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Global Tree Distribution and Diversity

The document discusses different types of trees and forests. It provides estimates that there are 3.04 trillion trees globally, with 46% in tropical and subtropical regions. Over the past 12,000 years of human agriculture, the number of trees worldwide has decreased by 46%. The document also describes different forest environments like the Daintree Rainforest in Queensland and coniferous boreal forests.

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80 views2 pages

Global Tree Distribution and Diversity

The document discusses different types of trees and forests. It provides estimates that there are 3.04 trillion trees globally, with 46% in tropical and subtropical regions. Over the past 12,000 years of human agriculture, the number of trees worldwide has decreased by 46%. The document also describes different forest environments like the Daintree Rainforest in Queensland and coniferous boreal forests.

Uploaded by

Illavarasan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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a tree including the branches and leaves,[29] while the

uppermost layer in a forest, formed by the crowns of the


trees, is known as the canopy.[30] A sapling is a young
tree.[31]

Many tall palms are herbaceous[32] monocots; these do not


undergo secondary growth and never produce wood.[9][10]
In many tall palms, the terminal bud on the main stem is
the only one to develop, so they have unbranched trunks
with large spirally arranged leaves. Some of the tree ferns,
order Cyatheales, have tall straight trunks, growing up to 20
metres (66 ft), but these are composed not of wood but of
rhizomes which grow vertically and are covered by
numerous adventitious roots.[33]

Distribution

The Daintree Rainforest

The number of trees in the world, according to a 2015


estimate, is 3.04 trillion, of which 1.39 trillion (46%) are in
the tropics or sub-tropics, 0.61 trillion (20%) in the
temperate zones, and 0.74 trillion (24%) in the coniferous
boreal forests. The estimate is about eight times higher
than previous estimates, and is based on tree densities
measured on over 400,000 plots. It remains subject to a
wide margin of error, not least because the samples are
mainly from Europe and North America. The estimate
suggests that about 15 billion trees are cut down annually
and about 5 billion are planted. In the 12,000 years since
the start of human agriculture, the number of trees
worldwide has decreased by 46%.[1][34][35][36]

In suitable environments, such as the Daintree Rainforest in


Queensland, or the mixed podocarp and broadleaf forest of
Ulva Island, New Zealand, forest is the more-or-less stable
climatic climax community at the end of a plant
succession, where open areas such as grassland are
colonised by taller plants, which in turn give way to trees
that eventually form a forest canopy.[37][38]

Conifers in the Swabian alps

In cool temperate regions, conifers often predominate; a


widely distributed climax community in the far north of the
northern hemisphere is moist taiga or northern coniferous
forest (also called boreal forest).[39][40] Taiga is the world's

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