Title from title page of PDF (University of Missouri--St. Louis, viewed February 24, 2010). Includes bibliographical references (p. 328-345).

Denna studie undersökte hur heterogenitet i skogsbestånd samt omgivningsfaktorerna träddiameter, variation i träddiameter, död ved och lövinslag påverkar förekomsten av 18 skogsfågelarter i södra Sverige. Fågelinventeringen utfördes med hjälp av linjetaxering längs 100 meter långa transekter. Omgivningsfaktorerna mättes i varje transekt i fem provcirklar med diametern 10 meter. Analysen av träddiameter visade att det främst var diameter på barrträd, men inte på lövträd som inverkade på förekomsten av fåglarna. Sambanden mellan diameter på barrträd och totalt antal fågelarter var övervägande negativa vid 0-30 centimeter i diameter och övervägande positiva vid 30-80 centimeter i diameter. Totalt antal fågelarter samt förekomsten av taltrast och nötväcka ökade även signifikant vid ökad variation i träddiameter. Vid ökad grundyta död ved sågs tendenser till att totalt antal fågelarter och förekomsten av flera enskilda fågelarter ökade. Att antalet arter ökade vid en diameter över 30 centimeter kan kopplas till att förekomsten av håligheter då är högre. I Sverige avverkas granar när de är cirka 30 centimeter i diameter. Resultatet tyder alltså på att avverkningen av gran sker vid den storlek då träden börjar få en positiv inverkan på antalet fågelarter. Att antalet arter ökade vid ökad variation i träddiameter kan bero på ett större utbud av mikrohabitat. Slutsatsen av resultaten är att framförallt diameter på träd, variation i träddiameter och till viss del död ved är viktiga omgivningsfaktorer som påverkar antalet fågelarter. För att bevara artrikedomen av fåglar i svenska skogar bör därför dessa parametrar ingå i den naturhänsyn som tas i samband med skogsbruk. / In this study, the occurrence of 18 forest bird species in southern Sweden was investigated in relation to parameters such as forest heterogeneity and the environmental factors tree diameter, variation in tree diameter, dead wood and fraction of deciduous trees. Birds were recorded along transects of 100 meters. The relationships between coniferous tree diameters and total number of bird species were predominantly found to be negative at trunk diameters of 0-30 centimeters, while mainly positive at trunk diameters of 30-80 centimeters. Also, the total number of species significantly increased with increasing variation in trunk diameter. There was also a tendency towards an increase of the total number of species with increasing basal area of dead wood. In Swedish forestry, spruces are felled when they are about 30 centimeters in trunk diameter. Thus the results indicate that felling of spruce is at the size when the trees start having a positive effect on the number of bird species. That the number of species increased at trunk diameter above 30 centimeters can be connected to the fact that the number of cavities is higher. That the number of species increased with increasing variation in trunk diameter can be due to a larger range of micro habitats. In conclusion, tree diameter, variation in tree diameter and dead wood were demonstrated as important environmental factors affecting the number of bird species. In order to maintain bird species richness in Swedish forests, these environmental factors should be considered in the context of forestry.

Ph.d.-afhandling. Den Kongelige Veterinær- og Landbohøjskole, 2006. / Haves også i trykt udg. Thesis (Ph.D.). 22 ill., 14 tables; approx. 90 ref. Summaries (Da, En).

Sirex noctilio is causing considerable mortality in commercial pine forests in KwaZulu- Natal, South Africa. The ability to remotely detect S. noctilio infestations remains crucial for monitoring the spread of the wasp and for the effective deployment of suppression activities. This thesis advocates the development of techniques based on remote sensing technology to accurately detect and map S. noctilio infestations. To date, no research has examined the potential of remote sensing technologies for the detection and mapping of Pinus patula trees infested by S. noctilio. In the first part of this thesis, the focus was on whether high spatial resolution imagery could characterize S. noctilio induced stress in P. patula forests. Results showed that, the normalized difference vegetation index derived from high spatial resolution imagery has the potential to accurately detect and map the later stages of S. noctilio infestations. Additionally, operational guidelines for the optimal spatial resolutions that are suitable for detecting and mapping varying levels of sustained S. noctilio mortality were defined. Results showed that a pixel size of 2.3 m is recommended to detect high (11-15%) infestation levels, and a pixel size of 1.75 m is recommended for detecting low to medium infestation levels (1-10%). In the second part of this thesis, the focus was on the ability of high spectral resolution (hyperspectral) data to discriminate between healthy trees and the early stages of S. noctilio infestation. Results showed that specific wavelengths located in the visible and near infrared region have the greatest potential for discriminating between healthy trees and the early stages of S. noctilio infestation. The researcher also evaluated the robustness and accuracy of various machine learning algorithms in identifying spectral parameters that allowed for the successful detection of S. noctilio infestations. Results showed that the random forest algorithm simplified the process by identifying the minimum number of spectral parameters that provided the best overall accuracies. In the final part of this thesis spatial modelling techniques were used to proactively identify pine forests that are highly susceptible to S. noctilio infestations. For the first time the random forest algorithm was used in conjunction with geographic information systems for mapping pine forests that are susceptible to S. noctilio infestations. Overall, there is a high probability of S. noctilio infestation for the majority (63%) of pine forest plantations located in Mpumalanga, South Africa. Compared to previous studies, the random forest model identified highly susceptible pine forests at a more regional scale and provided an understanding of localized variations of environmental conditions in relation to the distribution of the wasps. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.