PhD project offered by the IMPRS-gBGC in July 2021

Anchor

Monitoring structural changes and their significance for up-scaling approaches of ecosystem resilience to climate extremes in distinctive temperate forest stands

Henrik Hartmann , Christiane Schmullius

Project description

Climate extremes, like drought and heat, can have substantial impacts on forest tree species composition and structural properties (e.g., canopy height, tree age distribution) from tree decline and mortality. Such changes can severely disturb ecosystem functioning and threaten the sustainability of provision of ecosystem services, and information on the recovery and resilience of forests to climate extremes is badly needed. Structural changes can be assessed on the ground during forest inventories, but their spatio-temporal coverage is very limited. By contrast, remote-sensing approaches provide good spatio-temporal coverage, but often lack the required resolution to detect structural changes. A cross-scale approach is needed that combines information derived from different tools.

Objectives

To characterize relevant structural and vitality parameters for different forest stands on different geometric scales
To quantify aboveground carbon stocks and possibly fluxes for different tree components
To estimate carbon turnover (tree mortality)

Methods

Inventory of structural changes (tree mortality) in forest stands affected by climate extremes via field assessments;
interpretation of changes in stand vitality indicators (NDVI, EVI) before and after climate extremes derived from satellite time-series in the red and near-infrared wavelengths;
interpretation and comparison of very high resolution (VHR) drone image time-series in the visible and near-infrared wavelengths;
development of quantitative indicators of structural changes over time (partly using Terrestrial Laser Scans (TLS));
methodological development of physically solid upscaling models including point-cloud analyses from VHR to high resolution satellite data (5, 10 and 20 m pixel sizes).

Data

Up- and down-scaling (ground data-TLS-airborne-spaceborne sensors), radar-optical synergies (including point-cloud sand radar interferometric products), validation exercises (TLS, airborne lidar and photogrammetry).
Time frame of research: since start of the Sentinel-fleet in 2016, covering extreme events 2018-2019, with possible extension to earlier data (e.g. Landsat)

Working group & planned collaborations

MPI-BGC Department Biogeochemical Processes, FSU Jena Department for Earth Observation

Planned project collaborations and research sites

The MPI-Department of Biogeochemical Processes explores key processes and organisms that regulate exchanges between ecosystems and their surroundings. Department members are representatives of the IUFRO task force on monitoring global tree mortality patterns and trends and of the International Tree Mortality Network. During recent years, in particular following the extreme summers 2018 and 2019, cooperation with partners from the state forest research institute but also with local foresters aims to better understand fine-grained forest functional responses to climate extremes in selected forest sites. The FSU Department for Earth Observation has a twenty-year record of cooperation with the Thuringian federal forest service with research sites in the Holzland and Hainich National Park. Focus is on above-ground biomass retrieval from satellite data with special consideration of seasonal and spatial heterogeneities(i.e., changing under growth, variation of soil moisture) and disturbance detection of drought and/or insect infestations. Research sites are forest stands in Thuringia with well-established in situ forest information, partly TLS-coverage and drone time series.

Requirements

Applications to the IMPRS-gBGC are open to well-motivated and highly-qualified students from all countries. Prerequisites for this PhD project are:
  • a Master’s degree environmental science, geosciences, geography with a strong remote sensing background
  • Computational skills:
      programming skills (such as IDL, Matlab, R, Python or Julia)
      processing and analyzing large data sets
      machine learning techniques
      remote sensing data handling
  • Interest in field work in forests, including Terrestrial Laser Scans and drone campaigns
  • Excellent oral and written communication skills in English and German
The Max Planck Society seeks to increase the number of women in those areas where they are underrepresented and therefore explicitly encourages women to apply. The Max Planck Society is committed to increasing the number of individuals with disabilities in its workforce and therefore encourages applications from such qualified individuals.

Pine forest decline near the city of Jena (back-ground)
Pine forest decline near the city of Jena (back-ground)


>> more information about the IMPRS-gBGC + application