The Value of Biodiversity

Many unique ecosystems can be found in the Galapagos Islands. With so much animal and plant life, the Islands need to be carefully managed to protect the wildlife. In this chapter we will learn about how areas can be managed to protect biodiversity and the importance of involving local people in this process.

The value of biodiversity

Biological diversity or ‘biodiversity’ is a term that is used to describe the number of different living things, such as plants and animals, in an area. For example, an area that has many different types of bird, mammals and insects can be categorised as being more biodiverse than an area with only a few different types of birds, mammals and insects.

What is biodiversity like on the Galapagos Islands?

The Galapagos Islands are home to a wide range of species ranging from the iconic giant tortoises to lesser known plant and bug life that are often hidden away in the hard-to-reach areas. The Galapagos Islands are so biodiverse because of the many different habitat zones that can be found across the Islands. There are coral reefs, highland forests, sand dunes and scrubland, and the changing habitats from island to island.

Habitat Zones of Galapagos

Habitat Zones of Galapagos

Species diversity is only one piece of the biodiversity puzzle. There are many other parts that add up to make an areas biodiversity. Species diversity refers to the number of different species that can be found in an area. For example, in Galapagos there are 15 different types (or species) of Galapagos finch.

What makes the Islands so unique?

The Galapagos Islands are famous for their wide range of endemic species, species that cannot be found anywhere else in the world. When a species only exists in one place (such as the Galapagos giant tortoise) it is known as being endemic. Endemism on Galapagos is high due to the geographical isolation of the Islands from other places. 

The protection of endemic and keystone species is essential to ensure the sustainability of the Islands and ensure the Islands remain biodiverse. A keystone species is one that has an important impact on the whole ecosystem. If something were to increase or decrease the number of keystone species in an area, it would have a direct effect on many other species within the same ecosystem. You can learn more about the relationship between species in an ecosystem in the Ecology and Habitats chapter.

What is impacting biodiversity in Galapagos?

The influence of human beings on the Galapagos Islands is making its environment unsustainable. Farmland is often planted with just one species of crop (monoculture) to make it easier to farm and control pests and weeds. However this also makes it more likely to suffer from the effects of diseases: if a farmer is only growing one crop a single disease can wipe out his entire harvest for that year.

Therefore biodiversity has both economic (e.g. protecting crops from diseases which would otherwise reduce their profit) and environmental value. Biodiversity also has a social value but it is harder to recognise: we appreciate the way wildlife looks and many people believe it deserves conservation because they see human beings as guardians of the earth. Biodiversity therefore, has a role within each of the sustainability parts and this makes the case for its conservation in the Galapagos Islands ever stronger.

Next: Conservation and Sustainability – The Case for Conservation

Biodiversity and Ecosystem Health

The number of individuals in a population will increase and decrease due to natural and human factors. Natural fluctuations in population size occur due to factors such as food availability and the number of predators.

Humans can cause population sizes to change by introducing invasive species, hunting or changing the environment. A healthy ecosystem, with high biodiversity is important in helping reduce the effects of these factors on a particular species.

Factors affecting species populations

Species populations of Galapagos fluctuate due to natural and human factors. Species population growth or decline can be caused by either density-dependent or density-independent factors:

  • Density-dependent factors have varying impacts according to population size. Different species populations in the same ecosystem will be affected differently. Factors include: food availability, predator density and disease risk.
  • Density-independent factors are not influenced by a species population size. All species populations in the same ecosystem will be similarly affected, regardless of population size. Factors include: weather, climate and natural disasters.

Biodiversity and population health

High biodiversity can help to stabilise an ecosystem and reduce the overall impact of density-dependent and density-independent factors. Biodiversity is a measure of the difference between the living organisms within an ecosystem.

With many endemic species and a great range of wildlife, Galapagos has a high level of biodiversity. This is due to the number of very different habitat zones found in Galapagos, and also due to more acute environmental differences between the habitats of each island.

Biodiversity is an important factor in ensuring a healthy ecosystem. For example, an ecosystem with a wide range of producers will provide the primary consumers with a stable and varied food supply. Each species also plays a unique role in servicing the ecosystem, ensuring that it operates smoothly. Ecosystems with a high level of biodiversity are more able to recover from disasters, whether natural or man-made (anthropogenic).

A fluctuation in the size of one species population can impact on other species within the ecosystem. A species that will have a large impact on the ecosystem is known as a keystone species. The more biodiverse an ecosystem, the less vulnerable it will be to fluctuation in keystone species populations.

Case study: Galapagos giant tortoise

Galapagos Wildlife: Santa Cruz Giant Tortoise © Catherine Rouse

A Galapagos giant tortoise munching on some greenery in Santa Cruz © Catherine Rouse

The Galapagos giant tortoise is a keystone species and its population has declined as a result of human activity. During the 18th and 19th centuries, whaling ships would stop at the Galapagos Islands and hunt giant tortoises to feed their crew.

Giant tortoises continued to be targeted as the Islands’ settlements expanded and the human demand for food increased. Their population was estimated to be around 250,000 in the 1500s, when they were first discovered. However, a 1974 census recorded just 3,060. Research suggests that 13,000 giant tortoises were taken from the Islands between 1831 and 1868 by whaling crews.

The decline of the Galapagos giant tortoise population impacted on Galapagos ecosystems. Even plant and animal species directly unaffected by human activity began to experience great population change.

Galapagos giant tortoises shape their habitats by grazing on plants, dispersing plant seeds and trampling areas of vegetation. They therefore play an important role in germinating seeds, as well as in thinning out and opening up new areas of ground for different types of vegetation to grow.

Without the giant tortoises constantly changing the environment, a few fast-growing plant species could dominate a much less biodiverse ecosystem.

Previous: Ecology and Habitats – Food Chains and Webs

Next: Ecology and Habitats – Environmental Threats