254
Antoni Escarre, Ferran RodA, Jaume Terradas and Xavier Mayor
(unpubl. data). Nutrient concentrations in litterfall are taken from Verdu
(1984) and Mayor (1990) for Montseny and from Clemente (1983) and Bellot
et al. (1992) for Prades. Nutrient concentrations in companion species at
Prades (Phillyrea latifolia, Arbutus unedo and Viburnum tin us) are from
Clemente (1983).
Nutrient pools and fluxes considered in this chapter are average estimates
for holm oak stands in the Avic catchment at Prades and in closed-canopy
plots in the Torrent de la Mina catchment at Montseny (Chap. 2). At both
sites, aboveground stand biomass and production were obtained by repeated
forest surveys and dimensional analysis of sample plots (Chap. 3). At Prades
69 2s-m 2 plots were used, while at Montseny 18 closed-canopy ls4-m 2 plots
were considered. Data for belowground biomass and production correspond
to Chapter 4, and the estimates for canopy leaching are taken from Chapter
15 (data sets Prades-1 and Montseny-2).
Published comprehensive data on nutrient concentrations in holm oak are
scarce (cf. the review by Rundel 1988). In our studies on nutrient cycling in
the holm oak forests of Prades and Montseny large data sets have been obtained on nutrient concentrations in all major tree components, and on how
they vary with age, crown position, individual trees, season, year, topographic
position, and so on. For this chapter we have selected or computed those average nutrient concentrations for each tree component that we judged to
better represent the mean conditions in closed-canopy holm oak forests at
Prades and Montseny. Here we will deal mainly with those tree components
that have been used for computing nutrient pools and fluxes associated with
stand biomass and production.
18.3 Nutrient Concentrations in Holm Oak Trees
18.3.1 Differences Among Tree Parts
Nutrient concentrations in the main components of holm oak trees at Montseny and Prades are shown in Table 18.1 for aboveground parts, and in Table
18.2 for belowground parts. Differences between both sites are not great,
though Ca levels tend to be higher in Prades, where soil pH and base saturation are much higher. Potassium concentrations in inflorescences and fruits
are also higher at Prades, but these can be affected by the degree of ripening
at the time of falling and by leaching. At both sites, mature holm oak leaves
have moderate nutrient concentrations, e.g. a mean foliar N concentration
between 12 and 15 mg g-l (all nutrient concentrations are on a dry weight
basis). Foliar nutrient concentrations decrease rapidly during the first weeks
after budbreak, but then they remain relatively stable in mature leaves for
about 2 years. Foliar Ca increases throughout the leaf lifespan while Nand P
tend to decrease, particularly in leaves older than 2 years. Twigs are as rich or
Antoni Escarre, Ferran RodA, Jaume Terradas and Xavier Mayor
(unpubl. data). Nutrient concentrations in litterfall are taken from Verdu
(1984) and Mayor (1990) for Montseny and from Clemente (1983) and Bellot
et al. (1992) for Prades. Nutrient concentrations in companion species at
Prades (Phillyrea latifolia, Arbutus unedo and Viburnum tin us) are from
Clemente (1983).
Nutrient pools and fluxes considered in this chapter are average estimates
for holm oak stands in the Avic catchment at Prades and in closed-canopy
plots in the Torrent de la Mina catchment at Montseny (Chap. 2). At both
sites, aboveground stand biomass and production were obtained by repeated
forest surveys and dimensional analysis of sample plots (Chap. 3). At Prades
69 2s-m 2 plots were used, while at Montseny 18 closed-canopy ls4-m 2 plots
were considered. Data for belowground biomass and production correspond
to Chapter 4, and the estimates for canopy leaching are taken from Chapter
15 (data sets Prades-1 and Montseny-2).
Published comprehensive data on nutrient concentrations in holm oak are
scarce (cf. the review by Rundel 1988). In our studies on nutrient cycling in
the holm oak forests of Prades and Montseny large data sets have been obtained on nutrient concentrations in all major tree components, and on how
they vary with age, crown position, individual trees, season, year, topographic
position, and so on. For this chapter we have selected or computed those average nutrient concentrations for each tree component that we judged to
better represent the mean conditions in closed-canopy holm oak forests at
Prades and Montseny. Here we will deal mainly with those tree components
that have been used for computing nutrient pools and fluxes associated with
stand biomass and production.
18.3 Nutrient Concentrations in Holm Oak Trees
18.3.1 Differences Among Tree Parts
Nutrient concentrations in the main components of holm oak trees at Montseny and Prades are shown in Table 18.1 for aboveground parts, and in Table
18.2 for belowground parts. Differences between both sites are not great,
though Ca levels tend to be higher in Prades, where soil pH and base saturation are much higher. Potassium concentrations in inflorescences and fruits
are also higher at Prades, but these can be affected by the degree of ripening
at the time of falling and by leaching. At both sites, mature holm oak leaves
have moderate nutrient concentrations, e.g. a mean foliar N concentration
between 12 and 15 mg g-l (all nutrient concentrations are on a dry weight
basis). Foliar nutrient concentrations decrease rapidly during the first weeks
after budbreak, but then they remain relatively stable in mature leaves for
about 2 years. Foliar Ca increases throughout the leaf lifespan while Nand P
tend to decrease, particularly in leaves older than 2 years. Twigs are as rich or