Metsataimede levikuökoloogia ja mõisaparkide panus metsade elurikkuse hoidmisel

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Metsade pikaajaline ja intensiivne kasutamine on oluliselt vähendanud elurikkusele tähtsa biotoobi pindala ja halvendanud ökosüsteemi looduslikku seisundit. Isegi Eestis, kus metsamaa osakaal on viimase sajandiga kasvanud ja katab nüüdseks umbes poole maismaast, on metsaelupaikade kvaliteet jätkuvalt halvenenud. Seepärast on oluline toetada metsade elurikkuse kiiret taastumist uudistekkelistes metsades. Maapiirkondade mõisapargid pakuvad ainulaadset mudelsüsteemi uurimaks metsaliikide pikaajalist levikuökoloogiat. Käesoleva doktoritöö eesmärgiks oli tuvastada tegurid, mis mõjutavad metsaliikide asustamist uutes kasvukohtades ning hinnata mõisaparkide ökoloogilist väärtust metsaelurikkuse seisukohast. Doktoritöö tulemused viitavad, et vanad mõisapargid suudavad anda olulise panuse metsade elurikkuse säilitamisse. Parkide varjulistes osades leidus palju salumetsadele iseloomulikke taimeliike ja neid toetavaid vanametsadele omaseid struktuure, mida tänapäeva raieküpsetes metsades kohtab harva. Lisaks selgus, et metsataimed suudavad edukalt asustada uusi elupaiku, kui anda neile piisavalt aega, sobivad maastikutingimused ja elupaigakvaliteet. Maastiku tasemel on määravaks piisavas koguses liikide levikuallikateks sobivate metsade olemasolu ja omavaheline ühendatus. Elupaiga tingimustena tuleb eelkõige tagada puistu piisav suurus ja keskmiselt varjulised tingimused. Seejuures on lisaks puuvõrade liitvusele oluline ka mõningane põõsaste ja järelkasvu olemasolu. Metsaspetsiifilised liigid eristusid levikukoridore ja avamaastikke kasutada suutvatest liikidest paindliku paljunemis- ja levimisstrateegia poolest ning olid madalama kasvu ja väiksema mullatoitelisuse nõudlusega. Ühtlasi selgus, et metsataimede omadustest olid limiteerivamateks just asustamisega seotud taimetunnused. Mõisaparkide mitmekülgseks väärtustamiseks peaks nende kaugemaid varjulisi osi kujundama ja hooldama looduslähedaselt, keskendudes laialeheliste metsade tingimuste jäljendamisele. Elurikkuse kujunemise toetamisel uutes metsades on tähtis mitmekesise puistustruktuuri loomine ja selle pikaajaline säilitamine, mistõttu tuleks ka parkides säilitada liigirikas puistu- ja põõsarinne ning pargi kaugemates osades ka üksikud vigastatud puud. Toetamaks metsaomaste liikide edenemist parkides, tuleks hilisemate õitsejate soodustamiseks vältida varjuliste pargialade varajast niitmist.Forests are among the most-threatened ecosystems in Europe. Severe human impact has reduced forest cover and decreased the habitat quality in remaining stands. Even in Estonia—where forests cover about half of the country—habitat quality is often diminished. Throughout history a large number of rural manor parks have been established across Estonia. The landscape setting and history of these parks make for a unique study system to disentangle the colonisation ecology of forest species. Therefore, the aim of this thesis was to identify factors affecting colonisation ecology of forest-dwelling species and the ecological value of old rural manor parks. This thesis shows that old rural manor parks can contribute to forest biodiversity. Especially the closed-canopy parts of parks harbour forest specific species and stand characteristics typical to old-growth nemoral forests. Many of these habitat properties are rare in contemporary mature forests. The results also show that forest species are able to colonise forest-like habitats when given enough time, a suitable landscape setting and favourable habitat conditions. At a landscape level this means ensuring the availability of species source habitats and supporting habitat connectivity. A favourable habitat is sufficiently large in size and has limited light conditions suitable for forest species. In addition to the sufficient closure of the tree canopy layer, it is important to have some shading by shrub and lower tree layers. Plant species that were successful in colonising park habitats were adapted to tolerate shade and flowered early in the growing season, but also had a higher requirement for soil nutrient and higher values for a ruderal life strategy. To support forest specialist species in parks, park management levels needs to be kept moderate or aim at mimicking broad-leaved forest conditions. Therefore it is important to support a diverse stand structure by retaining old or damaged trees and by avoiding early-season mowing

Spatial and temporal patterns of initial plant establishment in salt marsh communities

Questions: How are dispersal processes, abiotic and biotic interactions determining the initial salt marsh plant community establishment and development when connectivity is different? We aim to answer this question by analysing the spatial and temporal patterns of plant establishment along the environmental gradient at two connectivity settings. Location: Back‐barrier salt marsh and tidal flats of Spiekeroog, northwest Germany Methods: We established an experiment along the salt marsh elevation gradient with bare sediment open for spontaneous colonisation on the natural salt marsh and on the experimental salt marsh islands built on the tidal flats approximately 500 m from the natural salt marsh for low connectivity. Plant establishment was identified from georeferenced photos at least monthly. Results: Experimental islands as low connectivity plots had limited colonisation by annual halophytes that produce large number of small seeds. Number of individuals increased with higher connectivity at salt marsh enclosed patches. Number of individuals was highest at the mid elevations whereas peak species richness was at the upper salt marsh. Temporal patterns of seedling emergence showed increasing plant numbers until end of April followed by gradual incline over the season at the pioneer and lower salt marsh zones. Upper elevations on the other hand had a stable number of low individual counts over time. Spatial clustering of plant individuals indicating possible facilitation was important at the initial stages of salt marsh development at pioneer and lower salt marsh elevation, but only early in the season. Conclusions: Stochastic patterns of early salt marsh colonisation indicated that success of species colonisation was determined by seed properties, seed availability and environmental conditions mediated by elevation. We found indications, that further colonisation was supported by already colonised plants at initial stages, but shifted to avoidance later in the season

Experimental salt marsh islands: a model system for novel metacommunity experiments

Shallow tidal coasts are characterised by shifting tidal flats and emerging or eroding islands above the high tide line. Salt marsh vegetation colonising new habitats distant from existing marshes are an ideal model to investigate metacommunity theory. We installed a set of 12 experimental salt marsh islands made from metal cages on a tidal flat in the German Wadden Sea to study the assembly of salt marsh communities in a metacommunity context. Experimental plots at the same elevation were established within the adjacent salt marsh on the island of Spiekeroog. For both, experimental islands and salt marsh enclosed plots, the same three elevational levels were realised while creating bare patches open for colonisation and vegetated patches with a defined transplanted community. One year into the experiment, the bare islands were colonised by plant species with high fecundity although with a lower frequency compared to the salt marsh enclosed bare plots. Initial plant community variations due to species sorting along the inundation gradient were evident in the transplanted vegetation. Competitive exclusion was not observed and is only expected to unfold in the coming years. Our study highlights that spatially and temporally explicit metacommunity dynamics should be considered in salt marsh plant community assembly and disassembly

Continuous meteorological observations at DynaCom automatic weather station, Spiekeroog, Germany (2021-01)

Data presented here were collected within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) of the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were created in the back barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog. Meteorological data were collected near the experimental setup, with a locally installed weather station located approximately 500m north of the southern shoreline. The weather station system used here was a ClimaSensor US 4.920x.00.00x that was pre-calibrated by the manufacturer (Adolf Thies GmbH & Co. KG, D-Göttingen). Data were recorded and saved within the Meteo-Online (V4.5.0.20253) software in a sampling interval of 1 min, with an averaging time of 10 s. Date and time were given in UTC and the position was derived from the internal GPS system. Data handling was performed according to Zielinski et al. (2018): Post-processing of collected data was done using MATLAB (R2018a). Quality control was performed by (a) erasing data covering maintenance activities, (b) removing outliers, defined as data exhibiting changes of more than two standard deviations within one time step, and (c) visually checks

Continuous meteorological observations at DynaCom automatic weather station, Spiekeroog, Germany (2020-11)

Meteorological data were collected near the DynaCom experimental setup, with a locally installed weather station located approximately 500m north of the southern shoreline of Spiekeroog. The weather station system used here was a ClimaSensor US 4.920x.00.00x that was pre-calibrated by the manufacturer (Adolf Thies GmbH & Co. KG, D-Göttingen). Data were recorded and saved within the Meteo-Online (V4.5.0.20253) software in a sampling interval of 1 min, with an averaging time of 10 s. Date and time were given in UTC and the position was derived from the internal GPS system. Data handling was performed according to Zielinski et al. (2018): Post-processing of collected data was done using MATLAB (R2018a). Quality control was performed by (a) erasing data covering maintenance activities, (b) removing outliers, defined as data exhibiting changes of more than two standard deviations within one time step, and (c) visually checks

Continuous meteorological observations at DynaCom automatic weather station, Spiekeroog, Germany (2021-10)

Data presented here were collected within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) of the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were created in the back barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog. Meteorological data were collected near the experimental setup, with a locally installed weather station located approximately 500m north of the southern shoreline. The weather station system used here was a ClimaSensor US 4.920x.00.00x that was pre-calibrated by the manufacturer (Adolf Thies GmbH & Co. KG, D-Göttingen). Data were recorded and saved within the Meteo-Online (V4.5.0.20253) software in a sampling interval of 1 min, with an averaging time of 10 s. Date and time were given in UTC and the position was derived from the internal GPS system. Data handling was performed according to Zielinski et al. (2018): Post-processing of collected data was done using MATLAB (R2018a). Quality control was performed by (a) erasing data covering maintenance activities, (b) removing outliers, defined as data exhibiting changes of more than two standard deviations within one time step, and (c) visually checks