Ph.D Thesis


Ph.D StudentSegre Hila
SubjectModeling Alternatives for Planning and Management of
Ecological Corridors in Agricultural Environments
DepartmentDepartment of Architecture and Town Planning
Supervisors ASSOCIATE PROF. Assaf Shwartz
PROF. Yohay Carmel
Full Thesis textFull thesis text - English Version


Abstract

A major challenge in conservation planning today is to support the increasing food demand while minimizing environmental damages. Two strategies are commonly debated: land-sharing promotes wildlife-friendly farming to benefit agriculture and biodiversity; and land-sparing promotes intensive agriculture that spares land for nature conservation. The goal of this PhD dissertation was to understand how to plan and manage multifunctional agro-ecological landscapes that optimize between biodiversity and crop production, based on the sparing-sharing framework.

In this dissertation I compared the costs and benefits of land-sharing and land-sparing planning strategies for establishing ecological corridors in agro-ecological systems. Connectivity is highly important in ecological corridors and increasing the amount of natural habitat is essential to enhance connectivity. In this context I focused on uncultivated field-margins with natural vegetation as land-sharing and large pastures and riverbanks as land-sparing. Using a combination of landscape-scale surveys, field-scale experiments and models I assessed the contribution of both sparing and sharing to biodiversity conservation and to crop production. I used a large-scale survey to assess biodiversity, potential biological pest control and yield patterns across several habitats in the agricultural landscape (i.e. arable fields, orchards, field-margins and semi-natural patches). This data was used to conduct a cost-effectiveness analysis comparing land-sparing and land-sharing, and to construct a model to identify the most influential variables in the cost-effectiveness analysis. Additionally, I used a field-experiment to assess the mechanisms underlying the costs and benefits identified at the landscape scale.

The surveys showed there are differences in the response of species group and crop types to sparing and sharing. Hence, both sparing and sharing should be implemented at all spatial scales to provide the needs of multiple species, minimize damage to crops, and promote cost-effective conservation in agricultural landscapes. Overall, land sparing was favorable under a wide range of conditions, and it was less sensitive to landscape and economic context than land-sharing. However, I found evidence for mutual benefits for farmers and biodiversity conservation from field-margins in some crops, illustrating ‘win-win’ opportunities of land-sharing. These benefits were supported by the field-experiment showing pest and weed regulation provided by field-margins. Results from the field-experiment also support the notion that field-margins have a limited effect on biodiversity. By experimentally examining multiple services and disservices I show that benefits varied among crop types and that specific management of field-margins can enhance targeted services and biodiversity, and decrease disservices provided. Eventually a mixed planning approach was favored and the spatial allocation of sparing and sharing depended mainly on the cropping-system and its economic value. Hence, a planning process that combines sparing and sharing solutions and considers socio-economic factors will be more robust.  The results emphasize that sparing land is the backbone of planning ecological corridors, and that sharing practices such as field-margins can complement them to provide additional benefits in crops that gain from services such as biological pest control and weed control. Moreover, managing sharing practices according to specific targets, i.e. biodiversity or ecosystem services, will significantly increase their success.