20 Jan 2017
Today, we were accompanied by Felipe Velasco again, although this time instead of driving south toward Lake Tota we headed northeast toward the town of Mongua. We are extremely grateful for the time that Felipe has devoted to our efforts, as we would have had a difficult time finding these sites without him and it was reassuring to have a local person along. Our goal today was to explore and hopefully collect a core from Laguna Negra, a lake located in a different sort of paramo ecosystem. The drive was quite different than previous days, because we were able to see a much more industrial area of Boyaca. Between the cement factories and the steel mill, the pollution levels were quite high; in fact, much of the drive to Mongua smelled of a fragrant mixture of burning coal and diesel, and when we ascended the mountain above Mongua we observed a thick layer of smog in the valley. However, it was fascinating to see a fully functional steel mill, as gave me an appreciation of what Bethlehem Steel in Pennsylvania must have been like when it was operational. We observed many small family-owned coal mines along the road near Mongua, as this is the primary economic activity in this region.
Laguna Negra and the surrounding landscape was spectacular, and pictures really can’t convey the natural beauty of this place. While Jason and Jaime took measurements of the depth profile of the lake, I had the opportunity to hike around the lake margin. Unlike other lakes that we have visited, the lake margin was not peatland. Hypericum (St. John’s Wort) was common along the lake edge, along with a number of Carex species, and bright red Azolla grew in the littoral zone along with submerged aquatic plants like Myriophyllum. Inflow into the lake comes in the form of a spectacular waterfall, with abundant mosses and ferns growing adjacent to the waterfall in the perpetually humid environment.
The lake was about 9 meters deep with at least 3 meters of sediment, so we inflated a second boat, set our anchors, and commenced sediment coring. Mark Brenner and Felipe Velasco observed from shore, taking pictures of the coring process. We obtained several meters of mud, and once again we carefully kept the upper drive containing the mud-water interface upright on the trip back to Finca SanPedro.
On our way home we stopped in Mongua for some delicious empanadas and then went further down the road to Tópaga to take a look at the church on the main square. The Tópaga church is over 400 years old, and the inside is ornately decorated in gold. Colombia has abundant gold; in fact the yellow in the Colombian flag symbolizes the tremendous gold resources. This church in Tópaga is also probably one of the few churches that not only has artwork incorporating Jesus, the disciples, and other typical biblical representations, but also the devil. Yes, Lucifer himself is on a beam in the ceiling near the front of the church, directly center.
Our fieldwork is now complete. Tomorrow we will ship samples and cores from Sogamoso and then drive down to Bogota to pick up samples from our work in Manizales and prepare to depart on Sunday. This trip has been an amazing experience, and I feel extremely lucky to have had the opportunity to explore this fascinating country and see its amazing natural beauty. I am excited about this new collaboration, and the potential to develop long-term perspectives on water availability and ecology of the critically important paramo regions.
I sincerely thank Jaime Escobar for making this all happen. And I especially thank him for the doing all the driving!
15 Jan 2017
Today we visited the Tacurrumby – Laguna Negra Nature Reserve, which was located very close to the peatland we sampled yesterday. Felipe Vallejo of the Unversidad of Caldas accompanied us, and he was nice enough to secure permission for us to sample within the reserve. Felipe may also analyze diatoms (a group of algae with cell walls made of silica) in the surface samples that we are collecting, as just like testate amoebae they have been little studied in paramo ecosystems.
The painting on the trailhead sign at the nature reserve showed a ruddy duck (Oxyura jamaicensis), although from what I can find there is a fair amount of taxonomic uncertainty with species and subspecies identification (see wikipedia). There appears to be at least two subspecies, and some regard these as different species, the North American ruddy duck (O. jamaicensis jamaicensis) and the Andean ruddy duck (O. jamaicensis ferruginea). Other than differences in geographic distribution, the Andean ruddy has a completely black head whereas the North American ruddy white has a white face. Interestingly, the painting on the trailhead sign shows a white face, which seems to be consistent with the North American species. However, according to some there may also be a Colombian subspecies (O. jamaicensis andina) with some black coloration on the white face; however, these individuals may also just represent hybrids between the North American and Andean subspecies. And the painting on the sign doesn’t show any black coloration within the white face. Regardless, the Colombia population of ruddy ducks (O. jamaicensis ferruginea/andina) has declined over the past several decades, and according to the sign they are likely headed toward extinction here.
As we walked along the trail to the lake, we observed signs identifying some of the dominant plant and bird species, as well as highlighting the ecological value of the lake and associated wetland. The plant diversity was impressive, with large grass tussocks and many shrub species.
Upon reaching the lake we immediately spotted the bright blue bill of the flagship ruddy duck as advertised on the trailhead sign! However, unlike the painting the male duck’s head was completely black, consistent with the Andean ruddy duck, as one would expect here. Shortly thereafter we spotted a female Andean ruddy duck and a duckling! Add one more to the population size in Colombia.
After collecting surface samples, we drove up into the Nevado del Ruiz National Park to look for potential future research sites. After this excursion, we sampled another peatland located at a bit lower elevation than Laguna Negra. Over 70 samples collected so far!
General ecology (EES-152) students have finished resurveying a portion of the Lehigh Experimental Forest, with the goal of assessing changes in tree growth, mortality, and recruitment since 2013. A total of 690 trees were measured from across the forest, representing more than a 1/4 of all trees. In the three years since 2013, 70 of these 690 trees have died and only three new trees have established in the study area. Data for the dominant tree species are shown in the plot below.
We will use these data to discuss the processes controlling forest dynamics as the semester progresses. However, for now, students should answer the following questions:
- The dbh measurements were converted into estimates of area, assuming that each tree was a perfect circle in cross-section. Why do you think basal area was used to compare growth rates among the different species? Why was this expressed as the average change in basal area per tree? What factors might have caused the observed differences in radial growth among species?
- What does the pattern of mortality and recruitment suggest about the future of the Lehigh Experimental Forest? What factors might have caused the differences in mortality among species during these two years? What factors might be contributing to the lack of new tree recruitment in the forest?
- Assuming the rates of total tree recruitment and mortality are representative of future years, when will there be no trees left in this forest? In 2013, there were ~2000 trees in the forest. Show your work and describe how you arrived at your estimate. Do you think it is likely that the trees will really be gone by this time? Why or why not?
- Which species had both very high mortality and very low growth during this time period? Do some research on current threats to this particular species, and summarize your research in a short paragraph.
We have completed two weeks of wetland ecology at Pymatuning Lab of Ecology… only one more week to go. The Pymatuning wetlands spent the morning discussing freshwater marshes, swamps, and riparian wetlands. We examined vegetation dynamics, food web structure, and biogeochemistry of each of these wetland types, paying particular attention to similarities and differences. Our discussion of the vegetation dynamics of freshwater marshes highlighted the importance of seed banks, climate variability, and herbivores like muskrats (Ondatra zibethicus) in controlling interannual-to-multidecadal scale ecological changes in these systems. The topic turned out to be quite appropriate for today, given the results from our camera traps in the afternoon. We then went over the midterm exam, spending a considerable amount of time working through the details of how nitrogen cycling occurs in the context of the aerobic and anaerobic layers of wetlands. The students all promised that they would study the details of the nitrogen cycle, and other biogeochemical cycles in wetlands, if these will reappear on the final exam. I won’t disappoint.
We then went to Pymatuning Creek Marsh to collect the shallow wells that we installed last week to record water-level fluctuations within different vegetation zones. We also collected the camera traps. Clearly white-tailed deer occasionally use the marsh, but the students were particularly pleased that they captured video of a muskrat. There was clear evidence of them in the marsh, as there often is marsh environments; however, they tend to be active at night or around dusk so they are not often seen.
The video is embedded below.
And a raccoon….
Today was the midterm exam. The students looked a bit tired this morning. The first half of the exam was in the classroom and the second half was in the field. Word on the wetland street is that the first part was challenging, but the plant identifications were straightforward. As it should be.
We went to Geneva marsh this afternoon and began sampling macroinvertebrates as part of a comparative ecology project. We will sample marsh and shallow pond sites under open and closed canopies, and sites with and without fish. Two wetlands were sampled this afternoon, including Geneva marsh itself and a nearby pond. The students then spent the rest of the afternoon isolating the macroinvertebrates from their samples. One student in the class has been proclaiming that he really wants to see a walking-stick insect (because as he says, they don’t really want to be seen). I think he was pleasantly surprised that we did collect the “wetland-version” of this morphology today, a water-stick insect (family Nepitae).
Tomorrow we will sample another two sites and begin to identify and tally our collections.
The weather forecast called for severe thunderstorms, beginning around noon and lasting through the day, so the Pymatuning wetlanders went straight into the swamp this morning to complete their comparative vegetation project before the weather turned bad. The thunderstorms never materialized, and we successfully finished collecting the dataset before lunchtime. The swamp was quite botanically diverse, but we only added one species to the “must-know” list: royal fern (Osmuda regalis var. spectablis). I’ll bet you can’t say that scientific name three times fast.
We spent the rest of the day in the lab, observing and drawing plant adaptations to the wetland environment. Some of these students are quite artistically gifted. Aerenchyma tissue, submerged plants, anatomy of hydrophytic, mesophytic, and xerophytic leaves, carbohydrate-rich rhizomes, floating plants, and carnivorous plants. And of course, a close look at morphology and cell structure of Sphagnum moss (the “botanical beaver”).
Midterm exam on Wednesday! The second half of the test will take place in the field…25 plants…and there will not be a “wordbank.”
In the morning the Pymatuning wetland students continued learning about wetland hydrology, particularly how different wetland types are defined by differences in hydrology, including differences in hydroperiod, water source, and hydrodynamics. We also discussed how ecosystem processes like decomposition, primary production, and nutrient cycling are affected by differences in hydrology. Things then got a bit peaty, with a discussion of some of the unique features of peatland hydrology.
The students learned how to setup and launch data-logging pressure transducers, and suspended these in PVC surface wells in preparation for our fieldwork in the afternoon. We also setup four camera traps and brainstormed a bit about how we wanted to position them to assess differences in animal activity within a few microhabitats in a marsh. They clearly want to “capture” a muskrat (Ondatra zibethicus).
We spent most of the afternoon at Pymatuning Creek Marsh in Ohio. It was a sunny and warm day in the field, although the deer flies were particularly abundant and thirsty. We all donated a little energy to the ecosystem, but it was well worth it for the opportunity to add so many plants to our “must-know” list. The marsh was very dry this year, and walking through it was much easier than in years past; however, a few students did manage to find the holes in the muck. We installed wells in areas characterized by different vegetation, including an area with abundant spatterdock and standing water, and an area dominated by willow shrubs. The students also mounted camera traps in different microhabitats, and began their plant collections. We returned to the lab to press plants.
Tomorrow we will return to the marsh to collect quantitative data on the plant communities along a moisture gradient…