Using landscape structure to develop quantitative baselines for protected area monitoring

Changes in habitat extent as well as landscape and habitat structure are often caused by human pressure within protected areas and at their boundaries, with consequences for biodiversity and species distributions. Thus quantitative spatial information on landscape mosaic arrangements is essential, for monitoring for nature conservation, as also specified by frameworks such as the Convention on Biological Diversity (CBD), and the European Union's Habitat Directive. While measuring habitat extent is a relatively straightforward task, approaches for measuring habitat fragmentation are debated. This research aims to delineate a framework that enables the integration of different approaches to select a set of site- and scale-specific indices and synthetic descriptors and develop a comprehensive quantitative assessment of variations in human impact on the landscape, through assessment of habitat spatial patterns, which can be used as a baseline for monitoring. This framework is based on the use of established methodologies and free software, and can thus be widely applied across sites. For each landscape and observation scale, the framework permits the identification of the most relevant indices, and appropriate parameters for their computation. We illustrate the use of this framework through a case study in a protected area in Italy, to indicate that integrated information from multiple approaches can provide a more complete understanding of landscape and habitat spatial pattern, especially related to locations experiencing disturbance and pressure. First, identification of a parsimonious set of traditional LPIs for a specific landscape and spatial scale provides insights on the relation between landscape heterogeneity and habitat fragmentation. These can be used for both change assessment and ranking of different sections of the study area according to a fragmentation gradient in relation to matrix quality. Second, morphological spatial pattern analysis (MSPA), provides a pixel based structural characterisation of the landscape. Third, compositional characterisation of the landscape at the pixel level is provided by landscape mosaic analysis. These three approaches provide quantitative assessments through indices which can be used singly or in combination to derive three synthetic descriptors for a comprehensive quantitative baseline representation of landscape structure that can be used for monitoring: the first descriptor, landscape diversity profiling, based on the output of landscape mosaic analysis, at the landscape level, complements the evaluation which at the pixel level can be obtained by more complex modelling; the second descriptor, obtained combining of the outputs of MSPA and the landscape mosaic analysis, informs on the local structural pattern gradient across the landscape space; the third descriptor, derived from the integration of selected LPIs and those derived from MSPA into a discontinuities detection procedure, allows for the identification of “critical points” of transitions in management where threats to biodiversity and ecosystems integrity may be likely. The framework developed has significant potential to capture information on major landscape structural features, identify problematic areas of increased fragmentation that can be used to prioritise research, monitoring and intervention, and provide early warning signals for immediate response to pressures increasing habitat fragmentation, with the goal of facilitating more effective management.

► Quantitative landscape structure analysis is needed for monitoring protected areas.
► Different approaches yield complementary information on landscape pattern.
► Insights on the relation between landscape heterogeneity and fragmentation are gained.
► Through a baseline picture, monitoring priorities of problematic areas are defined.
► Monitoring protocols can provide early warning signals for management response.