Project Funding: 2014 - 2017

NRA: 2013 NASA: The Science of Terra and Aqua   

Funded by NASA

Abstract:
We propose to answer the cross-cutting question: "Where in the western hemisphere is the vegetated land surface changing significantly during the past 15 years in response to direct human impacts? Specifically, using the Human Impact Index and Anthromes as proxies for direct human impacts on ecosystem function, we formulate our question as a suite of testable hypotheses about changes in the vegetated land surface, as follows: [H1] Areas of significant positive change occur in areas of moderate human impact, due predominantly to agricultural land uses; [H2] Areas of significant negative change that occur in areas with low human impact, arise predominantly from forest pests and forest fires; and  [H3] Areas of significant negative changes that occur in areas with high human impact, appear predominantly associated with the expansion of human settlements, particularly cities. We will build and implement a system to detect significant changes in land surface properties using time series of key NASA remote sensing data products from sensors aboard Terra and/or Aqua, supplemented by products from NASA's Global Land Data Assimilation System and the Tropical Rainfall Measuring Mission. To detect, quantify, and assess the significance of land surface changes, we will use the Seasonal Kendall nonparametric trend test corrected for first-order temporal autocorrelation. We will calculate trends since 2001 for metrics of the vegetated land surface using the multiple sensor datastreams. We will also use the SK test for a range of key environmental variables from diverse sources. We call this system MIDST for Multiple Indicators Detecting Significant Trends. An important aspect of the system is trend analysis on two or more scales, e.g., 500m and 0.05 degree. We will use MIDST to highlight areas manifesting highly significant changes in land surface properties in North, Central, and South Americas to assess changes since 2001, with particular interest focused on [1] the rapidly transforming cerrado region of Brazil and [2] the hemisphere's largest conurbations. Six of the planet's 27 megacities (population >10M) are found in the western hemisphere: Mexico City, São Paulo, NYC, Buenos Aires, Los Angeles, and Rio de Janeiro. We will assess the accuracy of a significant subset of the significant changes by leveraging extant independent datasets on land change. We will analyze for the drivers and consequences of change through a combination of regularized generalized canonical correlation analysis, recursive partitioning, and probabilistic mixture modeling of land surface phenologies. We will disseminate the research results through a narrative website with downloadable kmz files and through social web media.

Publications:

Zhang, X., Liu, L., Henebry, G. M. 2019. Impacts of land cover and land use change on long-term trend of land surface phenology: a case study in agricultural ecosystems. Environmental Research Letters. 14(4), 044020. DOI: 10.1088/1748-9326/ab04d2

Zhang, X., Wang, J., Gao, F., Liu, Y., Schaaf, C., Friedl, M., Yu, Y., Jayavelu, S., Gray, J., Liu, L., Yan, D., Henebry, G. M. 2017. Exploration of scaling effects on coarse resolution land surface phenology. Remote Sensing of Environment. 190, 318-330. DOI: 10.1016/j.rse.2017.01.001

2015 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• Change in our MIDST: Toward Detection and Analysis of Urban Dynamics in CONUS   --   (Geoff Henebry, Kirsten de Beurs, Cole Krehbiel, Lan Nguyen, Braden Owsley, Xiaoyang Zhang, Baojuan Zheng)   [abstract]