Interannual variation of soil heat flux in a grass-dominated alpine tundra. Preliminary study from the Jeseníky Mts.
|Článek v odborném periodiku
|Časopis / Zdroj
|Czech Polar Reports
|Fakulta / Pracoviště MU
|alpine ecosystems; thermal regime; grassland; Nardus sp; Pinus mugo
|Soil heat flux (G) is an important component of the surface energy balance of terrestrial ecosystems. In polar and alpine tundra, G enters the subsurface layers during summer and relatively high G is released from soil during winter. Measuring of energy cycle in polar and alpine treeless ecosystems is challenging due to complex physics of seasonal changes associated with freeze-thaw cycle. That is why field data on G are much less abundant compared to the other World regions. In our 2 year study, we quantified soil heat flux in two alpine plots differing in the characteristics of vegetation cover. The first one was a wind-swept alpine grassland, while the other one was the same vegetation cover localized in a close neighbourhood of a patchy Pinus mugo stand. Our results suggest that both sites had similar yearly time courses of G with peak values of the heat flux to the soil recorded in spring season after the snow melt (April/May). Maxima of heat flux from the soil were found in the December-January period. In summer season (April-October), proportion of G to global radiation (R) reached low values, typically below 10%. Regression analysis revealed that in spite of similar vegetation cover and microrelief of the two study plots, the site neighbouring to the P. mugo stand responded to R more sensitively than the open plot dominated by a grassland community exclusive-ly. Data recorded and the relationships presented in the paper are discussed with the results of similar studies performed in polar and treeless alpine regions.