Epiphytic lichens of some anthropogenic habitats of the countryside (Zubtsov area, Tver region)

Species composition and ecology of the epiphytic lichens collected on 31 species of the trees and shrubs at the rural settlements and their surrounding area were studied. In total 71 lichens species including 25 species on the fruit and berry crops were found. On many trees, even in forests the variety of species of lichens is strongly depleted. This is especially true for rural settlements, razing places, keeping and running cattle. Bryoria and Usnea species at the rural settlements and their surrounding area were not found. It was shown that G. scripta is a pioneer species on the speckled alder under the conditions of relatively strong shading and humidity.

Cultivation of speckled alder under harsh mountain conditions

The aims of the paper were as follows: (1) to assess the applicability of speckled alder for pioneer stands on the mountainous clear-cut tracts and (2) to evaluate the effects of slow-release fertilizer on the survival and growth of speckled alder under harsh environmental conditions. On the basis of seven-year results we can presume that speckled alder is a convenient pioneer species that can be cultivated on harsh mountain sites where the climatic extremes need to be alleviated and a layer of surface humus renewed. The initial slow-release fertilization is, nonetheless, highly desirable. As contrasted to the control the surface and planting hole applications of amendment reduced the total seven-year mortality rate by 9.5% and 20.1%, respectively, and the periodic annual height increment (2003–2009) was promoted by 47% and 59%, respectively. Analogous results were obtained when the values of basal stem diameter and crown diameter were compared. As for the method of application, the placement of the slow-release amendment in the planting holes seems to be more efficient mainly in terms of survival promoting. The surface application is, nonetheless, less laborious and also yielded satisfactory results.     

Influence of pulverized limestone and amphibolite mixture on the growth performance of Alnus incana (L.) Moench plantation on an acidified mountain site

A young speckled alder (<I>Alnus incana</I> [L.] Moench) stand was planted on a tract clear-felled due to air pollution and located on a summit plateau of the Jizerské hory Mts. (Central Europe, Czech Republic) at an altitude of 950 m a.s.l. The aim of the experiment was to test the suitability of <I>Alnus incana</I> to form preparatory stands covering the site and thus enabling the reintroduction of more sensitive target species. A potential of <I>Alnus incana</I> to respond to slow-release fertilizing was tested as well. The control treatment showed sufficient growth dynamics, nevertheless, the fertilization significantly promoted the growth (documented by height, height increment and stem-base diameter). If some limitations of alder such as high light requirements are respected, the speckled alder can be recommended as a suitable species for preparatory stands even in the 7^th and 8^th altitudinal (vegetation) zones, especially when fertilized.

Beneficial influence of plant neighbours on tree growth in drained forested peatlands: a case study

In boreal forest, drainage can be successfully used to lower the water-table level of postharvest forested peatland stands suffering from watering-up. The later vegetation revival and growth is suspected to gradually create a water-table drawdown described in this study as biological drainage. Its effect on the annual stump diameter increment of planted eastern larch (Larix laricina (Du Roi) K. Koch) and naturally regenerated black spruce (Picea mariana (Mill.) BSP) was studied on a postharvested and drained forested peatland located in eastern part of the Canadian boreal forest. A factor describing the neighbourhood occupancy of every subject tree was used to illustrate biological drainage in a retrospective growth analysis. Results showed the dual effect of the neighbourhood occupancy factor: competing situations close to the ditch and growth-favouring situations farther from it. In the latter case, the studied trees demonstrated better growth with moderately increasing neighbourhood occupancy. This was interpreted as evidence of the beneficial effect of biological drainage on tree growth. The presence of speckled alder (Alnus incana subsp.rugosa (Du Roi) J. Clausen) in the neighbourhood of selected trees corresponded to improved growth for both studied species.

Distribution and abundance of infective, soilborne Frankia and host symbionts Shepherdia, Alnus, and Myrica in a sand dune ecosystem

We describe presence, abundance, and distribution of three sympatric nitrogen-fixing shrubs and their symbiotic diazatroph, Frankia, in a sand dune ecosystem differing in successional stage, vegetative cover, edaphic characteristics, and topography. Distribution of actinorhizal Myrica gale L., Alnus incana (L.) Moench subsp. rugosa (Du Roi) Clausen, and Shepherdia canadensis (L.) Nutt. was analyzed among 120 sampling locations representing a gradient of successional stages in a sand dune system along Lake Michigan. In a greenhouse study, seedlings of these species were employed to bioassay the presence and abundance of infective Frankia in soils. Shepherdia-infective Frankia was detected in 80% of the plots, while Alnus- and Myrica-infective Frankia were found in 65% and 64% of the plots, respectively, with no Frankia found in 18% of the plots. Only 14% of the plots supported actinorhizal host-plant species. Infective Frankia were present in soils of young dunes prior to the establishment of any actinorhizal hosts. Shepherdia-infective Frankia were more abundant in soils from drier, earlier successional sites, while Alnus- and Myrica-infective Frankia were more abundant in moister soils of later successional communities. A previous study had revealed that nodular Frankia strains at this site were host specific for Shepherdia and largely so for Myrica and Alnus, which had only a small proportion of shared strains (Huguet et al. 2001). The likelihood of host-plant nodulation by soilborne Frankia was increased by the presence of actinorhizal plants in general, but not by the presence of their respective specific host plants. Submerged soils had no infectious capacity, whereas soils with greater in situ moisture content and soils subject to intermittent saturation tended to have lower infectious capacities overall. Our results suggest that soilborne, infective Frankia genotypes are not only host specific, but are also associated with spatially and chronologically distinct sets of ecological conditions.Key words: speckled alder, sweet gale, Canada buffalo berry, actinorhizal, nitrogen fixation, Frankia, root nodules.

Effect of elevated carbon dioxide in the root atmosphere on nitrogenase activity in three actinorhizal plant species

In wet soils, nitrogen-fixing root nodules are subjected to elevated CO2. Only a few studies have examined the effect of elevated CO2 on nitrogenase activity, and the results have been mixed. We examined intact black alder (Alnus glutinosa (L.) Gaertn.) and sweet gale (Myrica gale L.) seedlings and field-collected speckled alder (Alnus incana ssp. rugosa (Du Roi) Claus.) nodules to clarify the effects of elevated CO2. Nitrogenase activity was measured via acetylene reduction in an open, flow-through system. We found that repeated measurements of the peak rate of nitrogenase activity, the only reliable measure of nitrogenase activity, could be made on the same plant via 150-s exposures to acetylene separated by 20 min without acetylene. Our results for elevated CO2 consistently showed that it had little effect on nitrogenase activity at low concentrations and increasingly inhibited nitrogenase activity as the CO2 concentration increased. In black alder, 0.5 kPa CO2 had little effect, whereas 3.0 kPa CO2 reduced nitrogenase activity 31–35%. Sweet gale, was less sensitive to elevated CO2 and was unaffected by 1.5 kPa CO2. Black alder grown with the roots, but not the shoots, in 1.3 kPa CO2 showed only minimal acclimation to elevated CO2.Key words: acetylene reduction technique, actinorhizal plants, Alnus, carbon dioxide, Myrica gale, nitrogen fixation.