SOSTPRO
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SOSTPRO - SOurce STream (headwater) PROtection from forest practices: what are the costs and benefits, and how best to do it? |
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Coordinator: Professor Dr. John S. Richardson |
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Projects Partner and Institution: |
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Key words: ecosystems, forestry, models, riparian, streams, water quality |
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Abstract: Source streams, i.e. the smallest of permanent streams on the landscape, are the most vulnerable to land use impacts, and yet also typically receive the least protection from development. In a forestry context, there are typically riparian reserves left along larger streams in an attempt to protect them from forest harvesting impacts, but the damage to stream networks usually occurs in source streams and then is transmitted downstream. Source streams are subject to summer heating, increased light, sediment inflows, higher nutrients, higher peak flows, and lower organic matter inputs as a result of the minimal amount of protection. We used two regions in each of three countries to document practices along source streams, and then the consequences for functional and structural aspects that are related to water quality and quantity for humans and aquatic ecosystems locally and downstream.
MAIN RESULTS TO DATE Large scale (up to 100 streams in each country) rapid assessment surveys (RAS) for source streams revealed that the implementation of buffers varies widely between the three countries based on jurisdiction-specific management regulations (Kuglerová et al. 2020a). Overall, fewer of the streams sampled in Canada had any riparian buffers at all compared to Sweden or Finland. On the other hand, the average width of the buffers that were present in Canada and Finland was much larger compared to Sweden. Similarly, the presence of harvest-related impacts, such as ditching operations, siltation, erosion and tree planting reflects the harvesting practices unique to each country. In all three countries, only a weak relationship between buffer width and catchment areas was detected, indicating that stream size does not drive buffer retention around the source streams. The results of the RAS survey further showed that buffers are important for maintaining key functional characteristics such as riparian shade but are not consistently related to wood recruitment into the channels. We explored the mechanistic effect of shading conditions and other habitat features through the intensive sampling dataset, below. Detailed studies of 23 to 24 sites per country were carried out to measure structural and functional aspects of streams in relation to the degree of protection from forest harvest. We contrasted streams with mature second-growth forest (reference), harvesting to the bank, and those with buffers of some width. We found in general that harvesting to the bank resulted in elevated temperatures, greater algal growth, higher sediment loads, faster decomposition of leaf litter, and lower biodiversity. The sites with buffers were typically intermediate between reference and clearcuts for most measures, showing buffers can help (but still allows degradation). We also found a large amount of variation, indicating the site-specific nature of some of these responses. Experimental studies in stream mesocosms showed strong responses by ecosystem processes (primary production, microbial respiration, bacterial production) and stream biofilm quality (fatty acid composition) to land-use induced water brownification and riparian shading. Also, bacterial community composition was altered as a response to increased concentrations of dissolved organic carbon in the stream water.
EXPECTED FINAL RESULTS The implementation of riparian buffers along source streams is more random than systematic. No overall variable can explain the motivation behind the applied buffer width or structure for any of the three countries, although historical management legacy seems to be partially driving contemporary buffer management in Sweden and Finland (Kuglerová et al. 2020b). We will provide evidence for the effects of different degrees of protection of source waters on water quality and freshwater ecosystems. This will contribute to discussions of trade-offs between timber value and protection of the value of other ecosystem services.
Finally, we are preparing an opinion piece intended to focus on the lack of clear objectives and measureable targets for protection of streams from forestry. This is to draw attention to the vague ways that governments state their intents for “protection” of our shared resource. |
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Project structure: The team will work on all three workplans together. Team meetings, including partners, will be held at least annually. |
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Implementation: Empirical and modelling frameworks will be used to develop the deliverables of the project. |
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Outcome/deliverables:
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References coordinator and leaders of each WP: |
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Main outputs:
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Contact Point for Communication/Dissemination activities: John. S. Richardson |
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Contact Point for Open Data/Open Access activities: TBD |
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