The St. Vrain watershed is part of the South Platte basin in northeastern Colorado and has a population of approximately 336,000 people. The watershed is 979 square miles of which 22% is protected. Forests cover 49% of the St. Vrain watershed.
Current Forest Health
Average air temperature looks at how warm or cool a year was overall. This is a helpful metric in comparing conditions across years. For the Forest Health Index, average air temperature is measured using a combination of air temperatures from across your watershed.
Extreme high temperatures in the summer stress forests and wildlife. These days increase water loss from transpiration and can damage trees. Additionally, extreme high temperature days increase the risk and severity of wildfires.
Critical Fire Risk
Fire plays an important role in fire ecology, helping to rejuvenate disturbance-driven systems and bring diversity to the age and type of plants in the forest. In the last century, however, humans have changed when and where fires happen on the landscape—sometimes starting fires themselves, sometimes preventing fires from spreading.
Total annual precipitation refers to the amount of water that fell from the sky in the last year. This includes rain and the water in snow, sleet, and hail. Precipitation plays an important role in plant survival, fire risk, insect outbreaks, and river levels.
Frost Free Days
Frost Free Days describes the number of continuous days between the last freeze in spring and the first freeze in fall. It is often associated with the growing season for many farmed or wild plants.
High elevation snowpack refers to of the amount of snow that piles up in the mountains during the winter. It is measured by how much water you would have if you took a column of snow and melted it—the “snow water equivalent” (SWE).
Bears are not just an interesting animal: because they rely on healthy forests to survive, they are also an excellent indicator of forest health.
Insect and Disease
In the Forest Health Index, Insects and Disease scores the amount of tree mortality caused by pests such as beetles and funguses. Tree-threatening diseases and insects, like bark beetles, play a natural role in the life cycle of forests.
Ozone (O3) is a chemical compound found in the upper layer of our atmosphere and closer to the ground. In the upper layer of the atmosphere, ozone helps to protect life by protecting our planet from the sun’s ultra-violet rays, but ground-level ozone is considered a pollutant and can harm human and plant health.
Peak streamflow refers to the date in spring when water levels in the river are highest. When water comes and how much is available are important factors for forests and for the humans living downstream of them.
Soil moisture refers to how much water is being held in the ground at any given time. It is important in determining whether plants are able to grow, flower, and survive. It also plays a role in how much water reaches streams and rivers during rain storms or spring snow melt.
Humans have a dramatic impact on the landscapes we inhabit. Communities can moderate their impact by using fewer resources, conserving water and electricity, and limiting trash.