The Hubbard Brook Ecosystem Study
word count (excluding references) 1492
The Hubbard Brook Study in New Hampshire takes place in a deciduous northern hardwood forest and is involved in important environmental research to improve the planet's ecosystem. There are inputs (light, precipitation, chemicals) and outputs (water and nutrients) used to discover how a fully integrated ecosystem functions. (Bormann and Likens 1979).There are long-term studies carried out, as short-term observations give false trends of data that is not realised at the time of study.
The Hubbard Brook Research Foundation (HBRF) generally aims to present an integrated view of ecosystem development in order to promote the understanding and caring for of forest and aquatic ecosystems. (Bormann and Likens 1979)
Objectives are specific statements of intention, which show either general or specific outcomes. These were to evaluate the effects of decreases in water overflow on several factors:
* The effect of photosynthesis on an ecosystem
* Study the effects of nitrogen leaching into streams.
* Measure the water stream level
5. Nutrient uptake by soil
Methods (Watershed approach)
Bormann and Likens (1979) carried out an experiment in the HBEF to calculate the response and recovery of a forested ecosystem to a disturbance. Disturbance includes conditions that lead to partial or total destruction of plant biomass, including the activities of chemical toxicity and physical destruction. Watershed 2 was subjected to clear cutting. All trees were felled in place, causing the minimal amount of disturbance. Herbicide was sprayed on this watershed for three years to inhibit any regrowth of the vegetation. An adjacent Watershed 4 was strip-cut three times, over a period of ten years. No herbicides were added "to discern differences in behaviour...and to study recovery mechanisms." This was related to stream chemistry, to measure the concentrations of different nutrients over time. In addition Watershed 5 was subjected to a whole-tree harvest but no herbicides were added. This was to test nutrient levels in the soil between watersheds 4 and 5. The two experiments were compared with an untouched watershed for forest managers to assess the long-term impact of differencing harvesting methods.
Water output was measured using weir gauging stations. Water was channelled at a precise angle over a v- shaped exit channel. As stream flow increases, the water height rises. The exact level was measured by a float inside an adjacent well. A pen on a chart provides a permanent record of the float position as it moves up and down to water flowing over the weir notch. The weir had to be securely cemented into bedrock, as all stream flow had to be measured. (Bormann and Likens 1979)
To assess carbon and nitrogen cycles in forested streams, Dissolved Organic Carbon was...