European landscape and a similar approach could also be applied to them.

The distribution of occupied and vacant sites and migration of the threatened butterfly Lopinga achine were studied in the province of ╓sterg÷tland, Sweden. The probability of occupation increased with increasing patch area and decreasing distance to the nearest occupied patch, presumably due to different probabilities of colonisation and survival of the populations inhabiting the patches. Probability of female emigration from and immigration to a patch increased with decreasing area. Middle-sized patches produced the largest number of female migrants, although the highest fraction was noted for the smallest patches, and the greatest number of females was marked in the largest patch. The fraction of resident females, but not males, increased with increasing area. The observed occupancy and migration pattern have important conservation implications: all but two populations comprising three or more individuals were within 740 m of the nearest neighbour, indicating the need for networks of suitable, closely situated patches. ⌐ 2001 Elsevier Science Ltd. All rights reserved.

The red-listed butterfly Lopinga achine was studied by mark-recapture methods in southern Sweden for three seasons. We examined movement within and between populations and egg production in relation to age. The majority of the movements were small with mean movements between recaptures of 45-54 m for males and 94-116 m for females. There were few movements between sites, 20 of 996 recaptured males moved and 36 of 391 recaptured females, even though the distance to other sites was in many cases < 100 m. The distance moved and the number of females moving between sites increased with increasing age. On average, a female that moves does so after laying two-thirds of its eggs in its natal site. It is therefore important to take account of the proportion of reproductive effort involved in dispersal when estimating colonisation ability. The males did not move more with increasing age. Female behaviour can be seen as a "spread-the-risk" strategy, an adaptation to the successional habitat of L. achine, whose natal site sooner or later will deteriorate. Butterflies like L. achine living in successional habitats may exhibit mobility that is intermediate between butterflies living in ephemeral habitats (very mobile) and in long-lived habitats (sedentary). ⌐ 2002 Elsevier Science Ltd. All rights reserved.

This thesis has two main focuses; first, the response of forest ground layer flora on forestry, mainly harvesting and secondly, the quality of the vegetation assessment methods, cover estimates by eye and presence/absence data.

The effect of harvesting intensity was evaluated with survey data from permanent plots as well as vegetation data from a field trial fourteen years after harvesting. Both data sets confirmed that response of ground layer flora increased with increasing logging intensity. Thereby, indicating that survey data is possible to use in research. From the survey data set, existence of a time lag was evident for several species and also a threshold level was evident in cutting intensity needed to affect a number of species. Logging had a modest, but significant positive effect on the change in species number per plot. Species turnover was influenced by the proportion of Picea abies in the tree canopy; site productivity; and logging intensity. In the field trial scarification had a strong effect that was different from the one created by cutting.

In plant ecology cover estimate by eye and presence/absence recording are the two most frequent methods used. The methods were evaluated with survey data and a field trial.

In the first data set vegetation was recorded independently by two observers in 342 permanent 100-m² plots. Overall, one third of each occurrence was missed by one of the two observers, but with large differences among species. Species occurring at low abundance tended to be frequently overlooked. Observer-explained variance in cover estimates was <10% in 15 of 17 species.

In the second data set, 10 observers independently estimated cover in sixteen 100-m² plots in two different vegetation types. The bias connected to observer varied substantially between species. The estimates of missing field and bottom layer had the highest bias, indicating that missing layers are problematic to use in analysis of change. Experience had a surprisingly small impact on the bias connected to observer. Analyses revealed that for the statistical power, cover estimates by eye carries a higher information value than do presence/absence data when distinguishing between vegetation types, differences between observers is negligible, and using more than one observer had little effect.

Question: How does the vegetation of boreal forests respond to harvesting and scarification?

Location: 650 m a.s.l., central Sweden (61°38' N).

Methods: The response of boreal forest vegetation to cutting and scarification was studied in a field trial, which consisted of three treatments plus conventional harvesting as a control in a complete block design with four replicates. The cutting was done 14 years prior to vegetation inventory and scarification and planting were conducted the first or second years after cutting.

Results: The species most abundant at higher cutting intensities were crustose lichens, Cladonia spp., Cladina arbuscula, Polytrichum spp. and pioneer mosses, the grass Deschampsia flexuosa, and the tree Betula pubescens, A few species had substantially lower abundance in treatments with higher cutting intensity, notably Hylocomium splendens and Vaccinium myrtillus. Scarification had a strong effect that was different from the one created by cutting. In scarification treatments, Polytrichum spp. were the only species with high abundance; most species had low abundance, i.e. Barbilophozia lycopodioides, Vaccinium vitis-idaea, Pleurozium schreberi, Carex globularis, Empetrum nigrum, Cladina arbuscula, Sphagnum spp.

Conclusions: Our results elaborate on the details of the well-known effect of cutting on ground-layer flora, and also give support for the profound and long-lasting effect that soil scarification has on forest vegetation.

The relationship between logging intensity and changes in ground cover vegetation was studied in 16 species and groups of species recorded at 10- or 11-year intervals in mature conifer-dominated forests. The 789 plots located in northern and central Sweden had been surveyed by the National Forest Inventory and the National Survey of Forest Soil and Vegetation. Thirty-seven percent of the plots had been subjected to a thinning or clear-cutting between the inventories. A principal components analysis showed that, of the variables considered, logging intensity had the highest explanatory power regarding change in ground cover vegetation between the inventories (the other variables were sum of temperatures, age of stand, timber volume, percentage Pinus sylvestris and site productivity). A multivariate direct gradient analysis technique (Redundancy analysis) showed that the logging intensity significantly affected the change in cover. This analysis also ranked the species in their responsiveness to logging. Epilobium angustifolium, narrow-leaved grasses and broad-leaved grasses, increased most with logging intensity. The response was not linear and only detectable at high logging intensities (>80%). In contrast, Vaccinium myrtillus seemed to decrease linearly with increased logging intensity. There was several years time-lag in the response to logging of E. angustifolium, V. myrtillus and narrow-leaved grasses. Several species and groups of species seemed unaffected by the logging. In sample plots unaffected by logging the cover of most species decreased.

 On two occasions, with a 10- or 11-year interval, species occurring in 650 plots (100 m2) in boreal production forests in Sweden were recorded within a monitoring program. During this interval, many of the plots had been subjected to varying degrees of timber extraction. The presence of 49 vascular plant species or species groups was recorded and we evaluated how species number varied over time. There was an overall increase in species number, probably partly reflecting changing attitudes and strategies for fieldwork. Logging had a modest, but significant positive effect on the change in species number per plot. When analysing individual species, three of 18 showed a differential response along the logging gradient: Linnea borealis was more likely to appear at low logging intensities while the opposite pattern was present in Epilobium angustifolium and Calluna vulgaris. A species turnover index was calculated per plot and used as the dependent variable in a multiple regression with six independent variables. Three of these contributed significantly to the model: turnover increased (i) with decreasing amounts of Pinus sylvestris in the tree canopy; (ii) with increasing site productivity; and (iii) with increasing logging intensity. Hence, greatest changes over time occurred in stands lacking P. sylvestris (consequently dominated by Picea abies) that occurred on fertile soil, and was amplified by logging.

Cover estimates by eye is a prevailing method to assess abundance. We examined cover estimates with regard to bias and random variation. Ten observers working with a national forest vegetation survey estimated sixteen 100 m(2)-plots, placed in two different vegetation types. These had similar species composition but were clearly distinguishable in the field. In species-wise analyses, observer bias varied greatly, with Dicranum spp., Vaccinium vitis-idaea and Vaccinium myrtillus having the largest bias. Experience had a surprisingly small impact on variation. Power analysis revealed only small differences between observers in the ability to distinguish the two vegetation types, and little value in averaging the assessments from two, three or four observers. Cover estimates did better than presence/absence data in separating the two vegetation types and multivariate analyses were more powerful than univariate ones.

Effects of inlet design and vegetation type on tracer dynamics and hydraulic performance were investigated using lithium chloride in 18 experimental free water surface wetlands. The wetlands received similar water flow but had different vegetation types: 6 emergent vegetation wetlands (EVWs), 6 submerged vegetation wetlands (SVWs) and 6 free development wetlands (FDWs). Two types of inlet designs were applied: half of each wetland vegetation type had a barrier near the inlet to help distribute incoming tracer solution, while the rest had no barrier. Residence time distribution (RTD) functions were calculated from tracer data using two techniques: method of moments and a novel Gauss modelling approach. RTD functions were used to quantify hydraulic parameters: active wetland volume (e-value), water dispersion (N-value) and hydraulic efficiency (λ-value).

For wetlands without barrier, significantly lower tracer mass recoveries were found from EVWs compared to FDWs and SVWs, signifying a risk of tracer methodological problems in small densely vegetated wetlands. These problems were minimized in wetlands with an inflow construction promoting distribution of incoming tracer solution.

Compared to the method of moments, Gauss modelling seemed to produce more reliable λ-values but less reliable N-values. Data for precise hydraulic quantification were lost by Gauss modelling, as indicated by overall lower variance in these data sets and lower mass recoveries. However, Gauss modelling may minimize uncertainties associated with lithium immobilization/mobilization. Parameters were significantly affected by the RTD data analysis method, showing that the choice of method could affect evaluation of wetland hydraulics.

The experimental wetlands in this study exhibited relatively high e-values and low N-values. This was probably caused by the small size of the wetlands and low water flow velocities, emphasizing that hydraulic parameter values obtained in small experimental wetlands may not be applicable to hydraulics in larger wetlands.

The method of moments revealed lower e-values from EVWs compared to SVWs and FDWs. It was indicated that lower e-values were mainly caused by vegetation volumes. This highlighted a need for regular maintenance to secure efficient treatment volume in wetlands with dense vegetation.

This study investigated, using a lithium salt tracer, how macrophyte species and hydraulic loading rate (HLR) of wastewater influenced hydraulics in constructed wetlands (CWs). Four pilot-scale CWs received 45 mm day(-1) of pre-treated sugar factory effluent and another four received 110 mm day(-1). Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Results showed a significant negative connection between tracer mass recovery and wetland water leakages. Also, a significant negative relationship between active wetland water volume and macrophyte density was detected. Further, a significant effect of HLR on mass removal rates of NH4+-N was observed. However, no significant effect of either HLR or macrophyte species on wetland hydraulic parameters was found.