GIS – Agricultural Biodiversity Weblog

June 10, 2026June 11, 2026

Himalayan maize: The saga continues

I decided to dig a little deeper into the climatic adaptation of Himalayan maize. You may remember from my last post on this that Genesys has 96 maize accessions from over 2000 masl in the Himalayas, collected at some 50-odd unique localities. When I ran these accessions through the Subsetting Tool in Genesys, I got the following histogram.

What struck me — and surprised me — was the spike of sites way at the left hand of the precipitation plot. So I took a closer look at the results of the subsetting analysis. And the clustering algorithm it uses to look for similar sites did in fact identify two climatically quite different groups of locations: 45 of the unique high altitude maize collecting sites (the blue ones) are indeed drier than the other 7 (in orange).

Much drier. (And also colder actually, but that’s another story.)

They’re the ones mainly collected in Pakistan and Afghanistan.

Now, I don’t know whether these areas really get 135 mm of annual precipitation, which seems really low, and in any case the agriculture there is clearly irrigated.

But those maize samples, mainly now conserved at CGN in the Netherlands incidentally, the results of something called the 1976 Netherlands-Pakistan Expedition by the Stichting voor Plantenveredeling, do seem to have some very unique adaptations.

June 9, 2026June 9, 2026

Maize location, location location…

A quick search on Genesys revealed 302 maize accessions from above 1500 masl in the Himalayas, and 62 above 2500 masl. Of course, there are many more maize accessions from high altitudes in Central and South America, but their photoperiod adaptation (among other things) is likely to be quite different.

That’s from a post I put up here a few days ago. Some people said I should back up that “among other things,” so here goes.

I extracted from Genesys lat/longs for 2,388 maize landrace accessions collected above 2000 masl in the Andes, and for 96 in the Himalayas. I then asked ChatGPT to calculate separate averages for the two sets of accession collecting localities for two climate variables, i.e. mean annual temperature and precipitation. It asked me to supply it with the WorldClim data as a zip file, which I duly did.

It told me the Andean sites had a mean annual temperature of about 12°C and the Himalayan ones of about 6°C. Mean annual precipitation was around 750mm and 640mm, respectively. So there could well be some significant overall differences in adaptation between the two sets of germplasm.

But…

I used the coarsest WorldClim dataset, which is probably not a great idea in mountain areas. And many accessions were collected at the same sites: those 96 Himalayan maizes for example come from only 52 distinct places. I should probably have only used unique collecting localities to make the calculations. The “Subsetting Tool” in Genesys does do that, and displays nice histograms, but it doesn’t give you average values for the whole subset. Incidentally, when I looked at the histogram for total precipitation for the Himalayan material, there was a suspiciously big spike way at the dry end. Really not sure what’s happening there.

Maybe some climatologists or geographers or GIS jockeys can explain. And do a better analysis. And come up with a really easy way of extracting climate data for a long list of localities.

June 3, 2026June 3, 2026

Stairway to maize diversity

There’s a nice article in Rising Kashmir highlighting that region’s cold-tolerant maize landraces as a unique source of genetic diversity. What I liked about it is that it doesn’t condescend to its audience. It’s unapologetically technical and niche, while successfully (I think) striving to be understood by all. That’s rare. The author, Dr Salika Ramazan, argues that long adaptation to Himalayan environments has produced valuable traits for climate resilience and future maize breeding, and advocates for urgent conservation before this irreplaceable diversity is lost.

A quick search on Genesys revealed 302 maize accessions from above 1500 masl in the Himalayas (yellow on the map below), and 62 above 2500 masl (red). Of course, there are many more maize accessions from high altitudes in Central and South America, but their photoperiod adaptation (among other things) is likely to be quite different.

Distribution of high-altitude maize accessions in the Himalayas (from Genesys).

May 18, 2026May 16, 2026

Brainfood: Spatial data edition

The ClimSat classification system—a global climate classification map based on long-term satellite-derived data. There’s a new global climate classification system in town, and it’s better ecologically than Köppen’s.
The first global agricultural field boundary map at 10 m resolution. Combined with the above, we can now characterize the climate of every agricultural field in the world.
GEM-Forest: A Global satellite EMbedding–based map of forests and tree crops for 2020. Do any of those fields have tree crops? And how far is the forest?
Global annual cropland dynamics 2015–2024. The next time we map agricultural field boundaries, there will probably be more of them.
Climate-induced range shifts support local plant diversity but don’t reduce extinction risk. Those new agricultural fields will be bad for wild plants.
‘SiteTool’: a ‘Shiny’ application for field site selection and evaluation. Cool new tool helps you select geographical sites based on ecological characteristics. Could be used to help decide where to collect or evaluate germplasm. Lots of opportunities for combining with some of the above, I suspect.
Current and future potential of cassava (Manihot esculenta) in Southern Africa: a scoping review. An example of what you can do when you combine different types of spatial (and other data). The area suitable for cassava in Africa will increase, and there’s lots of scope for higher yields too. If we can combine datasets, soon we’ll know which specific fields to grow it in, for higher production, to protect wild biodiversity…
Global and regional climate modes modulate armed conflict risk. …and to mitigate the risk of conflict.

May 13, 2026

Nibbles: Pearl millet redux, Garden plants, Armenian pics, Seeds galore, Heavenly Book, Pastoralism threats

Pearl millet is getting the hybrid treatment. And, loving it.
Want to know what to grow in your garden? Yes, even pearl millet.
Nice pics of Armenian landscapes, food and foodways. No pearl millet in sight.
The latest monthly newsletter from The Botanist in the Kitchen does seeds. Pearl millet unavailable for comment.
China is genotyping and phenotyping (almost) everything. Pearl millet feeling left out.
If pearl millet fails, there is always pastoralism. No, wait…