Pasture, tree and soil evolution in silvopastoral systems of Atlantic Europe

Abstract

Increased forest area and wood production is a key goal for the European Union, together with avoidance of hazards that damage forests. Galicia is a region of northwest Spain that belongs to the Atlantic biogeographic region with very high wood production, but due to climate fire has a major negative impact on forest productivity (i.e. it represents 16% of the fires of Europe). Silvopastoral systems offer the potential to enhance forest productivity as well as to obtain income from newly afforested areas in the short term. Herbaceous pasture production within such systems can be optimized through species selection and through fertilization. The aim of the present study was to evaluate effect of three types of fertilization on two sward mixtures established under Pinus radiata D. Don cover on abandoned agricultural land over an initial period of 7 years. Tree and pasture growth were enhanced with organic fertilization, tree growth rate not being limited by summer drought, and compared with mineral treatment, trees growing up on sludge treatment had around 35 and 30% more height and diameter, respectively. Acidity tendency of Galician soils was reduced with mineral treatment. Soil pH was positively affected by mineral fertilization as it was reduced in less extent in this treatment (pH 6) than in organic (pH 5.3) or no fertilization treatment (pH 5.6), as crop cation extractions were reduced. The proportion of Na and Mg in the effective CEC was higher in fertilization with dairy sludge and no fertilization plots due to better tree canopy development. The interchangeable potassium content in ryegrass sown plots was reduced when no fertilization was applied due to dicot extractions, which can explain lower tree growth than in non-fertilized cocksfoot plots. Correct tree and pasture management, using appropriate sowing mixtures and fertilization types, makes it possible to improve the productivity of both components of the silvopastoral system. Our present results indicate that it is better to use organic fertilizers in the establishment of cocksfoot or ryegrass on sandy soils for tree and pasture growth enhancement. #

Lime, sewage sludge and mineral fertilization in a silvopastoral system developed in very acid soils

“…Mineral fertilization in silvopastoral systems developed with Pinus radiata in initial neutral soils caused a significant reduction on tree growth. Rigueiro-Rodríguez et al (2000) and Mosquera-Losada (2006) observed that tree diameter and height were reduced by mineral fertilization compared with no fertilization or organic fertilization. This can be explained, first, because in fertile soils the soil pH did not limit pasture development and, therefore, the response of pasture production to mineral fertilization was positive, which enhances the competition between pasture and trees and reduces tree growth in the first development stages (initial tree height 20 cm).…”

“…Agenda 21 (UN 1992) describes silvopastoral systems as sustainable land management and as a way of increasing income from forestry in the short-and medium-terms (Mosquera-Losada et al 2006). Moreover, silvopastoral systems should be also implemented in Galicia as a way of reducing forest fires, one of the most important environmental problems in northern Spain, which contributes to 16% of the total annual area burnt in Europe (RigueiroRodríguez et al 2005b).…”

“…Liming and sewage sludge inputs can increase soil pH-depending on doses-and, therefore, reduce aluminium saturation in the interchange complex (Bailey 1995), causing an increase in soil chemical and physical fertility and the presence of sown species in pasture, which usually improves pasture quality and productivity (Wheeler 1998). Organic fertilizers, like dairy sewage sludge, can enhance both tree and pasture production in sandy neutral soils at short-and medium-term, but this fact can be different in very acid soils due to the different soil environment and the interaction between both crops (Rigueiro-Rodríguez et al 2000;Mosquera-Losada et al 2006).…”

Bases ecológicas para implementar un sistema de uso silvopastoral en la región patagónica de Aysén, Chile

“…Las sabanas naturales como ecosistemas donde coexiste la vegetación herbácea y la arbustiva y los grandes herbívoros también se han estudiado, en África (McNaughton 1979, Knoop y Waker 1985, Belsky et al 1989, Mordelet y Menaut 1995, Ong y Leakey 1999, Ludwig et al 2004, Sankaran et al 2005, Treydte et al 2007, Asner et al 2009) y en Norteamérica (McNaughton 1968, Belsky y Canham 1994, McPherson 1997, Jose et al 2004. En estas regiones y en otras más templadas también existen sistemas de uso ganadero que incorporan el arbolado (Cooper et al 1996, Feldhake 2001, Alavalapati et al 2004, Mosquera-Losada et al 2006, Guevara-Escobar et al 2007, Benavides et al 2009), con importantes beneficios para las características productivas de las comunidades herbáceas, la diversidad biológica y la provisión de servicios ambientales (Young 1989, Sanchez 1995, Etienne 1996, Altieri 1999, Jose et al 2004, Palma et al 2007, Benavides et al 2009, Jose 2009, Pastur et al 2012). …”

Optimising forest stand management in Galicia, north-western Spain

“…The developed model cannot be applied to all types of silvopastoral systems but only to those ones established by planting trees and sowing grass at the same time on abandoned agricultural lands (Mosquera-Losada et al 2006, Fernández-Núñez et al 2007. The model and the whole simulation-optimisation system can be improved with new information regarding the dynamics of the understory vegetation and the competition relationships among trees and bushes or herbaceous vegetation (Pollock et al 1994, Chang et al 2002, Peri et al 2002, Ares et al 2003 especially when both occupy the same strata (e.g., when tree plantations are young).…”