If you own any amount of property above 2 acres, you probably have one or more ecosystems on your property. It is now your responsibility to protect and maintain them to your best ability.
Keeping and maintaining a forest on private property is often incentivized by the government, which means that you could get a large tax break and assistance from your local Department of Natural Resources. This is because forests protect wildlife, the watershed and clean air for your community. Coordinating with experts to come up with a plan could mean identifying and clearing invasive species of plants, allowing foresters on to your property to conduct surveys, or allowing for the release of wildlife on your property.
Managing a pond can often lead to an education in chemistry, biology and physics. There are a lot of complicated, interlocking variables that work together to create a healthy pond. Maintaining a certain level of dissolved oxygen and flow in your lake can be achieved through aeration. You should learn to measure pH so you can diagnose any problems that arise, like dead fish or algal blooms. Although underwater vegetation is good, too many can mean you need to investigate aquatic weed control.
Often overlooked, grasslands are an important biome for your soil health, watershed and wildlife, as well. In order to ensure that native grasses dominate the landscape, you may have to participate in a controlled burn or mow the plot every so often, usually every other fall. However, you should consult with your local Department of Natural Resources to create a plan specific to you area and learn to identify invasive species you should be removing.
Even if you have mostly lawn on your large property, you can probably make a plan to help return it to its original state. Part of the joy of land ownership is becoming a steward of something bigger than yourself.