Muutused taimede liigirikkuses ja populatsioonide seisundis vastusena elupaikade kaole ja killustumisele

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Elupaikade kadu ja killustumine on tänapäeval üks olulisemaid elurikkust ohustavaid tegureid kogu maailmas. Me uurisime taimeliikide vastuseid maastike killustumisele Eesti loopealsetel, mis on viimase sajandi jooksul kaotanud rohkem kui 70% oma kunagisest pindalast. Tuvastasime, et Põhja-Eesti looalad on viimase sajandi vältel kaotanud ligi 30% oma loopealsetele iseloomulikest liikidest ning et Lääne-Eesti loodudel on samuti märgatav maastikumuutuste mõju populatsioonidele. Liigirikkus ja taimede tunnused olid tugevalt seotud elupaikade sidususega, mis võimaldab seemnete ja õietolmu liikumist alade vahel ning mille kahanemine vähendab populatsioonide geneetilist mitmekesisust ning alade liigirikkust. Mõõdukas inimmõju uuritud loopealsetel soodustas maastikumuutustele tundlike liikide ohtrust, samas kui liigne inimmõju vähendas populatsioonide geneetilist mitmekesisust. Nii geneetiline mitmekesisus kui taimede ja populatsioonide tunnused reageerisid maastikumuutustele ajalise viivitusega, sarnaselt liigirikkusele, mille reageerimist ajalise nihkega on tuvastatud mitmetes kooslustes üle maailma. Aeglane reageerimine maastikumuutustele muudab populatsioonid küll teatud mõttes muutustele vastupidavamaks, kuid aeglustab teisalt nende kohastumist uute olukordadega. Eriti oluline on võtta võimalikku viivet populatsioonide ja liikide vastuses keskkonna- ja maastikumuutustele arvesse pikaajaliste looduskaitseliste otsuste tegemisel.Habitat loss and fragmentation are one of the greatest threats to biodiversity in the modern world. We used Estonian alvar grasslands, which have gone through a major area loss over the last century as a model system to investigate plant species responses to habitat fragmentation. We found that alvar grasslands in northern Estonia had lost almost 30% of their former habitat specialist species richness and that plant populations in the western Estonian alvars also showed notable responses to past landscape changes. Species and trait responses revealed susceptibility to habitat connectivity loss, which hinders seed dispersal and pollen movement between sites and can lower the genetic diversity and site species richness. Moderate human impact is necessary for the persistence of these semi-natural grasslands and their specialist species. Our results confirmed that moderate human impact supported population performance of the species more susceptible to landscape changes. At the same time, overly intensive human impact lowered population genetic diversity. Genetic diversity, plant trait responses and population performance all showed a time-lag in their response to landscape changes, similarly to a delay in species richness recorded in many communities around the world. It is necessary to recognise that the current state of populations is transitory and that populations are still in progress of responding to landscape changes that occurred decades ago. This time-lag makes plant populations more resilient to changes on the on one hand, but at the same time cautions us to take it into consideration when making long-term conservation decisions

Patriotic values for public goods: transnational trade-offs for biodiversity and ecosystem services?

The natural environment is central to human well-being through its role in ecosystem service (ES) provision. Managing ES often requires coordination across international borders. Although this may deliver greater conservation gains than countries acting alone, we do not know whether the public supports such an international approach. Using the same questionnaire in three countries, we quantified public preferences for ES in home countries and across international borders. In all three countries, the people were generally willing to pay for ES. However, our results show that there is a limit to the extent that environmental goods can be considered global. ES with a use element (habitat conservation, landscape preservation) attracted a patriotic premium, such that the people were willing to pay significantly more for locally delivered services. Supranational management of ES needs to be balanced against the preferences that people have for services delivered in their home countries

Nõmmnelgi (Dianthus arenarius L.) kahe Eestis esineva alamliigi plastilisus

https://www.ester.ee/record=b5559126*es

Kahe niiduliigi tunnused killustunud lookooslustes

https://www.ester.ee/record=b5741165*es

Image_1_Differential Effects of Climate Warming on the Nectar Secretion of Early- and Late-Flowering Mediterranean Plants.PDF

<p>Floral nectar is a vital resource for pollinators, thus having a very important role in ecosystem functioning. Ongoing climate warming could have a negative effect on nectar secretion, particularly in the Mediterranean, where a strong temperature rise is expected. In turn, decreased nectar secretion, together with shifts in flowering phenology can disrupt plant–pollinator interactions and consequently affect the entire ecosystem. Under fully controlled conditions, we tested how temperature influenced nectar secretion (through nectar volume, sugar concentration, sugar content, and number of flowers produced) in six Mediterranean plant species flowering from winter to summer (viz. Asphodelus ramosus, Ballota acetabulosa, Echium plantagineum, Lavandula stoechas, Rosmarinus officinalis, and Teucrium divaricatum). We compared the changes in nectar secretion under temperatures expected by the end of the century and estimated the effect of climate warming on nectar secretion of plants flowering in different seasons. We found a significant effect of temperature on nectar secretion, with a negative effect of very high temperatures in all species. Optimal temperatures for nectar secretion were similar to the mean temperatures in the recent past (1958–2001) during the respective flowering time of each species. Increasing temperatures, however, will affect differently the early-flowering (blooming in winter and early spring) and late-flowering species (blooming in late spring and early summer). Temperature rise expected by the end of the century will shift the average temperature beyond the optimal range for flower production and the sugar produced per plant in late-flowering species. Therefore, we expect a future decrease in nectar secretion of late-flowering species, which could reduce the amount of nectar resources available for their pollinators. Early-flowering plants will be less affected (optimal temperatures were not significantly different from the future projected temperatures), and may in some cases even benefit from rising temperatures. However, as many earlier studies have found that early-flowering species are more prone to shifts in phenology, the plant–pollinator interactions could instead become affected in a different manner. Consequently, climate warming will likely have a distinctive effect on both plant and pollinator populations and their interactions across different seasons.</p

Contrasting latitudinal patterns in phylogenetic diversity between woody and herbaceous communities

AbstractAlthough many studies have shown that species richness decreases from low to high latitudes (the Latitudinal Diversity Gradient), little is known about the relationship between latitude and phylogenetic diversity. Here we examine global latitudinal patterns of phylogenetic diversity using a dataset of 459 woody and 589 herbaceous plant communities. We analysed the relationships between community phylogenetic diversity, latitude, biogeographic realm and vegetation type. Using the most recent global megaphylogeny for seed plants and the standardised effect sizes of the phylogenetic diversity metrics ‘mean pairwise distance’ (SESmpd) and ‘mean nearest taxon distance’ (SESmntd), we found that species were more closely-related at low latitudes in woody communities. In herbaceous communities, species were more closely-related at high latitudes than at intermediate latitudes, and the strength of this effect depended on biogeographic realm and vegetation type. Possible causes of this difference are contrasting patterns of speciation and dispersal. Most woody lineages evolved in the tropics, with many gymnosperms but few angiosperms adapting to high latitudes. In contrast, the recent evolution of herbaceous lineages such as grasses in young habitat types may drive coexistence of closely-related species at high latitudes. Our results show that high species richness commonly observed at low latitudes is not associated with high phylogenetic diversity.</jats:p