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

Authors: ABDELKRIM LIMANE, NORIA SMAIL-SAADOUN, AMEL BELKEBIR-BOUKAIS, KARIMA KISSOUM-HAMDINI

Abstract: Despite xeric conditions, Pistacia atlantica Desf. subsp. atlantica (Atlas pistachio) succeeds in developing impressive dendrometric dimensions (25-m high, 2-m trunk diameter). It is among the rare spontaneous phanerophytes of the North African steppe. With access to water being the primary condition for survival, we focused on its root system. According to a gradient of increasing climatic and edaphic aridity in Algeria, we recorded different root architectures set up by this tree. We sampled its underlying soil and determined its main physico-chemical characteristics. Root architecture is mainly of the superficial type with more than 60% of roots 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 superficial roots and their ramifications decrease, while their average circumferences, and the length and average circumference of the deep roots increase. These deep and thick roots allow access and storage of moisture present in the deep levels and protected there from evaporation, and, on the other hand, provide an important anchor in these soft soils. The Atlas pistachio adapts to increasing climatic and edaphic aridity by adopting a phreatophytic strategy.

Keywords: Pistacia, Atlas pistachio, roots adaptation, African steppe, arid soils, drought

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