Contents
xv
17.2.2 Temporal Variability .............................................................................. 240
17.2.3 Ion Relationships ................................................................................... 240
17.3 Soil Solution ........................................................................................... 242
17.3.1 Low-Tension Lysimeter Solution at Montseny ................................... 242
17.3.2 Centrifuge Solution at Prades .............................................................. 244
17.3.3 Differences in Soil Solution Between Prades and Montseny ............ 246
17.4 Soil Water Flow and Soil Solution:
Soil Processes and General Remarks ................................................... 247
17.5 Relationship Between Soil Water and Streamwater Chemistries ..... 249
References ................................................... .............................. ........................ 250
18
Nutrient Distribution and Cycling
A. Escarre, F. Roda, J. Terradas, and X. Mayor ..................................... 253
18.1 Introduction ........................................................................................... 253
18.2 The Database ......................................................................................... 253
18.3 Nutrient Concentrations in Holm Oak Trees ..................................... 254
18.3.1 Differences Among Tree Parts ............................................................. 254
18.3.2 Spatial Variations ................................................................................... 257
18.3.3 Foliar Retranslocation .......................................................................... 257
18.3.4 Comparison with Other Forest Ecosystems ....................................... 259
18.4 Nutrient Pools ........................................................................................ 259
18.5 Nutrient Fluxes ...................................................................................... 261
18.6 Holm Oak Forests and Other Forest Biomes ...................................... 263
18.7 Nutrient Use Efficiency ......................................................................... 265
18.8 Nutrient Cycling and Stand Structure................................................. 267
18.9 Spatial Variation in Nutrient Cycling .................................................. 267
References ........................................................................ ................................. 268
Part 5 Hydrology and Biogeochemistry of Catchments ................ 271
19
Water Balance in Catchments
J. PHiol, A. Avila, and A. Escarre ........................................................... 273
19.1 Introduction ........................................................................................... 273
19.2 Water Balance at Prades and Montseny Compared
to Humid Catchments ........................................................................... 274
19.3 Interannual Variability of Streamflow and Evapotranspiration ...... 275
19.4 The Quotient P lET: Key Variable for Determining Water Balance... 277
19.5 Representativeness of the Experimental Catchments
for Larger Areas ..................................................................................... 279
19.6 Water Balance in a Warmer Climate .................................................... 279
References ......................................................................................................... 281