Resource Use by Chaparral and Matorral

The comparative study of mediterranean type ecosystems has gained considerable momentum during the past two decades. Modem studies on these systems date from the work of Ray Specht, who studied the dynamics of the heath vegetation of south­ ern Australia. The results of these studies first appeared in 1957 (Specht and Rayson, 1957) and were summarized in 1973 (Specht, 1973). Specht followed this detailed work, which pointed to the central role of nutrients in limiting the productivity of the Australian heath, with a general comparison of the structural features of woody plant communities in mediterranean type ecosystems of Australia, southern France, and southern California (Specht, 1969a,b). The comparative studies emphasized remark­ able convergent features of these ecosystems, particularly in relation to structural features affecting primary production. Naveh (l967) also did comparative studies focusing on grassland types that occur in the mediterranean climatic zones of Califor­ nia and IsraeL About this same time, independent studies by Mooney and Dunn (1970 a,b) and Mooney et al. (1970) made preliminary structural and functional comparisons of the vegetations of mediterranean type ecosystems in California and Chile in an at­ tempt to derive an evolutionary model explaining the basis of their convergent natures. Much of the knowledge of these ecosystems up to 1973 was summarized in volume 7 of Ecological Studies, Medite"anean Type Ecosystems: Origin and Structure (di Castri and Mooney, 1973). This volume builds on its series predecessor in many ways.

Contenu

1. Conceptual Basis and Organization of Research.- 1.1. General Background.- 1.2. Objective of Research.- 1.3. Methodology.- 1.4. Conclusions and Discussion Regarding Hypotheses.- 2. Resource Availability and Environmental Characteristics of Mediterranean Type Ecosystems.- 2.1. Introduction.- 2.2. General Description of Regions.- 2.3. Wind, Temperature, and Atmospheric Humidity.- 2.4. Seasonal Patterns of Water Availability.- 2.5. Seasonal Patterns of Solar Irradiance.- 2.6. Environmental Influences on the Length of the Growing Season and Summer Drought.- 2.7. Hypothetical Plant Responses.- 2.8. Conclusions.- 3. The Plant Communities and Their Environments.- 3.1. Introduction.- 3.2. Species Abundance and Phyletic Similarity.- 3.3. Vegetation Communities in Southern California and Central Chile.- 3.4. Distribution of Species Along Gradients of Aspect, Elevation, and Moisture.- 3.5. Distribution of Growth Forms Along Gradients of Aspect, Elevation, and Moisture.- 3.6. Structural Similarity of Vegetation in Southern California and Central Chile.- 3.7. Conclusions.- 4. Biomass, Phenology, and Growth.- 4.1. Introduction.- 4.2. Biomass.- 4.3. Seasonal Biomass Dynamics.- 4.4. Annual Biomass Budget of Chaparral Shrubs.- 4.5. Conclusions.- 5. Microclimate and Energy Exchange.- 5.1. Introduction.- 5.2. Topographic Influence on Microclimates.- 5.3. The Partitioning of Solar Irradiance by the Canopy and Soil.- 5.4. The Partitioning of Absorbed Solar Irradiance in the Canopy.- 5.5. Conduction.- 5.6. Energy Budgets for Coastal and Montane Sites.- 5.7. Effect of Vegetation Form on Microclimate, Plant Temperature, and Energy Exchange Processes.- 5.8. Conclusions.- 6. Water Utilization.- 6.1. Introduction.- 6.2. Hydrologic Balance.- 6.3. Control of Species Water Relations.- 6.4. Diurnal and Seasonal Patterns of Plant Water Relations.- 6.5. Environment and Plant Influences on Water Capture Efficiency.- 6.6. Conclusions.- 7. Energy and Carbon Acquisition.- 7.1. Introduction.- 7.2. Patterns of Temperature and Light Dependency.- 7.3. Simulated Temperature Sensitivity.- 7.4. Simulated Fit of the Photosynthetic Temperature Optima.- 7.5. Quantum Efficiency at Light Saturation.- 7.6. Growth Form Effects on Photosynthetic Rate.- 7.7. Relation Between Photosynthetic Competence and Cover.- 7.8. Seasonal Patterns of Carbon Uptake.- 7.9. Conclusions.- 8. Carbon Allocation and Utilization.- 8.1. Introduction.- 8.2. Carbon Losses Through Respiration.- 8.3. Carbon-14 Dioxide Utilization.- 8.4. Root Turnover.- 8.5. Annual Carbon Budgets.- 8.6. Simulated Temperature Sensitivity of Carbon Metabolism.- 8.7. Organic Nutrient Levels.- 8.8. Conclusions.- 9. Mineral Nutrient and Nonstructural Carbon Utilization.- 9.1. Introduction.- 9.2. Seasonal Patterns of Plant Nutrient Content.- 9.3. Influences of Nutrients on Plant Growth.- 9.4. Conclusions.- 10. Nutrient Cycling in Mediterranean Type Ecosystems.- 10.1. Introduction.- 10.2. Intersystem Cycles.- 10.3. Nutrient Pools.- 10.4. Intrasystem Cycles.- 10.5. Conclusions Regarding Nutrient Dynamics During Ecosystem Development.- 11. Models of Plant and Soil Processes.- 11.1. Introduction.- 11.2. Canopy Process Simulator.- 11.3. The Mediterranean Ecosystem Simulator.- 11.4. Validation.- 11.5. Conclusions.- 12. Similarities and Limitations of Resource Utilization in Mediterranean Type Ecosystems.- 12.1. Introduction.- 12.2. Similarities of Resource Use and Resource-Use Efficiency.- 12.3. Environmental Limitations of Resource Use and Resource Use Efficiency.- 12.4. Functional Interpretation of Morphological and Physiological Characteristics of Mediterranean Shrub Vegetation.- 12.5. Relative Importance of Plant Adaptations Versus Environment in Affecting Resource Use and Resource-Use Efficiency.- 12.6. Conclusions.- Literature Cited.- Resumen / Gloria Montenegro.