Biodiversity refers to all living things, not just the organisms we can see, and not just the organisms people tend to like (cute furry animals, usually). While conservation biology aims to protect biodiversity, conservation also includes making choices about human use of the environment and prioritizing goals. There are no "right" answers in most conservation decisions.
Threats to Biodiversity: Habitat Loss
We said edges are bad in the context of habitat fragmentation. But you may have also heard that interesting things happen at habitat edges, where two habitats meet in the area called an ecotone. Sometimes a greater diversity of species is present in an ecotone because two different habitats meet there. However, when habitat fragmentation happens, it is usually habitat with buildings or crops at the edge, not other types of natural habitat. Buildings or crop fields may be habitat for some species, but they do not support the diversity that natural habitat does. They also displace whatever organisms were living there before.
Threats to Biodiversity: Invasive Species
Not all non-native species become invasive, but people sometimes call any species "invasive" that is not native. This is incorrect, because invasive species are defined by the harm they do to an ecosystem. Invasive species have many impacts in a variety of places—no two invasive species are the same, and one species can have different effects when it invades separate areas. A non-native species may not be invasive in one location and is invasive in another. Some invasive species have larger impacts than others.
Threats to Biodiversity: PollutionClimate vs. Weather
It happens all the time—a snowstorm hits in April, or winter is unusually cold, and people start saying we don't have to worry about global warming. There are two mistakes here:
1) The term "climate change" is more correct than "global warming" because even though on average the planet will be warmer, individual places will have different changes to their climates—some cooler, some wetter, some hotter, some drier.
2) Climate is not the same as weather. Climate means long-term patterns of weather, and weather refers to current or short-term conditions. Weather at any given point is a blip on the climate screen.
Threats to Biodiversity: Overexploitation
With all these pressures on food supplies and fisheries, it is hard to know what to eat! You do not have to grow all your own food to reduce your impact on overexploitation. The Monterey Bay Aquarium publishes guidelines on seafood (including sushi… sorry vegans!) to help consumers make sustainable seafood choices. Download their pocketguide here
Conservation Strategies: Populations and Species Level
The Allee effect is a little bit unintuitive because ecologists talk about competition between individuals in the same population—individuals compete for space, food, mates, and to be the next American Idol. However, the Allee effect is a cooperative affair; to keep each other alive, there have to be a certain number of individuals.
Conservation Strategies: Landscape and Ecosystem Level
We have thrown out the word "protected" a lot without really explaining what it means. That is because its meaning varies, depending on the type of protected area, the country, and the phase of the moon (well, not really). Usually it means some sort of activities are restricted to ease pressure on the animals, plants, fungi, or whatever organisms are supposed to be conserved. Keep reading for more on the different levels of protection and what activities are allowed in the US system of protected areas.
Conservation groups are plentiful, and each has slightly different goals. Some groups want to conserve habitat so they can hunt on it and use it for other forms of recreation; other groups want to preserve habitat as it is without extracting any resources. It is easy to lump all these conservation groups together, but keep in mind they are all different and use a variety of techniques to achieve their goals.
It is common to think that a protected area means all the wildlife inside that area is being preserved. This is true of National Parks, but is not true of all protected areas. National Forests are protected so that humans can use them, for logging and tobogganing and mountain biking.
Laws and Treaties
You may have heard of species being "listed" or "delisted." This means they are being added to the list of endangered and threatened species ("listed") or taken off that list ("delisted"). Species that are listed as threatened can be changed to endangered and vice versa, depending on their conservation status. Delisting can happen because species have recovered so well that they no longer need special protection. Other times, they are no longer listed because they have gone extinct. Sad face.