Sandy Loam – A soil containing much sand, but which has enough silt and clay to make it somewhat coherent. The individual sand grains can be readily seen and felt.
Sapwood – The outer portion of the wood that has living cells and transports water and nutrients and stores carbohydrates.
Saturation – In soil moisture, the condition in which both macro- and micropores are filled with water.
Scaffold – A large limb that is or will be part of the permanent branch structure of a tree.
Scarified – Soil that has been loosened or mechanically disturbed.
Silt Loam – A soil having a moderate amount of the fine fractions of sand and only a small amount of clay, over half of the particles being of silt size.
Sinker Roots – Roots that grow vertically from horizontal roots, adding stability to the tree and increasing the volume of deeper soil exploited by the roots.
Species – A group of plants that resemble each other closely and that interbreed freely.
Spiral of Decline –
Starch – A chain of sugars linked together that stores energy for later use by the plant.
Stem – A woody structure bearing foliage and buds that gives rise to other stems.
Stomata – Minute opening in the leaves through wihich gas exchange, including water vapor and carbon dioxide, occurs.
Stress and Strain – Stress is a potentially injurious, reversible condition, caused by energy drain, disruption, or blockage, or by life processes operating near the limits for which they were genetically programmed. When stress goes to strain, the tree dies; Generally attributed to over-pruning and root loss due to construction activity.
Structural Pruning – Pruning that influences the orientation, spacing, growth rate, strength of attachment, and ultimate size of branches and stems.
Structural Soil – Also known as “gap graded soil”. A mix of rock and soil that is used to provide surface support for hardscape without eliminating soil gas exchange.
Suckers – Adventitious stems arising from the lower trunk or roots.
Symbiotic – The relationship of two dissimilar organisms living together to the mutual benefit of each other.