Grantville Gazette 37

favored sites were in the valley bottoms (LambCHMW 251).

Climate, Agriculture and Fishing

Jabe McDougal was not the only up-timer who has the Little Ice Age on his mind. One May, after the death of Mabel Jenkins in 1632 (Grid), Joe Jenkins grumbles that 'there's snow on the ground' and 'it's still here from February.' He is worried that it won't be gone in time to plant corn and tomato, and adds, 'If it weren't for the wheat, I could just up and starve with this here 'Little Ice Age.'' (Howard, 'Golden Corn-A Tale of Old Joe on the Mountain Top,' Grantville Gazette 9).

In the broader scheme of things, climate change can affect what crops can be raised in a particular part of the world. The ability of a plant to grow in a particular place is dependent on soil and climate.

Too much or too little heat, or too much or too little rain, can result in crop failure. Both droughts and floods can kill crops. Floods can be caused, not just by excessive rain, but by normal rain after a prolonged dry spell, as a result of which the soil has lost its normal ability to absorb water (Brooks 60).

If food cannot be rapidly and economically brought in from an unaffected area, crop failure leads to famine. Famine several years in a row can result in a major increase in illness, death or emigration, or in political unrest resulting in overthrow of the government or bloody suppression of a rebellion.

The down-timers in Thuringia are growing grain (primarily rye, barley, and spelt), vegetables, grasses for hay, and woad for dyeing. Of course, those are already adapted to the local climate. How will the plants that passed through the Ring of Fire, and are accustomed to the conditions of West Virginia in 2000, fare in LIA Germany?

There are complex plant-specific crop models available for predicting the combined, nonlinear effects of temperature and rainfall on plant development. These take into account changes in the sensitivity of the plant depending on its growth stage.

That's too complex for us, but we can look at what are called 'cardinal temperatures'-minimum (base), optimum, and maximum (ceiling). Even those have their subtleties, as the cardinal temperatures may differ for germination, vegetative growth, and reproductive yield (which for grains is the crop yield).

Generally speaking, cool season crops (oats, rye, wheat, barley) have a base of 0-5^oC, an optimum of 25-31^oC, and a ceiling of 31-37^oC, and hot season crops (melons, sorghum) have a base of 15-18^oC, an optimum of 31-37^oC and a ceiling of 44- 50^oC (Change, Climate and Agriculture 75).

Crop maturation is a cumulative process and crop scientists sometimes use the concept of growing degree days, awarding one GDD (^oF or ^oC) for each degree (^oF or ^oC) that the mean temperature on a particular day exceeds the base (some versions truncate if the temperature exceeds a ceiling). For example, wheat has a base of 40^oF; corn, 50^oF; and cotton, 60^oF. Insects also have GDDs; 50^oF for the European corn borer. (Fraise).

A decline in mean summer temperature has a double whammy. It reduces both the height and breadth (growing season length) of the GDD curve. In England, in the coldest years of the LIA (1695, 1725, 1740, 1816), summer temperatures were about 2^oC below the modern norm, and the growing season 'was probably shortened by two months or even more.' (LambCHMW 223).

The principal Indian crop in New England was maize, and there's reason to believe that the native strains required 2000 growing degree-days (GDDs), base 50^oF, to reach maturity. (The Indians also grew beans but these reached maturity more quickly.) In the 1960s, Connecticut, Rhode Island, Massachusetts, the Connecticut River Valley (NH-VT border), southeast New Hampshire and southwest Maine all were receiving at least 2000 GDDs (the area around Boston typically received over 2500 GDDs). A 2^oF reduction in mean July and mean annual temperatures would put all of New Hampshire, Vermont and Maine, as well as northwest Massachusetts, under the 2000 GDD mark (Demeritt).

Grantville is based on Mannington, located in Marion County, WV. According to the 1997 Census of Agriculture, Marion County had only one farm growing wheat and oats for grain. It had 251 farms producing hay (primarily from alfalfa). You can figure that alfalfa would be cut at 750 GDD, base 41^oF, to yield a fiber content 40% neutral detergent fiber. For 45% NDF, you would allow another 220 GDD (Pennington).

While there is no commercial production of corn in Mannington, canon says that there was a small quantity of seed corn available in Grantville as of the RoF (Weber, 'In the Navy', Ring of Fire 1). There are also sunflower seeds, see Vance, 'Second Chance Bird, Episode Two,' Grantville Gazette 33. Sunflowers have a base of 44^oF and require a GDD of something like 2300. (Putnam).

We can compare these temperatures to those that are reconstructed for the places and times of interest.

Bear in mind that temperatures below the base temperature might not just stop growth, they might kill the plant altogether. Flowers and young fruits of fruit trees are often killed by mild frosts (0-5^oC) (Hatfield).

The USDA defines plant hardiness zones based on the extreme cold (expressed as the average minimum annual temperature) that a particular plant can tolerate. Zone 1 is -60^oF to -50^oF, zone 2 -50 to -40, and so on up to zone 11, 40 to 50. Each zone may be further subdivided into two subzones, 'a' and 'b,' with 'a' as the colder half. (Zones 0 and 12 are special cases; 0a is under -65^oF, 0b is -65 to -60, 12a is 50-55 and 12b is over 55.)

Plants vary in terms of what kind of climate they like. For example, the orange tree (Citrus sinensis) is considered hardy in zones 9a-11a, whereas the Scots pine (Pinus sylvestrus) grows in zones 1-4.

In 1990, the USDA prepared a map of North America depicting which areas are in which hardiness zones, based on their average annual lows (over the period 1974-86). This of course changes as the climate changes; in 2006, the Arbor Day Foundation updated the U.S. hardiness zones to reflect the most recent 15 years of data and perhaps half the U.S. (excepting California and Nevada) experienced a one zone (10^oF) increase.

The logic behind the hardiness zone definition is that even a brief exposure to a cold enough temperature will kill the plant. However, it ignores the fact that a plant may withstand a short exposure to say -5^oC yet be killed if there are too many days at 0^oC.

Also, it ignores the effects of day length, summer heat, wind, and the amount and distribution of rainfall, which in turn are influenced by latitude, elevation, continental position, and mountain barriers. The American Horticultural Society has a Plant Heat Zone map; the zones are based on the average number of days per year above 30^oC, thus accounting for summer heat. There are other zoning systems, that take additional factors into account, but we can't use them in LIA Europe because we lack some of the necessary data.

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Besides the direct effects of climate on plant growth, there are also indirect effects. Plant pests are also affected by temperature; a warm winter may mean a bumper crop of insects in the spring. In late 17^th-century Switzerland, cool springs led to crop losses as a result of attacks of the parasite Fusarium nivale, which is active under snow cover (LambCHMW 206).

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Domestic animals are also affected by climate. Animals can be killed by climate extremes, especially the combination of heat and drought. Even conditions that don't kill can reduce reproduction, growth rate, and milk production.

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Considering domesticated plants and animals together, both temperature and precipitation can have significant adverse effects. The so-called LIA-type impacts are:

March, April: cold decreases forage for dairy animals and the volume of the grain harvest.

July, August: rain interferes with the harvesting of crops.

September, October: cold forces animals into the barn earlier and reduces the sugar content of vine-must; prolonged rain reduces area sown and nitrogen content of the soil (thus affecting the following year's productivity).

Pfister2006 has combined temperature and precipitation monthly data to arrive at a 'biophysical climate impact factor.'

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