PhD. Topics

Plant Science and Biodiversity Center

Spatio-temporal development of forest fragments – how it affects diversity of various habitats?
PhD. program
Name of the supervisor
Mgr. Mária Šibíková, PhD. ()
Receiving school
Prírodovedecká fakulta UK
Forest fragmentation is the division of a forest patch into smaller, isolated patches, with negative consequences for most native forest biota. Reasons for forest fragmentation are various, in the past mainly the need for agricultural land and pastures, recently building of new infrastructure, river regulations, and construction of small dams. Fragmentation reduces the total forest area, possibly resulting in some species’ extinction. Fragmentation on the local scale is a dynamic process where habitats are progressively reduced to smaller patches which become more isolated and increasingly influenced by edge effects. These spatial structure alterations produce community composition changes in remnant patches. Fragments in anthropogenically altered forests are normally surrounded by a matrix of low biomass and structural complexity, such as pastures, croplands, or young secondary forest stands. Landscape factors such as the proportion of forest habitat in the landscape, the various sizes of fragments, the fragment shape, and the degree of fragment isolation are the main factors reducing forest biodiversity. All these changes can increase fragment vulnerability to external influences, including shifts in plant species composition, biological invasions, and decline in typical forest species populations. These changes tend to be more apparent in smaller fragments which are proportionately more affected by edge effect because of their higher edge/interior ratio, and because they support smaller populations than larger fragments. Many studies have concentrated on explaining how forest ecosystem fragmentation affects forest species diversity, the composition of species with different life strategies, and species from different functional groups. Some have suggested that the effect of habitat fragmentation on plant diversity is linearly negative, positive or non-linearly negative. From the facts mentioned above, it is evident that the real impact of fragmentation on forest ecosystems is not explored enough. We aim to add the syntaxonomical point of view into fragmentation effects analyses. The basic number of species could not explain effects precisely adequately, therefore we will consider species based on their fidelity to each forest community and will explore the occurrence of given forest species versus alien species or species syntaxonomically belonging to other vegetation units. Recently, the newest remote sensing methods could be used for a better description of forest fragments and their spatio-temporal changes.

We hypothesize that

Current species diversity and level of invasion of various forest habitats could be explained by spatio-temporal development of their area and their fragmentation throughout the time,
Fragmentation effect differs among forest habitat types depending on their geographic distribution (altitudinal gradient), environmental condition (extreme versus mesophilous stands) and management (native forests versus plantations).

Proposed methods: Forest fragments of different habitat type, area and shape will be chosen. Also fragments with stable area and fragments with variable area and shape development will be chosen using remote sensing techniques. Transects of phytosociological relevés together with species lists will be sampled in selected fragments. Data about spatio-temporal distribution of selected forest fragments, will be obtained using NaturaSat software developed at Institute of Botany within the project supported by European Space Agency. Distribution will be obtained from actual and older satellite images of Sentinel-2, satellite and historical maps. Time series of spatial characteristics in last 30 years will be created. NaturaSat software will be used to calculate fragmentation indices as Shape index or Core area and indices describing forest heterogeneity (Relative High Laplacian metrics). These indices will be used as explanatory variables for recent vegetation data, occurrence of non-native and diagnostic species in regression models (GLM, GLMM, beta-regression).