Trees: Their Natural History
Language: English
Pages: 408
ISBN: 0521133580
Format: PDF / Kindle (mobi) / ePub
Trees are familiar components of many landscapes and have been vital in determining the ecology of our planet as well as the development of human cultures and communities. Yet how much do we really understand about how they work? This updated and revised edition provides a comprehensive introduction to all aspects of tree biology and ecology and presents the state-of-the-art discoveries in this area. The wonders and mysteries of trees are explored throughout the book and questions such as why leaves turn spectacular colours in the autumn, how water reaches the top of the tallest trees, or why the study of genetics has caused so many name changes in trees are all brilliantly answered. Written with a non-technical approach, this book will be a valuable source of reference for students and those with a less formal interest in this fascinating group of plants.
huge vessels, which contrast distinctly with the smaller ones of the late wood (Figure 3.5). Looking at the cleaned cut end of one of these trees, the large holes or pores in the earlywood can be seen to follow each ring around the tree: hence ring-porous. In diffuse-porous trees (like birch, maple, beech, poplar, lime, walnut, mahogany and eucalypts) the pores are more even in size and evenly distributed throughout the ring, making the rings less obvious. But the boundary between rings can still
the pattern of wide and narrow rings can be matched to pieces of dead wood (2–4), they can also be dated. In this way long ‘chronologies’ can be built up. (Note that the ‘crossmatching’ between cores is never quite as perfect as shown here; there is always some variation from tree to tree requiring the use of computers to find the best match.) As well as acting as precise dating tools, tree-ring chronologies can also tell us a lot about past climates. In Scandinavia a chronology for Scots pine
types of seedling and will feed voraciously when a clump is found. Thus it is the odd isolated seedlings at the outer edge of the dispersal area that are most likely to be missed and survive to grow. This ‘escape hypothesis’ may go some way to explain why individuals of most tropical trees are usually well spaced through a forest and not clumped as in many temperate forests. New trees without seed: vegetative propagation There are several ways that new trees can be produced from pieces of an
and the Monterey cypress (Cupressus macrocarpa). The original Leyland cypress hybrid occurred at Leighton Park in Wales in 1888 where both parents happened to be growing near each other (in their natural range along the western seaboard of N America they don’t come within 300 miles of each other). Six plants were raised from seed collected from a Nootka Cypress by C.J. Leyland. In 1911 the reverse cross happened: seeds collected from a Monterey cypress produced 2 seedlings. Leyland cypress shows
by toxic materials in paint or allowed to desiccate, then the wound can only be covered by the slow growth of callus tissue from the living cambium and rays around the edge. As the callus grows, it starts off uniformly around the wound but the sides tend to grow more rapidly (Figure 9.2) resulting in a circular wound ending up as a spindle-shaped scar (just why this is so is portrayed below under Wind). Once the sides of the callus meet, the cambium joins so new complete cylinders of wood are