XVI
Contents
20
Element Budgets in Catchments
A. Avila, J. Bellot, and J. Pifiol ............................................................... 283
20.1 Introduction ........................................................................................... 283
20.2 Input Fluxes ........................................................................................... 284
20.3 Output Fluxes ........................................................................................ 285
20.3.1 Streamwater Chemistry ........................................................................ 285
20.3.2 Element Outputs in Streamwater ........................................................ 287
20.4 Net Outputs............................................................................................ 288
20.4.1 Elements with Net Retention: Nitrogen and Potassium .................... 290
20.4.2 Elements in Balance: Chloride and Sulphur ....................................... 291
20.4.3 Elements with Net Exports................................................................... 292
20.5 Weathering Rates................................................................................... 293
References ...................................................... ; .................................................. 295
21
Biogeochemical Models
A. Avila ............... :................................................................................... 297
21.1 Introduction ........................................................................................... 297
21.2 Description of MAGIC .......................................................................... 298
21.3 Application of MAGIC to Montseny .................................................... 299
21.3.1 Forest Management and Atmospheric Deposition Scenarios .......... 301
21.3.2 Climate Change Scenarios .................................................................... 305
21.4 Application of MAGIC to Prades ......................................................... 308
21.4.1 Historical Sequences ............................................................................. 309
21.4.2 Forest Management and Atmospheric Deposition Scenarios .......... 309
21.5 Concluding Remarks ............................................................................ 310
References ..................................................................................... .................... 311
Part 6 Responses to Disturbances.......................................................... 313
22
Soil Fertility After Fire and Clear-Cutting
I. Serrasolses and V.R. Vallejo ............................................................... 315
22.1 Introduction ........................................................................................... 315
22.2 Experimental Design ............................................................................ 315
22.3 Direct Effects of the Fire ....................................................................... 316
22.3.1 Nutrient Losses ...................................................................................... 316
22.3.2 The Ashbed Layer After the Fire .......................................................... 318
22.4 Changes in Forest Floor Weight ........................................................... 318
22.5 Nutrient Dynamics in the Forest Floor ............................................... 320
22.6 Phosphorus and Nitrogen Dynamics .................................................. 322
22.6.1 Soluble Phosphorus .............................................................................. 322