Ceballos and Ehrlich (2009) Discoveries of new mammal species .... PNAS 106:3841–3846

Hank's "Harper's Index" of Mammal Discoveries

• Number of categories of discovering new species: 3 (completely new finds (morphologically distinct), discovery that a well-known organism was actually > 1 species, and third, the elevation of subspecies to species. These last two are very similar, but the authors do not even address the > 600 cases of the third.)
• Number of new mammals found since 1993: 408
• Number of missing spellings of limestone forms: 1 (don't put the karst before the horse).
• Percentage of the land surface exploited, for crops, rangeland, building, and other: 70%
• Magnitude of the underestimate of unnoticed extinctions: gross (could we use range size to model this and actually quanitfy it?).
  
• Number of actual lemur species once thought to be only two species: 13
• Average range of previously known land mammals: 400,000 sq.km
• Average range of newly discovered land mammals: 84,000 sq.km
• Percentage of cells (cell=10,000sq.km) with rare species with low human population densities: 46%
• Percentage of cells (cell=10,000sq.km) with rare species with "relatively high" human population densities: >20%
• Number of commentators suggesting that the discovery of new species is a problem for conservation: 3
• Number of authors asserting that the discovery of new species is a not problem for conservation: 4

Sinclair, T. R. (2009) Taking the measure of biofuel limits. American Scientist 97:400-407.

I am enjoying greatly Sinclair's concise treatment of basic plant physiology, biochemistry, and the physical environment in which C3 and C4 crops are grown. It is the height of back-of-the-envelope artistry and clear thinking, which are hallmarks of strong quantitative, empirical biologists.

Sinclair starts with the loaming problem: the US Energy Independence and Security Act (currently) mandates that by 2022, the US should be producing 144 billion barrels of ethanol, roughly 25% percent or one barrel of ethanol for every three barrels of gasoline/diesel. This is the daunting task - it is a shit-load (my word, not his) of ethanol. Sinclair then asks whether the physical limits to plant growth will allow this mandate to be met by growing plants.

Having set up the problem, he goes about describing the elements of the puzzle:

Total annual ethanol production =
g Sugar / MJ of light intercepted by the canopy per day (C3 vs. C4) X
MJ incident light / sq. m. (max vs. average) X
days in the growing season X
grain vs. whole plant harvest X
gal ethanol / tonnes feedstock (corn vs. stalk) X
water use efficiency (C3 vs. C4 in dry vs. humid env.) X
Leaf area / land area (LAI) X
LAI / g nitrogen in tissue (C3 vs. C4) X
g N available in soil

I don't think that the above is a perfect rendering of Sinclair's elucidation, but it is close enough for now.

Sinclair next goes on to describes the sustainability of biomass harvest, in terms of N flux and the pool in the soil. He points out that the

rate of annual change in available soil N (g) =
annual application - harvest - runoff - leaching
+ production(cyanobacteria, thunderstorms)
+ mineralization(dead biomass)
+ N sequestration (perennials only)

Last, he considers land available, pointing out that most fertile land in humid regions is already in production. He concludes cautiously with

"... realistic assessments of the production challenges and costs ahead impose major limits."

This approach is a great companion to the work of Searchinger et al., Fargione et al., and Tilman et al. that have focused on land use and biodiversity issues. Much work lies ahead, and Sinclair has been of great help to me.