Arquivos de periódicos de abril 2020

19 de abril de 2020

April 2020 Status Report on Riparian Restoration and Alien Species Management - A Year's Effort Reviewed

The following message was sent to my list of local volunteers and allies here in Johnson City. This summary is a description of our year's efforts working on eradicating alien plant species from LBJ National Historical Park wetlands and adjacent areas on Town Creek, the major waterway that winds through downtown Johnson City, boyhood home of Lyndon Johnson, 36th President of the United States. iNaturalist member Clff Tyliick(@baldeagle ) was instrumental in demonstrating techniques of girdling we used in our eradication efforts. National Park staff, community volunteers, Pedernales Electric personnel, and many others contributed to making this past year's efforts important and successful. Especially important was the leadership and support given the project by the park's administration and specifically Superintendent Susanne MacDonald and her staff.

Hi everyone

Thanks to the Novel Corona Virus sweeping the world, we will not be meeting this month at the Settlement to conduct our voluntary efforts to eliminate non-native alien invasive species at LBJ NHP Settlement. Of course, you already know that and didn’t expect to hear from me, did you;-) Well, in the absence of physically working on the Settlement riparian areas this month - and next month, more than likely, our idleness offers an opportunity to summarize what we’ve done this past year and see where we stand in our efforts. With this message, I think you’ll get a good idea of what we’ve accomplished and where/how we need to redouble our efforts. Now the funny thing about this message is that when I was finishing photo taking to document our work on the riparian habitat, I thought I was going to tout a total success for our efforts. I had taken time to watch the Ligustrum and Chinese Tallow to make sure they were not sprouting and showing new growth thus far in the spring growing season. And things were looking really good this month and I was about to write an all encompassing declaration of victory. This week things changed and not for the better, although we will have accomplishments to appreciate, but facts are facts. Some of the trees - too many, really, are showing signs of survival. That’s the bad news. The good news is we know what we did wrong and can now correct our methods on these trees to make sure they do not survive. This means we now have a much better appraisal of our actives and impact on our targeted alien invasive species. In spite of our setbacks, we can now declare that we have expertise in riparian habitat restoration that few can match and while our setbacks are important, they are by no means a rejection of our methods, just our execution of those;-) And, before I forget, we have a surprise ending to our story you’ll find at the end of this message.

We focused on three species of alien invasive plants during our year’s work at the Settlement: Chinese Tallow, Japanese Honeysuckle, and Ligustrum species. We found these species growing heavily in the wetland area west of the bridge on the Settlement, an area increasingly populating with Bald Cypress trees and our native Dogwoods and Possumhaw, and at the pond near the Event Center and along the fence on the south side of the Settlement Trail to the bridge and beyond. Along Town Creek, Glossy Privet (Ligustrum lucid), with a good peppering of Chinese Tallow (Triadica sebifera) and Japanese Honeysuckle (Lonicera japonica) were taking over the banks of Town Creek.

Over the project’s history, we decided to experiment with techniques and see which were effective in eliminating our targets and which were not. It was decided by the National Park not to use either power tools or toxic chemical pesticides. Basically the techniques were these: uprooting (thanks to the National Park’s supply of heavy duty brush puller tools ), girdling - which involved eliminating the tree’s living tissue between the bark covering the tree and the hardwood center, the non-living center of a tree - and cutting down entire trees and covering the stumps with appropriate sized cans nailed onto the stumps left behind. The purpose of covering the stumps is to inhibit regrowth at the bottom of the tree by eliminating light to sections of the tree capable of using photosynthesis to remain alive. Let me describe each species separately remembering all the techniques we applied to our target trees. And over time I took photographs of our treated subjects and can show the impacts our efforts have had over time. These photographs have been used to create observations of our alien species on iNaturalist where I will tie together the identifications and photographs into a history of our project which by using this message become the basis of a journal entry on my iNaturalist page. The journal article will be linked to the observations which will allow anyone using iNaturalist in the world to trace our progress. Worthy of note is we also applied these methods downstream of the Settlement in Johnson City. Just so you won’t think all the work was on the National Park grounds;-) Here’s a breakdown of the three species and the results of our work:

Chinese Tallow - iNaturalist ID numbers

Over the months since last March we have been uprooting (best method of control), girdling, and cutting and canning stumps. Each of the methods we used has advantages and drawbacks, some more obvious than others. We felt, based on early observations of girdling cause by Buck White - tailed Deer, that girdling Chinese Tallows in a single long girdle (two feet long) that extended to the roots of the tree might be the most effective way to kill this species as I had seen that happen on the Settlement. Over time, we stopped stripping bark to the ground level and just produced a girdle about a foot in width around the circumference of the tree at about waist level or so. You can easily see the various girdles we applied to these trees.

The results of our girdling showed a great deal of promise early on. Some of the trees showed early signs of stress loosing their leaves and actually dying from the girdling. Other trees showed stress but retained their leaves above the girdle. We ascribed several reasons for this including a surplus of energy stored above the girdle. Knowing the tissue that carries the energy to the leaves underlies the bark, we made sure this tissue was stripped off the trees in the girdled sections. Ultimately, we had a mixed bag, but in most of the girdled trees, adventive shoots nearly always sprouted at the base of the trees. From prior experience, I knew these shoots would grow until they replaced the tree that expired due to girdling.

Seeing these developments compelled us to add another arrow to our quiver of tools to use on these trees, a method I call cut and can. I sawed down some of the girdled trees and covered the stumps with tin cans of various sizes that would completely shade the remains of the tree. The purpose of this is to deny the tree’s ability to send shoots off the base of the tree that will keep the tree alive. From the photos I provided for my iNaturalist observations, you can see the results of this ‘cutting and canning’ method. This use of shade to control invasive species is one that may not be used often enough by groups seeking to eradicate non-native species. While thus far we don’t see sprouts growing out of the bottoms of these stumps, it’s early in the growing season so time will tell.

Ligustrum species - iNaturalist observations:

We have at least two species of Ligustrum (Privet) growing along the banks of Town Creek in Johnson City; Chinese Privet and Glossy Privet. For all these species, we applied the same methods of control; girdling, uprooting and cutting and canning. The most effective method of control is uprooting. Many many Ligustrum were removed by this method, even fairly large specimen which involved the efforts of several people due to their size. Once Ligustrum obtain about a three inch diameter, we were no longer able to use the uprooter or exert enough force between several volunteers to successfully pull up the offender. Of course I cannot show the results of removal in a photograph because the bush or tree is no longer living and that is what I can call successful. The numbers of saplings and young Ligustrum that were also removed by hand - thanks to the moist wet soil we had as a result of fall/winter rains made the task seem almost fun. For those who worked on the saplings along the Settlement trail between the bridge and the wet land midway to the Event Center, the impact on those alien plants was obvious and the results impressive. This is perhaps one of our major victories and means many many fewer individual Ligustrum taking over the backsides of our creek system at LBJ NHP and downstream. Again it’s important to realize work was carried out downstream this past year as well. In all cases, there is still work to do.

The girdling method we used was based diretly upon instructions from Cliff Tyllick who, as I’ve mentioned often in these messages, heads up the Walnut Creek volunteers in Austin. Cliff was kind enough to travel to Johnson City and instruct me on his technique. When executed accurately, the girdling method yields real positive results as some of the photos at the Settlement show. A very good example of the effects of correct technique of girdling on Ligustrum is this one as posted above:

Japanese Honeysuckle

The Settlement and Town Creek downstream have numerous examples of the Japanese Honeysuckle vine growing on native trees along the banks of our streams. Japanese Honeysuckle not only competes with our native Honeysuckle species that produces a beautiful coral read flower, but also damages native trees that occupy the same habitat along the creek. The following iNaturalist observation shows this damage clearly and cheats us of our own more beautiful species. Notice this is growing in the middle of winter.

The only technique we used in an attempt to control this invasive species was uprooting. While the vine itself reproduces with root shoots called nodal rooting and from rhizomes, but also, of course, it’s beautiful odoriferous flower result in the production of berries containing seeds. These are eaten by birds and animals and distribute the plant widely. If you have Japanese Honeysuckle growing in your yard, consider finding a replacement plant and have yours pulled up by the roots, the most effective method of control.

So this is the summary of our work at the Settlement in the last year. We have made a huge impact on the invasive species on the creek and its adjacent wetlands. We have also worked downstream and continued our efforts at removing these invasive species resulting in a more beautiful natural Town Creek that is slowly becoming a local focus of interest for nature lovers and visitors alike. I know that because I met a person lately who told me that for years she’s been traveling through Johnson City and has kept her attention on Town Creek overtime she drives through town on her way from Austin to points west. Her testimony told me that means others would have similar points of view and that makes Town Creek a sort of unsung hero for travelers to the Hill Country. This year’s activities have gone a long way to enhance the asset that Town Creek is and of course, apropos such a status, we ended the effort with a great discovery when I stumbled upon an animal trackway that I was not expecting.

What am I talking about? What’s so great about animal tracks in the mud you say? Nothing unless other facts are taken into consideration. On one of my volunteer days I was wearing my waders and was girdling and cutting trees and shrubs as usual. The creek was running clear and cold from the winter’s rains and temperatures that clear the water because the bacterial and algal load of the creek diminishes seasonally. In the clear water, near the far side of the bank I was working I spotted a hole in the bottom I had seen before. I was thinking the hole was man made. About the size of a horse hoof print, it seemed like a post hole. So I waded the creek over to it, discovered another nearby and looked downstream now realizing there was a veritable trail of these holes. And they matched each other perfectly and proceeded down the bottom of the creek in single file. There were others too, and appear in echelon, some larger than others. The amazing realization came to me that the were Dinosaur footprints. Not only that, but they were recognizable because they were stamped into the stone for about forty feet of creek - or more. But they disappear under the mud of the bank of Town Creek.

I notified the proper owners of the tracks and showed the discovery off. After I got home I emailed a paleontologist friend of mine and sent him photos and got a reply that suggested the probability that the tracks were Sauropod tracks. That is exciting but what really excited me was the fact that the most perfect tracks which I photographed - see below - were of a baby Sauropod. Baby about the size of a grown horse!

Now I think there are larger prints in the bottom of the creek, but the water was too deep for me to wade and due to the dark bottom, it was hard to be sure. More than likely there were other individuals with the baby and their prints would be visible if they were not under the stream bank or further downstream and covered with rocks, gravel and sand. At any rate, there will be further investigations when the time is right, the Corvid-19 is not so great a threat and the level of the creek’s water level and clarity make it easy to see the trackway. If one were to visit the exact spot on the creek today, you wouldn’t see anything because the algae and murkiness of the creek water precludes an ability to see the prints at all. Below are photos I took at the time showing the trackway and baby Sauropod prints. Of course, all this is incumbent upon a clear identification and certification that these tracks indeed, belong to a Sauropod and not some other Dinosaur order.

What a way to end a year of work on Town Creek here in Johnson City. Once the Corvid-19 threat to our area is ended we can look forward to further work on Town Creek. What we might accomplish and discover can only be imagined. What other surprises lay in wait for us can only be imagined.



Posted on 19 de abril de 2020, 02:43 PM by billarbon billarbon | 12 observações | 0 comentários | Deixar um comentário