Biodiversity drivers in oceanic archipelagos and habitat fragments, explored by agent-based simulation models
Failid
Kuupäev
2023-05-02
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Saared on sajandeid tähelepanu köitnud oma põneva elustikuga. Üksikud saared võimaldavad uurida elurikkuse kujunemist ning saarestikud liikide levimist saarte vahel. Inimtegevuse tõttu killustunud elupaigad sarnanevad päris saarestikega nii oma looduskaitselise olulisuse kui ka isoleerituse poolest. Erinevalt päris saartest ei määra aga elupaigalaikude isolatsiooni ainult nende ruumiline paigutus, vaid ka rändavate organismide võime ümbritsevas maastikus toime tulla. Uurisin elurikkust kujundavaid tegureid sellistes süsteemides, kasutades simulatsioone elurikkuse kujunemise kohta Hawaii ja Galápagose saartel, Kanaaridel, Roheneemesaartel, Assooridel ning Eesti laialehistes metsalaikudes. Leidsin, et saarestikes on elurikkuse kujunemisel olulist rolli mänginud nii tänapäevane elupaikade mitmekesisus ja saarte asend üksteise suhtes kui ka saarestiku geoloogiline ajalugu ning maailmamere taseme muutused. Elupaikade mitmekesisus oli oluline kõigis uuritud saarestikes. Teiste tegurite kohta selgus, et kui saarestiku ajalugu kajastub hästi saarte tänapäevases asetuses, siis seletab tänapäevane geograafia saarte liigilist koosseisu; kui aga saarestiku ajaloos on toimunud suured geoloogilised muutused, ei ole tänapäevane saarte paigutus veel jõudnud mõju avaldada. Eesti vanametsalaikude simulatsioonid näitasid, et ümbritsevad nooremad metsad ei toeta rohurinde taimede, puudel kasvavate organismide ja mitmete mullaseente sidusust, kusjuures nooremate metsade kasutamist piirab enim sobivate mikroelupaikade puudus. Kokkuvõtteks võib öelda, et simulatsioonide kasutamine võimaldab välja selgitada põhjuslikke seoseid elurikkuse kujunemise kohta ookeanisaartel ja killustunud elupaikades, mis omakorda aitab vältida elurikkuse kadu neis väärtuslikes süsteemides.
Oceanic islands and habitat fragments within landscapes are both valuable ecological study objects, characterized by clear physical boundaries, immigration and extinction dynamics of well-defined populations, and high conservational priority. However, despite the apparent similarity, there is a crucial difference between these systems. Unlike real islands, isolation of habitat patches is not solely affected by their spatial arrangement, but also by organisms’ response to the surrounding landscape, or the ‘functional connectivity’. In this thesis, I used agent-based simulation models to explore the biodiversity drivers in oceanic archipelagos (Hawaii, Galápagos, Canary Islands, Cape Verde, Azores) and Estonian old-forest fragments, that are both characterized by spatial and functional isolation. I found that in oceanic archipelagos, modern habitat diversity and archipelago configuration, as well as geologic and eustatic history have affected biodiversity development. All studied archipelagos demonstrated the importance of habitat diversity, while the effect of modern archipelago configuration was significant only in those where archipelago history was strongly reflected in the present setting, with geologic and eustatic history being the more important determinants elsewhere. In Estonian forest study, I found that secondary forests on former agricultural land are not functionally connecting old-forest fragments in terms of ground layer vegetation, epiphytes, and several groups of soil fungi. Furthermore, I found that their ability to exploit younger forests is primarily limited by the availability of microhabitats. In conclusion, agent-based models allow us to gain crucial mechanistic knowledge about the biodiversity drivers in oceanic archipelagos and habitat fragments and to predict and avoid biodiversity losses in these isolated and valuable systems.
Oceanic islands and habitat fragments within landscapes are both valuable ecological study objects, characterized by clear physical boundaries, immigration and extinction dynamics of well-defined populations, and high conservational priority. However, despite the apparent similarity, there is a crucial difference between these systems. Unlike real islands, isolation of habitat patches is not solely affected by their spatial arrangement, but also by organisms’ response to the surrounding landscape, or the ‘functional connectivity’. In this thesis, I used agent-based simulation models to explore the biodiversity drivers in oceanic archipelagos (Hawaii, Galápagos, Canary Islands, Cape Verde, Azores) and Estonian old-forest fragments, that are both characterized by spatial and functional isolation. I found that in oceanic archipelagos, modern habitat diversity and archipelago configuration, as well as geologic and eustatic history have affected biodiversity development. All studied archipelagos demonstrated the importance of habitat diversity, while the effect of modern archipelago configuration was significant only in those where archipelago history was strongly reflected in the present setting, with geologic and eustatic history being the more important determinants elsewhere. In Estonian forest study, I found that secondary forests on former agricultural land are not functionally connecting old-forest fragments in terms of ground layer vegetation, epiphytes, and several groups of soil fungi. Furthermore, I found that their ability to exploit younger forests is primarily limited by the availability of microhabitats. In conclusion, agent-based models allow us to gain crucial mechanistic knowledge about the biodiversity drivers in oceanic archipelagos and habitat fragments and to predict and avoid biodiversity losses in these isolated and valuable systems.
Kirjeldus
Väitekirja elektrooniline versioon ei sisalda publikatsioone
Märksõnad
archipelagos, habitats, biodiversity, community dynamics, computer simulation, agent technology