Effects of different intensities of overstory thinning on tree growth and understory plant-species productivity in a semi-arid Pinus halepensis Mill. afforestation

Francisco Bruno Navarro, M. N. Jimenez, E. M. Cañadas, E. Gallego, L. Terrón, M. A. Ripoll


It is becoming more and more common in the Mediterranean basin to guard against forest fires by creating wooded firebreak areas by reducing the overstory density, pruning the remaining trees and slash mulching. Nevertheless, very few attempts have been made to analyse the effect of this practice upon tree growth and the productivity of the understory plant species in semi-arid areas by following a well defined experimental design over any length of time. To remedy this lack of information, during the spring of 2005 we thinned the overstory in a semi-arid Aleppo pine (Pinus halepensis Mill.) afforestation in SE Spain (planted in the winter of 1993-1994) from an initial density of about 1,500 trees per ha according to three different thinning regimes. The annual growth data of each stand (diameter at breast height, canopy cover and basal area) were measured in randomly situated plots of 20 × 20 m and the above-ground biomass of understory plant species was also harvested from quadrats of 0.5 × 0.5 m during the early summers of 2005 to 2009. Our results showed a positive and significant response from trees in thinned stands compared to the controls, in spite of periods of low-rainfall and plague stress that unfortunately occurred during the study period. There were also statistical differences in understory biomass production within the different areas of overstory thinning as a response to the new conditions. Nevertheless, this biomass was only a small fraction of the total above-ground biomass of the afforestation, which was much higher in control plots. These tree responses and structural changes to the afforestation could be of great interest because of their implications for forest management in the context of global change in an area where increases in temperature and reductions and irregularity in precipitation, together with higher fire risks, are forecast.


wooded firebreak areas; normal diameter; understory biomass; SE Spain

Full Text:



Aussenac G., 2000. Interactions between forest stands and microclimate: ecophysiological aspects and consequences for silviculture. Annals of Forest Science 57, 287-301. http://dx.doi.org/10.1051/forest:2000119

Aussenac G., Granier A., 1987. Effects of thinning on water stress and growth in Douglas fir. Canadian Journal of Forest Research 18, 100-105. http://dx.doi.org/10.1139/x88-015

Bergstedt J., Milberg P., 2001. The impact of logging intensity on f ield-layer vegetation in Swedish boreal forests. Forest Ecology and Management 154, 105-115. http://dx.doi.org/10.1016/S0378-1127(00)00642-3

Blondel J., Aronson J., 1995. Biodiversity and ecosystem function in the Mediterranean basin: human and non-human determinants. In: Mediterranean-type ecosystems: the function of biodiversity (Davis G.W, Richardson D.M., eds). Ecological Studies 109, Springer-Verlag, Berlin. pp. 43-119.

Bréda N., Granier A., Aussenac G., 1995. Effects of thinning on soil and tree water relations, transpiration and growth in an oak forest [Quercus petraea (Matt.) Liebl.]. Tree Physioogy 15, 295-306. http://dx.doi.org/10.1093/treephys/15.5.295 PMid:14965953

Cecatti A., Piutti E., 1998. Silvicultural alternatives, competition regime and sensitivity to climate in a European beech forest. Forest Ecology and Management 102, 213-223. http://dx.doi.org/10.1016/S0378-1127(97)00163-1

Deal R.L., 2007. Management strategies to increase stand structural diversity and enhance biodiversity in coastal rainforests of Alaska. Biological Conservation 137, 520-532. http://dx.doi.org/10.1016/j.biocon.2007.03.014

Eycott A.E., Watkinson A.R., Dolman P.M., 2006. Ecological patterns of plant diversity in a plantation forest managed by clearfelling. Journal of Applied Ecology 43, 1160-1171. http://dx.doi.org/10.1111/j.1365-2664.2006.01235.x

FAO-ISRIC, 1998. Base referencial mundial del recurso del suelo. FAO, Roma.

French L.J., Smith G.F., Kelly D.L., Mitchell F.J.G., O'donoghue S., Iremonger S.F., Mckee A.M., 2008. Ground flora communities in temperate oceanic plantation forests and the influence of silvicultural, geographic and edaphic factors. Forest Ecology and Management 255(3-4), 476-494. http://dx.doi.org/10.1016/j.foreco.2007.09.014

Gámez J., 1995. El espacio geográfico de Guadix: aprovechamiento agrario, propiedad y explotación. University of Granada and Caja de Granada Foundation, Granada, Spain.

Götmark F., Paltto H., Nordén B., Götmark E., 2005. Evaluating partial cutting in broadleaved temperate forest under strong experimental control: short-term effects on herbaceous plants. Forest Ecology and Management 214, 124-141. http://dx.doi.org/10.1016/j.foreco.2005.03.052

Halpern C.B., Spies T.A., 1995. Plant species diversity in natural and managed forests of the Pacific Nortwest. Ecological Applications 5, 913-934. http://dx.doi.org/10.2307/2269343

Hannertz M., Hånell B., 1993. Changes in the vascular plant vegetation after different cutting regimes on a productive peat-land site in central Sweden. Scandinavian Journal of Forest Research 8, 193-203. http://dx.doi.org/10.1080/02827589309382769

Kleintjes P.K., Jacobs B.F., Fettig S.M., 2004. Initial response of butterflies to an overstory reduction and slash mulching treatment of a degraded piñon-juniper woodland. Restoration Ecology 12(2), 231-238. http://dx.doi.org/10.1111/j.1061-2971.2004.00212.x

Lado L., Bautista I., Lidón A.L., Llinares J.V., Lull C., Galiana F., 2009. Comparación de la temperatura y humedad del suelo en parcelas sometidas a diferentes tratamientos selvícolas. In: Actas del 5º Congreso Forestal Español, CD-Rom (SECF-Junta de Castilla y León, eds). Sociedad Española de Ciencias Forestales, Ávila, Spain.

Martín D., Del Río M., Heinrich I., Helle G., Cañellas I., 2009. Efecto de las claras sobre el crecimiento y la relación clima-crecimiento en parcelas repobladas de Pinus nigra. In: Actas del 5º Congreso Forestal Español, CD-Rom (SECF-Junta de Castilla y León, eds.). Sociedad Española de Ciencias Forestales, Ávila, Spain.

Misson L., Antoine N., Guiot J., 2003. Effects of thinning intensities on drought response in Norway spruce [Picea abies (L.) Karst.]. Forest Ecology and Management 183, 47-60. http://dx.doi.org/10.1016/S0378-1127(03)00098-7

Pabst R.J., Spies T.A., 1998. Distribution of herbs and shrubs in relation to landform and canopy cover in riparian forests of coastal Oregon. Canadian Journal of Botany 76, 298-315.

Ripoll M.A., 2004. Aprovechamiento de escorrentías superficiales mediante la construcción de microcuencas: aplicación a la forestación en ambientes mediterráneos. Ph. D. thesis. University of Granada, Spain.

Rivas-Martínez S., Loidi J., 1999. Bioclimatology of the Iberian Peninsula. Itinera Geobotanica 13, 41-47.

Ruiz-Mirazo J., Cardoso J.A., Varela E., Ramos M.E., Robles A.B., González-Rebollar J.L., 2007. Los clareos en áreas cortafuegos: una herramienta para incrementar la biodiversidad. Proceedings of the 4th International Wildland Fire Conference, Sevilla, Spain, 13-18 May. http://www.fire.uni-freiburg.de/sevilla-2007/contributions/html/es/autor_R.html

Salguero M.L., Allúe C., García-Güemes C., Tapias R., González-Pérez A., Vázquez-Piqué J., 2008. Effects of Pinus sylvestris L. and Pinus nigra Arn. thinning on juvenile cork oak (Quercus suber L.) growth in Bozoo (Burgos, Spain). In: Suberwood, new challenges for the integration of cork oak forest products (Vázquez-Piqué J., Pereira H., González-Pérez A., eds). University of Huelva, Huelva. pp. 213-222.

Vázquez-Piqué J., Salguero M.L., Gonzálezpérez A., García-Güemes C., Tapias R., Macías R., Allúe C., 2009. Influencia de las claras de Pinus sylvestris L. y Pinus nigra Arn. en el crecimiento diametral del alcornoque (Quercus suber L.) en Bozoo (Burgos). In:Actas del 5º Congreso Forestal Español, CD-Rom (SECF-Junta de Castilla y León (eds). Sociedad Española de Ciencias Forestales, Ávila, Spain.

Vélez R., 2003. Los incendios forestales en la cuenca mediterránea. In: La defensa contra incendios forestales: fundamentos y experiencias (Vélez R., ed). McGraw-Hill, Madrid. pp. 3.1-3.52.

Wilson D.S., Puettmann K.J., 2007. Density management and biodiversity in young Douglas-fir forests: challenges of managing across scales. Forest Ecology and Management 246, 123-134. http://dx.doi.org/10.1016/j.foreco.2007.03.052

DOI: 10.5424/fs/2010193-8858

Webpage: www.inia.es/Forestsystems