flowering in 2011

Flowering of Echinacea angustifolia in almost all prairie remnants was down this year. Overall, approximately half as many plants flowered this year as last. Two areas distinctly bucked the trend: flowering was high at Hegg Lake WMA, which was burned this spring, and at our main experimental plot, which was burned this spring. Burning really encourages flowering!

We finished our first round of mapping all flowering plants in nearby remnants and a summary of the raw dataset is shown below. Each line lists the name of a site and the count of demo records and survey records at the site–also the difference in counts. We call our visits to remnants to find and refind plants “demography,” or demo for short. We call mapping the plants surveying because we used to use a survey station. Now we use a survey-grade RTK GPS (a Topcon GRS-1).

      site demo surv diff
1        x    1    0    1
2       aa  131  103   28
3      alf   79   52   27
4      btg    8    3    5
5       cg   20    5   15
6      dog    4    2    2
7     eelr   60   44   16
8      eri  153  122   31
9      eth    9    3    6
10      gc    7    1    6
11      kj   61   44   17
12    krus   69   21   48
13      lc    0    0    0
14     lce   58   45   13
15     lcw   48   31   17
16      lf    0    0    0
17     lfe   77  117  -40
18     lfw   65    0   65
19     lih    2    0    2
20    mapp    5    3    2
21    ness    7    3    4
22     ngc   28   12   16
23   nnwlf   20    7   13
24    nrrx   42   27   15
25    nwlf   27   10   17
26    on27   71   85  -14
27      ri  241  210   31
28     rlr    0    0    0
29    rndt   10    2    8
30     rrx   70   51   19
31   rrxdc    4    0    4
32     sap   80   38   42
33     sgc   10    4    6
34    sign    0    0    0
35     spp  126   78   48
36      th   19   12    7
37   tower   10    3    7
38 unknown    8    0    8
39     waa   10    6    4
40    wood   33   21   12
41     yoh   23    8   15

Notice that most sites have more demo records than survey records. This is because each data recorder enters an empty record at the beginning and end of demoing a site. Also, in certain circumstances we do demo on non-flowering plants.

Something strange is going on with the on27 site. I think someone may have entered the incorrect site name when doing demo. Also, lf looks strange, but is easily explained: lf is divided into two hills (lfe and lfw). We distinguished the two when doing demo, but not when surveying. Our next field activity is to verify the demo and survey dataset and make sure everything makes sense. Being people, we sometimes make mistakes in data entry. Because we know we make mistakes, we generate two separate datasets of flowering records (demo and surv) and compare them. When records don’t match, we go back and check.

We assess survival and reproduction of Echinacea plants in remnants to understand the population dynamics of these remnant populations. We want to know if the populations are growing, holding their own, or shrinking. To figure this out will take a few years because plants live a long time. Estimating a population’s growth trajectory based on just a couple of years of flowering records probably won’t be that informative.