9 Leaf Traits and Canopy Organization
Santiago Sabate, Anna Sala and Carlos A. Gracia
9.1 Introduction
Carbon, water and nutrient fluxes through forest canopies depend on the
functional and morphological attributes of individual leaves within the canopy, which, in turn depend on the amount and arrangement of foliage. Canopy structure and canopy function are tightly coupled attributes that result
in an optimal "functional structure" ultimately determined by abiotic and
biotic factors such as incident radiation, water availability, nutrient availability, competitive interactions, herbivory, etc. Holm oak (Quercus ilex 1.) is a
broadleaved evergreen tree characteristic of the western Mediterranean region that forms dense stands in a variety of environments (Chap. 1). Here, we
compile information on structural, and functional characteristics of holm
oak canopies at two locations in NE Spain, differing in resource availability:
the Avic catchment in the Prades mountains and the permanent plot at La
Castanya in the Montseny mountains (see Chap. 2). The Avic catchment is a
more xeric site with higher annual incident radiation and lower annual precipitation than La Castanya. Our goal is to analyse how much structural and
functional variation exists between and within canopies and how this variation relates to environmental conditions.
9.2 Total Leaf Biomass and Leaf Area Index
Variations in total canopy leaf biomass and leaf area index (LA!) of Mediterranean plants have long been related to environmental conditions (Specht
and Specht 1989). Reductions in exposed leaf area have been cited as a longterm response (years) to the intensity and duration of the summer dry period (Poole and Miller 1981). In Mediterranean regions, where the typical
long dry summer period limits plant growth and production, higher LAIs are
found in sites with higher water availability where moderate to high precipiEcological Studies, Vol. 137
Ferran Roda et aI. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999
Santiago Sabate, Anna Sala and Carlos A. Gracia
9.1 Introduction
Carbon, water and nutrient fluxes through forest canopies depend on the
functional and morphological attributes of individual leaves within the canopy, which, in turn depend on the amount and arrangement of foliage. Canopy structure and canopy function are tightly coupled attributes that result
in an optimal "functional structure" ultimately determined by abiotic and
biotic factors such as incident radiation, water availability, nutrient availability, competitive interactions, herbivory, etc. Holm oak (Quercus ilex 1.) is a
broadleaved evergreen tree characteristic of the western Mediterranean region that forms dense stands in a variety of environments (Chap. 1). Here, we
compile information on structural, and functional characteristics of holm
oak canopies at two locations in NE Spain, differing in resource availability:
the Avic catchment in the Prades mountains and the permanent plot at La
Castanya in the Montseny mountains (see Chap. 2). The Avic catchment is a
more xeric site with higher annual incident radiation and lower annual precipitation than La Castanya. Our goal is to analyse how much structural and
functional variation exists between and within canopies and how this variation relates to environmental conditions.
9.2 Total Leaf Biomass and Leaf Area Index
Variations in total canopy leaf biomass and leaf area index (LA!) of Mediterranean plants have long been related to environmental conditions (Specht
and Specht 1989). Reductions in exposed leaf area have been cited as a longterm response (years) to the intensity and duration of the summer dry period (Poole and Miller 1981). In Mediterranean regions, where the typical
long dry summer period limits plant growth and production, higher LAIs are
found in sites with higher water availability where moderate to high precipiEcological Studies, Vol. 137
Ferran Roda et aI. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999