Soil water availability regulates soil respiration temperature dependence in Mediterranean forests

• Autores: Chao Ting Chang
• Directores de la Tesis: Santiago Sabaté Jorba (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2017
• Idioma: español
• Tribunal Calificador de la Tesis: Jorge Curiel Yuste (presid.), Victoriano Ramón Vallejo Calzada (secret.), Romá Ogaya Inurrigarro (voc.)
• Materias:
  • Ciencias de la vida
    • Biología vegetal (botánica)
      • Ecología vegetal
  • Ciencias de la tierra y del espacio
    • Hidrología
      • Humedad del suelo
• Enlaces
  • Tesis en acceso abierto en:  Dipòsit Digital de la UB  TDX 
• Resumen

  • The variations of ecosystem and soil respiration are mainly driven by temperature and precipitation, but the importance of temperature and precipitation could vary across temporal and spatial. At diurnal to annual temporal scales, ecosystem and soil respiration generally increase with average annual temperature, but very low or very high soil moisture has been shown to diminish the temperature response of respiration. Therefore, in water-limited ecosystem, such as the Mediterranean region where the seasonal pattern is characterized with significant summer drought, precipitation patterns are likely to play a particularly important role in regulating ecosystem and soil respiration inter annual whereas temperature may be much less factor. In this dissertation, I try to reduce the uncertainties of terrestrial net ecosystem exchange in Mediterranean region by measuring the interaction between environmental factors and soil respiration at short (i.e., diurnal) and medium (i.e., seasonal-years) temporal scales. Three in situ experiments were employed to investigate how soil respiration responds to environmental variations and management. Together, these three studies gave a consistent picture on how soil moisture strongly affects the dynamic and magnitude of soil respiration in Mediterranean forests. Results elucidated a clear soil moisture threshold; when soil moisture is above this threshold, soil temperature is the main driver of soil respiration, meanwhile, when soil moisture is below this threshold, soil respiration decoupled from soil temperature and is controlled by soil moisture. This suggests that soil moisture modified, at least in Mediterranean ecosystems, the temperature sensitivity of respiration through threshold-like response.