Frank Götmark

University of Gothenburg | GU · Department of Biological & Environmental Sciences

Under the Paris Agreement, nations made pledges known as nationally determined contributions (NDCs): national climate plans detailing countries’ ambitions to adapt to climate change and reduce greenhouse gas emissions. Population growth is a driver of both climate vulnerability and climate-altering emissions. We asked, to what extent do countries t...

In northern Europe, a long history of human exploitation effectively eliminated legacies of natural disturbances in mixed oak forests and we currently lack understanding of the role of natural disturbance factors in affecting oak regeneration into the forest canopies. We compiled dendrochronological, observational and paleochrono-logical data from...

In even-aged clear-cutting forestry, the biodiversity effects of treatments must be well understood for proper forest management and conservation. While biodiversity on clear-cuts has been much studied, other common forestry stages such as thinning have received less attention. We studied saproxylic beetles, a highly diverse group with many red-lis...

Background: The world population is expected to increase greatly this century, aggravating current problems related to climate, health, food security, biodiversity, energy and other vital resources. Population growth depends strongly on total fertility rate (TFR), but the relative importance of factors that influence fertility needs more study. M...

This article clarifies the potential environmental impacts of more or less expansive EU immigration policies. First, we project the demographic impacts of different immigration policy scenarios on future population numbers, finding that relatively small annual differences in immigration levels lead to large differences in future population numbers,...

Forest cover is increasing in many regions due to spontaneous reforestation on abandoned pastures and fields. The resulting recent forests may need management to improve ecosystem quality, and this could possibly be combined with timber production in specific cases. Temperate deciduous (TD) trees have declined steeply during the past millennium, bu...

Many tree species worldwide are suffering from slow or failed natural regeneration with dramatic consequences for biodiversity and ecosystem services. However, it is difficult to disentangle the complex effects of factors influencing regeneration processes on long-lived tree species at large scales. In this study, we use long-term data from the Swe...

Secondary succession in protected oak-rich temperate forests reduces variation in habitats and leads to denser, shadier sites. Long-term experimental studies of the effects of conservation management alternatives are needed for such forests. Here we present a rare follow-up study of the response of beetles (a highly diverse taxon with many red list...

As the nations of the world grapple with the task of creating sustainable societies, ending and in some cases reversing population growth will be necessary to succeed. Yet stable or declining populations are typically reported in the media as a problem, or even a crisis, due to demographic aging. This is misguided, as economic analyses show that th...

I diskussionen om miljö och vår framtid bör också över-befolkning lyftas fram. Frågan undviks ofta i samhälls-debatten-trots att den är central. Vi uppmanar den svenska regeringen att ta upp frågan i FN, skriver flera debattörer. 21 jul, 2018 Svenska Dagbladet DEBATT | FOLKÖKNINGEN FN upprättade 2015 sjutton globala mål för Agenda 2030. Dessa mål u...

Opinion article, Immigration levels and environmental aspects

Nyheter 6 Folkbladet Söndag 12 november 2017 D en framtida folkökningen i världen-50 procent fler människor till 2100 enligt FN-beror främst på höga födelsetal i många länder. Ökade insatser inom familjeplanering kan minska födelsetalen. Sverige ligger nära den s k ersättningsnivån (två barn per kvinna) och invandringen gör nu att befolkningen ökar...

Review of population growth and overpopulation

T änk dig världen år 2100. En prognos förutsäger att det då finns 3,6 miljarder fler män­ niskor, utöver de 7,6 miljar­ der som finns idag. I Afrika, varifrån människor idag söker sig till Europa, förväntas befolkningen öka från 1,3 till 4,5 miljarder. I juni publicerade FN sin befolkningsprognos, men ingen tongivande politiker, beslutsfattare och...

We describe advantages for a shrub compared to a small tree with the same above-ground woody volume, based on larger cross-sectional stem area (Fig. 2b), larger area of photosynthetic tissue in bark and stem, larger vascular cambium area, larger epidermis (bark) area (Fig. 2c) and larger area for sprouting, and faster production of twigs and canopy...

Shrubs are multi-stemmed short woody plants, more widespread than trees, important in many ecosystems, neglected in ecology compared to herbs and trees, but currently in focus due to their global expansion. We present a novel model based on scaling relationships and four hypotheses to explain the adaptive significance of shrubs, including a review...

Opinion, in Newspaper, on population (Swedish)

Schultze et al. (Biodiv Conserv 23:3519-3542, 2014) analysed criteria for the selection of strictly protected forest reserves in central Europe, but did not clarify the value of strict reserves (IUCN type 1a) for scientific research. We suggest that research in protected areas (PAs) should be included in the criteria that are used for their selecti...

Svenska Dagbladet måndag 16 november 2015 20 T änk er följande nyhet: " FN:s långvariga förhandlingar har krönts med fram­ gång i Paris. Ett bindande avtal om begränsning av befolkningen har undertecknats av nästan alla länder. Avtalet innebär att befolknings­ ökningen sannolikt upphör 2050, och ett framtida mål om 6 miljarder människor. Forskare b...

Secondary succession is changing the character of many temperate forests and often leads to closed-canopy stands. In such forests set aside for conservation, habitat management alternatives need to be tested experimentally, but this is rarely done. The Swedish Oak Project compares two often debated alternatives: minimal intervention and non-traditi...

Many trees sprout after cutting and other disturbances, and individuals may persist for a long time. In 25 forests in Sweden subjected to thinning for biodiversity values, we tested whether survival and growth of sprouts are related to stump diameter. Stem diameters vary under conservation thinning and earlier work had indicated high survival of st...

In broadleaved temperate forests in Europe, oak (Quercus robur/Q. petraea) regeneration is reported to be weak or absent. However, most work concern seedlings or saplings, studied relatively few years. We studied a Picea abies stand in Sweden, windthrown and logged (all stems harvested) in 1969, testing the hypothesis that oaks regenerate in the lo...

The strongly increasing demand for biofuel from forests poses new challenges for biodiversity conservation. Methods that may combine biofuel production with conservation goals need to be tested for various forest types. One possible conservation-oriented management alternative is partial cutting of closed canopy oak-rich forests (may also be called...

In an earlier study (Franc et al., 2007), local species richness of saproxylic oak beetles (including red-listed beetles) in forests was predicted mainly by the landscape (area of woodland key habitat within 1km of plots). Such results are important for conservation work, but need to be backed up well, for reliable advice. We tested a two-stage met...

We studied occurrence of oak seedlings (Quercus robur L. and Q. petraea Liebl.) in 11 semi-natural oak-rich temperate forests in south Sweden after partial cutting (mean harvest; 26% of basal area). Earlier studies show that canopy openness is positively correlated with oak seedling performance. We used 20 pairs of subplots in each forest, with and...

The management of reserves and other forests with high biodiversity values is debated. Focusing on south Sweden (Fig. 1), I review non- or minimal intervention ("free" succession), traditional management (e.g. grazing, pollarding) and careful partial cutting (conservation thinning, stands with >75% canopy closure). The alternatives are based on 1)...

The process of protection (e.g. reserves, agreements) on the lands of non-industrial private forest (NIPF) owners sometimes leads to conflicts (conflict: a perceived threat to needs, interests or concerns; in this study, “threat” was important). To investigate predictive factors for such conflicts in southern Sweden, a questionnaire was sent to 132...

Although protected forests are usually kept as free of human disturbance as possible, careful cutting may favour biodiversity in such areas. However, the use of heavy machinery during cutting operations may have a negative impact on protected forests. The large oaks (Quercus spp.) found in many temperate nature reserves have a rich associated biodi...

The effect of harvesting biofuel and woodland restoration on biodiversity is debated. To evaluate the effects of partial cutting on more organism groups, we used pairwise experimental and undisturbed control stands in a large landscape. On average 26% of the basal area including 50–95% of the understorey was harvested at each of 15 oak-rich forest...

The appropriate management of forest reserves is debated; two major alternatives are succession to ‘wild’ state, or management to produce semi-open stands. For temperate conservation stands, there are no strong experiments replicated at landscape level. In each of 22 forests rich in oaks (Quercus spp.) in Sweden, we set up a closed-canopy wild plot...

Semi-open oak-rich forests may support many species adapted to large trees and coarse woody debris. Currently many oak-rich forests in northern Europe have more or less closed canopies due to lack of natural and cultural disturbances. In these forests, conservation oriented partial harvesting of biofuel may restore a desired forest structure and li...

Partial cutting is increasingly applied in European temperate oak-dominated forests for biofuel harvesting, and to counteract succession in protected stands. Effects on biodiversity of these measures need to be carefully evaluated, and species-rich but neglected taxa such as fungi should be considered. We studied the effects of partial Cutting on f...

The effectiveness of different conservation policies is debated, but the policies are rarely evaluated quantitatively. A voluntary or 'soft' policy based mainly on education provides information about ecosystems and effects of land use, to encourage conservation action. Swedish forestry relies mainly on soft policy, with substantial resources for e...

Aim  To investigate the relative role of local versus landscape factors for local species diversity of snails and slugs in conservation forests. In landscapes with small, isolated patches of semi-natural habitats, many species that require large habitat areas have disappeared or are threatened. We asked whether small sedentary taxa that depend on l...

Hooded Crows Corvus cornix, Great Black-backed Gulls Larus marinus and Herring Gulls L. argentatus were the main nest predators in an Eider population in southwest Sweden. The clutch sizes of Eider nests within gull colonies did not differ from those outside gull colonies. The proportion of Eider nests destroyed by predators was significantly lower...

In Europe, many semi-open pasture woodlands with oaks (Quercus robur and Q. petraea) have been invaded by other trees. The management alternatives for such stands are often debated. Protection (i.e. no cutting) versus partial harvest to favour oak regeneration was studied in two matched plots in 25 forests in Sweden. A mast year produced on average...

In the Nordic countries, sets of Indicator (Signal) species, predominantly cryptogams, have been used as one measure to find forest stands which may harbour Red List species. Such data could potentially also be used to prioritise among stands for protection as nature reserves. We studied if the number of Signal species indicates the number of Red L...

The influence of environmental factors on species richness and species composition may be manifested at different spatial levels. Exploring these relationships is important to understand at which spatial scales certain species and organism groups become sensitive to fragmentation and changes in habitat quality. At different spatial scales we evalua...

The first rnodern Swedish checklist of fungus gnats of the families Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae and Mycetophilidae is presented. The checklist results from a comprehensive literature research as well as treatment of a considerable determined and undetermined material from Swedish museum collections and recent material f...

The landscape context is crucial for forest conservation in regions where the natural forest is fragmented. The focus of practical conservation is currently shifting from local stands to a landscape perspective, but few studies have tested the relative effect of different spatial and temporal scales for occurrence and persistence of species of cons...

Bright plumage, song display, and aggressive resource defence in males may cause higher predation on males than on females during the breeding season. However, in birds, higher predation on females is sometimes observed. Parental investment may be high in females (egg-laying, incubation and feeding of offspring), which might lead to a high risk of...

Studies of Sparrowhawk Accipiter nisus predation have revealed a seasonal change in the predation risk of many prey species during spring and summer. Several species nesting in forest experienced decreasing risk of predation, while species in semi-open habitats (farmland, edge habitats and villages) faced increasing risk. The reason for this change...

Forests in south Sweden are dominated by spruce and pine, but broadleaved trees, especially "noble" (hardwood) tree species, are increasingly considered important for nature conservation and forestry. For saplings (from 130 cm tall to 5 cm in diameter at breast height) recorded in the National Forest Inventory 1998-2002, we show (Fig. 1) that the r...

In many birds, breeding males display bright colors, sing, and engage in active territory defense; whereas females are less conspicuous. Therefore, it is sometimes assumed that in the breeding season males suffer higher predation than females. Several studies have reported, however, higher female predation rates, which suggests that traits other th...

Partial harvesting of forest for biofuel and other products may be less harmful to biodiversity than clear-cutting, and may even be beneficial for some species or groups of organisms such as herbs. There are, however, few well-controlled experiments evaluating positive and negative effects, such as species losses directly after harvest. In closed c...

Forests and forestry in Sweden are dominated by conifers. Silviculture using mixed or broadleaved stands is often recommended, but the degree to which broadleaves regenerate naturally needs to be clarified. The Swedish National Forest Inventory is here used for a region-wide study of broadleaved saplings (1.3 m tall to 4.9 cm dbh) regenerated natur...

Buffer zones may reinforce protected areas and are often recommended, but have rarely been systematically studied in temperate forests. Globally, temperate broadleaved forest is considered to be the most disturbed biome, with small, scattered natural fragments. In theory, it is often assumed that nature reserves have heavily exploited surroundings....

Absence of, or poor, oak ( Quercus spp.) regeneration is a problem in uneven-aged, mixed closed-canopy broadleaved forests. Browsing by ungulates on small trees may contribute to poor oak regeneration in such forests. This possibility was investigated in 25 Swedish stands, and browsing damage was analysed in relation to landscape and stand factors....

Predators may regulate prey populations if predation rate increases with prey density. Alternatively, if space-limited (e.g. territorial) predators become 'satiated' when prey exceed a certain density, increased prey abundance may lead to reduced predation rate. These alternatives have been difficult to test experimentally for mobile prey in the wi...

Fungus gnats in boreonemoral forests of south Sweden are studied using material collected with Malaise and window traps from 17 localities in the years 2001 and 2002. 250 species are recorded including 78 species new to Sweden. 14 of these are found in Fennoscandia for the first time: Docosia setosa LANDROCK, D. sp. (indet. s. HUTSON et al.), Brevi...

Dead wood is essential for biodiversity in forests and is therefore often surveyed in conservation inventories. Usually only coarse downed trees (logs) and standing dead trees (snags) are surveyed, but dead wood also occurs on living trees, in stumps, and in fallen branches. Attached, standing (including stumps) and downed dead wood with a diameter...

Dead wood is considered important in forest conservation, but patterns of fungal diversity on dead wood have rarely been quantified. We investigated the relative importance of coarse (diameter >10 cm) and fine woody debris (1–10 cm) for fungi in broadleaf forests in southern Sweden. The numbers of species per unit wood volume and per forest area we...

The optimal size of nature reserves has been debated for some time. Although edge and core habitats are often recognized, it is commonly assumed in theory and in studies of a particular habitat type that reserves or patches of different sizes have similar habitat structure. However, for older, highly fragmented landscapes it has been suggested that...

Analyzed the extent to which landscape and habitat types in Sweden are represented in areas protected by the Nature Conservation Act. A total of 1175 national parks, nature reserves, and nature conservation areas comprised 4.7% of the total Swedish territory on 31 December 1986 (the proportion increased to 5.9% in 1990). Among landscape types, a ve...

The selective pressures determining timing of reproduction and brood or litter size in animals remain to be clarified, despite much research. In several detailed studies of birds, selection for an early start of breeding has been demonstrated. Young born early in the season are often assumed to benefit from long experience, high dominance in flocks...

Buffer zones around reserves are often suggested, but have rarely been evaluated. We examined their design for small forest reserves (5–225 ha), where buffer zones (200 m wide) would protect the reserves and reduce negative edge effects. The potential buffer zones could be partly protected, but remain as private land. Alternatively, the state may b...

Ecologists are developing methods for the design of reserve systems, but non-ecological factors or criteria may limit their applicability (e.g. threat, initiative, low-cost opportunities). Threat before reserve acquisition (i.e. direct threat, contributing to reserve establishment) and the actors proposing reserves were studied for a random sample...

A general assumption is that bright colours, song and other traits of male birds lead to high predation risk; lower risk is often assumed for the more cryptic females. However, the reversed scenario is also a theoretical possibility, as breeding females spend much time foraging, which may increase predation. We examined predation on breeding chaffi...

Parental preferences during feeding and care-giving may select for ornamental traits in young, such as bright coloration. For chicks of coots, there is experimental evidence for this idea. We examined the hypothesis that bright yellow, orange and red mouths of chicks of songbirds have been favoured by feeding preferences in parents. In a field expe...

Parental preferences during feeding and care-giving may select for ornamental traits in young, such as bright coloration. For chicks of coots, there is experimental evidence for this idea. We examined the hypothesis that bright yellow, orange and red mouths of chicks of songbirds have been favoured by feeding preferences in parents. In a field expe...

Effects of egg size and parental quality on lapwing Vanellus vanellus chick survival were studied in southwestern Sweden over 6 years. Chicks from large eggs were heavier at hatching and survived significantly better than those from small eggs. To control for the confounding effect of parental quality on egg size and chick survival, we performed a...

A brightly coloured mutant may suffer increased predation (by being conspicuous) or may be favoured by reduced predation (if predators avoid novel or rare varieties). These alternatives were examined in a 2-year study of great tits,Parus majorby painting and ringing 1655 fledglings near 27 pairs of nesting sparrowhawks,Accipiter nisusA minority (<1...

Conspicuous color patterns in birds may lead to increased risk of predation. Alternatively, bright birds may be aposematic or unprofitable prey, which leads to decreased predation. During four autumns, I examined whether the black-and-white plumage of (stuffed) magpies Pica pica increases or reduces the risk of attack by migrating goshawks Accipite...

Predation is a fundamental ecological process, but there are few studies of predation risk for adult, breeding birds. In this study, we quantified Relative Predation Risk (RPR) for 46 species of passerine birds preyed on by sparrowhawks during the breeding season in south-western Sweden. The sparrowhawk is a major predator of smaller birds in Euras...

1. The initial evolution of bright colouration in animals is unclear. Many theoretical models assume that rare, conspicuous mutants suffer increased predation risk; however, decreased risk of predation is also a theoretical possibility. 2. In an earlier study where stuffed (dead) European Blackbirds, Turdus merula, were exposed in the field, Goshaw...

Several theoretical models assume that bright plumage in male passerine birds makes them easier to detect, increasing the risk of predation. Female plumage, on the other hand, is assumed to be cryptic. These assumptions have not been tested in the wild, and are not necessarily true: crypsis takes many different forms, and the sexes may evolve to an...

Bright colors in birds might signal that they are undesirable as prey (aposematic), an idea that has been difficult to test. When stuffed pied flycatchers Ficedula hypoleuca are exposed to migrating sparrowhawks Accipiter nisus in spring or in autumn, the hawks attack cryptic females more often than bright males. To achieve better statistical contr...

Detailed studies of edibility of birds suggest a negative correlation between visibility and edibility; in other words, bright birds may be aposematic (Cott 1947, Cott and Benson 1970). Cott used only females to assess visibility (judged not only from plumage but also behaviour and habitat). Here I reanalyse Cott's data, taking into account also pl...

Bright coloration in animals may be explained by sexual selection, defence against predators (aposematism), and other factors. However, the initial evolution of colourful coats is unclear. Theoretical models often assume that rare, bright mutants suffer increased predation risk. In the blackbird Turdus merula, I tested whether a novel colourful plu...

Conspicuous plumage in male birds may evolve through competition between males and choice of bright males by females. Male brightness might be constrained by increased risk of predation or other mortality agents. Alternatively, bright male birds may signal to predators that they are unprofitable as prey. These hypotheses, which have been difficult...

To study the influence of plumage coloration on male-male interactions and female choice of males, I dyed territorial males of the White-crowned Sparrow Zonotrichia leucophrys pugetensis. I compared (1) control males with normal black-and-white crown, (2) males with (dyed) black crown, showing less contrast than normal males, and (3) males with nor...

Sexual selection theory suggests that conspicuous plumage in male birds evolves through contest competition between males and choice of bright males by females. A basic assumption is that brightness is limited by increased predation or other mortality agents. Alternatively, the unprofitable prey hypothesis suggests that conspicuous birds signal to...

We examined 15 criteria used for selection of 1175 natural areas protected by the Swedish Nature Conservation Act. We categorized criteria as “scientific,” having botanical, ornithological, and geological values, or “political,” having human-oriented recreational, landscape, and cultural values. On average, 2.3 criteria were used per protected area...

Many passerine birds with open cup-shaped nests lay blue or blue-green eggs. In thrushes, blue eggs may be cryptic and provide camouflage by imitating spots of light on green leaves. Alternatively, egg coloration may be selectively neutral because nest predators detect nests and not eggs, or it may be maladaptive because organisms are not always we...

To learn about the behavior and ecology of nesting birds, we often study them when they occupy nesting territories. But by visiting territories or nests, the investigator may to a greater or lesser extent disturb the birds and affect the parameters being studied. Thus, we want to learn about the behavior or performance of birds under natural condit...

We examined whether artificial arctic loon (Gavia arctica) nests could be used to estimate predation rates on real unattended nests. In 1983 and 1984, only 3 (9%) of 34 artificial nests were preyed upon within 4 hours after they were laid out. However, if predators memorized the location of real nests and returned to prey upon unattended nests, use...

It has been suggested that colonies of terns function as information centres from which unsuccessful foragers follow other birds to feeding sites. From a sandwich tern colony in south-western Sweden, foragers departed in temporal synchrony and birds leaving at the same time headed preferentially in similar directions. However, unsuccessful foragers...

Gull predation on eider ducklings Somateria mollissima in an archipelago on the Swedish west coast is described. Both gull encounter rate and gull predation rate were 200–300 times higher on crèches disturbed by boats than on undisturbed crèches. Encounter rates increased with the proximity of the crèche to breeding sites of gulls and to passing bo...

An earlier study showed that, during incubation, predation on Eider Somateria mollissima nests in gull colonies was lower than on nests elsewhere. Surprisingly, Eiders do not strongly favour nesting in gull colonies. One reason for this could be a high risk of nest predation in gull colonies during the Eider laying period, when gulls have not start...

We studied 20 pairs of arctic loon (Gavia arctica) at 2 adjacent lakes 2 years before and 5 years after 1981, when public access to most nesting islands was prohibited. The mean annual production of young/territorial pair was 0.08 before and 0.38 after sanctuaries were established. Hatching success increased in sanctuaries but not on unprotected is...

It has been suggested that white underparts in gulls and other seabirds render them inconspicuous to their aquatic prey against the bright sky. White underparts may therefore facilitate capture of prey and act as ‘hunting, camouflage’. To test this idea, black-headed gulls, Larus ridibundus, were allowed to hunt schooling bleak, Alburnus alburnus,...

Bird censuses in two wetland habitats (bogs and wet meadows) in SW Sweden were used to test the applicability of five conservation indices suggested for birds. The censused sites were first evaluated and ranked by the authors, then ranked according to each of the indices. Two indices based on species diversity (H′ or Λ) showed a poor agreement with...

Flock-foraging and the role of white plumage in gulls and other seabirds have been the subject of much debate. At first sight it seems that competition within the flock would render flock formation against the interest of the bird who finds the fish school, as the fish must then be shared with birds joining the flock. However, it is also possible t...

It is often suggested that colonial breeding reduces nest predation for birds with a high defence capacity, but experimental comparison of predation at solitary and colonial nests is seldom feasible within a single species. We here report on such a test in the common gull (Larus canus). The rate of predation on experimental eggs was significantly l...

Tested whether avian predators are attracted to islands in S Sweden where observers flush incubating Somateria mollissima. Abundance of hooded crows Corvus cornix was slightly lower after disturbance than before, although many eider nests were exposed after disturbance crows did not increase their foraging effort or success in finding nests on the...

Larus marinus mainly eats fish, and feeds more on birds than the other species. L. argentatus feeds on refuse, fish offal, marine invertebrates and sometimes also takes earthworms and grain on fields. L. fuscus mostly eats fish, which may be caught or taken at fishing boats; it also forages on fields, and takes refuse (though to a lesser extent tha...