Productivity model and reference diagram for short rotation biomass crops of poplar grown in Mediterranean environments N. Oliveira a,* , H. Sixto a , I. Ca ~ nellas a , R. Rodrı´guez-Soalleiro b , C. P  erez-Cruzado c a Dpto. Selvicultura y Gesti on de los Sistemas Forestales, INIA-CIFOR, Madrid E-28040, Spain b Unidad de Gesti on Forestal Sostenible, Universidad de Santiago de Compostela, Lugo E-27002, Spain c Chair of Forest Inventory and Remote Sensing, Georg-August-Universit€ at G€ ottingen, D-37077, Germany article info Article history: Received 16 May 2014 Received in revised form 5 August 2014 Accepted 18 September 2014 Available online xxx Keywords: Poplar Short rotation coppice (SRC) Density management diagrams Reference diagrams Biomass abstract A Reference Diagram (RD) was constructed for first rotations of the Euroamerican poplar ‘I- 214’ grown as short rotation coppice (SRC). Data from 144 plots, established in eleven sites in Mediterranean environments, were used to develop the model. The density at estab- lishment of the plantations ranged between 6666 and 33,333 stools ha 1 , covering the usual densities ranges used in short rotation forestry (SRF). The RD was based on a density- independent mortality model that relates the density of living stools to the average height of dominant shoot and the initial plantation density, and it includes a system of two simultaneously fitted equations relating a) quadratic mean basal diameter of dominant shoots to the average height of dominant shoot and the final density, and b) total above- ground woody dry biomass to quadratic mean basal diameter and final density. The iso- lines in the RD represented mortality, quadratic mean basal diameter of dominant shoots and total above-ground woody dry biomass at the end of a first rotation of three years. The final yield in terms of biomass ranged from 1 to 85 Mg dm ha 1 . The RD enables rapid and straightforward comparison of different situations, both at planting and at harvesting, and is a useful tool, based on a wide range of empirical data, for management and decision making regarding short rotation poplar crops. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Woody biomass is a renewable resource that is suitable for getting different bioproducts, including bioenergy for different applications (heat, electricity or second generation biofuels) [1,2]. Use of woody biomass for bioenergy purposes represents a promising opportunity to contribute to the mitigation of climate change, to the extent that the presence of this resource may become important in the overall energy mix. The production and management of woody biomass may provide a new opportunity for economic development of rural areas [3] involving many different productive sectors. Forestry crops represent one source of supply of woody biomass, which is characterized by its spatiality and * Corresponding author. Tel.: þ34 913 473579; fax: þ34 913 572 293. E-mail addresses: nerea.oliveira@inia.es, nereadeoliveirarodriguez@gmail.com (N. Oliveira). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy xxx (2014) 1 e12 Please cite this article in press as: Oliveira N, et al., Productivity model and reference diagram for short rotation biomass crops of poplar grown in Mediterranean environments, Biomass and Bioenergy (2014), http://dx.doi.org/10.1016/j.biombioe.2014.09.019 http://dx.doi.org/10.1016/j.biombioe.2014.09.019 0961-9534/© 2014 Elsevier Ltd. All rights reserved.