Saturday July 31, 2010

We had two enormous storms during the previous week. The first came on Sunday July 18 which knocked out power for nearly three days. The second storm hit on Thursday July 22. Matthew Henson Park suffered some significant damage:





Some of the boulders, that were put in place to control erosion were displaced.



The morphology of the stream has been altered dramatically in several places. This area was once water, now it is dry land.



This was the same area three weeks ago:



Here is another area where the stream bed has changed. Notice the deposition in the middle:



Compared to two months ago:

How Effective are my Invasive Plant Removal Efforts?

Today, I began to evaluate the effectiveness of my project to restore Turkey Branch to a more natural state – without litter and invasive species. Since litter never stops, I decided to analyze the effectiveness of my invasive plant removal efforts. In order to do this, I selected 9 areas that I have weeded since May 2010. I measure a 3 feet by 3 feet square section with a tape measure.



I count all of the invasive plants [according to species] and remove [by pulling] them from the square. I then count the remaining native [and non-native non invasive plant species] which remain in the ground and checked my records to indicate when I weeded these areas:



The next step was to do the same measurements in an area that I have not cleared in the past. I took an 70 feet cross section of the stream, and sampled 3 feet by 3 feet squares, every 10 feet moving from the stream to the trail. I counted the invasive plants [and removed them] and counted the native plants which remained in the ground.

Before:



After:



Success in Removing Invasive Plants

Here are my data along with a calculation of the mean number of invasive plants per square yard:



Sadly, it is clear that some invasives, mostly notably Japanese Stilt Grass, return in areas that have previously been weeded. When these data are plotted graphically [invasive plants per square yard versus weeks since last weeded] a rather depressing observation emerges:



It is clear that, as time elapses after an area is first weeded, the invasive plants return. The next question: is the average number of invasive plants [per square yard] statically different for the areas that I previously weeded and the control areas which I did not weed? In other words, is the weeding of invasive plants an effective method to restore the natural ecosystem?

In order to test this, I will use the student t test:



Where:

X1 = the average number of invasive plants/square yard in areas I weeded

X2 = the average number of invasive plants/square yard in areas I have not weeded

s1 is that variance of weeded areas and s2 the variance of the untreated area and n1 and n2 are the number of samples.

Here are the calculations:



At the 90% confidence interval, with 14 degrees of freedom ((n1+n2) – 2) the table value is higher than -0.71 which indicates that the average number of invasive plants/ square yard are not different - statistically - in areas that were weeded than in the control area. A greater number of samples need to be taken because the variance is too high.

Success in Restoring Native Plants

Next, I did the same type of analysis for the native plants and found some encouraging results.



It appears that the number of native species in a sample area is directly related to how long ago the area was cleared of invasive plants. This can be seen graphically:



The Student t Test was also conducted to test whether the number of native plants/square yard are significantly different between areas that I weed and the control areas which I did not weed.

Here are the calculations:



There appears to be no statistically significant difference between the number of native plants per square yard between weeded and control areas.

More samples need to be taken over a longer period of time before I can make any conclusions. However, it appears that weeding invasive plants has some impact on controlling their future growth.

Saturday July 24, 2010

It is another 100 degree day! The stream level is the lowest that I have seen this year. Algae now covers the bedrock in the stream.



Here is a video of the Algae bloom:



As usual, I simply cannot be surprised at what people dump in the park!



I also checked on a possible invasive water plant:



I decided to work in the shade, so I selected an area full of Mile-a-Minute Vines and Japanese Stilt Grass.

Before:



After:



Native grasses are growing in areas that pulled [and re-pulled] Japanese Stilt Grass:



I spent this remainder of the afternoon picking up the usual cans and bottles along the stream.

Planting a Rain Garden in my front yard

My concern for my local stream is now extending [literally] to my own backyard – actually it is my front yard. During periods of intense rainfall, there is flooding and “sheet wash” runoff from our front yard into the street.

So I urged my father to plant a “Rain Garden”. The first step was something I just can’t get away from doing – removing invasive plant species. In this case, English Ivy.



We then dug a trench away from the downspout and filled it with pond stones.



We had to cut our hedges back because they were damaged during last winter’s heavy snows. I planted a number of native plant species in this garden, including Inland Sea Oats, Wild Indigo, Western Sunflowers, and Aromatic Asters.



The stone-filled trench was extended into the lawn and adjacent flower beds, which contain native Wild Lupines.

Saturday July 17, 1010

Today was another 100 degree day! I decided to do some work in the shade, near the stream where it was cooler. Today was dedicated to pulling Japanese Stilt Grass and Mile-a-Minute vines.

Before:



After:



The compost pile:



I find a lot of interesting things in Turkey Branch, but this is by far the most unusual:



There were a number of large Monarch butterflies:



I cleaned about a quarter of a mile of the stream around Grenoble Drive and Federal Street. Along with the usual trash, I found a 20 feet section of industrial tubing, a tire and an exhaust pipe from a truck!



The fish population of Turkey Branch appears to be increasing. I noticed many new hatchlings:



I also followed a deer down the trail:



We also ran into some friends from Friends of Rock Creek's Environment [FORCE].

Sunday July 11, 2010

Today is dedicated to the removal of Wine Berry bushes [Rubus phoenicolasius]. It is very important to remove these bushes before they produce berries. Once there are berries, the birds eat them and spread the seeds throughout the area. The drought has helped us this year. There are not as many berries on the bushes and the berries that are there are not well developed thanks to the lack of rain.

Notice the native Blackberry bush [Rubus fruticosus] in the foreground. This bush was discovered when I removed the invasive Wine Berries, hopefully, it will take over this area, displacing these invasives.



I found additional native Blackberry bushes in other areas that I cleared of Wine Berries. These bushes needed some water since the Wine Berries nearly overtook them in growth.



The earlier work, devoted to clearing Japanese Stilt Grass, has opened space for native wildflowers Yellow Crownbeard [Verbesina occidentalis]:



I also saw another deer today.



A Parks Police officer, who was on a motorcycle patrol of the Park, stopped and talked to me for a few minutes. He recognized my Weed Warrior hat and thanked me for the work that I was doing.

Friday July 9, 2010

It finally rained! Not much, but at least enough to keep the plants growing.

Here are some videos:







The water level is almost back to normal in the stream, and some trees have fallen into the stream since last week.



I checked on the area where I cleared a large area of Japanese Stilt Grass and Mugwort. I found a number of patches of native grasses which were growing: in the foreground Inland Sea Oats [Chasmanthium latifolium]and in the background Indian Grass [Sorghastrum nutans]. Both are growing well, but our old foe, the Japanese Stilt Grass, is attempting to make a comeback!

Thursday July 8, 2010

We are in the middle of a mini drought. Seasonal rainfall is about 5 inches below what we normally have. Therefore, I went to water the native species, which were drying out. Most of the plants were in good condition. Some have apparently been eaten.



I found a suspect:



The irony of this is that deer do not eat invasive plant species [with the exception of Mulit-Flora Roses], but love native plants!

The stream level is the lowest that I have ever seen, so I had to haul several gallons of water.



Here are two native species that are growing in an area that I cleared of invasive Stilt Grass. The popular native flower Wild Indigo [Baptisia australis] is growing nicely, next to another "native" that is not as popular!



The native species are doing well:

Monday July 5, 2010

This afternoon is very hot, over 100 degrees! I checked on the flora, and most are doing well:



Unfortunately, it appears that deer, or some other animal, are snacking on the native plants.



The native grasses [Sorghastrum nutans], have replaced the Stilt Grass, are growing nicely and are going to seed:



One of the first areas that I cleared is showing progress, Blackberry bushes [which are a little dry due to the lack of rain] are growing and Yellow Crownbeard [Verbesina occidentalis] is beginning to blossom in an area once over-run by invasives.



Most of today's work was removing dozens of Wine Berry bushes. It is important to do this now, before the birds eat the berries and spread the seeds.



Here are some Wine Berries and native Blackberrys in the foreground:



I finished that day with a cool walk in the stream in my new "leak-proof" boots. The stream level was very low due to the drought. I picked up about 30 pounds of trash, including a pair of boxer shorts. I noticed thousands of Darter hatchlings and many small Cray Fish.