Water and Nutrient Limitations to Primary Production
193
increased availabilities of soil resources, (2) it does so relatively quickly, and
(3) the high stem densities and the probable old age of the stools do not prevent holm oak from taking advantage of increased resource availabilities.
Holm oak responded quite differently to water and to nitrogen additions.
Increased soil water availability during the warm season greatly increased
the diameter growth rate of tree stems, both in the case of irrigation and in
the case of a year of abundant spring-summer rainfall. Surprisingly, increased water availability led to a decrease in leaf fall, even on a multi-year
average. On the other hand, N fertilization did not increase the stem diameter growth, at least during the 3 years after the first application, but it did
have a strong effect on canopy dynamics. This suggests that holm oak preferentially allocates the increased soil N to leaf and twig production, thus improving its light interception capacity. Phosphorus addition had remarkably
few effects on this stand, perhaps because of the already relatively high
phosphorus availability in this circumneutral soil.
Our experiment demonstrates that water and nitrogen simultaneously
limit ANPP in the widespread high-density holm oak stands of resprout origin. In managing holm oak stands, therefore, it is essential to preserve the
water-holding capacity of the soil, and to minimize nitrogen losses from the
site.
References
Bellot J, Sanchez JR, Lled6 MJ, Martinez P, Escarre A (1992) Litterfall as a measure of primary
production in Mediterranean holm oak forest. Vegetatio 99/100:69-76
Binkley D, Reid P (1984) Long-term responses of stem growth and leaf area to thinning and fertilization in a Douglas-fir plantation. Can J For Res 14:656-660.
Cannell MGR (1989) Physiological basis of wood production: a review. Scand J For Res 4:
459-490
di Castri F (1981) Mediterranean-type shrublands of the world. In: di Castri F, Goodall DW,
Specht RL (eds) Mediterranean-type shrublands. Elsevier, Amsterdam, pp 1-52
Farquhar GD, Hubick KT, Condon AG, Richards RA (1989) Carbon isotope fractionation and
plant water-use efficiency. In: Rundel PW, EhIeringer JR, Nagy KA (eds) Stable isotopes in
ecological research. Springer, New York, pp 21-40
Field C, Mooney HA (1986) The photosynthesis-nitrogen relationship in wild plants. In: Givnish
TJ (ed) On the economy of plant form and function. Cambridge University Press, Cambridge, pp 25-55
Gower ST, Vogt KA, Grier CC (1992) Carbon dynamics of Rocky Mountain Douglas-fir: influence of water and nutrient availability. Ecol Monogr 62:43-65
Hellmers H, Bonner JF, Kelleher JM (1955) Soil fertility: a watershed management problem in
the Sant Gabriel mountains of southern California. Soil Sci 80:189-197
Kruger FI, Mitchell DT, Jarvis TUM (eds) (1983) Mediterranean-type ecosystems. The role of
nutrients. Springer, Berlin
Landsberg JJ (1986) Physiological ecology of forest production. Academic Press, London
Lled6 MJ (1990) Compartimentos y flujos biogeoquimicos en una cuenca de encinar del Monte
Poblet. PhD Thesis, University of Alicante, Alicante
193
increased availabilities of soil resources, (2) it does so relatively quickly, and
(3) the high stem densities and the probable old age of the stools do not prevent holm oak from taking advantage of increased resource availabilities.
Holm oak responded quite differently to water and to nitrogen additions.
Increased soil water availability during the warm season greatly increased
the diameter growth rate of tree stems, both in the case of irrigation and in
the case of a year of abundant spring-summer rainfall. Surprisingly, increased water availability led to a decrease in leaf fall, even on a multi-year
average. On the other hand, N fertilization did not increase the stem diameter growth, at least during the 3 years after the first application, but it did
have a strong effect on canopy dynamics. This suggests that holm oak preferentially allocates the increased soil N to leaf and twig production, thus improving its light interception capacity. Phosphorus addition had remarkably
few effects on this stand, perhaps because of the already relatively high
phosphorus availability in this circumneutral soil.
Our experiment demonstrates that water and nitrogen simultaneously
limit ANPP in the widespread high-density holm oak stands of resprout origin. In managing holm oak stands, therefore, it is essential to preserve the
water-holding capacity of the soil, and to minimize nitrogen losses from the
site.
References
Bellot J, Sanchez JR, Lled6 MJ, Martinez P, Escarre A (1992) Litterfall as a measure of primary
production in Mediterranean holm oak forest. Vegetatio 99/100:69-76
Binkley D, Reid P (1984) Long-term responses of stem growth and leaf area to thinning and fertilization in a Douglas-fir plantation. Can J For Res 14:656-660.
Cannell MGR (1989) Physiological basis of wood production: a review. Scand J For Res 4:
459-490
di Castri F (1981) Mediterranean-type shrublands of the world. In: di Castri F, Goodall DW,
Specht RL (eds) Mediterranean-type shrublands. Elsevier, Amsterdam, pp 1-52
Farquhar GD, Hubick KT, Condon AG, Richards RA (1989) Carbon isotope fractionation and
plant water-use efficiency. In: Rundel PW, EhIeringer JR, Nagy KA (eds) Stable isotopes in
ecological research. Springer, New York, pp 21-40
Field C, Mooney HA (1986) The photosynthesis-nitrogen relationship in wild plants. In: Givnish
TJ (ed) On the economy of plant form and function. Cambridge University Press, Cambridge, pp 25-55
Gower ST, Vogt KA, Grier CC (1992) Carbon dynamics of Rocky Mountain Douglas-fir: influence of water and nutrient availability. Ecol Monogr 62:43-65
Hellmers H, Bonner JF, Kelleher JM (1955) Soil fertility: a watershed management problem in
the Sant Gabriel mountains of southern California. Soil Sci 80:189-197
Kruger FI, Mitchell DT, Jarvis TUM (eds) (1983) Mediterranean-type ecosystems. The role of
nutrients. Springer, Berlin
Landsberg JJ (1986) Physiological ecology of forest production. Academic Press, London
Lled6 MJ (1990) Compartimentos y flujos biogeoquimicos en una cuenca de encinar del Monte
Poblet. PhD Thesis, University of Alicante, Alicante