Riparian buffers have been created as a sustainable and effective way to combat the harmful effects of excess nitrogen and soil salinity in riparian settings. The goal of this research was to determine what species will I) germinate in saline environments and II) establish and produce sufficient biomass while being exposed to increased nitrogen. Incubation of eight native riparian graminoid species were evaluated for their ability to germinate in MgSO4-induced salinity. In a greenhouse study, seven riparian graminoid species were evaluated to quantify their ability to survive and take up nitrogen, mimicking buffer strips exposed to high inputs of runoff nitrogen. Slender wheatgrass and green needlegrass were able to germinate successfully when exposed to MgSO4 with EC levels up to 16 dS m-1 and 8 dS m-1, respectively. Of the graminoid species tested, smooth brome yielded sufficient biomass and nitrogen uptake percentages in a controlled setting.

The aim of the thesis is evaluation of occurence of rusts on the selected types of grass, their specific diagnosis and valorization of their influence on the important agricultural qualities. The experiment was carried out in a cooperation with SS Větrov. In a two-year period (in 2009 and 2010) the samples of infested plants, which were subsequently evaluated microscopically, were taken. The ascertained results were processed through the Kruskal-Wallis test and the Independent Group T-Test. In 2009 and 2010 the occurrence of stem rust on the tested types of grass was significantly higher than occurence of crown rust. From the total number of 513 tests stem rust was found in 353 cases, whereas crown rust was found only in 103 cases. In 27 samples the occurrence of both types of rusts was found and there was no occurence found on the rest of the plants. The results show that in our climatic conditions stem rust becomes the most frequent pathogen which causes rustiness of grass. In 2010 the results of turf experiments proved that the selection of genotype of perenne reygrass with a lower infestation by stem rust had a positive impact on health conditions and better appearance of the offspring of the selected plans. Effectivenes of selection was confirmed. Among the tested materials there were chosen very predisposed genotypes which could be useful as the infectious material in the planned greenhouse tests for the resistance against rusts. Currently, we have also been abble to recognize the genotypes which are relatively resistant against particular rusts. If their resistance is confirmed in the following period, they might be used as donors of resistance in xenogamy and as immune standards in tests. The introduced results from the first stage of cooperation are only preliminary and it will be necessary to verify them at the following stages.

Assembly is a process that shapes the abundance and identity of species in a community. Niche and neutral theory explain assembly processes with mechanisms driven by either species differences, or functional equivalence and stochastic dispersal. In 2017 I sampled vegetation and environmental variables at 59 sites in the Noxubee National Wildlife Refuge and Tombigbee National Forest of Mississippi to explore forest understory community assembly. I developed and assessed a framework of predictions concerning general patterns and underlying mechanism. Evidence of dispersal limitation and functional equivalence were expected under neutral theory. Local environmental characteristics, surrounding landscape variables, and fire were significant determinants of beta diversity. Dispersal was not a strong predictor of beta diversity. I found evidence of both niche complementarity and functional equivalence, as well as niche differences among common vines and an introduced vine (Lonicera japonica). Overall, the results were more congruent with predictions expected under niche theory.