So it's been a while since I last posted, of course that doesn't mean that ecological restoration along the Bronx River is stalled. Quite the contrary, we have been so busy at the Natural Resources Group cramming in last minute field work that I've been falling asleep at my computer each night!
The muddy river water post-hurricane Irene
While the highly anticipated hurricane Irene turned out to be a bust for most of the city, the weather did take it's toll on the river and it's banks. The river was so flooded that we had to postpone fieldwork in the weeks following lest we decide to don snorkel and swimsuit to get to out plots!
Tree practically underwater from elevated water levels
Once the water finally receded we were eager to get out into the forest and see what remained of our plots along the bank of the river. In spots where the japanese knotweed once dwarfed my 5'8" frame we found a mess of knotweed knocked over by the elevated water levels and buried beneath inches of sediment and sand.
Knotweed buried beneath sediment from upstream in the aftermath of the hurricane.
While this compacted mess of knotweed, sediment and sand made our plot monitoring difficult we dutifully laid down out 2 meter x 2 meter plots and got down to work.
Plot monitoring along the river
Our study was extensive, within each plot we identified all vascular plants and estimated their percent cover (how much physical space in the plot each species occupies). We then measured average knotweed height, density (how many stems per plot) and cover. Our study also included data on the health and growth of each tree within the plot. Remember when I first told you about our plots? If you recall we decided to plant a pin oak (Quercus palustris) in the center of each plot. This was to determine if re-vegetation with native tree species could impact knotweed along the bank and to see how each of the control methods (cutting and grubbing) would impact the tree health. Shockingly most of the pin oaks were still alive, even inspite of being half knocked over, shaded out and taken over by the knotweed, definitely a promising sign.
Measuring tree trunk diameter with calipers; the range in tree growth from plot to plot was surprising!
After a full day and 60 plots we finally wrapped up our field work and plopped out tired bodies into the seats of our trusty truck. Plot monitoring is hard work but it sure helps when the forest is your office!
Our beautiful Bronx Forest, looking as good as ever!
