3.1.1 Factors influencing biodiversity
Globally, biodiversity levels vary widely across land and oceans. Both physical and human factors influence levels of biodiversity and these factors operate at a variety of scales from local to global. Global physical factors such as variations in climate, play a major role in controlling the presence or absence of limiting factors, such as:
• Temperature
• Availability of light
• Humidity
• Nutrient supply
• etc.
An absence of limiting factors leads to high levels of primary productivity and the energy produced leads to high levels of biodiversity. Conversely, where limiting factors are strongly evident, e.g. in cold temperatures such as the Arctic, arid regions like deserts, darkness, etc. this will lead to low levels of biodiversity. The size of the area is another key factor, as the larger the continuous area the more species that can flourish in it. Hence the recent ‘size matters’ mantra, and the creation of huge transnational conservation areas such as the Peace Parks of Africa.
Locally, there are numerous factors that may have an impact on biodiversity:
• Disturbance from a natural disaster e.g. hurricanes, volcanoes, tsunamis on both land and ocean ecosystems, Asian tsunami 2004 – destroyed some mangrove forests
• Quasi-natural disasters, e.g. wildfires (Victoria, Australia 2009), hunting, fishing, slash and burn farming
• Eutrophication from high-tech agricultures
Physical factors Human factors
• Climate, e.g. temperature, rainfall, amount of light (limiting factors)
• Latitude, altitude and gradient
• Nutrients – vegetation and rate of nutrient recycling
• Topography – age and size of the area being investigated
• Island
• Endemism
• Climate change • Level of protection or management
• Level of poverty
• Exploitation of fauna and fawna: hunting, fishing, over-harvesting
• Clearance – agriculture, deforestation
• Human population – the growth, rate of development and use of available technology
• Local ecosystem factors – succession disturbance (plagio climax), competition, colonisation, dispersion rates

When considering human factors, it is necessary to consider both direct factors, such as hunting, and indirect human factors, such as climate change. Human factors can be considered as negative threats or as positive dealing with a spectrum of conservation strategies.
3.1.2 Hotspots
Hotspots are areas of high biodiversity. The initial terrestrial hotspots were a collection of 25, designated in 1999 as a result of the work of N. Myers, covered only 1.4% of the Earth’s land surface yet contained 44% of all the known plant species and 35% of all known animal species.
These hotspots are conservation priorities because of their high levels of biodiversity and endemism. These environments, however, are also under the greatest threat, which leads to environmental degradation of these valuable ecosystems. The sheer variety of the resources available in these hotspots increases their demand and thus are heavily threatened; potentially more-so in the future with an increasing demand due to an increasing global population. Many people argue that with scarce eco-funds it is logical to save the best-bits.
Most of the original hotspots were located in tropical areas, especially rainforests – many in LDCs where poverty is the root cause of threats to these hotspots. A criticism of this evaluation was that coverage of the world’s ecosystems was uneven because marine areas and many unusual terrestrial ecosystems such as those found in Polar Regions were initially excluded. Concept of Global 200 eco regions, the development by WWF, hopes to conserve representative samples of all ecosystems as a priority as an alternative approach.
Recently, Conservation International has updated the analysis of the Earth’s biodiversity and has identified 34 terrestrial hotspots that between them contain over 50% of the Earth’s known plants. A much wider location spread has therefore been developed, and includes several areas within the Mediterranean basin.
Coral reef destruction – Conservation International has identified 11 marine hotspots, including the Coral Triangle (Indonesia, Philippines and Papua New Guinea) which was subdivided into three hotspots:
1. Indonesia
2. Sundaland
3. Wallacea
These hotspots contain 25% of the world’s coral reefs and 34% of restricted range endemic species but only cover 0.02% of the oceans. Most of these marine hotspots are adjacent to terrestrial hotspots and experience land-based threats of pollution, over-fishing and tourism development. The marine hotspots encompass future planning and include some areas such as Chagos Island in the north Indian Ocean, which is currently a wilderness area with almost