Forestry Research and Outreach

Trees and Plants

Understanding how trees grow is essential to assessing the condition of the forest resources on a property and being able to steward it towards the landowner's desired condition. Trees participate in a competitive struggle with each other and other plants for water, sunlight and nutrients. Getting to know tree physiology, tree species and tolerances, and their competitive strategies is the critical first step in understanding how to steward a forest. 

Tree Identification 

There are many tree, plant, and animal identification field guides available as books or online. Read about some of the many California conifer species on their respective pages:

Vulnerable Plants

Although extinction is a natural process, the current rate of plant extinction around the world is one thousand times that which occurred before humans began to exert large-scale pressure on the world’s ecosystems. The major cause is habitat loss. Landowners with vulnerable plants on their property, or potential habitat for those species have a special opportunity and responsibility to safeguard unique species. Each species has its own unique needs and requires its own specialized management approach. 

Typical management techniques may include:

  • removing invasive plants
  • excluding herbivores
  • restoring drainage patterns to an area
  • rerouting trails
  • changing the timing of livestock grazing
  • conducting prescribed burns
  • other actions 

Pest Plants

Invasive yellow starthistle
Invasive yellow starthistle.

Exotic or non-native plants become pest plants when they aggressively invade natural ecosystems. Pest plants possess traits that help them outcompete natives such as abundant reproduction through easily dispersed seed or vegetative means, ability to quickly dominate disturbed sites, and rapid growth. Exotic pest plants can drastically alter basic ecological processes such as fire regimes, nitrogen fixation, and aquatic conditions to the detriment of native species. They may provide poorer habitat for wildlife and livestock than their displaced native counterparts and contribute to the decline of endangered plants. They also create large economic losses for agriculture by reducing livestock forage production. 

Major pest plants in California include:

  • Brooms (including French, Scotch, Portuguese, and Spanish)
  • Gorse
  • Yellow starthistle
  • Cape ivy
  • Tree of heaven
  • Eucalyptus
  • Pampas grass
  • Tamarisk
  • Purple loosestrife
  • Giant reed 

Prevention is the most effective and least costly way to avoid pest plant problems. Some common sense preventive precautions include:

  • minimizing soil disturbance
  • re-establishing vegetation quickly
  • buying construction material from weed free suppliers
  • inspecting the property to detect new weed populations while they are still small (when eradication can be practical and effective) 

University of California Resources

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