- ISA - International Society Of Arboriculture
- The International Society of Arboriculture is a worldwide professional organization dedicated to fostering a greater appreciation for trees and to promoting research, technology, and the professional practice of arboriculture.
- ISA – UK and Ireland Chapter
- The Chapter formed in 1992 to represent the UK based professional arborist and to promote an international platform for the advancement of the science of arboriculture.
- AIE – Arboricultural Information Exchange
- The AIE is dedicated to sharing information and news relating to arboricultural issues. It is primarily intended for use by arboriculturists who may need to quickly source information on a given subject.
- Woodland Trust
- The Woodland Trust is the UK's leading woodland conservation charity.
- Northwoods exists to support the tree and timber businesses of North East England.
- QTRA (Quantified Tree Risk Assessment)
- The Quantified Tree Risk Assessment (QTRA) system applies established and accepted risk management principles to tree safety management.
- CAS (Consulting Arborist Society)
- The Consulting Arborist Society website is a resource for the general public to use in order to quickly find a suitably trained and experienced Tree Consultant capable of offering reports to satisfy a range of specific problems.
- Forestry Commission
- The Forestry Commission is the government department responsible for the protection and expansion of Britains Forests and Woodlands.
The FC Website is a wealth of information regarding all tree matters.