Write a response to this students short essay. What did you think of the topic? What do you have to ad to the topic? Use at least one source.
This week I chose riparian ecosystems as my ecological function topic.
In the western states, riparian ecosystems are narrow ecotones between aquatic and terrestrial ecosystems (Goodwin, Hawkins & Kershner, 1997). They consist of several fluvial surfaces including channel islands and bars, channel banks, flood plains and lower terraces as depicted in the top figure below. This reference also includes zone areas that are directly influenced by frequent flooding (zone I) and adjacent areas to rivers that were formed by past fluvial action but are generally not currently influenced by fluvial process (zone II). These two zones together constitute the valley floor. Zone I is moist, lower more frequently flooded surfaces. Zone II is on an inactive floodplain and are higher and drier and less subject to flooding.Zones
Areas in Zone I are closely linked to stream ecosystems and the two ecosystems exchange energy and matter (Goodwin, Hawkins & Kershner, 1997). This energy and matter exchange in zone II mostly unidirectional with zone II providing material and affecting energy inputs to both zone I and the stream ecosystem. The shallow depth of the ground water in zone II allows domination by phreatophic species in which they could not survive in dryer upland areas.
Understanding the processes that created the riparian ecosystem is crucial to planning successful restoration projects (Goodwin, Hawkins & Kershner, 1997). In addition, by understanding how to restore specific riparian systems requires that we recognize the specific disturbance that affected the system.
Dams, reservoirs and diversions are modifications to streams flows and have significantly affected riparian ecosystems (Goodwin, Hawkins & Kershner, 1997). There are some solutions that counter the effects of these implementations. Hill (1991) suggests riparian maintenance flows similar to channel maintenance flows. Others suggest further research in order to quantify the necessary flow regimes for critical species (Auble et al. 1994, Rood & Mahony, 1990). It may seem complex to some but some restoration projects may use Global Satellite Positioning (GPS) guided earth moving equipment (Clewell & Aronson, 2013, p. 169). Monitoring and evaluating the project outcomes can inform future ecologists restoration practice on the effects of the restoration methods used (Clewell & Aronson, 2013, p. 181). Providing proof that a project was completed and demonstrations of accountability is important to financiers.
The greatest challenge to making true progress in riparian ecosystem restoration lies in understanding the underlying physical and ecological process of the riparian zone and the interactions and feedback surrounding these processes (Goodwin, Hawkins & Kershner, 1997).
In addition to understanding the hydrogeomorphic framework and recognizing the potential physical and biological processes on the restoration sight, a project manager must thoroughly understand the anthropogenic disturbance that created the degradation (Goodwin, Hawkins & Kershner, 1997). There are three specific questions that must be addressed that will help guide the restoration activities: Is the disturbance local to the riparian area or does it originate outside the area in the adjacent upland or watershed? Is the disturbance ongoing – can it be eliminated if so? Will recovery occur naturally if the disturbance is removed?
Riparian restoration requires a priori specification of a set of physical and ecological conditions to be established on site (Goodwin, Hawkins & Kershner, 1997). These conditions must be naturally sustainable given water, sediment and energy fluxes. If the conditions cannot be naturally sustained the restoration project will fail to meet original goals.
Goodwin, C. N., Hawkins, C. P., & Kershner, J. L. (1997). Riparian restoration in the western United States: overview and perspective. Restoration Ecology, 5(4S), 4-14.
Clewell, A.F., & Aronson, J. (2013). Ecological restoration: Principles, values, and structure of an emerging profession (2nd ed.). Washington, D.C.: Island Press.
Hill, M. T., Platts, W. S., & Beschta, R. L. (1991). Ecological and geomorphological concepts for instream and out-of-channel flow requirements. Rivers, 2(3), 198-210.
Auble, G. T., Friedman, J. M., & Scott, M. L. (1994). Relating riparian vegetation to present and future streamflows. Ecological applications, 4(3), 544-554.
Rood, S. B., & Mahoney, J. M. (1990). Collapse of riparian poplar forests downstream from dams in western prairies: probable causes and prospects for mitigation. Environmental Management, 14(4), 451-464.
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