 Biodiversity is a key concept in ecology and has importance on both local and global scales. Biodiversity is the degree of variation of life, or, put it more simply, the number of different individuals and life forms in an area. Scientists usually measure biodiversity on either genetic, species or ecosystem levels. For example, if you wanted to measure the biodiversity of beetles on a global scale, you would find there over 350,000 known species of beetle on the planet. However, if you wanted to measure the biodiversity of beetles locally, you might find only up to 10 or 20 species. The reason for this difference is that biodiversity varies greatly with the location, habitat and species being surveyed. In general terms, biodiversity tends to be highest at the equator and decreases at higher latitudes, i.e. as you get further away from the equator. Knowing this information, where would you expect to find the habitats with the lowest biodiversity? Pause the video and have a think. Habitats at the equator, such as tropical rainforests, usually have the highest biodiversity. So if you thought habitats at the north or south poles, such as the polar desert, you're correct. It's important to know that biodiversity is not a static measure, but is responsive to numerous factors, including climate change. In fact, global biodiversity is generally thought to be declining right now. Biodiversity has declined in the past, and the total of five major extinction events have occurred. Currently, we are in the planet's sixth major extinction event, known as the Holocene extinction. There are many proposed reasons for the current drop in biodiversity. Some of those reasons are anthropogenic, meaning caused by humans. Anthropogenic factors include things like introduced or invasive species, such as the introduction of rabbits to Australia, human-induced hybridisation, such as implants to create optimal species of crop. Over-harvesting of resources, and global climate change caused by human activities. While humans aren't responsible for all of the current extinction events, there is good evidence to suggest that humans are affecting the world on a global scale and causing the loss of many important species. The loss of biodiversity could have catastrophic effects on our society and even result in the loss of our food crops. For example, bees are in huge decline and they are extremely important in the pollination of many plants, including our crops. There are lots of ways we can reduce biodiversity loss and even increase biodiversity, such as managing our land better, growing more than one crop and including plants that encourage insect diversity, and also creating cities with space for other species. We shouldn't just focus on the rural areas, urban places can do their bit. By increasing the local biodiversity, we can help the environment to sustain itself and give it a better chance of understanding the effect of global climate change. A healthy and diverse ecosystem can withstand and recover from disasters. Biodiversity is an important topic that affects us all. As a global community, we need to take action to protect our biodiversity on both local and global levels. Here are just a few of the free services a healthy biodiverse ecosystem provides us with.