Also, at night the plants breath out Carbon Dioxide. Their net carbon sequestration depends on their mode of photosynthesis combined with day length and degree of cloud cover. I was talking with a friend of mine who did research on photosynthesis in trees. he said that when a cloud coverd the sun, the photosynthesis would crash. :)
M On Tue, January 15, 2008 11:30 am, David Bryant wrote: > Bill, > > Indeed. I should also point out that logging increases C respiration > from decay woody debris and increased sol temperature... > > IMHO: he only form of biofuel production that is sustainable, and C > neutral, is waste conversion. I.e biodiesel from waste oil, ethanol > from waste cellulose and methane from manure. While all do include > some energy inputs, so does waste disposal and it does not provide > any energy benefits. I doubt however if a corporate infrastructure > of biofuel production can avoid being seduced by the lure of > sustainable profits from unsustainable biomass to energy from primary > agricultural sources . > > > David > > On Jan 15, 2008, at 5:38 AM, William Silvert wrote: > >> Although David is correct about long-term carbon budgets, this too >> is an >> oversimplification. Biomass is a form of carbon sequestration, and >> when >> forests are cut down to develop biofuel plantations, as is >> happening in >> Indonesia and elsewhere, a lot of carbon is removed and ultimately >> gets into >> atmospheric CO2. Furthermore much biofuel production is energy- >> intensive, >> perhaps the worst example being the growth of corn in the US where >> much >> energy goes into the production of fertilizers and pesticides, as >> well as >> irrigation. And of course there are other environmental costs in >> addition to >> energy. >> >> So far as I am aware, the only significant forms of carbon >> sequestration are >> biomass and carbonates -- am I wrong about this? Maintenance of >> high forest >> biomass can help, and as for carbonates, I think the main mechanism is >> through creation of calcium carbonate by marine organisms, which we >> can't do >> much about. Perhaps someone has better information, but it seems to >> me that >> it is highly desirable both to reduce the consumption of fossil >> fuels and to >> promote conservation of high plant biomass. >> >> Bill Silvert >> >> >> ----- Original Message ----- >> From: "David Bryant" <[EMAIL PROTECTED]> >> To: <[email protected]> >> Sent: Monday, January 14, 2008 10:24 PM >> Subject: Re: ESA Press Release: Nation's Ecological Scientists >> weigh in on >> biofuels >> >> >>> This statement that biofuels are combustables, and therefore give off >>> CO2, is a commonly promoted oversimplification, oft stated by less- >>> than-knowledgeable reporters. The carbon in biofuels WAS in the >>> atmosphere last winter/growing season (depending on your latitude) >>> and therefore biofuels are technically C neutral from the perspective >>> of the C Cycle. Just like the rain/snow that falls on us today was >>> in the ocean days/weeks before and does not contribute to the sea >>> surface level rise. > Malcolm L. McCallum Assistant Professor of Biology Editor Herpetological Conservation and Biology http://www.herpconbio.org [EMAIL PROTECTED] [EMAIL PROTECTED]
