The conversion of natural forests to production land uses has led to huge losses of biodiversity and continues to threaten remaining terrestrial flora and fauna throughout the world. The global demand for wood products and energy, which was partly responsible for the loss of primary native habitat, is now one of the leading drivers of afforestation with significant new areas of plantation replacing former agricultural lands. While plantations do not support the same biodiversity values as natural forests they do provide significant habitat for a range of species. Saproxylic invertebrates (species that are dependent on deadwood) are strongly affected by the temporal and spatial availability of different deadwood resources. Previous research on saproxylic invertebrates has largely been restricted to natural or managed natural forests predominantly in the Northern Hemisphere, where forest management practices have been modified to conserve these species This thesis fills a distinct research gap in New Zealand and is the first large scale study to quantify the effects of deadwood age, wood species, and landscape composition on saproxylic invertebrates in our plantation forests by direct rearing. In this thesis I show that thinning residues, which are currently retained in many plantation forests, provide significant habitat for a range of native invertebrate taxonomic groups, including diverse assemblages of Coleoptera and Hymenoptera. Deadwood age is an important attribute determining taxonomic richness of saproxylic invertebrates. Richness of invertebrate orders/classes and Coleoptera species all increased in older deadwood material, and a stepwise multidimensional analysis procedure indicated that the age of deadwood was the most important factor structuring saproxylic invertebrate community composition in Pinus radiata thinning residues. Deadwood age was a stronger predictor of community composition in thinning residue than measures of landscape composition, such as the proportion of remnant native forest cover. The change in saproxylic invertebrate composition that occurs with deadwood age was related to changes in the feeding guilds, with a transition from primary wood feeding species to predators/parasitoids and fungal feeders with increasing dead wood age. Because thinning’s are carried out at prescribed times throughout the stand rotation, stand age could be adopted as a proxy for deadwood age in these systems allowing forest managers a simple method for monitoring saproxylic beetle habitat availability . My research provides strong empirical evidence that supports the existing conservation paradigm that forest managers should seek to create a mosaic of habitats at the landscape scale to enhance biodiversity opportunities in plantations. In addition to the habitat opportunities provided by P. radiata deadwood that is derived from silvicultural practices there are several sources of native wood in plantations. Native woody resources are found in either the embedded remnant areas of native forest or in the understory of stands as many native woody species colonise this habitat. As yet the importance of native understory deadwood resources for saproxylic species is unknown. In addition it is unclear how the importance of such understory resources is influenced by proximity to remnant native forest patches. I used experimental wood billets of four tree species (3 native and the exotic P. radiata) placed along replicated transects spanning native habitat and adjacent early stage regenerating plantation stands to assess the saproxylic invertebrate assemblages associated with different deadwood species as a function of proximity to native forest. I found that an interaction between wood host specificity (local scale) and proximity to interior native forest (landscape scale) was the most important factor regulating saproxylic invertebrate community structure. Deadwood of the native subcanopy trees Schefflera digitata, Melicytus ramiflorus, Aristotelia serrata and the exotic conifer P. radiata provided habitat for different subsets of the saproxylic fauna. The most pronounced differences in saproxylic community structure were between the native sub-canopy broadleaf species and the exotic P. radiata. Surprisingly the P. radiata supported a greater species richness and abundance of saproxylic Coleoptera in native remnants than the native wood species in the same habitat. In general, species richness was higher in native forest habitats and declined with increasing distance from native habitat. These results suggest that both the diversity of deadwood resources that are available and their proximity to native remnants are important for maintaining saproxylic communities in plantations. However, two of the native wood species (M. ramiflorus and A. serrata) exhibited steep declines in species richness at the plantation native forest boundary, suggesting that the contrasting stand types (native remnant and young regenerating plantation stands) with their different microclimate may have had a significant influence. Future research needs to compare the saproxylic fauna of dead wood in mature plantation stands with adjacent native remnants to ascertain if the effect of native habitat proximity is due to landscape composition or a reflection of microclimatic differences. The large diversity of saproxylic species observed during this study highlights the importance of plantations as habitat for saproxylic species, particularly in heavily fragmented landscapes that retain little original native forest. My research findings provide forest managers with options for improving forest management to enhance opportunities for the conservation of saproxylic invertebrates. In addition my thesis provides one of the most comprehensive multi-taxon data sets of saproxylic species associated with a variety of deadwood resources. This information will be invaluable to future researchers that continue to work on New Zealand’s saproxylic fauna.

Plantation forests ecosystem functions provide a range of indirect benefits known as forest services. There is lack of knowledge and estimation of the value of forest services.The main aim of the research was to investigate the environmental and social value of plantation forests in New Zealand. Each step of the research was built up on the perspectives of the stakeholder groups identified. A stakeholder analysis revealed that the most relevant stakeholder group was Adjacent neighbours. Through a postal survey forest managers and stakeholders indicated they considered as most relevant Erosion control and Water regulation (quality and quantity) Employment, Increased living standard, and Recreation. These services became the focus for the rest of the study. Through focus groups, the most relevant stakeholder groups, identified and ranked positive and negative aspects in forestry, and selected attributes describing the forest services. These were: Amount of sediment in water (water quality), Algae in water (water quality), Percentage of land stabilisation (erosion control), and Level of water flow (water quantity). The attributes for the attitudinal questions were classified as Community, Employment, and Recreation. The environmental value of plantation forests was estimated through choice modelling. The valuation survey was carried out only in Hawke's Bay. The payment vehicle used was increased regional council rates with the objective of monitoring environmental quality of soil and water. Several models were estimated by adding interactions between variables. Model 15b was selected as it provided best model fit and integrated respondents' demographic and attitudinal characteristics. The results of the model indicated that respondents who had university studies and positive attitude towards plantation forest community values were more willing to pay for improved levels of land stabilisation. The implicit prices estimated indicated that the wider community in Hawke's Bay have a greater appreciation for water quality (lower levels of algae and sediments). The responses to the attitudinal questions indicated that most respondents had positive attitudes towards the community and practical uses of plantations and employment-related values, particularly older respondents. The environmental and social values identified were linked with forest operations in order to analyse the impact they have. Land preparation and planting, road construction, and harvesting are the forest operations that have a greater impact on the levels of sediment in water.

Alors que la superficie des forêts de plantation continue d'augmenter dans le monde, leurcontribution à la conservation de la biodiversité reste controversée. L’objectif de cette thèse estd'identifier les facteurs clés, à la fois au niveau de l'habitat local et à celui du paysage, qui influent surla diversité des papillons de jour dans les paysages en mosaïque dominés par des plantations de pins.Les communautés de papillons ont été échantillonnées en lisière et à l’intérieur de plantations de pinmaritime, pare-feux, ripisylves et fragments de forêts de feuillus variant par la taille et le degréd’isolement spatial. Les traits biologiques et écologiques des papillons ont été liés auxcaractéristiques de l’habitat et aux variables paysagères.Les éléments les plus importants pour la conservation des papillons dans les paysages dominés parles plantations de pins sont les habitats semi-naturels: forêts de feuillus, pare-feux et lisières. Lesripisylves se révèlent être les plus riches en papillons forestiers, abritant des espèces spécialisées. Lespare-feux hébergent deux fois plus d'espèces que les autres types d'habitats et sont importants pourla conservation de plusieurs espèces menacées. Toutefois les plantations de pin ne sont pas vide depapillons. La qualité de l'habitat, notamment la présence de plantes hôtes, est le facteur le plusdéterminant de la composition des communautés de rhopalocères. La composition et laconfiguration du paysage ont également une influence importante sur la diversité des papillons. Denombreuses espèces de papillons ont été observées dans plusieurs types d'habitat suggérant que lacomplémentation et supplémentation des ressources soient des processus clés pour maintenir ladiversité des papillons dans les paysages forestiers hétérogènes. / While the area of plantation forests continues to increase worldwide, their contribution to theconservation of biodiversity is still controversial. The aim of this thesis is to identify key habitat andlandscape factors that drive butterfly diversity in mosaic landscapes dominated by pine plantations.Butterfly communities were sampled at edges and interiors of five successional stages of pine stands,in firebreaks, riparian forests and in deciduous woodlands varying in fragment size and isolation.Biological and ecological traits of butterflies were related to habitat patch attributes and tolandscape composition and configuration.The results highlighted the critical importance of semi-natural habitats for butterfly conservation inpine plantation mosaics, i.e. deciduous woodlands, firebreaks and edges. Riparian forests wereespecially rich in forest butterfly species, harboring specialized species with both narrow habitat andthermal ranges. Firebreaks had twice as many species as other habitat types and were ofconservation value for several threatened butterfly species. Our results also showed that pine standswere not ‘free of butterflies'. Habitat quality, particularly the presence of host plants, was the mostimportant driver of butterfly community composition. Landscape composition and configuration alsoinfluenced butterfly diversity. Many species used more than one distinct habitat type, suggestingthat resource complementation and supplementation are important mechanisms of butterflydiversity persistence in pine plantation mosaics.

We are currently faced with the global challenge of conserving biological diversity while also increasing food production to meet the demands of a growing human population. Land-use change, primarily resulting from conversion to production land, is currently the leading cause of biodiversity loss. This occurs through habitat loss, fragmentation of remaining natural habitats, and resulting edge effects. Land-sparing and land-sharing approaches have been discussed as alternative ways to engineer landscapes to mitigate biodiversity loss while meeting production objectives. However, these represent extremes on a continuum of real-world landscapes, and it will be important to understand the mechanisms by which adjacent land use affects natural remnant ecosystems in order to make local land-management decisions that achieve conservation, as well as production, objectives. This thesis investigates the impact of juxtaposing production and natural forest on the community-wide interactions between lepidopteran herbivores and their parasitoids, as mediated by parasitoid spillover between habitats. The first and overarching objective was to determine whether herbivore productivity drives asymmetrical spillover of predators and parasitoids, primarily from managed to natural habitats, and whether this spillover alters trophic interactions in the recipient habitat. The study of trophic interactions at a community level requires understanding of both direct and indirect interactions. However, community-level indirect interactions are generally difficult to predict and measure, and these have therefore remained understudied. Apparent competition is an indirect interaction mechanism thought to be very important in structuring host-parasitoid assemblages. However, this is known primarily from studies of single species pairs, and its community-wide impacts are less clear. Therefore, my second objective was to determine whether apparent competition could be predicted for all species pairs within an herbivore assemblage, based on a measure of parasitoid overlap. My third objective was to determine whether certain host or parasitoid species traits can predict the involvement of those species in apparent competition. My key findings were that there is a net spillover of generalist predators and parasitoids from plantation to native forest, and that for generalists, this depends on herbivore abundance in the plantation forest. Herbivore populations across the edge were linked by shared parasitoids in apparent competition. Consequently, an experimental reduction of herbivore density in the plantation forest changed parasitism rates in the natural forest, as predicted based on parasitoid overlap. Finally, several host and parasitoid traits were identified that can predict the degree to which host or parasitoid species will be involved in apparent competition, a finding which may have extensive application in biological control, as well as in predicting spillover edge effects. Overall, this work suggests that asymmetrical spillover between production and natural habitats occurs in relation to productivity differences, with greater movement of predators and parasitoids in the managed-to-natural forest direction. The degree to which this affected species interactions has implications for landscape design to achieve conservation objectives in production landscapes.