(Arboricultural-styled) 'Fact of the Day'

[Gary Prentice]

Just spent an enjoyable half hour with a perspective client explaining 'amenity values' and the intrinsic benefits of trees. I stopped talking when I observed the glazed look in her eyes, yawning and the look suggesting that she wished she hadn't asked:biggrin:

 

Sorry, a prospective not perspective client:biggrin:

[Kveldssanger]

Haha

[tree-fancier123]

good thread - was just thinking how slow evolution works compared to the length of a human life - wonder when the last discovery of a 'new' species of tree was in the british isles? Must have found them all hundreds of years ago.

[Kveldssanger]

Funny you ask. Sorbus admonitor (no-parking whitebeam) was found rather recently. Pretty hilarious: https://en.wikipedia.org/wiki/Sorbus_admonitor

 

The 'scaffold' of our native tree species was established many moons ago, though the finer intricacies where new (sub-)species develop on local levels will mean we may find more over time. Improvements in identification (due to microscopy, etc) and genetic sequencing mean we can actually ascertain whether a suspected new species is indeed a new one. That is something we could not do 100 years ago.

Edited August 23, 2015 by Kveldssanger

[daltontrees]

Funny you ask. Sorbus admonitor (no-parking whitebeam) was found rather recently. Pretty hilarious: https://en.wikipedia.org/wiki/Sorbus_admonitor

 

The 'scaffold' of our native tree species was established many moons ago, though the finer intricacies where new (sub-)species develop on local levels will mean we may find more over time. Improvements in identification (due to microscopy, etc) and genetic sequencing mean we can actually ascertain whether a suspected new species is indeed a new one. That is something we could not do 100 years ago.

 

And hybridisation is a continuous phenomenon, with succesful natural hybrids best suited to local situations changing the local genetic balance. Eventually after a few generations these may lose the ability to back-cross with their progenitors, and that combined with even minor genetic mutations along the way is the essence of a new subspecies or even a new species. For species taking decades to reach sexual maturity, this will be slow, but the likes of willow and birch hybridise freely and are sexually mature in no time.

[tree-fancier123]

2009, wow, good to know it's not all done and dusted

[Kveldssanger]

Great addition to the discussion there, Julian. Generational turnover is indeed a driver of species and sub-species development. I do wonder that as forest patches become more fragmented whether associated genetic drift will reduce the likelihood of new species developing. It can work the other way too however, with fragmented pockets of a species slowly evolving into a new sub-species (ultimately it would depend on the starting genetic pool of a species, and wouldn't work for vegetative propagation - perhaps genuses and species that reproduce primarily vegetatively don't therefore have as many species and sub-species respectively?). I wonder if there is any research on such a topic...

 

As for today's fact, it's going back to the basics and is again from Shigo's Modern Arboriculture (still reading it!).

 

23/08/15. Fact #13.

 

Photosynthesis, which is an autotrophic means of energy synthesis, involves the conversion of solar radiation (that comes in waves or particles: photons) to sugars (glucose). In the rawest sense, the photon strikes an electron within the chlorophyll molecule, the electron gets excited as a result, and in the process of it returning to an unexcited state the energy it gives off is captured and utilised to split a water molecule and to then bond the split molecule to a carbon dioxide molecule, producing glucose.

 

The two principal drivers of photosynthesis (excluding plant vigour and vitality - genetic trait and situational trait respectively) are light and temperature. Efficient photosynthesis can occur, at least on paper, when light availability is akin to 1,500 foot candles and temperature is between 28-35 degrees Celsius. Once temperature reaches 40 degrees or above, regardless of light availability, efficiency is significantly impacted.

 

Interestingly, only 0.1%* of the sun's solar energy is captured by plants (for any given increment of time - a second, a minute, an hour...). Of this 0.1%, 50% is captured by trees.

 

Source: Shigo, A. (1991) Modern Arboriculture. USA: Shigo & Trees, Associates.

 

*I believe the 0.1% would be of 1.08x10(to the power of 14) kW, going by this source. That means 108,000,000,000 kW (one hundred and eight billion) of energy is utilised by plants per second, of which 54,000,000,000 kW (fifty four billion) is used by trees (someone please double-check this!).

Edited August 23, 2015 by Kveldssanger

[tree-fancier123]

when light availability is akin to 1,500 foot candles and temperature is between 28-35 degrees Celsius

 

not checked any plant biology books, but surely the range doesn't refer to air temperature, or what

[agg221]

Really interesting thread. In the spirit of contributing, some additional comment re. Fact #1 on coppice woodland development, taken from Edlin H.L. (1973) Woodland Crafts of Britain so rather an old source but probably still valid.

 

The history of hazel coppice in southern sheep farming areas dates back a long way - sheep cropped the downs close, preventing regeneration, so the need for wood was met by reserving and enclosing areas in each parish for hazel coppice. This was supported by statute passed by Edward IV in 1483 authorising the enclosure of woods for a term of seven years after cutting to prevent encroachment of stock. Since seven years is the standard rotation for hazel this effectively placed former common land in the hands of the Lord of the Manor, but in the process also created a new trade in coppice management.

 

Alec

[tree-fancier123]

so they just grow slower up north