Importance of dispersal limitation in determining dark diversity of plants across spatial scales
Kuupäev
2018-04-27
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Elurikkuse hoidmine on looduskaitse ülim eesmärk, ent sageli on elurikkus võimalikust liikide hulgast palju väiksem ehk kooslused pole täielikud. Kuna vaid elurikkad kooslused suudavad inimkonnale pakkuda erinevaid looduse hüvesid, nagu mulla teke, (kultuur)taimede tolmeldamine ja looduslik kahjuritõrje, on äärmiselt oluline teada, miks osad liigid on sobivatest elupaikadest puudu ehk moodustavad tumeda elurikkuse. Antud töö eesmärgiks oli hinnata millisel määral võib taimede kehv levimisvõime (vähene seemetoodang ja levimiskaugus) põhjustada liikide puudumise sobivatest kasvukohtadest nii Kesk- ja Põhja-Euroopas kui ka Läänemere regiooni rohumaadel. Lisaks uurisime, kuidas levimispiirangu osatähtsus sõltub kohalikest keskkonnaoludest ja inimmõjust. Tumeda elurikkuse leidmiseks analüüsisime liikide koosesinemise mustreid, levimisvõimekuse hindamiseks kasutasime erinevaid seemnelevi mõjutavaid liigitunnuseid. Analüüsid näitasid, et tumedasse elurikkusesse kuuluvate liikide seemnetoodang ja levimiskaugus oli üldjoontes väiksem kui koosluses esindatud ehk vaadeldud liikidel. Seega põhjustas taimede kehv levimisvõime liikide puudumise sobivatelt aladelt. Levimispiirangu osatähtsus oli aga väiksem keskkonnastressi puhul ja suurema inimtegevusega piirkondades. Põllumajandusmaastikes, kus kasvuks sobivate rohumaade pindala oli väike, kuulusid tumedasse elurikkusesse hoopiski hea levimisvõimekusega taimeliigid. See omakorda viitab ohule, et head levijad satuvad killustatud põllumajandusmaastikes sageli mittesobilikele aladele. Antud töö näitab, et taimede levimisvõime määrab suurel määral ära koosluste täielikkuse. Selleks, et suurendada elurikkust meie põllumajandusmaastikes on äärmiselt oluline soodustada kohalike liikide edukat seemnelevi killustunud rohumaalaikude vahel elupaiga pindala suurendamise ning rohumaade mõõduka karjatamise või niitmise abil.
The ultimate goal of nature conservation is to avoid biodiversity loss. However, biodiversity is often only partially realized in local sites, i.e. communities are not complete. As only diverse communities can offer various nature´s benefits to people, such as pollination and natural pest control of (cultural) plants, it is essential to know why some species are absent from suitable sites and constitute dark diversity. In this thesis, we aimed to estimate the extent to which poor dispersal ability of plants (low seed abundance and short dispersal distance) may cause species absences from suitable sites in Central and Northern Europe and within grasslands ecosystems in the Baltic Sea Region. Additionally, we explored how the importance of dispersal limitation depends on local environmental conditions and human activities. We estimated dark diversity by analysing species co-occurrence patterns; to estimate dispersal abilities, we used various plant characteristics influencing seed dispersal. Our results showed that dark diversity species typically produced fewer seeds and dispersed shorter distances than observed species, indicating that poor dispersal abilities caused absences of many suitable species. The importance of dispersal limitation decreased with more stressful environments and with human activities. Species with good dispersal abilities belonged more likely to dark diversity in agricultural landscapes characterized by small areas of suitable grasslands. Overall, this thesis shows that species´ dispersal abilities largely determine completeness of plant communities. To increase biodiversity in agricultural landscapes, it is important to promote successful seed dispersal of native species between isolated grassland patches. This can be archived by increasing the area of grasslands (which also prevents the “loss” of seeds to unsuitable sites) and through moderate grassland management (e.g. grazing and mowing).
The ultimate goal of nature conservation is to avoid biodiversity loss. However, biodiversity is often only partially realized in local sites, i.e. communities are not complete. As only diverse communities can offer various nature´s benefits to people, such as pollination and natural pest control of (cultural) plants, it is essential to know why some species are absent from suitable sites and constitute dark diversity. In this thesis, we aimed to estimate the extent to which poor dispersal ability of plants (low seed abundance and short dispersal distance) may cause species absences from suitable sites in Central and Northern Europe and within grasslands ecosystems in the Baltic Sea Region. Additionally, we explored how the importance of dispersal limitation depends on local environmental conditions and human activities. We estimated dark diversity by analysing species co-occurrence patterns; to estimate dispersal abilities, we used various plant characteristics influencing seed dispersal. Our results showed that dark diversity species typically produced fewer seeds and dispersed shorter distances than observed species, indicating that poor dispersal abilities caused absences of many suitable species. The importance of dispersal limitation decreased with more stressful environments and with human activities. Species with good dispersal abilities belonged more likely to dark diversity in agricultural landscapes characterized by small areas of suitable grasslands. Overall, this thesis shows that species´ dispersal abilities largely determine completeness of plant communities. To increase biodiversity in agricultural landscapes, it is important to promote successful seed dispersal of native species between isolated grassland patches. This can be archived by increasing the area of grasslands (which also prevents the “loss” of seeds to unsuitable sites) and through moderate grassland management (e.g. grazing and mowing).
Kirjeldus
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