Root architecture adaptation of Pistacia atlantica subsp. atlantica according to an increasing climatic and edaphic gradient: case of a north south transect in Algeria

Abstract

Despite xeric conditions, Pistacia atlantica Desf. subsp. atlantica (Atlas pistachio) succeeds in developing impressivedendrometric dimensions (25-m high, 2-m trunk diameter). It is among the rare spontaneous phanerophytes of the North Africansteppe. With access to water being the primary condition for survival, we focused on its root system. According to a gradient ofincreasing climatic and edaphic aridity in Algeria, we recorded diferent root architectures set up by this tree. We sampled its underlyingsoil and determined its main physico-chemical characteristics. Root architecture is mainly of the superfcial type with more than 60% ofroots located in the top 50 cm of soil along the north south transect. With the decrease in precipitation and the rising of temperatures,length of the dry season, and the content of sand in soil, the number of superfcial roots and their ramifcations decrease, while theiraverage circumferences, and the length and average circumference of the deep roots increase. Tese deep and thick roots allow accessand storage of moisture present in the deep levels and protected there from evaporation, and, on the other hand, provide an importantanchor in these sof soils. Te Atlas pistachio adapts to increasing climatic and edaphic aridity by adopting a phreatophytic strategy.