153
Doñana Shrub-Species Mapping
The shrub communities that populate the stabilised sand ecosystem are a very
important habitat of the DNP. DBR develops important research and conservation
programs underpinned by a deep knowledge about both the habitats and the ecosystem. In this sense, the actual location of shrub species is required for monitoring of
ecological process and management activities.
The main purpose of the Doñana Biological Station (DBS) is to perform biological research in the DNP and in this case to liaise with INTA to carry out hyperspectral flights over the DNP. Following the guidelines of the protocol illustrated in
section “Plant species mapping”, the procedure for mapping the dominant species
of the Doñana’s shrublands with the AHS sensor is as follows:
(i) As the user organization, the DBS provided the auxiliary data required: a digital topography map at 1:25.000 spatial scale, an ecological map at 1:40.000
spatial scale, a habitat map at 1:50.000 spatial scale, and a DEM at 10 m spatial resolution.
(ii) For measuring the cover of plant species, we distributed stratified plots by
elevation: first by separating the Manto Arrasado and Naves zones, and then
the upper and lower parts of dunes. The location of the plots was constrained
by the local topography and often situated near pathways due to inaccessible
areas of very dense vegetation. The size of the plots was 30 m × 30 m and was
determined by the resolution of the AHS imagery. The cover of plant species
was measured using the line intercept method (Canfield 1941), whereby three
parallel transects were sampled inside each plot.
(iii) The spectral reflectance curves of the five dominant species (E. scoparia,
H. halimifolium, U. australis, R. officinalis and S. genistoides) were measured
in several field spectroscopy campaigns, with the primary aim of generating a
plant spectral library and extracting the species endmembers. We selected
more than 15 individuals for each species (not-randomly) covering the ranges
of the Leaf Area Index (LAI measured in m
2
/m
2
) ranges present. Targets were
marked and measured in both seasons. The protocol that we followed is
described in Jiménez and Díaz-Delgado (2015). The field spectroradiometer
used was the ASD FieldSpec3
®
(Analytical Spectral Devices, Boulder, CO,
USA), which collects energy using a fiber optic with the option of adapting a
fore optic lens. It has a spectral range from 350 to 2500 nm with a spectral
resolution of 3 nm and a sampling interval of 1.4 nm for the VNIR (350–1000
nm) and 10 m and 2 m for the SWIR-1 ( 1000–2500 nm ) and SWIR-2 (1750–
2500 nm) spectral regions respectively. In parallel to spectral measurements,
we took hemispherical canopy photographs for each plant with the aim of
estimating the LAI. A 180 degree photograph was taken from beneath looking
with a NIKON FC-E8 fisheye lens adapted to a Nikon 4000 Coolpix digital
camera. We took the photographs shortly before sunset following the protocols for field acquisition outlined by Chen and Cihlar 1995.
Sub-pixel Mapping of Doñana Shrubland Species
Doñana Shrub-Species Mapping
The shrub communities that populate the stabilised sand ecosystem are a very
important habitat of the DNP. DBR develops important research and conservation
programs underpinned by a deep knowledge about both the habitats and the ecosystem. In this sense, the actual location of shrub species is required for monitoring of
ecological process and management activities.
The main purpose of the Doñana Biological Station (DBS) is to perform biological research in the DNP and in this case to liaise with INTA to carry out hyperspectral flights over the DNP. Following the guidelines of the protocol illustrated in
section “Plant species mapping”, the procedure for mapping the dominant species
of the Doñana’s shrublands with the AHS sensor is as follows:
(i) As the user organization, the DBS provided the auxiliary data required: a digital topography map at 1:25.000 spatial scale, an ecological map at 1:40.000
spatial scale, a habitat map at 1:50.000 spatial scale, and a DEM at 10 m spatial resolution.
(ii) For measuring the cover of plant species, we distributed stratified plots by
elevation: first by separating the Manto Arrasado and Naves zones, and then
the upper and lower parts of dunes. The location of the plots was constrained
by the local topography and often situated near pathways due to inaccessible
areas of very dense vegetation. The size of the plots was 30 m × 30 m and was
determined by the resolution of the AHS imagery. The cover of plant species
was measured using the line intercept method (Canfield 1941), whereby three
parallel transects were sampled inside each plot.
(iii) The spectral reflectance curves of the five dominant species (E. scoparia,
H. halimifolium, U. australis, R. officinalis and S. genistoides) were measured
in several field spectroscopy campaigns, with the primary aim of generating a
plant spectral library and extracting the species endmembers. We selected
more than 15 individuals for each species (not-randomly) covering the ranges
of the Leaf Area Index (LAI measured in m
2
/m
2
) ranges present. Targets were
marked and measured in both seasons. The protocol that we followed is
described in Jiménez and Díaz-Delgado (2015). The field spectroradiometer
used was the ASD FieldSpec3
®
(Analytical Spectral Devices, Boulder, CO,
USA), which collects energy using a fiber optic with the option of adapting a
fore optic lens. It has a spectral range from 350 to 2500 nm with a spectral
resolution of 3 nm and a sampling interval of 1.4 nm for the VNIR (350–1000
nm) and 10 m and 2 m for the SWIR-1 ( 1000–2500 nm ) and SWIR-2 (1750–
2500 nm) spectral regions respectively. In parallel to spectral measurements,
we took hemispherical canopy photographs for each plant with the aim of
estimating the LAI. A 180 degree photograph was taken from beneath looking
with a NIKON FC-E8 fisheye lens adapted to a Nikon 4000 Coolpix digital
camera. We took the photographs shortly before sunset following the protocols for field acquisition outlined by Chen and Cihlar 1995.
Sub-pixel Mapping of Doñana Shrubland Species