Faculty and research guide

Laboratory of Macroecology

Quan Wang, Rei Sonobe

Research foci of Macroecology Lab are on carbon/water cycles and energy balance in diverse ecosystems ranging from messic to xeric and across multiple temporal and spatial scales. Spatial attentions are paid on coupling remote sensing data with gas exchange models, for which both field monitoring, lab experiments and modelling activities are intensively involved. Research key words include ecophysiology, hyperspectral remote sensing, radiative transfer models, and gas exchange models.

1) Ecophysiology and gas exchanges in beech forests
Functional responses of plants to ambient environmental factors with the special attention on the seasonal trajectories of physiological parameters include photosynthetic capacity parameters (Vcmax, Jmax, Rd…) and transpiration are continuously investigated. Periodic field measurements and automatic monitoring systems were applied to gather time series data for retrieving seasonal patterns. Both internal and external factors are examined in detail for identifying the controlling factors on seasonal patterns. Photosynthetic capacity parameters as well as leaf morphological characteristics were mainly based on frequently periodic field measurements using either detached or intact leaf samples, while tree level transpiration was mainly monitored through Granier sap flow sensors. In addition, ecosystem scale gas exchange is monitored using eddy covariance system.

2) Hyperspectral remote sensing and radiative transfer models
A number of remote sensing activities is currently ongoing for revealing the underlying biophysical, biochemical and physiological mechanisms of reflected spectra. Hyperspectral information contains subtle absorption features from foliar and can be used to study the correlations of these minor absorption features with biochemical and biophysical parameters, from which they can be retrieved inversely. Special attentions are paid for identifying indices that have close relationships with biochemical parameters (e.g. Vcmax, gs…) at different temporal scales and their underlying links are investigated by inverse reflectance models. On the other hand, radiative transfer models of both leaf and canopy will be used to simulate absorption, transmission and reflection in various scales. Inverse models are applied to investigate the sensitivities of biophysical and biochemical as well as structure parameters to light distribution, which further provide physical and physiological bases for linking remote sensing data with ecophysioloigcal parameters.

3) Remote sensing applications
Satellite-born remote sensing data suffers serious atmospheric and topographic effects preventing the direct applications on them. This is even getting more serious in rugged terrain due to the complex redistribution of radiation and other climate conditions. Radiative transfer models coupling with DEM are used for corrections and in situ measurements are providing validation data sets. Thoroughly corrected remote sensing data will be used for land cover classification and change detection, and both empirical and inverse models will be used to derive LAI from remote sensing data with the challenge in rugged terrains. 

4) Researches on dry areas

We are studying environmental preservation and carbon fixing, in the context of natural vegetation growing in various dry regions. Main sites are located in central Asia including China and Tajikistan. Research approaches include plant physiology, modeling, and remote sensing technology. With these studies, we would like to develop new monitoring techniques on carbon and water cycles in xeric ecosystems.

Tower site of 900m (X1) in Naeba beech forests (Fagus crenata)

Measuring spectral reflectance characteristics of tree crowns

A typical landscape in Central Asia. The dominant species here is Haloxylon ammodendron.