Mechanical site preparation (MSP) is commonly used to enable forest regeneration of clear-cuts. Less intense methods may be more suitable from an environmental point of view, but such a method can result in the lack of natural regeneration. We compare the influence of three MSP methods on natural regeneration of Scots pine. The methods differ in their degree of soil disturbance. The effects of MSP by forest plough (FP), active plough (AP), and forest cutter (FC) on density, quality, and biometric parameters of one-year old seedlings were determined. The highest density of seedlings was obtained in the FP treatment (188,000 seedlings ha ). The best quality seedlings were found in the FC variant, and the worst -in the FP treatment. Most biometric parameters of seedlings did not differ by MSP method, except for the root length and root:shoot ratio. By the end of growing season, in the FP treatment, 1-year old seedlings formed a top bud more than twice as often as the seedlings from the AP and FC treatments. The FP method led to the best Scots pine natural regeneration. The results obtained in the FC variant were not as good as in the FP method, though they were still acceptable from the silvicultural point of view. The FC method was the least intensive method of site preparation, yet it is considered the most appropriate from the environmental (soil protection) point of view.

Some studies indicate that metal nanoparticles can be used in plant cultivation as fungicides and growth stimulators. The aim of this study was to evaluate the effect of silver (AgNPs) and copper nanoparticles (CuNPs) on the growth parameters, on the extent of leaves infected by powdery mildew and on spontaneous ectomycorrhizal colonization of English oak (Quercus robur L.) seedlings growing in containers. Nanoparticles were applied to foliage four times during one vegetation season, at four concentrations: 0, 5, 25 and 50 ppm. The adsorption of NPs to leaves was observed by microscopical imaging (TEM). The tested concentrations of AgNPs and CuNPs did not have any significant effect on the growth parameters of the oak seedlings. TEM results showed disturbances in the shape of plastids, plastoglobules and the starch content of oak leaves treated with 50 ppm Cu-and AgNPs, while no changes in the ultrastructure of stems and roots of oak plants treated with NPs were observed. No significant difference in powdery mildew disease intensity was observed after NP foliar app lication. Four ectomycorrhizal taxa were detected on oak roots (Sphaerosporella brunnea, Thelephora terrestris, Paxillus involutus and Laccaria proxima). Oak seedlings treated (foliar) with CuNPs and AgNPs at 25 ppm were characterised by the highest degree of mycorrhization (respectively, 37.1% and 37.5%) among all treatments including the control treatment. None of the tested NPs manifested phytotoxicity in the examined Q. robur seedlings under container nursery conditions.

Chitosan has become a promising biological agent for disease control and plant growth promotion. The objective of this study was to assess the effects of chitosan, applied as an active ingredient of Beta-chikol (Poli-Farm, Łowicz, Poland), to control damping-off and Lophodermium needle cast on Scots pine seedlings growing in field conditions. Beta-chikol was used for seed treatment and as a foliar spray at recommended rates and concentrations. For each experimental variant (chitosan, fungicides, unprotected), inventories of seedlings were performed, after germination and again after six weeks. In the aboveground parts of seedlings, the concentration of endogenous salicylic acid was determined by HPLC. At the end of the growing season, seedling growth parameters were determined. Beta-chikol used as foliar spray limited infection by the damping-off fungi but was ineffective when used as a seed treatment. Lophodermium needle cast was not observed during the study period. After the application of Beta-chikol, the concentration of salicylic acid did not increase. The application of Beta-chikol enhanced all growth parameters under investigation. Our results indicate the possibility of using chitosan in the form of Beta-chikol to stimulate plant growth and protect pine seedlings against parasitic damping-off in forest nurseries. OPEN ACCESSForests 2015, 6 3166

Nanomaterial is material with one dimension below 100 nm, while this definition also encompasses the nanoparticles as atomic or molecular aggregates in which two dimensions are in the 1-100 nm range (Klaine et al. 2008). Such small dimensions set against relatively large surface areas ensure that nanoparticles have physical-chemical and biological properties markedly different from homogeneous materials of the same kind (Nel et al. 2006). In turn, in line with origin, nanoparticles can be termed natural, incidental or engineered.While the presence of natural nanoparticles in the environment (as moon-dust or volcanic ash, for example) reflects

While some tree species can regenerate naturally without mechanical site preparation (MSP), Scots pine has been shown to benefit from this process. We compared three methods: using a double-mouldboard forest plough (FP), an active single-disc plough (AP), and a forest mill (FM), as well as a no-MSP control, in terms of growth, survival and density of occurrence of pines during the first 4 years of natural regeneration. Moisture conditions were expressed via calculated de Martonne aridity indices, while the microhabitats generated via different MSP methods were further characterised by the total contents of N and C, and the C/N ratio, P2O5, and base cations, as well as bulk density and actual moisture. The trials showed inferior regeneration without MSP in terms of the density and cover of young pines. Any of the studied treatments influenced survival, though the best growth was achieved by seedlings using the FP and AP methods, while the best density and evenness results were obtained using AP. The factors most influencing regeneration features were high precipitation during the first growing season after sowing and reduced competition with other vegetation in the cleared area. This impact seems far more important than the capacity of different MSPs to produce differentiation in soil microhabitats in terms of nutrient status or bulk density.