Distribution and Physiology of Juniperus seravschanica Trees in the Genow—The Southernmost and Arid Habitat of Iran

Abstract

Juniperus seravschanica is the southernmost population of Juniperus that has a limited habitat in the world near the equator. In Iran, the lone habitat of this species in the Genow mountains has been endangered with thin foliage, abscissing needles, and dried shoots. The current study investigated the effects of climatic, genetic factors, and physiologic indices on the distribution of J. seravschanica. Distribution was evaluated for 450 ha and physiological indices were evaluated for two groups: (A) trees with dried branches and (B) trees without dried branches. Results showed that the distribution of J. seravschanica in the Genow habitat was influenced by elevation, slope degree, aspect, and distance to stream. Results also indicated that max temperature and precipitation are two effective factors that have the highest effects on falling needles and drying branches of J. seravschanica. Chlorophyll, relative water content (RWC), and relative turgidity (RT) are significantly influenced by max temperature. Endangered trees with dried branches had a lower chlorophyll content, RWC, and RT than trees without dried branches. Vulnerability of J. seravschanica was significantly influenced by its genetic structure. Results of AMOVA showed 83% genetic variability between two groups of J. seravschanica trees.

Factors Limiting Radial Growth of Conifers on Their Semiarid Borders across Kazakhstan

“…Indeed, data from a meta-analysis [ 88 ] showed a decrease in the acclimatization potential of evergreen trees to warming temperatures from boreal to tropical biomes, which is associated with higher background temperatures, among other things. For tropical juniper stands, there is evidence supporting that their growth is limited primarily by maximum temperatures [ 89 , 90 ]. However, regardless of the biome, heat waves have a negative impact on tree growth at all scales, from inhibition of photosynthesis and respiration to shedding of foliage and a decrease in the rate of apical and radial growth [ 91 ].…”