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Badano wpływ dwóch szczepionek endomikoryzowych (Endomix i Endorize-mix) oraz Eko-kompostu (0; 10 i 20% v/v) na wzrost krzewów pięciornika krzewiastego Potentilla fruticosa ‘Gold Drop’ uprawianych w pojemnikach oraz nawożonych nawozem mineralnym Osmocote Standard 5-6M (w dwóch dawkach: 1,5 oraz 3 g∙dm-3. Badania przeprowadzono w latach 2007-2008. W każdym sezonie wegetacyjnym oceniano wysokość roślin, masę wytworzonych pędów, liczbę kwiatów, stopień zasiedlenia systemu korzeniowego przez grzyby endomikoryzowe. Przeprowadzone badania wykazały, że krzewy pięciornika krzewiastego ‘Gold Dropʼ uprawiane w podłożu z dodatkiem Eko-kompostu oraz szczepionek mikoryzowych szybciej uzyskują rozmiary handlowe, są wyższe, mają większą masę pędów oraz wcześniej zakwitają. Najwyższy stopień zasiedlenia systemu korzeniowego przez grzyby endomikoryzowe obserwowano w drugim roku uprawy.
Grazing can change plant community composition and structure, which may alter the functions of the shrub meadow ecosystem. Grazing effects on Potentilla fruticosa shrub community in the headwater region of the Yellow River, which is in core area of the Qinghai-Tibet Plateau, are studied to provide adequate protection decision-making. We investigated continuous grazing and seasonal enclosure effects on P. fruticosa shrub communities. Three sites of P. fruticosa shrub comprising both continuous grazing and seasonal enclosure treatments were selected. The size of each fenced plot of P. fruticosa shrub was about 3000 m², the stocking rate was about 5 heads per 100 m² in continuous grazing treatment. Three samplings were made in each growing season of 2003 and 2004. Cover of vegetation, plant species composition and vegetation height were investigated in seven 1 × 1 m quadrates in each treatment. Above-ground biomass was measured in five 0.5 × 0.5 m quadrates. Shrub, forb, graminoid and sedge plant materials were clipped at ground level and oven-dried at 85ºC to a constant mass. Plant composition was affected by long term continuous grazing and changes were caused by forb species shifting. No apparent difference in species richness between the grazed and ungrazed communities over the growing months were found but the Shannon’s diversity indices of the grazed communities in June and July were higher than that of the ungrazed but lower in the late August and September. Live vegetation cover was reduced by 6.7%, 7.3% and 11.5%, respectively, owing to grazing in July, August and September, but not in June (P> 0.05). Forbs took up more than 50% cover of the vegetation in both grazed and ungrazed treatments. Relative cover of sedges and forbs in ungrazed treatment decreased in July, August and September, while that of graminoids increased more than 70% in the same period. Live vegetation height was reduced by 27% (2004) and 23% (2003) in late August and early September, but not in early growing season. Grazing reduced total above-ground biomass by 35%, 37% and 36% in July, August and early September, respectively, and the reduction was mainly in forb biomass. Continuous grazing affects plant composition and species diversity. The quantitative characteristics of P. fruticosa communities were influenced by grazing over growing months, but the effects were offset by non-growing season grazing.
The facilitative and competitive effects of shrubs on herbaceous species have been extensively studied, but little is known about the roles of the shrub distribution patterns in such effects. On a heavily grazed pasture on the Tibetan Plateau, we investigated the effects of Potentilla fruticosa Linn. shrubs of different distribution patterns on the small-scale vegetation pattern of the herb layer. We made same-sized releves at five micro-site types, i.e., beneath and outside the canopies of solitary Potentilla individuals, beneath and outside the canopies of edge-of-patch individuals and at the central openings of torusshaped large Potentilla patches. Shrubs protected certain species by increasing their frequencies of occurrence or flowering. However, only few species benefited from shrubs and more occurred or flowered more frequently outside. The data at community level indicated that species richness and diversity index were higher outside. The patch openings did not benefit species richness, pooled cover, diversity index or evenness of central vegetations. No special species was found growing beneath shrubs exclusively and few species were found with higher occurrences beneath shrubs. Furthermore, no significant difference was found between the two different distribution patterns at either community or species level. Vegetation ordinations confirmed this and vegetations beneath and outside the shrubs were distinguished merely. In conclusion, Potentilla facilitated some species in the herb layer and the patch openings did not show large protective effects. Also, distribution patterns of Potentilla did not affect the difference between vegetations beneath and outside shrub canopies.
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