Ecosystem structure and processes, the value of and threats to biodiversity, and conservation and management strategies.

What this dot point is asking

WJEC wants you to explain how ecosystems are structured and function, why biodiversity is valuable and under threat, and how it can be conserved and managed sustainably, with located examples.

The answer

Ecosystem structure and processes

Energy enters through producers (photosynthesis) and passes along trophic levels in food chains and webs, with roughly $90$ per cent lost as heat through respiration at each transfer, which limits chains to four or five links. Nutrients cycle between biomass, litter and soil stores in the Gersmehl model, with transfers by uptake, fallout and decomposition. The balance of these stores differs sharply between ecosystems: a tropical rainforest holds most nutrients in fast-cycling biomass, while a Welsh peat bog locks carbon and nutrients in cold, waterlogged, slowly decomposing litter and soil.

The value of and threats to biodiversity

Welsh examples include the loss and degradation of peatlands, which cover much of upland Wales and store vast amounts of carbon, plus pressure on coastal and upland habitats from drainage, grazing and recreation. Globally, deforestation in the Amazon and tropical rainforests and warming drive the fastest biodiversity loss, with knock-on effects on the carbon and water cycles, because a damaged ecosystem stores less carbon and regulates water less effectively.

Conservation and management

Conservation uses protected areas (national parks such as the Pembrokeshire Coast and Eryri, sites of special scientific interest, and marine protected areas), rewilding and habitat restoration (peatland rewetting through the National Peatland Action Programme in Wales, native woodland planting), sustainable management of resources, and international agreements (CITES controlling trade in endangered species, and the Convention on Biological Diversity). Effective conservation balances protection with local livelihoods, so communities support rather than resist it, for example where ecotourism gives local people an income from intact habitat.

Examples in context

Example 1. Welsh upland peatlands. The blanket bogs of upland Wales, including areas within Eryri (Snowdonia) and the Cambrian Mountains, are the standard Welsh ecosystem case study. They store carbon and water but have been degraded by drainage and grazing. The National Peatland Action Programme rewets and restores them, demonstrating the link between ecosystems, biodiversity and the carbon cycle, and showing conservation as habitat restoration rather than simply fencing land off. The case lets you discuss structure, threats, value and management in one located ecosystem.

Example 2. Tropical rainforest conservation. The Amazon and other tropical rainforests provide a contrasting global ecosystem with the planet's highest biodiversity and rapid nutrient cycling in biomass. Threats include deforestation for cattle, soya and logging, plus climate change. Conservation strategies span protected reserves, indigenous land rights, REDD+ payments for forest carbon, and ecotourism that gives local communities an economic stake in intact forest. The rainforest case highlights that conservation works best when local people benefit, and that international agreements and finance are needed because biodiversity loss has global consequences for the carbon and water cycles.

Try this

Q1. Define the term ecosystem. [2 marks]

• Cue. A community of interdependent organisms together with the abiotic physical environment they interact with.

Q2. Explain why energy is lost between trophic levels in a food chain. [3 marks]

• Cue. Energy is lost as heat through respiration, and in movement, excretion and uneaten parts, so only about 10 per cent passes to the next level, limiting chain length.