Kangaroo Island’s large gums, those species (particularly sugar gums and pink gums, Eucalyptus cladocalyx and E. fasciculosa) which provide hollows to many birds and mammals, are diminishing in number.
It’s not only a matter of less habitats for the fauna: big, old trees are a central part of ecosystems, and their disappearance is having an enormous ecological impact planet-wide.
The three following links provide basic information on the matter:
http://www.sciencedaily.com/releases/2012/12/121206162519.htm
http://www.sciencedaily.com/releases/2012/05/120502184416.htm
http://www.guardian.co.uk/environment/2012/jan/26/giant-trees-dying
See also
Rate of tree carbon accumulation increases continuously with tree size — Stephenson et al 2014
For those who wish to get to more primary sources, here are three scientific documents in pdf format :
Lindenmayer’s et al (2012) article in PLoS One :
“major_loss_of_large_trees_with_cavities_Lindenmayer_012”
Lindenmayer’s et al (2012) article in Science (my thanks to Prof. Lindermayer for providing me with this article):
“Global_decline_in_large_old_trees_Lindenmayer_012”
Lutz’s et al (2012) article in PLoS One :
“Large-diameter_trees_importance_Lutz_012”
Those with large property on the island could plant more sugar gums (Eucalyptus cladocalyx) and pink gums (Eucalyptus fasciculosa), if they wish to help addressing a serious bottleneck in the local ecological system. There are now more than enough she-oaks (Allocasuarina verticillata) to feed 10 / 20 times the population of glossy-black cockatoos (to the great joy of rainbow lorikeets, who appreciate the abundance of sheoak nuts), but accommodation has become rare. Plus, the flowers of these large gums are much appreciated by many birds and insects, so they provide much food to many species in addition to shelter.
Time to refocus.
It’s a long-term project for any land owner, but worth it, scientifically and… esthetically: these gum trees have much character.
A caveat, though: of course, do not plant such branch-dropping trees close to habitations…
Dr Gabriel Bittar, Kangaroo Island
The following article in Nature demonstrates how old large trees are very active carbon processors:
“Rate of tree carbon accumulation increases continuously with tree size“, Stephenson et al. (2014)
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12914.html
Published online 15 January 2014
Highlights:
– Trees accelerate their growth as they get older and bigger
– Rapid growth in giant trees is the global norm and can exceed 600 kg per year in the largest individuals
– In absolute terms, trees 1 m in trunk diameter typically add 10-200 kg of dry mass each year, averaging 103 kg per year. This is nearly three times the rate for trees of the same species at 50 cm in diameter, and is the mass equivalent of adding each year an entirely new tree of 10-20 cm in diameter
– This finding contradicts the usual assumption that tree growth eventually declines as trees get older and bigger
Abstract
Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle — particularly net primary productivity and carbon storage — increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age.
Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree.
The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
The two following links vulgarise the results:
http://www.sciencedaily.com/releases/2014/01/140115132740.htm
http://www.theguardian.com/environment/2014/jan/15/trees-grow-more-older-carbon