Paradigm Shift in Urban Land Use: Ecological Blocks

As a response to urban crises, cities must change the way they legislate, moving beyond indicators that regulate only the built mass strictly within lots. Under the model that has prevailed since Federal Law No. 6.766/79 — known as the Urban Land Subdivision Law—there is no provision for trees within lots. Planning is carried out in isolation, resulting in fragmented and sporadic patches of green areas, with trees appearing only sparsely on sidewalks or in backyards. In municipal zoning codes and master plans, there is no requirement for intra-lot tree planting. Control rules are limited to indicators such as occupancy rate, building height, minimum permeable surface, and parking spaces. As a result, the largest portion of formal urban land is made up of a built-up fabric dominated by concrete, asphalt, paving, masonry, and impermeable soil. This “normative formula” of city-making produces heat islands, thermal discomfort, flooding, barren public spaces, degraded landscapes, and the inability to confront the climate crisis. Exceptions are found in wealthy neighborhoods, where generous green areas exist in low-density gated communities—where trees are treated as a luxury item, rather than a collective necessity for all. Conversely, densely populated favelas, with high building density and no space for tree planting due to the stacking of self-built housing both vertically and horizontally, suffer severely from heat waves. This is exacerbated by ongoing deforestation caused by informal urbanization, itself a consequence of negligent public housing policies that have historically excluded the poor from the formal housing market, reinforcing the environmental racism embedded in Brazilian cities. As a response to this dual urban reality—the formal and the informal—the lecture Multifunctional Ecological Blocks will present a paradigm shift in the occupation of urban land, positioning tree planting as an indispensable element not only in permanent preservation areas, squares, and parks, but also in future urban developments. In growing cities, vacant land must legally integrate trees as a mandatory indicator in planning projects. The proposal is simple yet forceful: in future developments, projects without trees in block-level planning should not receive municipal approval. To this end, the proposal is to guide urban form through Multifunctional Ecological Blocks (MEBs), which combine in the same space — and according to the principles of sustainable and walkable urbanism — the minimum and maximum number of housing units, trees, and mixed uses (residential, commercial, leisure, and services), in a way that is adaptable to the climate crisis. This method can also contribute to planned relocations of poor families who lose everything as a consequence of informal urbanization in risk areas. For instance, in Brazil, 20 million people were displaced by floods and landslides in 2022 (CEMADEN, 2022). Another large-scale environmental tragedy has been unfolding in Maceió, Alagoas, due to salt mining by Braskem, which has literally caused entire neighborhoods of the capital to sink. It is estimated that more than 14,000 properties were vacated and around 60,000 people affected. What these cases have in common is the urgent need for safe and environmentally sustainable urban land to relocate this massive population. Planning residential density under such conditions must accommodate the largest possible number of housing units, with varied typologies, integrated into the urban fabric, and avoiding excessively standardized, impersonal, massive housing blocks built far from urban opportunities. The spatial design and scale of intervention to guide land occupation under these conditions are the Multifunctional Ecological Blocks (MEBs), thanks to their small land fraction requirement for housing and their versatility in being located across different vacant sites within municipalities. Ultimately, in times of climate crisis, adequate housing in urban planning cannot disregard tree planting. This method reconciles housing, mixed use, and trees in the same space, adopting as a planning benchmark 24 trees per hectare—a quantitative and qualitative parameter for oversight agencies in the urban planning process.