Detecting tree hedgerows in agroforestry landscapes

The practice known as agroforestry concerns land use systems involving trees in combination with agricultural crops and/or livestock. Scattered or linear trees (planted or naturally growing) constitute the woody component of agroforestry systems, which can be located either inside the field or along the field boundaries, as tree hedgerows. Such tree systems, belonging to the category of Trees Outside Forest (TOF), serve important ecological and economic functions. Only recently, the recognition of TOF in natural resource assessments has emerged as an important research issue. However, due to the complexity of surveying, scarce information is available concerning the current extent of agroforestry systems. Agroforestry is increasingly perceived as providing ecosystem services, environmental benefits, and economic commodities as part of a multifunctional working landscape. These services and benefits occur over a range of spatial and temporal scales: from the farm/local scale, through the landscape/regional scale up to the global scale. Additionally, the value of ecosystems services of an agroforestry system is strongly dependent on trees number, size and spatial distribution. The use of Remote Sensing and GIS spatial analysis is of the utmost importance for detecting the landscape patterns, for understanding the interactions between biological and physical components, and for assessing, mapping and quantifying the social and economic value of the agroforestry ecosystem services.