Ecohydrology of the Galapagos Islands

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This new research project is in collaboration with Dr. Diego Riveros-Iregui from the University of North Carolina Chapel Hill. The goal of this research project is to understand the ecohydrology of the Galapagos Islands.

While the flora and fauna of the Galapagos Islands have well described, far fewer studies have been hypotheses driven (with notable exception, Drs. Rosemary and Peter Grant). Even fewer studies have examined hydrological or plant physiological processes.

Background

Tropical Montane Cloud Forests (TMCF) are important ecosystems in tropical regions worldwide given their high degree of endemism of fauna and flora and their critical role as headwaters that provide water to downstream communities during dry periods.

The extent of TMCF is decreasing globally, with more than half of these forests converted into other land-use practices. Trees in TMCF are unique in that they benefit from high rates of rainfall during the rainy season while also taking advantage of ‘occult’ precipitation (i.e., mist, cloud water, and fog) during periods when rainfall is low.

Climate observations show that many TMCF across the world have experienced a persistent warming trend and an increase in elevation of the cloud formation during the second half of the 20th century, and future climate predictions suggest even less overall water availability for these potentially vulnerable ecosystems.

Significance

The increase in cloud height formation has been coined the “cloud lifting” hypothesis; however, while many modeling studies suggest this phenomenon, no field-based studies have documented this.

As a result, high uncertainty exists in our current forecasts of the sensitivity of TMCF to changing climatological regimes, especially when evaluating the response of tree species to drought.

Research Goals

Our main goal is to quantify the importance of fog on the Galapagos islands.  To address this goal, we ask the following questions:

1.  How does fog contribute to stream or ground water?

2.  Do plants rely on fog as an important water source?

3.  What are the physiological responses of TMCF plants to decreasing fog/cloud cover?

3.  Can we use tree cores and stable isotope analysis to document changes in fog/cloud frequency during the last century?