Прирост кормовых видов лишайников рода Cladonia (Cladoniaceae) на пастбищах домашнего северного оленя [Growth rate of forage Cladonia lichens (Cladoniaceae) on summer and winter pasture of Domestic Reindeer]

Соковнина (Абдульманова) С.Ю. &. Эктова С.Н. [Sokovnina (Abdulmanova) S.U. &. Ektova S.N]
Растительные ресурсы [Rastitelnye Resursy]
56(3): 221–240
DOI: 10.31857/S0033994620030085
[in Russian with English summary:] Overgrazing caused by reindeer husbandry has been a serious problem for the regions of the boreal and tundra zones for many years [3]. Terricolous fruticose lichens are the most sensitive component of Northern ecosystems [2, 8–10]. Currently, valuable forage lichens in the tundra zone of the Yamal Peninsula maintaining high occurrence, have a low abundance. The greatest impact of reindeer grazing and trampling is typical for summer pastures and driving paths. The study is aimed to estimation of the growth rate of Cladonia lichen thalli on summer pastures of the Yamal and Gydan peninsulas with different levels of vegetation cover degradation. The main objects of the study were valuable forage species of shrubby fruticose lichens – Cladonia arbuscula (Wallr.) Flot, C. rangiferina (L.) F. H. Wigg, C. stellaris (Opiz) Pouzar & V“zda, C. stygia (Fr.) Ruoss. In this research 2 gradients were considered: zonal and plant communities. Shrub tundra subzone: shrub tundra, exposed tundra communities, hummock bogs. Typical tundra subzone: shrub tundra, exposed tundra communities and hummock bogs. Arctic tundra subzone: dwarf shrub-lichen tundra, spotted grass-moss-lichen tundra and hummock bogs. The growth rate was calculated as a ratio of lichen podetia height to the number of branches [17], which characterizes lichen growth potential in the study area. And the growth rate of the living part of lichen podetia [18] was estimated, to assess the potential of lichen productivity. This method is recognized in the international scientific community [19, 20]) and confirmed by modern methods [21]. For analysis, we used one-factor or two-factor analysis of variance, methods of multivariate analysis, using forward sorting, and univariate regression. In the study area, the growth rate of shrubby fruticose lichens varied from 1.2 to 6.3 mm/ year. There is no significant decrease in lichen growth rate from south to north. The lowest growth rate of shrubby fruticose lichens was observed in the communities of the southern (shrub) tundra. That is in opposition to the expected maximum. The height of podetia in the southern (shrub) tundra is 21% lower than in the arctic. Arctic tundra communities exist under less impact. The height of the living part of podetia in the zonal gradient does not change. However, the highest values were found in the southern (shrub) tundra, which indicates a higher growth potential of lichens. The relative age of the podetia and its living part vary insignificantly in the “south – north” gradient. In the southern (shrub) tundra in shrub plant communities, model lichen species grow significantly faster. The density of shrubs is the single significant biotic factor that positively affects the growth rate of lichens. In the plant community series of the northern (typical) tundra differences in the growth rate were not revealed. The maximum growth rate was observed in communities of hummock bogs and decreased in shrub tundra by 13% and in exposed tundra by another 6%. The single significant biotic factor for the lichen growth rate is the thickness of the moss-lichen layer. With an increase in pasture impacts, the contribution of lichen mat height to the growth rate variation increases from 6 to 28%. In the arctic tundra subzone the growth rate of lichens in the hummock bogs is significantly higher than in other types of plant communities. The lichen mat height and percentage cover of mosses are significant biotic factors. The variation in the height and age parameters of the lichen podetia in the plant communities gradient is similar to lichen growth rate changes. Among the model species, the minimum growth rate and growth rate of the living part of podetia were revealed for C. stellaris, the species most sensitive to trampling. However, the maximum values of the height and age of the living part of the podetia prove that this species has the greatest potential for growth and production. The most resistant to pasture impact is C. stygia, a species characterized by the maximum growth rates of the podetia and its living part, and maximum height of the podetia. Keywords: Yamal peninsula, Gydan peninsula, West Siberia, tundra zone, shrubby fruticose lichens, genus Cladonia, growth rate, geographical gradient, ecological gradient, grazing influence.
Tuesday, 02 May 2023 15:29