Climate Syndromes of Seasonality (Climate SoS): Perspectives on Future Climate Change

2014-15 New Investigator Award

This project seeks to understand climate syndromes of seasonality from both ecological and atmospheric perspectives. Initial research is focusing on seasonally dry tropical forests, a biome that exhibits strong wet season/dry season variations in ecological, hydrological and physical characteristics. These forests are expected to be strongly impacted by climate change, and long-term trends in precipitation seasonality have already been observed. However, there is as yet very little understanding as to how these forests will respond to accompanying changes in seasonal availability of water and light. The central objective of this research is to determine how ecological trade-offs among acquisition of water and light act to constrain seasonally dry tropical forest productivity in the context of changing seasonal resource availability. This project will advance knowledge by testing and developing a paradigm for the resource acquisition trade-offs made by different plant species.

This research has broad environmental implications. Worldwide, 1,048,700 km2 are classified as seasonally dry tropical forests. Locally, seasonally dry tropical forests help regulate climate, ensure freshwater resources, protect fertile topsoil from erosion and provide economic benefit in the form of ecotourism. Regionally and globally, these forests are important because they exhibit significant levels of biodiversity, show high resistance to invasion by exotic species and could provide reservoirs of species already adapted to drier environments if climate change makes these conditions more prevalent. Likewise, they are the ancestral biome for many major crops and could provide clues for their improvement and response to climate change.

Figure 1. Schematic representation of the plant hydraulic module in the updated model. The water flow from the soil to the air is abstracted and likened as electrical circuits with resisters and capacitors. Following the conventions in electrical sciences, grey cylinders represent hydraulic resistance and parallel lines represent hydraulic capacitance. Water potentials (Ψs,i, Ψstem and Ψleaf) are specified along the water flow route with black dots. Driven by the differences among the water potentials, water in general flows from soil layers within root zone to the base of the stem (Qi), forms sapflow (J) and is transpired away to the air (T). The hydraulic capacitance of stem (Cstem) and leaf (Cleaf) influence the rates of change in water potentials (equations on the left side)

Educational Impacts

The educational activities of this project will include year-round undergraduate research opportunities and the development of a new undergraduate course. Undergraduate research opportunities will include modeling and analysis of seasonally dry tropical forest sites in Costa Rica, Mexico, Colombia and Brazil. In addition, undergraduates may carry out research on aspects of seasonality in other ecosystems, including the broadleaf deciduous forests of the eastern U.S. and the needleleaf deciduous (larch) forests of northern Eurasia.

It is anticipated that the new undergraduate course will be offered for the first time in Fall 2015, and then offered annually thereafter. The course will discuss seasonality from the perspectives of the atmosphere and the terrestrial biosphere in the context of contemporary and projected future climate. Assignments will expose students to observational datasets, climate model simulations, and the application of models for vegetation seasonality. The course will investigate different syndromes of seasonality, including (i) the seasonally cold eastern U.S., (ii) the seasonally wet Mexico and Mesoamerica, and (iii) the rapidly warming sub-arctic and arctic.