TITLE: Investigation of vegetation functions by satellite remote sensing accompanied with ground-based forest survey in Alaska

Transcription

1 RESEARCH AREA NO.: 2 THEME NO.: 6-1 TITLE: Investigation of vegetation functions by satellite remote sensing accompanied with ground-based forest survey in Alaska PI: Rikie Suzuki (RIGC/JAMSTEC) Co-PI: Yongwon Kim (IARC/UAF) Participant: Reiichiro Ishii (RIGC/JAMSTEC), Shin Nagai (RIGC/JAMSTEC), Taro Nakai (IARC/UAF), Jeremy Nicoll (GI/UAF), Hideki Kobayashi (RIGC/JAMSTEC) MEMBERSʼ ROLES: Development of the algorithm to estimate the forest photosynthetic potential and biomass by satellite remote sensing data in the boreal forest in Alaska

2 Background: Significance of vegetation functions in the environmental carbon cycle for the understanding of climate change atmosphere Carbon flow between land surface and atmosphere through photosynthesis and respiration Requirement to estimate the leaf area index (LAI), a biophysical parameter of photosynthetic potential, by satellite remote sensing. Carbon stock Requirement to estimate the biomass of vegetation by satellite remote sensing. Biosphere

3 OBJECTIVES: A) Forest above-ground biomass mapping by ALOS/PALSAR a. Algorithm development to estimate the forest above-ground biomass (FAGB) b. Reduction the contaminations in ALOS/PALSAR data due to the terrain effect c. Monitoring of the FAGB change of forests by forest surveys as a ground truth of satellite remote sensing B) Observational study of the bi-directional reflectance distribution function (BRDF) of the boreal forest for accurate estimation of LAI and FAGB for GCOM-C/SGLI remote sensing C) Investigation of boreal forest phenology as revealed by satellite remote sensing (cf. Aqua, Terra/MODIS) accompanied with ground-based survey

4 METHODOLOGY: In FY2011, we have mainly carried out following research activities concerning with the objectives (B) and (C). For the objective (B) a. Spectral reflectance (BRDF) of the black spruce forest at PFRR in snow season was measured in March 2011 from the 17m observation tower. This snow season BRDF was compared with no-snow season BRDF that was observed in July b. Gap fractions were measured along three 220 m long transects at the black spruce forest for the estimation of LAI in September to October, For the objective (C) The seasonal change of forest landscape was monitored by the interval camera system at the top of the 17m observation tower. The landscape change was compared with the satellite-derived vegetation indices.

5 RESULTS FROM THE LAST YEAR (Objective (B)-a.) Bidirec'onal Reflectance Distribu'on Func'on (BRDF) of black spruce forest in Poker Flat Research Range around 1020 AKDT on July 7, Top panel: RED and NIR reflectance and NDVI in Principal Plane (PP). Posi;ve angle indicates sun ward (forward scaber) direc;on. BoBom panel: RED and NIR reflectance and NDVI in Orthogonal Plane (OP). Posi;ve angle indicates the direc;on at 90 degree measured clockwisely from the sun ward direc;on.

6 RESULTS FROM THE LAST YEAR (Objective (B)-a.) Bidirec'onal Reflectance Distribu'on Func'on (BRDF) of black spruce forest in Poker Flat Research Range around 1323 AKDT on March 17, 2011 Top panel: RED and NIR reflectance and NDVI in Principal Plane (PP). Posi;ve angle indicates sun ward (forward scaber) direc;on. BoBom panel: RED and NIR reflectance and NDVI in Orthogonal Plane (OP). Posi;ve angle indicates the direc;on at 90 degree measured clockwisely from the sun ward direc;on.

7 RESULTS FROM THE LAST YEAR (Objective (B)-b.) The view angle dependency of the apparent clumping index of the black spruce forest in PFRR. By the inversion of the gap frac;on, we found that landscape scale PAI e at PFRR was By dividing PAI e by apparent clumping index, we evaluated the quasi true PAI=0.62. With ancillary informa;on, we have goben landscape LAI=0.73 at PFRR.

8 RESULTS FROM THE LAST YEAR (Objective (C)) Seasonal pabern of cloud free daily satellite observed NDVI values (MODIS) during Jan to Dec in Poker Flat Research Range (PFRR). Typical images of the forest landscape by the interval camera installed at the top of the 17m observa;on tower are presented at the top of figure.

9 EXPECTED ACHIEVEMENTS IN THE NEXT YEAR Objective (A) A paper in terms of forest above-ground biomass (FAGB) estimation by ALOS/PALSAR will be submitted to the JICS collected papers in Polar Science. The decadal change of FAGB in forest plots along the Dalton Highway will be delineated. Objective (B) The LAI over the black spruce forest in Alaska will be estimated and mapped based on gap and BRDF survey data by using the forest radiative transfer model. Objective (C) A paper in terms of forest land scape seasonality and satellite-derived seasonality will be submitted to the JICS collected papers in Polar Science

10 SUMMARY Objective (B)-a. As to the BRDF in the principal plane in the no-snow season, the forward scatter was smaller than the back scatter. By contrast in the snow season, back scatter was smaller than the forward scatter, that is, reverse of that of the no-snow season. NDVI was nearly zero due to the high reflectance of the snow. Objective (B)-b. We evaluated that the quasi-true PAI of the black spruce forest in PFRR was Furthermore with these ancillary information, we have gotten landscape LAI of the forest as Objective (C) The evergreen black spruce trees showed almost no seasonal change, while the forest floor presented drastic changes by snow and floor vegetation. As a result, NDVI showed the bell-shaped seasonal pattern that increased rapidly in spring and decreased rapidly in autumn.