Michelle Y. Wong

I'm a terrestrial biogeochemist and an ecosystem ecologist.

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I use experimental field and lab-based methods to study how plants and microbes interact with nutrients to shape ecosystems. Utilizing observational and modeling-based approaches, I evaluate how nutrients affect ecosystem processes, such as nitrogen fixation and denitrification. I study how nutrients cycle in the environment and evaluate how anthropogenic activity has altered nutrient cycling.

How do plants get the nutrients they need?

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Tropical forests are often situated on highly weathered, nutrient-depleted soils, but are often some of the most productive ecosystems in the world. Across secondary forests of Panama in Agua Salud and in collaboration with scientists at the Smithsonian Tropical Research Institute, we are investigating how plants overcome nutrient limitation through the use of nutrient acquisition strategies such as root phosphatases and symbioses with arbuscular mycorrhizal fungi and nitrogen-fixing symbionts.

How do disturbances affect nutrient availability, and how do ecosystems recover?

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Tropical forests face rapid rates of land-use change. At Fazenda Tanguro in Mato Grosso, Brazil, we studied how forest fires affected the availability of key nutrients, such as nitrogen, phosphorus, and molybdenum, and what role nitrogen fixation played in forest recovery.

Are there global patterns in nutrient limitation?

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Molybdenum and phosphorus commonly limit one of the most important processes on earth—nitrogen fixation. From limited empirical evidence, nitrogen fixation rates are thought to be high in tropical forests, but tropical forests are often situated on nutrient-depleted soils and often low in molybdenum and phosphorus. We tested the hypothesis that highly weathered soils isolated from atmospheric sources are strongly limited by rock-derived nutrient availability through a fertilization experiment.

How do atmospheric processes cycle nutrients around the world, and what are the implications on ecosystem function?

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Atmospheric processes such as the movement of sea-salt spray, volcanoes, and mineral dust can move nutrients thousands of kilometers, redistributing these nutrients to new environments. When these nutrients are limiting, they can impact the ecosystems where they are deposited.

We quantified molybdenum in Saharan dust, and modeled deposition rates of various processes, both natural and anthropogenic, and evaluated the potential impact on terrestrial nitrogen fixation.

Collaborations

How are nutrients stored and distributed, and what controls these processes?

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Led by Maya Almaraz, we are synthesizing observations of deep nitrate stocks around the globe. You can check out the talk from ESA 2020 here.

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How can we use syntheses to highlight knowledge gaps?

Denitrification, the microbial conversion of nitrogen back to the atmosphere in the form either N2 or N2O, is a commonly measured process, but we know little about what controls the production of N2 or N2O. This is important because the two end products have very different outcomes. With Wendy Yang and Maya Almaraz, we synthesized the literature to identify knowledge gaps and opportunities to improve our understanding on the topic.

How can we improve the way we measure these fundamental ecosystem processes?

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Nitrogen is a tricky element to measure, as it makes up 78% of our atmosphere. Led by Joy Winbourne, we evaluated the error associated with symbiotic nitrogen measurements across Neotropical sites and where to focus efforts to improve our estimates.