Turning observations into information for over ten years

Proper pruning is essential to tree health, structural integrity, and longevity. Understanding the anatomical features of branch attachment and the biological mechanisms by which trees respond to injury allows practitioners to minimize damage and reduce the risk of decay. Central to this understanding is the concept of CODIT, or Compartmentalization of Decay in Trees, which describes how trees limit the spread of injury and decay rather than repairing damaged tissue.

Woody tree trunks exhibit a complex internal structure that reflects their functions in transport, support, storage, and long-term growth. Unlike herbaceous stems, tree trunks undergo secondary growth, resulting in an increase in diameter over time. This growth is produced by lateral meristems and gives rise to the characteristic tissues of wood and bark.

Accurate tree identification relies heavily on vegetative characteristics, particularly when reproductive structures such as flowers or fruits are absent. Bud arrangement, twig anatomy, leaf morphology, and growth form provide reliable diagnostic features that remain visible for much of the year. Understanding how these traits vary among angiosperms allows for systematic identification across seasons and habitats.

Successful tree transplanting depends on an understanding of plant adaptability, root biology, and soil–root interactions. While trees possess an inherent capacity to tolerate environmental variation, transplanting represents a significant physiological disturbance. Proper site preparation, planting technique, and early management are therefore critical to long-term establishment and structural stability.

Notes from ISA exam study session Soils function as chemically active systems largely because soil particles carry electrical charges. Clay minerals and organic matter possess a net negative charge, which allows them to attract and temporarily retain positively charged nutrient ions. This property underlies cation exchange capacity, the soil’s ability to hold and exchange nutrient cations such as calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), ammonium (NH₄⁺), iron (Fe²⁺/Fe

An overview of soil science for aborists

This guide focuses on observable traits  for field identification. Each species is introduced by its common and Latin name, and its...

By Roger Erismann, Casey Usher Form, Function, and Taxonomy The coast redwood ( Sequoia sempervirens ), also known as California redwood,...

The Giant Sequoia (Sequoiadendron giganteum) is an iconic conifer, known as the largest tree by volume on Earth. Native to California’s Sierra Nevada, it reaches up to 310 feet (95 m) tall and up to 35 feet (11 m) in diameter. Most individuals range between 250–275 feet in height and 15–20 feet in diameter at breast height. The bark, fibrous and furrowed, can be up to two feet thick, offering exceptional fire resistance.

Coast Douglas-fir is one of the tallest tree species on Earth, commonly reaching 200–250 feet in height and 5–6 feet in diameter. Exceptional specimens, such as the Doerner Fir in Oregon, have been measured at over 320 feet. In old-growth forests, these trees often live for 500 to 1,000 years. Young trees have thin, gray bark with resin blisters, while mature specimens develop thick, corky bark that protects them from fire. The foliage features spirally arranged, yellowish-gr

The Ponderosa Pine, Pinus ponderosa, is one of the most iconic coniferous trees of western North America and a keystone species across many forest types. This long-lived, evergreen conifer belongs to the Pinaceae family and is known for its impressive stature, fire-adapted traits, and wide ecological amplitude.

The California buckeye is a deciduous, woody shrub or small tree, typically 12 to 36 feet tall, though exceptional specimens can exceed 40 feet. It displays a broad, rounded crown and distinctive palmately compound leaves with 5 to 7 finely serrated leaflets. Its showy floral display — dense, upright panicles of white to pale rose flowers up to a foot long — blooms from May through June, with some variation based on climate.

The Gray Pine—also known as foothill pine, bull pine, gray pine or ghost pine—is one of California’s most distinctive native conifers. Often maligned for its irregular, “unkempt” appearance, Pinus sabiniana nevertheless represents a remarkable evolutionary response to some of the state’s most challenging growing conditions. Mature trees typically reach 40 to 80 feet, with sparse, twisted crowns, long, silver-green needles, and multiple upright trunks that self-prune over time

California black oak is a deciduous member of the red oak group (Quercus sect. Lobatae) and is the most widespread oak species on the West Coast. Mature trees typically reach heights of 50–110 feet and can live 100–200 years,

Among California’s native oaks, valley oak, interior live oak, and blue oak often share overlapping ranges but occupy distinct ecological niches shaped by soil, moisture, and climate.

Known for its ability to thrive where other oaks falter, this evergreen stalwart is a key component of both natural ecosystems and water-wise landscapes — a true botanical workhorse in one of the most fire-prone, drought-stressed regions of North America.

The blue oak, Quercus douglasii, is a California endemic and a standout among the state’s diverse oak species. It occupies a distinctive ecological niche in the hot, dry, and rocky foothills encircling California’s Central Valley, thriving where few other trees can.