Indicators of forest soil quality under environmental constraints.

• Main Author: Cécillon, Lauric
• Other Authors: Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Université Joseph-Fourier - Grenoble I, Jean-Jacques BRUN([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2008
• Subjects: Soil Science; Soil quality; Indicators; Near Infrared Reflectance Spectroscopy; Wildfire; Science du Sol; Pédologie; Qualité des sols; Indicateurs; Spectroscopie proche infrarouge; Nématodes; Permafrost; Feux de forêts; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; permafrost
• Online Access: https://theses.hal.science/tel-00396553; https://theses.hal.science/tel-00396553/document; https://theses.hal.science/tel-00396553/file/phd_thesis_lauric_cecillon_2008.pdf

Mountain soils are facing strong changes in land-use and climate, which expose them to three main threats: erosion, loss of biodiversity and organic matter decline. This thesis focuses on mountain soil quality, through key ecosystem processes (decomposition and aggregation of soil organic matter) occurring in topsoils. These key processes control the provision of several soil ecosystem services such as carbon sequestration, nutrient supply, and biological activity. We have tested both simple and composite soil quality indices under environmental constraints in two study sites. Both sites are characterized by a strong vegetation gradient generated by natural constraints (sporadic permafrost in Dévoluy mountains, Isère, France), or human constraints (wildfire chronosequence in the Maures mountains, Var, France). Our results demonstrate that both soil microclimate and wildfire constraints affect soil attributes linked to decomposition and aggregation processes in topsoils. Soil biota (microflora and microfauna) is markedly affected, indicating modifications in soil processes controlled by soil foodweb (main decomposition and aggregation pathways, potential nitrification and denitrification). Near infrared reflectance spectroscopy (NIRS) is found to be a powerful tool for assessing the modifications of physico-chemical and biological quality of soils under environmental constraints. Les sols des régions de montagne sont confrontés à de fortes modifications climatiques et d'usages qui les rendent particulièrement sensibles à trois menaces : l'érosion, la perte de matière organique et de biodiversité. Cette thèse aborde la question de la qualité des sols sous l'angle de processus clés (décomposition et agrégation de la matière organique) au sein de différents compartiments de la partie superficielle du sol vivant (épipédon). Ces processus clés interviennent dans l'intensité des services rendus par les sols comme la séquestration de carbone, la fertilité des sols et le maintien de leur activité biologique. Parmi les ...