-B8, 2012 
ity, and growth 
ound-based and 
ullewa, Western 
oisture was well 
/Sis using the 
stage. This also 
ated by the PLS 
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ige. To sum up, 
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t, "The 2009 and 
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nter (ERSDAC). 
[an C Lau at the 
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ly and airborne 
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wheat growth 
data in western 
onal Geoscience 
p. 3338-3341. 
fano, M., 2008. 
for estimating 
a canopy scale 
urements in rice. 
pp. 156-172. 
nal visible, near- 
ies in relation to 
mote Sensing of 
  
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
PLANT SPECIES MONITORING IN THE CANARY ISLANDS 
USING WORLDVIEW-2 IMAGERY 
L. Nunez-Casillas * *, F. Micand*, B. Somers?, P. Brito^, M. Arbelo* 
* Grupo de Observación de la Tierra y la Atmósfera (GOTA), Universidad de la Laguna, 
38206 La Laguna, Tenerife, Spain - (Inunez, marbelo) @ull.es 
b Flemish Institute for Technological Research (VITO), Centre for Remote Sensing and Earth Observation Processes 
(TAP), Boeretang 200, BE-2400 Mol, Belgium - ben.somers @ vito.be 
¢ Departamento de Biologia Vegetal, Universidad de la Laguna 38206 La Laguna, Tenerife, Spain - pbrito@ull.es 
KEY WORDS: Forestry; Monitoring; Detection; Multispectral 
ABSTRACT: 
The physical and climatic features of a relatively small volcanic island such as Tenerife (Canary Islands, Spain) cause increased 
difficulties to vegetation monitoring by means of moderate resolution satellite data. The use of multispectral very high resolution 
WorldView-2 (WV2) imagery provides promising perspectives for vegetation mapping in such a heterogeneous landscape. In order 
to assess its potential to estimate the cover fraction of dominant plant species in endemic Macaronesian laurel forests and 
heathlands, a hierarchical Multiple Endmember Spectral Mixture Analysis (MESMA) was performed within a study area where 
different patches from mature forest, to degraded forest and pine plantations can be found. First, a selection of pure pixels in the 
WV2 image for fern, Morella faya Ait., Laurus novocanariensis and the introduced species Pinus radiata were used to build a 
spectral library for each species. Last species Erica arborea L. was characterized in field by means of an ASD FieldSpec 
spectroradiometer, due to the rarity of pure pixels in this case, and to the simultaneous presence of two spectral subclasses 
depending on its flowering onset; WV2-adjusted spectral signatures from field reflectances were estimated by empirical 
calibration. Preliminary results showed a good separation of degraded from mature native forests and from plantations, although 
pine cover fraction is, in general, underestimated. The second MESMA cycle was useful to tell between most similar species, like 
in case of M. faya and L. novocanariensis. 
1. INTRODUCTION 
In Tenerife (Canary Islands) native monteverde forests are 
subtropical ecosystems as part of the Macaronesian region, at 
present a hotspot of biodiversity. They comprise endemic laurel 
forests and heathlands, where Morella faya (Ait.) Wilbur 
usually constitutes the tree cover of Myrico fayae-Ericetum 
arboreae communities in association with Erica arborea L. 
and other plant species (del Arco Aguilar, 2010). Both species 
are present in laurel forest Ixantho-Laurion azoricae, a more 
complex ecosystem, where several different tree species, like 
Laurus novocanariensis (Rivas-Martínez et al., 2002) are 
abundant. Native and foreign species of pine have historically 
been introduced in some areas. The environment in the study 
region is a challenge for detailed monitoring of plant species 
distribution, due to its very high orographic heterogeneity and 
vegetation cover density. 
The recently launched WorldView-2 (WV-2) satellite, partially 
conceived for applications in precision agriculture and natural 
resources monitoring, provides spectral information in 8 
spectral bands: the 4 most common spectral regions (red, blue, 
green, near-IR) and 4 new bands (red edge, coastal, yellow and 
near-infrared 2) (Updike and Comp, 2010). Splitting the NIR 
region for more information and adding the narrow Red Edge 
band beyond the Red band, highly increases the sensitivity of 
  
this sensor compared to other multispectral sensors in 
vegetation monitoring. 
Spectral Mixture Analysis (SMA) (Adams et al., 1993; Roberts 
et al., 1993; Settle and Drake, 1993) is commonly used for 
species detection and mapping in heterogeneous ecosystems 
(Schmidt and Skidmore, 2003; Somers et al, 2009; 
Youngentob et al., 2011). The high degree of similarity among 
plant species from the study area would make preferable the 
use of hyperspectral rather than multispectral data. However, 
the lack of hyperspectral data, either from air- or space-borne 
sensors other than 30-m Hyperion data, in a study region with 
very high spatial heterogeneity, impel us to seek for alternative 
approaches. Here, the potential of a hierarchical Multiple 
Endmember Spectral Mixture Analysis (MESMA) (Roberts et 
al, 1998; Franke et al., 2009), in combination with WV2 
imagery is explored, in order to map plant species distribution 
in this complex ecosystem. MESMA is a modification of 
simple SMA — where each pixel spectrum is modeled as a sum 
of weighted “pure spectra” or endmembers corresponding to 
their different proportions within the pixel (Adams et al., 1993; 
Roberts et al., 1993; Settle and Drake, 1993) — that allows a 
per-pixel variation of the number and types of endmembers. 
Finally, consecutive MESMA cycles will allow us to better 
discriminate between species with highest degree of similarity. 
* Corresponding author. This is useful to know for communication with the appropriate person in cases with more than one 
author.