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Pine plantation bands limit seedling recruitment of a perennial grass under semiarid conditions

Navarro-Cano, J.A., Barbera, G.G., Ruiz-Navarro, A., Castillo, V.M.
Journal of arid environments 2009 v.73 no.1 pp. 120-126
Pinus halepensis, forest plantations, forest litter, grasslands, semiarid zones, Stipa tenacissima, grasses, seedling emergence, seedling growth, soil properties, understory, Spain
Pine plantations coexist with Stipa tenacissima grasslands in many semiarid western Mediterranean areas. We compared three microsites created by a 30-year-old Pinus halepensis plantation: below pine plantation line (BP), below canopy of pines (BC) and interline bare band (BA). They were evaluated in terms of soil properties, pine litter and suitability as recruitment niches for S. tenacissima. Next, in a manipulative experiment in growth chambers we tested the hypothesis that pine litter interferes with the seedling emergence of S. tenacissima. Three treatments in pots were compared: (a) soil from BA; (b) intact soil + litter from BP; and (c) soil + litter from BP, which was mixed in the laboratory (BPMX). In the field the main microsite differences were pine cover and litter cover and thickness. Seedling emergence was significantly greater in BA than in BP. Emergence and litter depth fits a linear regression model. In the growth chamber litter did not interfere with the emergence of S. tenacissima. However, seedlings grown without litter were 28% longer and their mass was 27% greater than in the litter treatments. The detected pine litter interference may be relevant for plant dynamics and might be considered in forestry management programs.