Ruth Yanai

View Calendar
November 15, 2021 11:30 am - 12:30 pm

What Limits Productivity in Northern Hardwoods?  Surprising Findings from the First Long-Term N x P Addition Experiment in a Temperate Forest

The productivity of temperate forests on glaciated soils has been assumed to be nitrogen limited, although theory suggests that ecosystem productivity should be co-limited by multiple nutrients, including phosphorus. Experimental tests of N vs. P limitation in temperate forests are needed to better understand the capacity of ecosystems to balance the acquisition of limiting resources. In 2011, in the White Mountains of New Hampshire, USA, we began a full-factorial N x P fertilization experiment in 13 stands of young, mid-aged, and mature northern hardwoods in three sites that span a range of native soil fertility. Contrary to past assumptions, but credible after decades of anthropogenic N deposition, after 4 years we found a greater response of aboveground growth to P addition than to N addition. Consistent with aboveground P limitation, retranslocation of foliar P was proportionately higher than retranslocation of N, and P addition decreased foliar N, suggesting an alleviation of growth limitation by P. Surprisingly, this aboveground response was not associated with reduced allocation to root production under P addition; instead root growth increased in response to N addition, at the plot scale. Soil respiration, similarly, which should reflect effort allocated belowground for nutrient acquisition, was higher pretreatment where N availability was low and was also most reduced by N addition where N availability was low. There was no effect detected of P addition on soil respiration. In summary, both diameter growth and foliar responses suggested P limitation, while both root growth and soil respiration suggested N limitation. The combination of N limitation belowground and P limitation aboveground may contribute to the maintenance of co-limitation of forest production in these northern hardwood ecosystems.

Related upcoming events

  • October 3, 2022 11:30 am - October 3, 2022 12:30 pm

    Methane Plume Mapping Over Offshore Oil and Natural Gas Platforms in the Gulf of Mexico

    Alana Ayasse

    Research Scientist

    Carbon Mapper

    University of Arizona

    Abstract

    Offshore oil and natural gas platforms are responsible for about 30% of global oil and natural gas production. Despite the large share of global production there is little known about the greenhouse gas emissions from these production facilities. Given the lack of direct measurements, studies that seek to understand the greenhouse gas contribution of offshore oil and gas platforms are incredibly important. The use of airborne remote sensing to map greenhouse gases from onshore oil and gas infrastructure has become a prominent method to quantify and attribute large individual emissions to their sources. However, until now, this method has not been used offshore due to the lack of consistent reflected radiance over water bodies.  In this talk I will present the results from a 2021 study where we used visible/infrared imaging spectrometer data collected over the Gulf of Mexico to map methane emissions from shallow water offshore oil and natural gas platforms. I will discuss the methods we employed to map methane in the offshore environment and how that differs from the onshore environment. I will show how remote sensing can efficiently observe offshore infrastructure, quantify methane emissions, and attribute those emissions to specific infrastructure types.

    Bio

    Dr Alana Ayasse is a research scientist at Carbon Mapper and the University of Arizona. She earned her BA in Geography and Environmental Studies from UCLA and her PhD in Geography from UCSB. Her research focuses on improving remote sensing techniques to map methane and carbon dioxide plumes, understanding the role of satellites in a global carbon monitoring system, and using remote sensing data to further understand trends in carbon emissions.

  • October 10, 2022 11:30 am - October 10, 2022 12:30 pm

    TBD

  • October 17, 2022 11:30 am - October 17, 2022 12:30 pm

    TBD

  • October 24, 2022 11:30 am - October 24, 2022 12:30 pm

    TBD

  • October 31, 2022 11:30 am - October 31, 2022 12:30 pm

    TBD

  • November 7, 2022 11:30 am - November 7, 2022 12:30 pm

    TBD

  • November 14, 2022 11:30 am - November 14, 2022 12:30 pm

    TBD

  • November 21, 2022 11:30 am - November 21, 2022 12:30 pm

    TBD

  • November 28, 2022 11:30 am - November 28, 2022 12:30 pm

    TBD

  • December 5, 2022 11:30 am - December 5, 2022 12:30 pm

    TBD