Landscape structure in urban and periurban areas in the Metropolitan Region of Buenos Aires (MRBA)

Abstract

Urban and peri urban landscapes, as well as rural landscapes, exhibit diverse spatial patterns related to components or uses diversity (e.g: agricultural lots, forests, urban reserves, city settlements among others). Landscape ecology permits spatial understanding based on three particular characteristics: structure, functions and change. In this research, landscape indexes in urban and peri urban areas in the Metropolitan Region of Buenos Aires (MRBA) were identified. The associated research hypothesis states that: landscape characteristics will be differentially affected according to urbanization level (urban and peri urban). Landscape indexes (estimated and measured) were made for each municipality: heterogeneity; diversity, dominance; patch density. Also, the following levels were analysed: urban and peri urban; urbanization circular distribution (crowns): 1, 2, 3, 4 and urbanization radial distribution (subzones): North West and South. Landscape quantitative indexes were associated with uses: extensive agriculture: EA; intensive agriculture: IA; urban and peri-urban agriculture: UPA; green areas: GA; urban use: URB. EA and IA were affected according to urbanization level and crown (p <0.05). UPA and GA presented significant differences between subzones and crowns: fourth crown and southern presented higher UPA percentages. In the southern subzone, urban and peri urban expansion occurred diminishing natural ecosystems and augmenting EA and IA uses. UPA presented a wide variation in the total number of patches between municipalities. The number and the average surface of the patches expressed as patches density presented differences between municipalities. Diversity index presented differences between municipalities, presenting values ranging between 0.18 and 1.09 in CABA and Berazategui, respectively. The results showed that dominance of EA and IA uses with greater surfaces may affect the occurrence of other natural uses in the landscape. Matrix characteristics showed a degree of fragmentation influenced by the differential heterogeneity between municipalities. Vegetated uses human uses (EA, EI, GA, UPA) can help decrease landscape fragmentation, increase diversity conservation and homogenization in MRBA and as seen in regions worldwide. MRBA characteristics come from the original ecosystem transformation, which generated a fragile landscape that requires human actions over time in order to keep urban ecosystem working. This research could be useful to evaluate landscape ecological processes within MRBA and mega cities worldwide.