Effects of soil compaction and light on growth of Quercus pyrenaica Willd.
(Fagaceae) seedlings
Marı
´
a Dolores Bejarano
a,c
, Rafael Villar
a,
*
, Ana Marı
´
a Murillo
a
, Jose
´
Luis Quero
b,d
a
A
´
rea de Ecologı
´
a, Edificio C-4, Campus de Rabanales, Universidad de Co
´
rdoba, 14071 Co
´
rdoba, Spain
b
Departamento de Ecologı
´
a, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada, Spain
c
Departamento de Ingenierı
´
a Forestal, Escuela Te
´
cnica Superior de Ingenieros de Montes, Universidad Polite
´
cnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
d
Forest Ecology and Forest Management Group, Centre for Ecosystem Studies, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
1. Introduction
Tree seedling performance is affected by various abiotic factors,
but particularly light, temperature and nutrient and water
availability (Canham et al., 1996; Holmgren, 2000; Sack, 2004).
In addition, seedling growth may be influenced by various physical
properties of soil including compaction (Kozlowski, 1999, 2002;
Mo
´
sena and Dillenburg, 2004; Alameda and Villar, 2009; Pe
´
rez-
Ramos et al., 2010). In fact, compaction increases the bulk density
and penetration resistance of soil, and decreases the size and
proportion of voids in it, which in turn reduces soil permeability,
and water and air diffusivity (Gayoso and Iroume
´
, 1991;
Verpraskas, 1994). A soil with an increased bulk density and
penetration resistance may require greater energy investments for
root development, thus raising energy costs for plants and
potentially reducing their growth rate and performance. In this
way, soil compaction may diminish root development (Verdu
´
and
Garcı
´
a-Fayos, 1996; Passioura, 2002) and stem growth (Wolfe
et al., 1995; Ferree and Streeter, 2004). However, compaction may
also have favourable effects on plant growth (Brais, 2001; Fleming
et al., 2006), especially in coarse-textured soils with a low water
retention capacity. Alameda and Villar (2009) found growth and
biomass allocation in woody species to respond differently to
changes in soil compaction. Also, they found the response to
depend on the particular soil compaction range; thus, the effects
on plant growth were generally positive in the low to medium
compaction range, but negative at high compaction levels.
The seedling stage is usually a critical phase in the regeneration
of woody species under natural conditions (Pulido and Dı
´
az, 2005;
Aca
´
cio et al., 2007); thus, the risk of environmental stress during
this stage is very high, and so is the likelihood of seedlings dying as
a result (Aca
´
cio et al., 2007). Because early seedlings must develop
effective roots to obtain water and nutrients, soil compaction may
have a strong effect on the earliest development stages of woody
Soil & Tillage Research 110 (2010) 108–114
ARTICLE INFO
Article history:
Received 12 January 2010
Received in revised form 30 April 2010
Accepted 4 July 2010
Keywords:
Biomass allocation
Soil bulk density
Mediterranean oak
Root biomass
Root length
Soil penetration resistance
ABSTRACT
Soil compaction and light availability influence plant growth via different mechanisms. In general, soil
compaction has a direct effect on roots, whereas light affects leaves and stems. Although plants in nature
are exposed to variable levels of soil compaction and light, no study on the potential mutual interactions
of these limiting factors in woody plants has to the authors’ knowledge been reported to date. The aim of
this work was therefore to elucidate the effects of soil compaction and light availability on growth and
biomass allocation in the deciduous oak Quercus pyrenaica. To this end, a study was conducted at two
light levels (viz. 3% and 100% of incident light, designated as low-light and high-light, respectively) under
a wide range of soil compaction (0.02–3 MPa as penetration resistance) in a greenhouse. Total biomass
was found to be positively affected by both light and soil compaction. There was marginally significant
interaction between the effects of the two factors on total biomass, which was positively affected by soil
compaction only under high-light conditions. Soil compaction had a strong, negative effect on the length
of the main root; thus, at maximum soil compaction, such a length was roughly one-half that observed at
lower compaction levels. Also, the specific root length of main root (root length to root mass ratio) was
reduced by roughly one-half in highly compacted soils. These results suggest that an unfavourable
combination of soil compaction and light availability may have severely adverse effects on woody plant
performance in drought periods since plants with short roots can hardly access water at deep soil levels.
The strength of this effect may be modulated by light availability.
ß 2010 Elsevier B.V. All rights reserved.
* Corresponding author. Tel.: +34 957 218635; fax: +34 957 218233.
E-mail address: bv1vimor@uco.es (R. Villar).
Contents lists available at ScienceDirect
Soil & Tillage Research
journal homepage: www.elsevier.com/locate/still
0167-1987/$ – see front matter ß 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.still.2010.07.008