From mixtures to monocultures: Bird assemblage responses along a production forest conifer-broadleaf gradient

Increasing the prevalence of broadleaf trees in conifer-dominated production forests is a recommended means of improving habitat availability for broadleaf and mixed-forest species. The implications for biodiversity are often measured by contrasting broadleaf-conifer mixtures with conifer-dominated stands. However, few studies include broadleaf-dominated stands in these assessments. Here we contrasted the bird assemblages of even-aged production forests along a mixture gradient from Norway spruce (Picea abies) dominated, to birch (Betula spp.) dominated stands in southern Sweden. We conducted point count surveys of bird individuals exhibiting breeding behaviour within 30 stands varying from <0.5% to over 98.5% broadleaf by basal area. A total of 355 birds were detected, comprising 36 bird species, seven of which are classified as near threatened by the Swedish Red-list. Our results indicate i) a distinct shift in bird community composition linked to the percentage of broadleaf trees at stand and landscape scales, ii) significantly higher bird species richness, evenness, and abundance in stands with a higher proportion of birch, iii) higher bird abundance in birch-dominated stands than in mixtures, and iv) shifts in bird species guilds as related to stand basal area, the amount of shrubs in the understory, and quantities of dead wood. All of these results have implications for the ways in which production forest management could be altered to enhance avian diversity, and we discuss these with respect to the use of broadleaf versus mixed-species stands

The Nutritional Ecology of Spider Monkeys (Ateles chamek) in the Context of Reduced- Impact Logging

Selective harvesting of timber in tropical forests can remove substantial amounts of primate food sources, resulting in significant reductions in population densities. As frugivorous primates are important seed dispersers in tropical forests, it is crucial for long-term ecological sustainability to maintain their populations within forestry concessions. One way of achieving this goal is to gather relevant information regarding the importance of commercial timber tree species in the diet of seed dispersing primates and ultimately suggest adjustments to timber extraction rates to minimize detrimental impacts on primate food resources. In this thesis I first describe the diet and temporal patterns of food consumption by the Peruvian spider monkey, Ateles chamek, inhabiting a semi-deciduous moist forest that is incorporated in a certified forestry concession in lowland Bolivia (Chapter 2). I then determine what governs their diet selection (Chapter 3), and analyse how this nutritional strategy influences seasonal diets and the resultant nutritional states of individuals, and estimate the relative value of different food sources (Chapter 4). These threads of information are combined to assess the importance of timber tree species in the diet of these primates as a basis for recommendations for forest management and primate conservation (Chapter 5). As such, an overreaching aim of this thesis is to contribute to the understanding of the effects of certified tropical forestry on biodiversity conservation. Six general conclusions arise from this thesis: 1. Feeding ecology of Ateles chamek in La Chonta differed from other documented spider monkey diets because of the dietary dominance of ripe and unripe figs. 2. Diet selection was governed by protein-dominated macro-nutrient balancing, rather than energy or protein maximization, or avoidance of plant secondary metabolites. 3. The food intake strategy employed by individuals and their resultant nutritional state depended upon the seasonal availability of different foods. Due to seasonal availability of fruits rich in soluble carbohydrates and lipids, intake of these macro-nutrients was 50% higher during peak fruiting season than during the period of fruit scarcity. 4. Figs were nutritionally-balanced foods for spider monkeys, and the inclusion of a diverse array of ripe fruits in their diet appeared to be used as a strategy for persisting through times of fig scarcity. 5. Timber tree species provided spider monkeys with 50% of their macronutrient intake, comprised their staple food, and dominated their peak season and fall-back diets. 6. Under current prescriptions for timber extraction the spider monkeys in La Chonta are expected to lose significant proportions of their food sources. This is a likely explanation for the observed declines in population density post-logging. Harvesting limitations should be considered for the timber tree species Ficus boliviana, Spondias mombin and Pouteria nemorosa

The proximity of rapeseed fields influences levels of forest damage by red deer

Deer can show transitional use between agricultural fields and forests for foraging and shelter. Such transitional use may affect forest damage as nutrient balancing theory suggests that if deer ingest large amounts of nutrient-rich food, complementary browse, such as bark, may be required to balance the diet.We investigated the relationship between the level of red deer Cervus elaphus bark-stripping damage in 68 Norway spruce Picea abies stands and the presence of rapeseed Brassica napus fields – an energy-rich crop preferred by red deer – in the surroundings, hypothesizing that damage increases with decreasing distance to rapeseed fields. We also considered other potentially influencing factors, such as supplemental feeding, alternative forage availability, and deer use of spruce stands as indexed by a pellet group count.Spruce stands closer to rapeseed had a significantly higher proportion of damaged stems. The increased level of bark-stripping damage was not explained by a higher stand use of deer closer to rapeseed fields, indicating that deer increase their consumption of bark in order to balance their diet. Similarly, spruce stands closer to supplemental feeding stations had significantly higher damage levels.In line with earlier findings, damage levels were negatively related to the amount of available browse in the forest. This emphasizes the importance of alternative forage for reducing the damage risk in forest plantations.Our study shows that the availability of fields with nutrient-rich food, such as rapeseed, as well as supplemental feeding needs to be considered when predicting the level of forest damage. With a high availability of nutrient-rich food in the vicinity of forest stands, a higher damage level can be expected and counteractions could be taken such as increased disturbance, harvest or changed choice of both crop and supplemental feed types. These actions may also be combined with a push–pull strategy where the deer are steered to disturbance-free zones insensitive to damage and with alternative forage. The importance of alternative forage availability on damage levels highlights the necessity for managers to actively promote tree and shrub forage within and around their production stands

Priorities in policy and management when existing biodiversity stressors interact with climate-change

There are three key drivers of the biodiversity crisis: (1) the well known existing threats to biodiversity such as habitat loss, invasive pest species and resource exploitation; (2) direct effects of climate-change, such as on coastal and high elevatio

Nutritional niche separation between native roe deer and the nonnative fallow deer-a test of interspecific competition

On an evolutionary time scale, competition for food drives species formation by genetic adaptations to the environment and subsequent niche separation. On a short-term scale, animals use different strategies to meet their nutritional requirements, which ultimately influence their fitness. Understanding these adaptations in herbivores is especially important in temperate climates where animals have adapted both physiologically and behaviorally to seasonal variations in order to meet their nutritional requirements. The aim of this project was to investigate temporal variation in chemical composition of rumen content between two coexisting species of large herbivores, the native roe deer (Capreolus capreolus L.) and the introduced fallow deer (Dama dama L.), as well as a potential effect of competition on niche separation (interspecific differences in rumen nutrient composition). We analyzed 345 rumen samples collected from animals at one 95 km(2) estate, Koberg, in southwestern Sweden. Based on samples from all seasons, temporal variation in nutrient composition and interspecific differences between the two deer species were investigated under two contrasting fallow deer population densities. Results revealed that nutrient composition varied between species and across seasons. Roe deer had a higher proportion of rumen protein compared to fallow deer, with the highest proportions in spring. In contrast, fallow deer had a higher proportion of rumen hemicellulose compared to roe deer in spring, while no differences in nutrient composition between species could be found in fall. Overall, there were greater differences between the two species when fallow deer density was high and competition likely more pronounced than when fallow deer density was low. The results from this study can be used to understand interspecific competition and how it fosters niche separation between coexisting large herbivores

Direct and indirect effects of food, fear and management on crop damage by ungulates

Foraging on crops by wild ungulates may create human–wildlife conflicts through reducing crop production. Ungulates interact with and within complex socio-ecological systems, making the reduction of crop damage a challenging task. Aside from ungulate densities, crop damage is influenced by different drivers affecting ungulate foraging behaviour: food availability and food quality in the landscape (i.e. the foodscape) as well as fear from hunting and scaring actions (i.e. the landscape of fear) may together affect the degree of damage via both direct and indirect effects. A better understanding of the individual effects of these potential drivers behind crop damage is needed, as is an appreciation of whether the effects are dependent on ungulate density.We investigated this by applying path analysis to test indirect and direct links between ungulate density, foodscape, landscape of fear and human management goals on crop damage of oats and grass, respectively.Our results suggest that crop type is the major driver behind crop damage, with more damage to oats than to leys, implying that human decisions (i.e. changing crop type) influence the level of crop damage.We found that management goals and actions influenced the foodscape and the landscape of fear, by affecting the amount of forage produced in the agricultural landscape and the amount of scaring actions. Additionally, we found that supplementary feeding influenced the local ungulate densities in the area.Our results highlight the importance of including human actions on multiple levels when assessing drivers behind damage by ungulates in managed landscapes. We suggest that more studies using path analysis on multiple scales are needed in order to tackle complex issues, such as crop damage and other human–wildlife conflicts

Natural versus National boundaries

Applying biogeographical insights to the regulation of production forestry and the determination of forest reserve strategies is expected to increase the effectiveness of biodiversity conservation actions. Here, we assess the extent to which such applications take place. By using Sweden as a case study, we demonstrate fundamental differences among biogeographical regions in natural patterns and processes, past land-use, and anthropogenic impacts that need to be better incorporated into strategic conservation planning and decisions. Furthermore, assessment of specific forestry regulations and biogeographical variation in a number of other countries/provinces embracing boreal and temperate biomes also indicate that natural boundaries are insufficiently considered in forest management policies. We suggest that a substantial potential exists to better align conservation priorities with biogeographical characteristics. To illustrate the application of such an approach, we present a decision support model on how forest conservation policies that rest on natural boundaries and ecological processes can be developed

Nutrient balancing or spring flush - What determines spruce bark stripping level by red deer?

The distribution and population density of red deer (Cervus elaphus) are increasing in several regions of Europe. The deer may cause severe damage in commercial forestry and agriculture. Bark stripping is the main problem in forests, especially on Norway spruce (Picea abies), and is thought to mostly occur during winter when other forage is scarce. It has been suggested that an imbalance in the nutrient intake, and especially a diet including high amounts of easily-digestible macronutrients, such as agricultural crops, can lead to an increased urge to consume bark. Feeding on brassicas, for example rapeseed (Brassica napus) might have this effect. The aim with this study was to investigate the relationship between intake of rapeseed and bark stripping on Norway spruce by red deer during early spring. We did this by a controlled feeding experiment with four groups of captive red deer in southern Sweden. All groups were given spruce logs every week, while only two groups had access to freshly harvested rapeseed plants. In addition, influence of air temperature and forage nutritional composition was taken into account. Our results show that red deer bark stripping can be considerable not only during winter but also during spring green-up. We found no significant influence of rapeseed on bark stripping performed by the deer. However, at a threshold temperature, deer suddenly started to ingest large amounts of bark biomass, coinciding with a significant change in the bark's concentration of starch. We suggest that the lack of effect of rapeseed feeding can partly be explained by overshadowing effects caused by such seasonal changes of bark character-istics, and partly by the fact that the rapeseed plants in our study contained lower than expected concentrations of easily-digestible macronutrients (apart from protein). We conclude that the risk of damage on spruce can be especially high during certain periods, something that is important to consider when mitigating bark stripping. However, several interactive effects are involved and must be considered in order to more efficiently mitigate damage

Effect of fire on the palatability of plants in an African woodland savanna: varying impacts depending on plant functional groups

Fire and herbivores are two important drivers of changes in vegetation composition, quality and dynamics and both are highly related to each other. Herbivores are known to respond to fire both in terms of foraging decisions and distribution. However, little is known about the actual changes in plant chemistry following a fire event and how long these changes will last. We investigated the effect of fire on two different plant functional groups (grasses and woody species) in a woodland savanna of southern Africa. We studied chemical compounds known to be important for palatability of five perennial grass and seven woody species (trees and shrubs) common in the woodland savanna and known to be utilized by herbivores. We wanted to know if plant chemistry differs between a recently burned site (burned 2 years ago) and a control site, burned 16 years ago, and if grasses and woody species show similar relative differences between sites (i.e., the plants' response to fire). We found a clear difference in chemical composition patterns between the plant functional groups, with an almost homogenous response to fire among woody species, but higher variability in response among grass species. Furthermore, we found that woody species maintained a higher nutritional value even 2 years after burning, whereas grasses did not show clear differences among the two investigated sites. Hence, few years after burning, woody plants might still serve as an attraction for herbivores, especially browsers, in contrast to grasses. The knowledge about these differences between the two functional groups in response to fire is beneficial for the development of management strategies for large herbivores whether domestic or wild

Forage availability, supplementary feed and ungulate density: Associations with ungulate damage in pine production forests

Populations of large herbivores, including members of the deer family Cervidae, are expanding across and within many regions of the northern hemisphere. Because their browsing on trees can result in economic losses to forestry and strongly affect ecosystems, it is becoming increasingly important to understand how best to mitigate resultant damage. Previous research has highlighted the importance of regulating deer density and the availability of alternative forage to reduce browsing damage levels in conifer production stands. However, often only one or two proxies of forage availability have been used instead of applying a broad foodscape approach and more knowledge is needed to understand which types of alternative forage best mitigate damage. We conducted field inventories of damage that occurred during the previous fall/winter in 112 production stands in southern Sweden, while also measuring forage availability and cervid faecal pellets in the surrounding landscape (16 ha). Local landowners provided data on supplementary feeding. We found that variation in cervid (Alces alces, Capreolus capreolus, Cervus elaphus and Dama dama) browsing damage to top shoots or stems of young Scots pine trees (Pinus sylvestris, hereon pine), was better explained by the availability of alternative natural forage (using several indices and species of trees and shrubs) than by supplementary feeding. The proportion of damaged pine trees was higher in stands with a lower density of pine stems; in landscapes with a lower density of key broadleaf tree species (genera Sorbus, Salix, Populus and Quercus); and in landscapes with more open land (agricultural fields and paddocks). Damage was also higher in stands where relatively large amounts of moose faeces was found, while not related to the amount of faeces from other cervid species. The amount of supplementary feed (silage or other types such as root vegetables) did not explain variation in pine damage, but the result was possibly affected by relatively few study areas supplying sufficient data on supplementary feeding. The results from our inventory illustrate the efficacy of using naturally growing forage to mitigate browsing damage to young pine trees in managed landscapes. Creation of such forage is also recommended over supplementary feeding because of co-benefits to forest biodiversity and ecosystem services