QUANTIFYING THE IMPORTANT ROLE TREES PLAY IN THE BOREAL HYDROLOC CYCLE
Understanding how water moves through terrestrial ecosystems is not just a fundamental concern for hydrologists, but is also highly relevant for the long-term productivity of our forests, the continuity of fresh water supplies, and maintaining flourishing lakes and streams. Sustaining these ecosystem services requires a clear understanding of the key factors regulating the terrestrial hydrologic cycle. One of the major challenges yet to overcome is the partitioning of evapotranspiration (ET) into evaporation and transpiration, which in the past have commonly been lumped together by hydrologists and treated as a “black box.” However, transpiration and evaporation represent two fundamentally different pathways of water loss from terrestrial ecosystems. They are controlled in different ways and to varying degrees by environmental factors and, thus, are likely to respond differently to climate change. In this project, I will use recent advances in stable isotope techniques to partition ET into evaporation and transpiration across multiple spatial and temporal scales in a boreal forest watershed. This new approach will allow for novel, mechanistic assessments of the interactions and feedbacks between vegetation and the terrestrial hydrologic cycle as well as evaluate how these interactions and feedbacks may respond to a changing climate.
ASSESSING THE TRADE-OFF BETWEEN BIOMASS PRODUCTION AND ECOSYSTEM SERVICES
A major challenge of a sustainable bio-based economy is to balance the trade-offs between maximizing production of raw materials while at the same time minimizing negative impacts to ecosystem services, and in turn, improving people’s livelihoods. Globally, much of the bio-based production will be directed towards the humid tropics, where it is projected that during the next 15 years more than 80% of the growing global demand for forest products will occur. In this project we will quantify biomass production and a range of ecosystem services across multiple spatial and temporal scales in already established, long-term forest management experiments in northern Borneo – one of the world’s biodiversity hotspots. We propose to use a multi-disciplinary approach, including aspects of economics, social science, silviculture, plant ecophysiology, ecology, human health and biogeochemistry, to identify sustainable management practices that can maximize the production of raw materials while at the same time minimizing negative environmental impacts. Using this holistic approach our overall objective is to obtain and communicate novel information to scientists, private, and government stakeholders about trade-offs between biomass production and ecosystem services to aid the transition to a sustainable bio-based economy.
Assessing the vulnerability of mature and secondary tropical to climatic stress in southeast Asia
The frequency and intensity of drought events are predicted to increase in tropical monsoon forests of Southeast Asia;
ecosystems which are known to be biodiversity hotspots and a persistent carbon sink in the global carbon cycle. Such
increases could drive rapid and large-scale shifts in forest structure and species composition as well as cause dramatic
decreases in the amount of carbon stored by these tropical forests. The majority of forested areas in the tropics are '
secondary forests, yet compared to mature forests we know relatively little about the ecophysiology of secondary forest
ecosystems. In this project we will use a combination of traditional ecophysiological and stable isotope measurements
to assess tree hydraulics and drought vulnerability of the dominate tree species in both secondary and mature forests.
Such information is crucial in order to more accurately predicted how future climate change will affect the cycling of
carbon and water in tropical forested ecosystems.
ecosystems which are known to be biodiversity hotspots and a persistent carbon sink in the global carbon cycle. Such
increases could drive rapid and large-scale shifts in forest structure and species composition as well as cause dramatic
decreases in the amount of carbon stored by these tropical forests. The majority of forested areas in the tropics are '
secondary forests, yet compared to mature forests we know relatively little about the ecophysiology of secondary forest
ecosystems. In this project we will use a combination of traditional ecophysiological and stable isotope measurements
to assess tree hydraulics and drought vulnerability of the dominate tree species in both secondary and mature forests.
Such information is crucial in order to more accurately predicted how future climate change will affect the cycling of
carbon and water in tropical forested ecosystems.
ISOTOPE PARTITIONING TO REVEAL THE IMPORTANCE OF METHANE OXIDATION
Partitioning net ecosystem CO2 exchange (NEE) into its different flux components is crucial as it provides a mechanistic framework to better assess how the terrestrial carbon cycle may respond to projected environmental change. This is especially important for northern boreal peatlands, which store approximately one-quarter of the world’s soil carbon and yet at the same time are projected to experience some of the greatest environmental changes in the future. The main goal of this project is to use stable isotopes at natural abundance levels to partition heterotrophic respiration into CO2 being derived from soil organic matter mineralization by saprotrophic microbes and methane oxidation by methanotrophic bacteria across multiple temporal and spatial scales.
CARBON AND NITROGEN EXCHANGE IN MYCORRHIZAL SYMBIOSES
Ectomycorrhizal (EM) symbioses have traditionally been considered a classic mutualism with many experimental investigations showing that both plant and fungal symbionts benefit from the reciprocal exchange of resources. However, recent studies have shown that this may not always be the case. I am involved in a number of projects aimed at quantifying the exchange of C and N in EM associations and how this exchange of resources is affected by soil N availability. I also recently performed a large-scale shading experiment to better understand how changes in belowground tree C allocation to EM fungi, independent of changes in N supply, affect the transfer of N in intact plant-soil-microbe systems in the field. See a gigapixel panorama of the shading experiment here: (http://gigapan.com/gigapans/112528).