Stand Biomass Dynamics of Pine Plantations and Natural Forests on Dry Steppe in Kazakhstan

Biomass dynamics were studied in isolated relict stands of scots pine (Pinus sylvestris) on the dry steppe of Kazakhstan (53-54N) where potential evaporation is 500-600 mm yr-1 and the rainfall is 250-260 mm yr-1. Samples were taken from 7 plots in natural stands on sandy forest soils (age 13-110 years) and 10 plots in plantations on dark-chestnut-coloured soils (age 5-50 years). Nine or 10 sample trees were taken from each plot, giving a total of 68 and 96 sample trees in natural and plantation stands respectively. Root systems were excavated and fractionated in 11 plots. Analyses indicated that the stability of these stands becomes critical at 10-20 years when foliage biomass reaches its maximum (7-13 t ha-1 dry weight), both in plantations and natural stands. Self-regulating mechanisms in natural stands provide stability that may not develop not observed in some plantations. Natural stands may show an abrupt decrease in foliage biomass at the time of canopy closure, but it increases again by age 40-50 years. In plantations this critical period may cause dieback and may trigger stand collapse before maturity. Stem and root biomass increases monotonically and does not depend upon stand origin. The total biomass production is influenced by ground water level and the presence of and depth to the clay layer underlying the sandy sediments

Novel magnetic stoichiometric superconductor compound EuRbFe4As4

Confrences and Symposia.In the new stoichiometric high-temperature ironbased superconductor RbEuFe4As4, superconductivity coexists with a peculiar long-range magnetic order of the Eu 4f states; their coexistence is an enigma and a challenge for both experiment and theory. Using angle-resolved photoemission spectroscopy (ARPES), resonant photoemission spectroscopy (ResPES), Andreev reflection spectroscopy, scanning tunneling spectroscopy, and DFT band structure calculations, we have made significant progress in solving this puzzle. Our results unambiguously indicate a separation between the electronic states of Fe (superconductivity) and Eu (magnetism) and demonstrate the existence of superconducting and long-range magnetic orders almost independently of each other.K S P and V M P are grateful for the support of the Russian Science Foundation (project no. 21-12-00394). S V E is grateful for financial support within the framework of the State Assignment of the Institute of Strength Physics and Materials Science of the Siberian Branch of the RAS (project FWRW-2022-0001). V S S and I A G are grateful for support in their STS research from the Russian Science Foundation (project no. 18-72-10118).Peer reviewe