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CSEC Research Projects

 

Cloud Forest Soils of Costa Rica


As a part of our research on the effects of global climate change on sensitive ecosystems and environments, we are examining soils of the Costa Rican cloud forest soils. Cloud forests are wet mountain forests, mainly on the Pacific slopes of the Cordillera de Tilaran (in western Costa Rica), that receive much of their moisture from the soaking clouds that hug the slopes. In January 2007 and 2008, the Costa Rica class (BIO 128) visited the Santa Elena Forest Reserve in the Monteverde area and took soil cores from 1) old growth (primary) cloud forest, 2) 30-year-old secondary forest (an area that started reforestation in 1977), and 3) a ranch immediately outside of the forest reserve. 

One objective is to compare the organic carbon in the upper part of the soil profile from these sites to examine the effect on soil carbon storage of land clearing and reforestation. Another objective is to begin a program of monitoring the soils (thickness of the organic layer, and carbon and nitrogen content in the A and B horizons) that will last for at least ten years (and hopefully much longer), the goal being to identify changes in the soils as a result of gradual climate change.

Although soils in the primary forest exhibit the strongest horizonation of the three sites, they also consistently yield the highest carbon and nitrogen contents, 14.8% and 0.8% respectively, in the upper 25 cm. Secondary forest and pasture soils both display similar levels of both carbon, 9.6% and 10.2% respectively, and nitrogen, 0.6% and 0.7%. The pasture soils typically contain a well-defined coarse sandy layer 10 to 20 cm below the surface. We interpret this as a sediment layer deposited across much of the landscape following widespread erosion, likely a consequence of the deforestation. Our preliminary results suggest that reforestation is ineffective at returning soil carbon levels to pre-land use levels on a decadal time scale.

Costa Rica

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Soil Formation in Iceland


In the last century, recession of outlet glaciers of the Vatnajökull ice sheet has exposed glacial ground moraine and outwash deposits to pedogenesis (soil formation) and floral colonization. In Skaftafell National Park, the Skaftafellsjökull has retreated over 1000 m in the last 75 years, leaving a broad proglacial plain interrupted by recessional morainal ridges. Formation of very young soils on the glacially derived volcanic sediments (andic cryofluvents) involves the accumulation of organic carbon in the uppermost soil layer and minor root turbation.

Organic carbon content in this layer, as measured by combustion analysis using the LECO Truspec C/N analyzer in the Department of Biological Sciences, ranges from a high of >3% on older (60+ years), more heavily vegetated surfaces, to less than 0.5% on outwash surfaces less than 20 years old. The oldest land surfaces (more than 100 years) are almost completely vegetated, with mats of mosses up to 17 cm thick and birches averaging over 1 meter height. Surfaces less than 65 years old are at most 75% vegetated, with moss thickness averaging ~6 cm. Surfaces that are 25 years old or less are at most 30% covered, with wooly willow dominating the shrub layer. The floral cover on the youngest surfaces is 5% or less, with moss and shrubs mainly on sheltered slopes. 

 

The nearby Svinafellsjökull has a history of recession interrupted in the late twentieth century by episodes of surging, and consequently, a more complex periglacial topography. No clear correlation exists between land surface age and soil carbon content for this glacier, possibly, in part, due to the effects of continued livestock grazing in this area.

  This research was presented at the meeting of Northeastern section of the Geological Society of America in March 2007 and at Scholars Day, April, 2007, by Annie Walker and Jessica Curry.

This research continued in Summer 2008 with additional field work performed by the members of the BIO 126 class. These students collected new data measuring floral diversity as a function of surface age.

See video clips of the Le Moyne 2008 trip on YouTube! Click on the links below.

1) The group hiking in to the front of Skaftafellsjokull (Skaftafell Glacier) at Skaftafell National Park.

2) A visit to the Jokulsarlon (Glacier Lagoon).

Iceland

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