September 2011 Archives

Hi all!
I've been back at Grinnell for about a month now, and so far my semester's off to a great start! Very busy, but not busy enough to prevent me from finishing up my data analysis.

It looks like Echinacea purpurea's breeding system is similar to Echinacea angustifolia's. Styles that receive compatible pollen shrivel up within a few days, whereas styles that don't persist longer, often for more than a week. In addition, E. purpurea is self-incompatible. (This means that an individual plant can't pollinate itself, it needs pollen from another plant of the same species.)

To complicate things a little:
Not all of the flower heads I was studying had finished flowering by the time I left Minnesota, so I do not have much data on the top several rows of styles on many of them. Since styles in higher-up rows persist somewhat shorter than in lower rows, I cannot be sure that the trends I saw in my data hold for the top rows of all flower heads.
Also, some of the statistical tests I ran showed that style persistence in the self-pollination treatment differs significantly from the control treatment, while others do not. I'm not sure why that would be.

Here are my csv file and my analysis in R:

If anyone has any suggestions for improvement or other things I could look at with this data, please let me know!

And I posted much of my data analysis on H. helianthoides already, but here are the "final" versions. (But, again, I'm open to suggestions for further improvement!)

| No Comments

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.

| No Comments

After a good 3 months of sunshine and storms and flower-counting, it's time to head back to civilization and school. Here are my project status updates and associated files. The doc files (MWang_Dichanthelium.doc and MWang_Compatophen.doc) explain what the associated documents are. Some files (perhaps older versions) can be found on the shared drive.


Scanned datasheets that don't really have much information:
View image
View image
View image
View image


I will be continuing work on my projects in the fall.

| No Comments

Howdy folks! This week field work was delayed by a couple of wet spells, but thanks to reinforcements (thanks Ruth!), we conquered seedling refinds at Loeffler's Corner on Tuesday; East Riley and Riley on Thursday. Due to lack of time/manpower, we decided to scale back on seedling refinds (by focusing on searching circles that were reported to have at least 1 seedling). The frame maps made using R and the frame coordinates we recorded in June were really helpful.

Yesterday after lunch, the 4 of us (Stuart, Josh, Katherine and I) went out to Hegg Lake. I brought my bike out so I could pull in my Dichanthelium flags from my sites at Hegg Lake, and then I biked to C2 to join in the head harvest. I believe we harvested just over half the heads from C2. After that we headed back to Hjelm House and started harvesting in C1 until it was time to go.

This morning we went out to Staffanson in the truck. Stuart, Josh, and Katherine flagged plants for seedling refinds and harvested Echinacea heads as part of Amber Z's project. I did my final round of collection at Staffanson and then pulled in flags from the plot that was planted with seedlings in June. After lunch, we paired up and continued harvesting in C1. We filled up NINE grocery bags with Echinacea heads in just one afternoon! Uff da! That was really a heck of a harvest! Good job Team Echinacea!

| No Comments