Poplar Short Rotation Coppice Plantations under Mediterranean Conditions: The Case of Spain

Abstract

Developing a circular bioeconomy based on the sustainable use of biological resources, such as biomass, seems to be the best way of responding to the challenges associated with global change. Among the many sources, short rotation forest crops are an essential instrument for obtaining quality biomass with a predictable periodicity and yield, according to the areas of cultivation. This review aims to provide an overview of available knowledge on short rotation coppice Populus spp. plantations under Mediterranean conditions and specifically in Spain, in order to identify not only the status, but also the future prospects, for this type of biomass production. The analysis of available information was conducted by taking into consideration the following aspects: Genetic plant material; plantation design, including densities, rotation lengths and the number of rotations, and mixtures; management activities, including irrigation, fertilization, and weed control; yield prediction; biomass characterization; and finally, an evaluation of the sustainability of the plantation and ecosystem services provided. Despite advances, there is still much to be done if these plantations are to become a commercial reality in some Mediterranean areas. To achieve this aim, different aspects need to be reconsidered, such as irrigation, bearing in mind that water restrictions represent a real threat; the specific adaptation of genetic material to these conditions, in order to obtain a greater efficiency in resource use, as well as a greater resistance to pests and diseases or tolerance to abiotic stresses such as drought and salinity; rationalizing fertilization; quantifying and valuing the ecosystem services; the advance of more reliable predictive models based on ecophysiology; the specific characterization of biomass for its final use (bioenergy/bioproducts); technological improvements in management and harvesting; and finally, improving the critical aspects detected in environmental, energy, and economic analyses to achieve profitable and sustainable plantations under Mediterranean conditions.

Study of the Thermochemical Properties of Lignocellulosic Biomass from Energy Crops

“…Results obtained for the clones selected in this work are quite high (84.5-87%) compared to those commented in literature, which usually vary from 78.4% to 84.8% [35][36][37]. No great differences are observed between varieties or age clones, although is considered that the short rotation coppice (SRC) usually shows high volatile content [38,39]. Volatile fraction of crust samples is lower than that wood samples, which is in concordance with its lower heating values (see Section 3.9).…”

Lengthening single-stem rotation improves biomass yield and water use efficiency in black poplar genotype multi-stem rotation coppice plantations

“…However, the studied hybrid poplar genotypes were subjected to markedly different climatic conditions than those observed in southern Mediterranean areas. Among the tested hybrid poplars, five are selected by the Belgic breeding centre (Table 1), and are widely cultivated in Central and Western European countries [50], which have relatively shorter growth season and longer summer rainfall periods than southern Europe. In Western European, rainfall is distributed evenly with a variation lower than 20% from the average annual precipitation.…”

Growing Poplar in Acid Soils: Biomass Yield and Ash Behavior

“…This study shows how balsam poplar species and hybrids with 50% presence of these species responded better in terms of mortality and production. Figure 2 shows a comparison of the yield obtained for the clones yielding the best results for acid soils under Atlantic conditions (Trichobel, Raspalje, Beaupré, and Unal) (black) relative to the yield cited for said clones by Oliveira, et al [1], both at the national level (green) and at the European level (blue). Yield clearly increased with planting density, at least up to the limit of 20,000 cuttings ha −1 (Figure 2).…”

“…The need for a better characterization of biomass for its final use (either as bioenergy or bioproducts) has been pointed out in several reviews of poplar short rotation coppice (SRC) plantations [1][2][3]. Such improvements should be coupled with genotype testing in a range of environments to increase biomass production, which would also ensure good quality biomass for generating bioproducts and bioenergy for different applications (heat, electricity, and second-generation biofuels) [3].…”

“…ex Marsh.). Balsam poplars and their hybrids have been tested in suboptimal conditions in Spain, having shown their ability to grow in soils of moderate fertility (see Table 3 in Oliveira, et al [1]).…”