Root Structure and Belowground Biomass of Hybrid Poplar in Forestry and Agroforestry Systems in Mediterranean France

Abstract

In poplar, one of the most used species of forestry and agroforestry, below ground biomass allocation plays an important role in providing anchorage as well as efficient nutrient and water distribution channel. Available literature on this aspect is not enough in hybrid Poplar, Populus euramaricana I-214. Therefore, the study was aimed at finding how this species developed its root system and how much belowground biomass was allocated in Forest System (FRS) and Agroforest System (AFS). This was done using soil excavation and root coring methods. Coarse roots were distributed in all directions but their number and proximal cross section area (CSA) were not uniform. In the case of AFS tree maximum CSA was distributed in the south and south-west direction while in FRS it was in the north-east and south-east direction. Fine roots were observed throughout the rooting zone along with coarse and medium roots up to a maximum depth of 2.4 m in FRS and 2.8 m in AFS. Total belowground biomass was higher in AFS tree (130 kg tree^-1) than FRS tree (120 kg tree^-1). But on hectare basis FRS accumulated (24.5 Mg ha^-1) more biomass than AFS (18.1 Mg ha^-1). However, if practiced in surplus agriculture area and considered the system as a whole, AFS allows grain production in lieu of some biomass deficit.