Científico en el Blog de trabajo: un paraíso para la diversidad vegetal

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Fredy GómezIn Las Orquídeas National Park in Colombia, it rains throughout the year and trails are difficult. Mud pools turn into deep trenches with the passage of time.

Paola Pedraza, assistant curator of the Institute of Systematic Botany at the New York Botanical Garden, writes about her recent expedition to catalog the flora of Las Orquídeas National Park, Colombia.

Julio BetancurThe park is named after its orchids, a prominent component of its flora.

Our destination is Las Orquídeas National Park, a protected area named after the many orchids that grow abundantly across the park’s great altitudinal range. The park is located in western Colombia, on the slopes of one of the three separate cordilleras (mountain ranges) of the northern Andes of South America. The park has a reputation as a paradise for plant diversity that can be traced back to 1848, when European collectors started traveling to this general region to extract prized orchids. Nevertheless, botanical exploration of the region has been stymied by its extreme isolation, rough terrain, torrential rains and, in more recent times, the violence caused by the armed conflict in Colombia.

Our goal is to document the plant diversity of Las Orquídeas National Park, and we are heading to Los Venados, a field station in the upper lowland Chocó forest that will be our home and laboratory. Our team of 11 people includes botanists, graduate students and park rangers; all of us are coming from different places and meeting in Urrao, a charming agriculturally oriented town. From here we will have to navigate bumpy dirt roads, but the comfort of vehicles ends very early in the trip, because for two weeks we will have to ride mules and walk. We are heading to a forested area with very rough terrain, so mules are preferred over horses as they are strong, withstand bad weather and have better footing on narrow and muddy passages.

Julio BetancurThe team of botanists, graduate students and park rangers spent two weeks riding mules and walking in the mountains and piedmont.

Urrao, in northwestern Colombia, is about 13 hours from Bogotá, the country’s capital, and it is the last town on the main paved road. After Urrao we won’t find supply stores or medical centers, so we need to bring with us everything we may need and more. From Urrao we travel to La Encarnación in four-wheel-drive vehicles, bringing with us the remainder of the cargo that the advance team a week earlier could not carry to the entrance of the park. La Encarnación, a very small village that was practically abandoned after a massacre two decades ago, is a couple of hours from Urrao. Though some buildings have not been reconstructed, bearing witness to the dark past, today the village is a lively place on the weekends as the Indians and farmers that live in and beyond the park pass through on their way to Urrao to buy supplies and trade.

This region is very rainy, and the larger truck gets stuck in the mud almost immediately. It turns out not to be a major problem, but I am concerned that it could be a sign of the bad roads and trails ahead of us. This will definitely be a challenging expedition.

Although it took a day to get to La Encarnación, it is from here that our long journey will really begin, on the back of skilled but stubborn mules. The field station Los Venados is two days from La Encarnación, and we will need to spend the night at the park’s entrance after six hours descending on mules through lush cloud forests. From there, it will be another five hours to the expedition’s main base. Calculating travel time on a scientific expedition is tricky business; we do not walk or ride mules as fast as locals do (we wish we could), and we are constantly distracted by every single bit of green before our eyes. Temptation in this national park is too great. We have come to collect plants in one of the most biologically diverse and threatened places in the world, and we could spend the entire day working in the same patch of forest without advancing more than a hundred meters. Thus, to reach the park’s entrance before nightfall, our strategy is to stay on the mules during the long descent.

After repacking the equipment in sacks made out of agave fibers and watching how skillfully the loads are tied to the mules waiting for us at La Encarnación, we are finally ready to go. We have a big convoy of 17 mules heading to Los Venados before midday — what a success! With all the people, equipment and hard terrain ahead of us, this is a logistically challenging expedition. Fortunately all the preparation is finally paying off, largely thanks to the collaboration of the staff of Las Orquídeas National Park.

Fredy GómezWe are a large team, and it would be dangerous to move in the forests after nightfall. We struggle to ignore the plants along the way.

The pace is slow because the mud pools are deep. Mules occasionally get stuck. The trails are sometimes carved into the mountain, turning into narrow trenches excavated by water and decades of transit. They can be more than six feet deep and only a couple of feet wide. In the narrowest passages, we have to pull our legs up sometimes or risk getting scratched or worse. For sure, the mules we are riding are saving us energy, but riding on these treacherous trails is not an easy job. We have to be constantly alert to duck under low branches hanging over the trail, be ready to awkwardly jump over fallen trees with the mules, and avoid slippery slopes. Moreover, mules can have strong personalities and act like, well, mules. Soon enough some of the animals realize we are not mule herders and make our lives more interesting by making their own decisions and ignoring our pleas to stop or turn. A few times I just decide to close my eyes and let my mule, Manzanilla, do her job. She probably knows what is safer; at least, I hope so.

As we are riding downhill most of the time, we have to keep hugging the mules with our legs and knees. By the time we reach the cabin at the park’s entrance we are eager to get off the animals and stretch our legs. At this point I do not think anybody is too thrilled about riding again tomorrow, but we are excited by the work ahead of us as we have seen many trees and shrubs in flower or fruit.

Fredy GómezPrimary forest in Las Orquídeas National Park, Colombia, home to a spectacularly diverse flora.

Colombia does not have a reputation as a paradise of biological diversity. But it is a country with a remarkable richness of species, considered the second-richest country in the world in plant species and orchids. And western Colombia, where we are, is regarded as one of the most exciting frontiers for botanical exploration in the New World tropics. Much of Colombia’s territory remains understudied and unexplored, and tomorrow we will experience firsthand the richness of the plants of the endangered Andean and Chocó forests.

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Científico en el Blog de trabajo: la leyenda de Zhayi Zhaga

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Amanda SchmidtLooking through prayer flags at Zhayi Zhaga at the highest spot on the kora (circumambulation). This spot is sacred to local people and has numerous prayer flags set up at the top.

Amanda Schmidt, an assistant professor of geology at Oberlin College, writes from Sichuan Province, China. She is studying the relative natural hazards of some places where people choose to live.

Saturday, Aug. 13

On Wednesday morning a group of us started a three-day trip circumambulating the local sacred mountain, Zhayi Zhaga. The kora (circumambulation) starts at Zharu Village, but we took advantage of the paved road to cut about 10 kilometers off the hike by driving to the end of the road. Driving up the road, I filled in my friend Kieran, who works for the park doing marketing to foreigners, on what we’ve learned during our month of fieldwork. The short drive was the perfect place to show him what we suspect are old lake deposits caused by a landslide dam.

After Xenna and I found river rocks in what looked like landslide deposits, we took our University of Washington colleague to see these strange rocks. It turned out to be a miserably wet day, so we showed him only one outcrop, and he pointed out that the rocks were rounded and thus unlikely to be landslide debris. Hmm. At the time our colleague suggested that maybe these were delta deposits or possibly glacial outwash (although we don’t know the extent of past glaciations in the park). Because of the danger of hammering pipes into somewhat unconsolidated debris piles that contain large boulders during a downpour, we didn’t take any samples that day; the cold temperatures sent us back to the office rather quickly in any case.

Amanda SchmidtLooking up from Guodu Village in Zharu Valley at the landslide scar that I suspect may be responsible for the upstream lake deposits.

With an eye out for lake deposits, I went back to get samples a few days later. I managed to take one optically stimulated luminescence (O.S.L.) sample at the suspected delta, as well as a few samples for grain size analysis. Farther down the valley was a spot that almost certainly is rock fall burying river deposits (no rounding in the rocks, rocks all are limestone, some crushed clasts are still all together in one place). I tried to get a sample for O.S.L. dating here, but when bits of the deposit started falling down around me, I decided that hammering a metal pipe into this rock pile might not be such a good idea. However, I did find some really cool places where there had been soft sediment deformation, probably from the rocks landing in marshy areas next to the river. This landslide deposit pretty much rules out the idea that the deposits farther upstream are glacial outwash.

My working theory, which I hope will be refined during some computer-based analysis and future field seasons, is that the mountain above Guodu Village failed massively (during an earthquake?) and dammed the river, forming a lake. Over time the river eroded out the debris, but we still see evidence of the lake in the landslide deposits as well as delta deposits coming out of the tributary valleys. The O.S.L. sample from the suspected delta deposit could give us information on when the landslide happened and the lake formed. This theory does not, however, explain the lakelike deposits that we see farther down the valley, or the strange flat spots that contain fluvial sediments more than 100 meters above the current valley bottom. Farther afield it seems that there may be lake deposits in the main valleys of the park as well as in the main valley outside the park.

Amanda SchmidtDeformed soft sediments. I suspect that it was some kind of a backwater channel along the river when a landslide (or rock fall) deposit deformed and buried it, preserving this pattern in the sediments. (Scale: About 5 inches wide.)

During our last office day, I told Kemo about these strange deposits. She told me that there was a legend in the area that Zhayi Zhaga and the other sacred mountain had a big battle and that one of the mountains drained the lake, filling Jiuzhaigou valley and forming the beautiful landscape of pools, smaller lakes and waterfalls that we now see. Although local people pass the story off as a legend, the connections to the geology made both of us excited for me to get financing to return and investigate the timing and extent of old lakes in the Jiuzhaigou area. Sorting out this story seems important for understanding the local landscape evolution.

Amanda SchmidtA view of Zharu Valley from our campsite the first night of the kora. Zhayi Zhaga is to the right, outside the image. In accordance with local tradition, we are walking counterclockwise around the mountain.

As we started our hike up Zharu Valley and around Zhayi Zhaga, I kept my eyes out for signs of old river deposits in strange places. We had a great trip and saw evidence of glaciers above 3,500 meters, but I didn’t see any more river- or lake-related deposits until two days and a successful kora later. The kora ends above Old Zharu Village, and as we were walking down through the woods Xenna and I noticed that we were walking among the first forested terraces we’d ever seen. Then something strange happened: The loess in the terraces wasn’t on top of crushed rock anymore — it was on top of very finely laminated clay-rich sediments. We didn’t see any river rocks, but this kind of lamination looked a lot like lake or backwater channel deposits. How did they get so high? What are they from? How old are they? Could there have been a really large dam that caused a deep lake in both Zharu and the main valleys and is older than the loess deposits?

Amanda SchmidtThese deposits look suspiciously like some kind of lake or backwater channel deposits, but they are several hundred meters above the current valley floor and underneath loess deposits in terraces. Where did they come from?

These questions and many others will have to wait until the next field season to be answered, as we are now sitting in the Jiuzhaigou airport waiting for our flight to Chengdu. We return to the United States on Tuesday after a few days in Chengdu, where, among other things, we will be mailing samples.

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Científico en el Blog de trabajo: caras y artefactos en Zharu viejo

Amanda SchmidtLooking hacia la aldea de Guodu y la cicatriz de deslizamiento gigante desde la pista hasta el Zharu viejo.

Amanda Schmidt, profesor de geología en Oberlin College, escribe desde la provincia de Sichuan, China. Estudia los peligros naturales relativos de algunos lugares donde la gente elige vivir.

Lunes, 8 de agosto

La jornada comenzó con una vigorosa caminata hasta el viejo Zharu, un conjunto de terrazas y una aldea abandonada por encima de la aldea de Zharu actual. Nos tomó cerca de una hora para llegar desde el pueblo nuevo a las terrazas del pueblo viejo, donde derrumbó en la sombra para recuperarse de la caminata. Nuestro plan para hoy fue simple: para ver si podíamos mapa de desplazamiento en las terrazas, obtener cosas hasta la fecha y obtener más muestras para análisis de tamaño de grano. Como fuimos básicamente en la parte superior de las terrazas, decidimos trabajar cuesta abajo a lo largo del día y en la aldea abandonada entre las antiguas casas.

Amanda SchmidtSomeone había divertido caras en el loess en este afloramiento de talla. Xenna y fueron un poco asustados por ellos pero luego disfrutó viendo cómo se hizo la talla.

Al principio que nos estábamos muy confundidos por la estratigrafía que estábamos viendo en las terrazas. Las primeras terrazas pocos no tenían en común casi depósitos: uno sería ser todo flujo depósitos y al día siguiente todos loes. Estábamos totalmente desconcertados por cómo no podríamos tener ningún flujo de loess justo debajo de una terraza con todo el flujo y no loes, pero cuando revuelto a una cornisa poco para intentar obtener una muestra de la luminiscencia ópticamente estimulada (O.S.L.) como más arriba de lo posible, hemos descubierto algunos flujo en la parte superior. Ufff. Más abajo en las terrazas fue un fabuloso paleosol que podemos utilizar para medir el desplazamiento entre dos terrazas (unos 12 metros, similares a lo que encontramos en Heye). Curiosamente, en una de las terrazas inferiores encontramos loess que parecía había fluyó un poco y se mezcla con bandas de roca triturada. Tal vez se había trasladado el loess como un bloque y el contacto con la base había mezclado un poco. Esto fue muy diferente de los otros lugares donde encontrar loes con rocas, como aquí el loess estaba intacta, sólo con pequeños focos de roca triturada.

Amanda SchmidtLooking de Old Zharu en todo el valle a la aldea de Pengbu y una vieja pista de aterrizaje. Aunque no son realmente el mismo valle, una falla se ejecuta a lo largo de una línea bastante recta conectar los pueblos. La parte inferior del Valle parece menos continua en tres ríos diferentes.

Aunque previamente hemos encontrado artefactos arqueológicos en el Valle de Heye (principalmente capas de carbón y huesos), Zharu nos sorprendió. En parte porque nadie ha excavado aquí, no esperaba encontrar muchos artefactos o signos de ocupación previa — algunos artefactos previamente habían encontrados sólo en terrazas inferiores. Pero en una fabulosa afloran donde nos muestra de caracoles (eran enormes!), carbón vegetal y tamaño de grano, Xenna la mitad de una perla encuentra en una capa de carbón unos dos metros por debajo de la superficie y un metro por encima del suelo. En otro lugar se encontró lo que parecía un viejo fogatas. Se trataba de un metro de espesor, enterrado por un medidor de flujo y de por lo menos un metro de loess.

Amanda SchmidtSome de las terrazas mayor de edad Zharu. Las plataformas son lugares donde las personas construcción terrazas para casas o para más espacio de jardín; las fogatas que encontramos es fuera del fotograma a la izquierda.

Las capas de carbón parecía casi laminadas en el loess y fueron intercaladas con loes. En algunos lugares hubo rojas capas claylike que a menudo son signos de uso de fuego anteriores. En otro sitio, cerca de donde se escondía un burro en la sombra, Xenna encontró un paleosol con carbón y gran número de huesos. Posiblemente fue un lugar donde la gente preparada animales. También encontramos unos cerámica sospechoso, pero no sabemos lo suficiente como para estar seguros de que no son piezas delgadas de arenisca. Ya que son diferentes de las rocas que normalmente vemos, nos agarró a compartir con los arqueólogos en Chengdu.

Muestreo de Amanda SchmidtXenna de carbón en el primer paleosol realmente claro que nos encontramos. El suelo más rojo fue probablemente la superficie lo suficiente para desarrollar un suelo. Muchos de los ricos de carbón han sido las capas que hemos encontrado este viaje en paleosols.

Nuestro trabajo aquí es liquidación: dejamos de Chengdu el sábado. Con nuestra gran colección de muestras, tuvimos la suerte de encontrar algunos expatriados de Chengdu que manejaba aquí y nos ayudará a llevar todo atrás. Pero será un dolor para llevar las muestras O.S.L. (en tubos de metal y no puede estar expuestos a la luz) en el avión. Aunque se siente como que no hemos estado aquí mucho, Xenna y yo somos bastante cansado y listo para un descanso; llevamos 15 días completos y cuatro medio día en el campo en los últimos 21 días. Nos hemos metido mucho hecho, pero me siento como que todavía estamos luchando para terminar el trabajo que tenemos que hacer. Es una buena cosa mi postdocs con el parque son de dos años y vengo puedo volver próximo verano.

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