Official approaches to squatter settlements and the housing of the urban poor have changed over time from policies of clearance and relocation to schemes which promote the involvement of the private sector and nongovernmental organizations in supporting poor residents to improve their own housing and neighborhoods.n this article, the main debates surrounding squatter settlements are outlined, focusing on definitional issues and their geographical distribution. The changing nature of policies toward these settlements is also covered.
Lichen. Lichen is a structure that commonly grows on trees; it is a result of a symbiotic relationship between algae and fungi. The fungus provides a structure that collects water and nutrients that the algae takes advantage of; the algae in turn uses its chlorophyll to produce food for both itself and the fungus.Species of the Trentepohlia genus are commonly found in lichens.he fungus provides a structure that collects water and nutrients that the algae takes advantage of; the algae in turn uses its chlorophyll to produce food for both itself and the fungus. Species of the Trentepohlia genus are commonly found in lichens.
Scientists typically classify lichens based on the fungal partner, and the lichen name is the same as the scientific name of the fungal partner. By far the most common fungi found in lichens are sac fungi, or ascomycetes, which produce reproductive spores in special cells shaped like sacs.ichen, living partnership of a fungus and an alga (see Algae). The fungus component is called the mycobiont and is composed of intertwined, threadlike fibers called hyphae that are tightly packed into a tissuelike sheet.