Development of the science of the Critical Zone requires an ensemble of theory, models and analytical methods from its various parent disciplines including ecology, hydrology, geomorphology, (bio)geochemistry, and soil science.  Research at the Catalina-Jemez CZO is advancing disciplinary science in each of these areas.  Some examples of how each discipline is contributing to an improved understanding of CZ structure and function, as well as to advancing knowledge within the respective disciplines, are given below.

Ecology:  Ecosystem structure and dynamics (e.g., canopy and understory species photosynthetic growth, respiration, and senescence, heterotrophic microbial activity) affect net ecosystem exchange (NEE) of both water and carbon between land and atmosphere.  Quantifying the relative importance of species-specific contributions to system-scale NEE is a challenge for ecology.

Soil Science:  Infusion of water and photosynthate into soil promotes primary mineral weathering and precipitation of secondary clays, stimulates microbial activity and associated exudates, and leads to the formation of mineral-organic complexes and higher order aggregate structures that sustain plant growth.  Developing a conceptual model for soil structure formation requires combining concepts from soil physics, chemistry and biology.

Geomorphology:  The distribution of soil depth across the landscape is controlled by the balance between the rate of soil production from bedrock weathering and its erosion due to sediment transport.  However, internal feedbacks between these processes are important since, e.g., soil depth also affects the rate of its production from bedrock weathering. Precipitation, bioturbation (e.g., tree throw), and disturbance (e.g., fire) drive erosive sediment transport that redistributes soil on the landscape in episodic pulses when particular thresholds are exceeded.

Hydrology:  Precipitation in excess of evapotranspiration infiltrates the soil where it is distributed between matrix and macropore flow, with vertical transport predominating until saturated subsurface conditions arise from convergent flow regimes.  The role of precipitation intensity in affecting lateral subsurface flows, and the impacts of initial conditions on catchment mean transit times (i.e., the time a packet of water remains in the catchment before reaching the outlet) can be unraveled using continuous measurements of catchment input-output data on stable water isotopes.  Deducing the evolving pathways taken during water transport through montane catchments requires a multi-faceted, state-of-the-science approach to hillslope hydrology.

Geochemistry:  The weathering porous media (soil, saprolite, bedrock) contacted by migrating water during its transport through the catchment imprints the water with a geochemical “fingerprint” of local reactions that can be deduced by studying pore waters collected at different catchment locations.  Over long times, the solid phase weathering profile becomes depleted in those elements preferentially released to water, and the various catchment sources sampled by migrating waters are revealed in the time-dependent change in hydrochemical signature of emanating surface waters.