Point 6 of 7 — Ecological Balance in Earth Systems, Biogeochemical Cycles and Food WebsQuestion bank: 0 questions (0 with pictures)
06 Ecological balance, biodiversity and threats
An ecosystem keeps its balance through negative feedbacks: prey increase → predators increase → prey decrease → predators decrease. The more species and the more interconnections, the more ways there are to absorb a shock (resistance) and to recover (resilience).
Keystone species hold a community together out of proportion to their numbers; removing them changes the whole structure.
Succession is the orderly replacement of communities after a disturbance — lichens and mosses, then grasses, shrubs and finally forest on bare rock (primary succession), or re-growth on existing soil after a fire (secondary).
Threats: habitat loss and fragmentation, over-exploitation and over-fishing, pollution of water air and soil, invasive alien species that find no natural enemies, and climate change that shifts the ranges of species faster than they can adapt.
Egypt's measures: protected areas such as Ras Mohammed and Wadi El-Gamal, breeding and re-introduction programmes, the national biodiversity strategy, fishing and hunting regulation, afforestation belts (the "Green Wall") against desertification, and wetland restoration in the north.
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