from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A transitional zone between two communities containing the characteristic species of each.
from The Century Dictionary.
- noun In phytogeography, the line along which two types of vegetation compete for the same ground. See
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun a transition area between two adjacent ecological communities (
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
Remember the tree line is not a line, but an ecotone, which is the case of latitudinal tree ‘lines’ can be very broad.
Give it a zone of transition — an ecotone — where both land and water can be occupied simultaneously.
The scrubland (cotos) and heathland ecotone (vera) are the richest habitats for most animals apart from waterbirds.
The heathland (vera) which forms a narrow ecotone between the dunes and the marsh and also covers the land furthest from the Guadalquiver, is a series of low ridges and hollows.
The extensive ecotone between boreal forest and tundra (a tree line 13500 km long) is a prominent feature of the northern boreal region (some of the major climate-related fluctuations of the tree line are discussed in Chapter 14).
The transition zone has been called forest tundra, subarctic, and the tundra – taiga boundary or ecotone.
Geometrid moths of two species occur in the mountain birch (Betula pubescens ssp. czerepanovii) forest that makes up the ecotone between boreal forest and the tundra of Fennoscandia.
Arctic lands are extensive beyond the northern limit of the tundra – taiga ecotone, encompassing an area of approximately 7,567,000 square-kilometers (km2), including about 2,560,000 km2 in the former Soviet Union and Scandinavia, 2480000 km2 in Canada, 2167000 km2 in Greenland and Iceland, and 360000 km2 in Alaska .
Landscape-scale interactions between vegetation and disturbance are particularly important in the forest – tundra ecotone  where vegetation change is very likely to have large feedbacks to climate .
Transient ecotone response to climatic change: some conceptual and modeling approaches.