AbstractsGeography &GIS

Drivers of ecological and geomorphological patterns in the complex beach system

by Tua Nylén

Institution: University of Helsinki
Department: Department of Geosciences and Geography, biogeotieteen osasto
Year: 2015
Keywords: maantiede
Record ID: 1145696
Full text PDF: http://hdl.handle.net/10138/154146


General patterns and processes of the unique land uplift beaches are still insufficiently understood. Advanced modelling methods and large homogeneous datasets provide novel opportunities to analyse spatio-temporal environmental processes. This doctoral thesis aims at expanding on the knowledge of the beach and adjacent coastal dunes as an ecogeomorphic system. More specifically, the thesis aims at answering: (1) which abiotic, biotic and temporal factors are the main determinants of substrate and vegetation properties, (2) what are the effects of the main drivers on substrate and vegetation properties, (3) how temporal processes interact with main spatial drivers in determining species richness and (4) how these effects differ between functional groups representing different adaptive strategies? Two advanced statistical methods, boosted regression trees and generalised linear mixed models, are utilised to analyse the effects of multiple factors on substrate and vegetation. My results demonstrate that substrate properties vary stronger along regional than local environmental gradients. The main drivers of textural properties are parent material and shore exposure, while organic properties are also determined by the local disturbance regime. Vegetation is mainly controlled by time, disturbance, productivity and biotic interactions. Specialist species richness and distribution are also influenced by habitat patch size and connectivity. The study highlights three mechanisms in shaping the mosaic of vegetation patterns: biotic interactions (i.e. competition and facilitation), the interplay of spatial and temporal processes and functional group (or species-) specific responses to environmental drivers. The doctoral thesis contributes to understanding the components of the ecogeomorphic beach system by identifying the main drivers of substrate and vegetation. Particularly, I demonstrate the variety of ecologic responses and the importance of dominant species in shaping vegetation assemblages. Furthermore, the feasibility of extensive homogeneous datasets and advanced modelling methods are demonstrated in analysing beach processes. Thus, the thesis may serve as one step towards a more in-depth understanding of the complex beach system and provide new methodology for further research. This knowledge is vital to the conservation of beaches that are unique landscapes and considerably contribute to biodiversity but are subject to multiple land use pressures. Maankohoamisrannikon ainutlaatuisten hiekkarantojen prosessit tunnetaan edelleen puutteellisesti. Edistyneet tilastolliset mallit ja laajat yhtenäiset havaintoaineistot tarjoavat uusia mahdollisuuksia näiden alueellis-ajallisten prosessien tutkimiseen. Tämän väitöskirjan päämäärä on syventää hiekkarannan ja dyynien ymmärrystä ekogeomorfologisena systeeminä. Ekogeomorfologiassa tarkastellaan elollisen ja elottoman luonnon prosesseja toisistaan erottamattomina, vuorovaikutuksessa olevina osina luonnonsysteemiä. Täsmällisemmät tavoitteet ovat: 1) tunnistaa tärkeimmät…