Tuesday, May 28, 2013

Weather or Climate

I have been trained in science and engineering and thus the facts are the facts. Do we have global warming? Global, I cannot say, but locally we have some short term trends. The above is the bloom dates from the beginning of the year for early blooming Hemerocallis. I have 22 years worth of date and well, there may be a trend. But when you look at the data one is always asking what is going on. This graph is a composite of four species. Let us examine each.
H minor shows a downward sloping trend. Namely we are seeing earlier bloom times. Over 21 years we see from the regression a change from 147 days down to 135 days. That is a significant change. But what if we eliminate outliers? It would get worse. 2010 and 2012 were warm spring seasons and thus early blooms. They would drag everything down. So we just let the data speak for itself.
H dumortieri is a late bloomer, relatively. We see it going from 142 down to 137, only a five day decrease.

H middendorfii goes from 142 down to 131. That is a 9 day drop. It is generally one of the earliest. But look at the data, it is quite spread out.
H flava is of too little data. Not clear that we can say much.

But the question is; can we say that this is a trend or just normal variation? Trends would result in February blooms at some time which is doubtful. But it is interesting to always look at facts and species plants do tell us a great deal. The problem is the "noise" from any micro climate changes. For example the Hurricane got rid of many tall trees. Yet the flowers come out before any significant tree foliage. Thus perhaps we have a stable micro climate. Just a thought.