[Scpg] How your garden can weather climate change...

[LBUZZELL at aol.com]

How Your Garden and Yard Can Weather Our  Changing Climate
By Carol Deppe, Chelsea Green  Publishing
Posted on February 8, 2011
_http://www.alternet.org/story/149851/_ 
(http://www.alternet.org/story/149851/) 
Editor's Note: The following is an excerpt from Carol  Deppe's _The  
Resilient Gardener: Food Production and Self-Reliance in Uncertain  Times_ 
(http://www.chelseagreen.com/bookstore/item/the_resilient_gardener:paperback)  from 
Chelsea Green Publishing. 
My house has been much hotter in the summer in the last decade than it used 
 to be. Global warming? Probably not. The two huge Douglas fir trees south 
of the  house died and had to be cut down. The effect of that loss on the 
temperature of  the house in summer was immediate and dramatic. Local often 
trumps global. When  it comes to our home and yard, two big trees may matter 
more than global  warming. 
Global warming is happening, however. It's been happening since the glacial 
 maximum about 20,000 years ago, so it is nothing new. How fast it is 
happening  and how much is caused by people isn't the subject of this article. 
Nor will I  address the global aspect of global climate change. I will instead 
consider the  small and personal. What effect will climate change have on 
your yard and garden  next year and in the next few years and decades? Here's 
my synthesis, based upon  information from many sources. (See chapter 3 end 
notes and references  in _The  Resilient Gardener_ 
(http://www.chelseagreen.com/bookstore/item/the_resilient_gardener:paperback) .) 
That the overall trend for the planet for the last 20,000 years has been 
one  of warming is incontrovertible. However, climatic trends are full of  
irregularities and hiccups. Any period of a thousand years in which the overall 
 trend is in one direction has periods of years, decades, and sometimes 
even  centuries in which the climatic trend reverses temporarily. The Little 
Ice Age,  from about A.D. 1300 to 1850, is named for the seriously colder 
weather in North  Atlantic Europe and America. It was a period of several 
hundred years that was  part of the overall global warming trend that has been 
occurring since the last  ice age. 
Even if the globe is warmer on average in years to come, that doesn't mean  
your yard will be any warmer, even on average. Climate change causes 
changes and  irregularities in the patterns of ocean currents and winds. The local 
effects of  those changes are huge compared with the few degrees cited as 
likely increases  in average global climate in the next few decades. A change 
in wind patterns  that brings Arctic inland air masses to you instead of 
mild ocean air will  matter much more than a few degrees higher average global 
temperature. 
Even major trends are region specific, not globally uniform. And water may  
matter more than temperature. The Medieval Warm Period was lovely for 
Europe.  Famines and diseases were rare. Populations swelled. Civilization and 
cities  expanded and flourished. The same period was devastating for Mexico 
and the  American Southwest, which experienced horrific droughts--droughts 
that probably  contributed to the collapse of civilizations and the vanishing 
of entire  populations. In the Sahara, the Medieval "Warm" Period was cooler, 
not warmer,  and marked by more prolonged droughts. In many other parts of 
the world, the  main impact of the global warming of the Medieval Warm 
Period also seemed to be  droughts. Says Brian Fagan in The Great Warming, "with 
respect to  California, it's sobering to remember that the past seven 
hundred years were the  wettest since the Ice Age." Pointing to prolonged droughts 
that lasted decades  and even generations, Fagan says that, viewing the 
overall global situation, not  just that of Europe, "it is tempting to rename 
the Medieval Warm Period the  Medieval Drought Period." The American 
Northwest, California, the Southwest, the  inter-mountain West, and the lower Hudson 
River Valley are all vulnerable to  increased aridity and droughts. 
Finally, for agriculture, the regularity of weather patterns may matter 
much  more than averages or overall climate change trends. In spring of 1350, 
it  started raining in northern Europe and rained for the next several 
months. That  spring marked the beginning of five years of colder, wetter, 
stormier, more  erratic weather that was the obvious beginning of the Little Ice 
Age, which  lasted another 550 years. Most of the famines in northern Europe 
during the  Little ice Age were as much or more associated with erratic, 
rainier, stormier  weather than with temperatures. In the Year without a Summer 
in New England  (1816), the freezes were unremarkable, as New England 
freezes go. What mattered  was that they happened right through the entire summer. 
Long term tree-ring chronologies and other data indicate that the weather  
patterns of the last hundred years have been unusually stable. There has 
also  been an unusually low level of volcanic activity; volcanoes also affect 
weather  and climate. Our current gardening and farming patterns depend upon 
that  relatively stable climate and predictable weather. We have, 
effectively, been  growing "good-time" gardens and farms. We now need to expand our 
perspectives  and learn, or relearn, how to garden and farm in wilder times. 
Agricultural  humanity has adjusted to global climate change before, however, 
as, for example,  during the Little Ice Age. We can review and rejuvenate 
patterns that worked in  such periods in the past as well as extend them with 
modern information. 
In summary, we gardeners may or may not experience an increase in average  
temperature in our yards and gardens. What we are almost  certain to 
experience, however, is wilder, less predictable weather with many  more unusual 
seasons, unusual weather events, and more severe weather  extremes. 
Furthermore, we need to be as ready for cold as for heat, and  for droughts as well as 
deluges. 
Every act of planting is a gamble. In times of erratic weather, every act 
of  planting is a bigger gamble. I discuss how to minimize the gambles and 
hedge the  bets with respect to annual, biennial as well as perennial plants 
in detail  in _The  Resilient Gardener: Food Production and Self-Reliance in 
Uncertain  Times_ 
(http://www.chelseagreen.com/bookstore/item/the_resilient_gardener:paperback) . In this article I will limit my discussion to 
perennials,  specifically trees (and bushes). These are the plants where we lose the 
most if  we lose a gamble with the weather. 
What I have seen written about the implications of global warming for  
gardeners all suggests that we can now plant varieties that  are associated with 
climatic zones somewhat warmer than our own. These  writers assume that 
global warming of the planet by a fraction of a degree per  year actually means 
that our yards will be warmer. As I have explained, however,  global 
warming of the planet does not translate into greater warmth in your  yard. It is 
instead more likely to translate into more erratic weather with  greater 
extremes. But go ahead and experiment with annual plants, though. It's  always 
a good time to experiment with annual garden plants, I say, climate  change 
or not. 
When it comes to planting trees and bushes, however, I  suggest doing 
exactly the opposite from what is suggested by the words "global  warming." If 
you are zone 8, for example, plant trees suitable for zone 7  or less instead 
of expanding in the warmer direction and taking on plants  typical of zone 
9. Even if the average of the winter low temperatures is going  up in your 
back yard (which it might or might not be), that doesn't help if you  now 
experience more extreme lows occasionally. In order to avoid freezing out  your 
trees, you need every single year to have a lowest temperature that is  
permissive, not just some years. The average lowest temperature isn't really  
what matters. 
Nursery catalogs often list the specific degree of freeze tolerance for 
tree  varieties. Knowing that, in my own experience here in maritime Oregon, 
for  example, there have been at least a couple of winters in which the winter 
low  was about 0ºF, these days I would refrain from planting any tree with 
a freeze  tolerance of less than -10ºF. And I would prefer -20ºF. 
On the other hand, winter lows are not always the characteristic that 
limits  a perennial to a zone warmer than our own. Sometimes we plant or don't 
plant a  fruit tree variety based upon characteristics such as whether we 
usually have  enough summer heat for the fruit to ripen. In that case, we can 
better afford to  experiment. The gamble over whether there is enough heat to 
ripen the fruit any  particular summer risks only one crop, not the lives of 
the trees  themselves. 
So to make appropriate gambles with perennials, it's a good idea to know  
exactly why that more southerly variety you have been coveting isn't usually  
grown in your region. For varieties released in recent years or varieties  
commonly grown commercially, there is often excellent information on the  
Internet provided by the breeder or by your local land-grant university. You 
can  often find the exact degree of freeze-hardiness, the exact amount of 
summer heat  (degree days) needed, the length of growing season required, and 
many other  advantages and limitations, including diseases that may be the 
factor that  limits the geographic appropriateness for any particular variety. 
My own approach in the coming years will be to gamble  more with annuals 
but less with perennials than I did in the era of more regular  weather. There 
are some fruit tree varieties that have been favorites and  dependable 
producers in maritime Oregon for decades. I'm figuring these are the  place to 
start for main crop plantings, with the gambles limited in number, or  
limited to branches grafted onto varieties that are established dependable  
favorites. 
Altered weather patterns can translate into changes in  disease or pest 
patterns. Now would not be a great time to plant a  thousand-foot-long hedge of 
just one kind of bush or tree to be the visual  highlight of your driveway. 
I say this as someone who once lived in St. Paul  Minnesota on a street 
lined with stumps of elm trees. Dutch Elm disease had  destroyed them all. The 
city did not have the funds to replace all the street  trees at once. In the 
coming years, rejoice in biodiversity. 
Don't fertilize too much. It's better if your woody  plants don't grow as 
fast as possible. Overly fertilized plants make  bigger cells that make 
softer weaker wood than the wood of plants that grow more  slowly. This makes the 
plants into "good-time" plants that will be more  sensitive to freeze 
damage as well as more likely to break in wind and  storms. 
For many of us, more and longer droughts are likely to be  typical of the 
coming years. One of my basic rules is, "Don't water what  you can't eat." 
Let the grass be types that don't require watering in your  region. And if 
this means it goes brown in August, but then revives, let it. If  grass doesn't 
grow without irrigation in your region, grow something else that  does. 
Water needs are a matter of spacing. Pioneers grew fruit and nut trees  t
hroughout most of the East, Midwest, and maritime West, and they usually grew  
them without irrigation. Here in maritime Oregon, I know several people who 
have  "old-time" orchards, and they never irrigate except for newly planted 
 replacement saplings. This is in spite of our usually completely rainless  
summers. These trees have generous spacing, usually at least twice as much 
space  as modern recommendations for commercial irrigated orchards. I 
strongly  recommend planting trees with generous, traditional, pioneer-style 
spacing. Such  plantings will better withstand drought, loss of 
electricity/irrigation, or loss  of your labor (which is required to do the irrigating). 
Wider spaced trees are  more resilient trees. (You can water a newly planted 
tree the first couple of  years by just placing three or four 5-gallon buckets 
with pinholes in their  bottoms in the root zone of the plant and filling 
the buckets with water as  needed.) [Note: permaculture might disagree with 
this prescription if proper  swaling and water harvesting earthworks are in 
place.] 
If there are ornamental plantings that require irrigation that you simply  
cannot do without, consolidate them so that they can be watered with just 
one  swath of drip lines or one setting of a sprinkler. And remember that less 
 frequent deep watering promotes deeper stronger root systems than frequent 
 shallow watering for grass as well as other plants. 
Don't fertilize trees during a drought.  Fertilizing promotes branch 
growth, which increases the water needs. Likewise,  light pruning during a drought 
can be counterproductive. It, too, promotes  water-demanding growth. In a 
major drought when you are in danger of losing  trees, you might be able to 
rescue them by cutting them back dramatically,  however. Remove a third to a 
half of the biomass. This both removes lots of the  transpiring leaf surface 
as well as sets the trees back so dramatically that  their water needs go 
down. 
Among the various types of fruits, figs, apples, and  grapes need the least 
water. Apricots, plums, and pears need somewhat more  water. Then come 
cherries, peaches, and nectarines. Raspberries, strawberries,  blueberries, and 
domestic blackberries all need a lot of water. I have  never seen these 
latter four fruits grown successfully here in the maritime  Northwest without 
irrigation. On good, adequately deep soil, traditionally  spaced orchards with 
all the rest of these fruits can thrive here in the  maritime Northwest 
without irrigation. 
It is often said that standard trees are more able to scrounge their own  
water than dwarfs. However, I haven't seen any actual data on that, and 
suspect  that people are just guessing. Furthermore, I have seen many an 
unirrigated  dwarf that was doing just fine. Even a dwarf fruit tree has a bigger 
root system  than most perennial weeds and grasses, which can do fine 
unirrigated.  Furthermore, the dwarf also has a smaller mass of transpiring leaves, 
so less  water needs than a bigger tree. The balance between roots and 
leaves may be what  most matters. I suspect that the specific variety of the 
fruit tree probably  also matters, but have seen no data on that either. Plant 
what you want, I say.  But just plant a joyous diversity of types of trees 
and varieties, and give them  way more space than is currently usually 
recommended. 
Corvallis, Oregon plant breeder Carol Deppe has a Ph.D. in Biology from  
Harvard University and specializes in developing public domain crops for 
organic  growing conditions, sustainable agriculture, and human survival. She is 
author  of The Resilient Gardener: Food Production and Self-Reliance in 
Uncertain Times  and Breed Your Own Vegetable Varieties: The Gardener's and 
Farmer's Guide to  Plant Breeding and Seed Saving. Visit her website 
_www.caroldeppe.com_ (http://www.caroldeppe.com/) . 
 
 
 
 
 
----------------------------------------------------------------------------
-----------------------------------------------------------------


Thanks to George Vye for sharing this with us
_gmvye at me.com_ (mailto:gmvye at me.com) 

_http://dieoff.org/_ (http://dieoff.org/) 
_http://www.vhemt.org/_ (http://www.vhemt.org/) 


"Asking where we will find enough food to feed this growing population is  
like asking where we will we find enough fuel to feed this growing fire."
   ~ Source  unknown



=
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.permaculture-guilds.org/pipermail/southern-california-permaculture/attachments/20110216/62a0f88f/attachment.html>