Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250347
Title: Controls on landcover patterns in two adjacent stream catchments, south-east Spain
Author: Willshaw, Katherine
ISNI:       0000 0001 3569 897X
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2001
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Abstract:
The Sorbas basin lies within the Betic Cordillera of south-east Spain. It is a recently uplifted sedimentary basin with readjustment of drainage systems still occurring, and hence intense erosion is found in places. This erosion, coupled with a semi-arid climate and a history of human impact has lead to a variably patchy vegetation cover throughout the catchment. This thesis examines controls on vegetation cover patchiness in a pair of adjacent catchments using a landscape ecology approach. These catchments display contrasting patterns of landcover and represent two stages in an erosion-stabilisation cycle driven by base level change on the Rio Aguas into which they both drain. Cover and species type data were collected in the field along with soil samples. The vegetation analysis programs DECORANA and TWINSPAN were used to explore the cover and species data collected in the field. Results of the analyses were correlated with environmental variables to identify controls on distribution. Airborne Thematic Mapper (ATM) data were acquired from a NERC ARSF flight in 1996 along with aerial photographs of the study area. The ATM data were used to produce a clustered landcover image based upon the clustering of an NDVI image followed by interpretation of the six end groups using the cover data collected in the field. The aerial photography was used to produce a digital elevation model, and from this the environmental variables aspect, slope gradient and wetness were derived. The digital elevation model was also used in conjunction with the aerial photographs to produce an orthorectified image of the study area. Geology was found to be the most significant control on cover type distribution, closely followed by geomorphology and soil chemistry. Species type distribution is also strongly controlled by geology with geomorphological history being almost as significant, and soil chemistry controlling the distribution at a fine scale. Slope gradient and aspect were not particularly associated with either cover or species distribution. The clustered landcover image, in which the six classes of cover ranged from very sparse to very densely vegetated, was analysed in conjunction with aspect, slope gradient and wetness to identify which of variable had the closest relationship with cover distribution. It was found that aspect had greatest association with cover, and wetness the least. However, all three show a statistically significantly relationship to cover class. The clustered landcover image was then used in conjunction with FRAGSTATS, a landscape metrics program, and a class buffering technique was used in order to quantify the landcover patterns in the two catchments. The quantification of pattern enabled an assessment of the relative controls of each of the environmental variables on the cover pattern in both catchments. Geology was found to be the most important control on the cover distribution, with geomorphological history and aspect important at a finer scale. Slope gradient, wetness and soil chemistry were not found to be very significant controlling factors.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.250347  DOI:
Keywords: Landscape ecology
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