Monday, July 1, 2019

July 2019 science journal article summary

      Above: People floating down the river Rhine, see rivers articles below


Here is another grab bag of articles on landscape conservation, research impact, rivers, climate change, and coastal wetlands. If you know someone who wants to sign up to receive these summaries, they can do so at

Once again Steve Wood (from The Nature Conservancy) has kindly added a couple of his own guest reviews, which I've broken out below to avoid confusion. Thanks Steve!

Burivalova et al. 2019 is a literature review of how effective four strategies were in delivering environmental, social, and economic outcomes. They looked at creating protected areas (PAs), forest certification and reduced impact logging (RIL), payment for ecosystem services, and community forest management. The results are varied and complex but Figure 2 summarizes them very well - no strategies always succeed, but all sometimes succeed (and note the caveat that each square is not equivalent). PAs performed well environmentally (after certification & RIL), but very poorly socially and economically. The authors conclude that there are surprising gaps in the literature on monitoring the efficacy of conservation strategies, and that before implementation local evidence should be examined to minimize the chance of failure or even having a strategy backfire.

White et al. 2019 surveyed land managers from the U.S. Forest Service about how they received and used scientific information in decision making. One key finding is that they believe science is less useful in making decisions with high public consensus (although even then only 19% of managers thought public priorities should have more weight than science, with 36% wanting equal weight and the remainder giving more weight to science, see Figure 3a). This study also reports low engagement with scientists, but Figure 1 shows that they primarily measured managers actively seeking out scientists rather than the reverse (which could be more common).

Bogenschneider et al. 2019 interviewed legislators in WI and IN about how research contributes to policymaking. While research was only infrequently mentioned as changing or even informing their positions on issues, it was seen serving several purposes (see Table 1), including persuading others, designing good legislation, educating others, improving debate & dialogue, and building trust. However, several quotes imply that they tend to seek out research that backed up their beliefs rather than exploring with an open mind. At the same time, the results highlight the importance of clear scientific conclusions that allow legislators to evaluate the potential impacts of actions they're considering (as opposed to more circuitous findings sometimes favored by scientists).

Grill et al. 2019 estimates only about a third of the world's longest rivers (<1,000 km) are freely flowing (defined here with a new metric that means neither dammed, nor significantly impacted by water consumption or infrastructure in riparian areas and floodplains). Those long free rivers are mostly in remote parts of the Amazon, Arctic, and Congo. On the other hand, shorter river reaches are doing better: 56% of long rivers (500-1000km) are freely flowing, rising to 80% and 97% for medium (100-500km) and short (10-100km) rivers respectively. However, since they rely on global dam databases, they caution that they likely overestimate freely flowing rivers due to missing data on small dams. The figures (and table 1) have great details on how well connected each river reach is, what limits connectivity most (96% one of the impacts of dams: fragmentation, flow regulation, and sediment trapping), and connectivity broken down by river length.

Cui et al. 2016 estimates how sediment built up behind Matilija dam would be released after dam removal (or partial removal / breach). They conclude that upon removal the main sediment pulse is likely to only last a few hours, and almost certainly < 3 days (with a worst case scenario of 8 days). The authors then argue that halting water diversion (e.g. for agriculture) until the sediment stabilizes should have minimal impact given the short time for sediment to be flushed out.

Gonzalez 2018 is an unsurprising but interesting reframing of current and projected climate change impacts: national parks are harder hit than the rest of the US (getting warmer and drier). This is largely driven by the fact that 63% of national park area is in Alaska (!), with most of the rest in the Western US (see Figure 2). This shows the need for parks to be actively planning how to respond to climate change, and is a useful reminder that protected areas are not protected from climate change.

Renzi et al. argues that to successfully restore coastal wetlands, reducing stress & competition isn’t enough. To make restoration more effective at replicating intact habitat we should incorporate ‘positive species interactions’ (where one or both organisms benefits from the other without being harmed, aka ‘symbiosis’ in lay terms but in ecology symbiosis has a broader meaning). Examples include clumps of seagrass helping each other by capturing more nutrients and reducing erosion, or sponges on mangrove roots exchanging nutrients and carbon so both grow faster (See Fig 1 & 2 for more examples). Key recommendations are :to clump (not evenly space) plantings of seagrass or mangroves (in most but not all cases, context is important),  introduce a diverse set of plants and animals (rather than hoping for colonization later), and consider proximity to other wetlands.

Guest reviews from Steve Wood:

Many environmental groups have focused on using natural ecosystems to drawdown carbon dioxide to achieve climate goals. Baldocchi & Penuelas 2019 walks through the science of how that drawdown works. They cover the mechanistic science of limits to plant fixation of carbon, but in an extremely accessible way. Although they write from a neutral perspective, there are hints of doubt that drawdown could be achieved at scale to have climate-relevant impacts.

Herbicide residues from widespread chemical weed management can have negative impacts on terrestrial and aquatic ecosystems. Combined with herbicide resistance and lack of innovation of new herbicides has led people from corporations to ecologists to advocate for ecological approaches to weed management. Barberi 2019 gives an overview of ecological weed management approaches, with a lens on sub-Saharan Africa. They focus specifically on practices to: reduce weed seedling emergence; improve crop competitiveness; and reduce weed seedbank size. There is a particular emphasis on Striga management. This is a very thorough literature survey and would be a great entry point to understanding the literature. They do not, however, quantitatively synthesize the literature through tools like formal meta-analysis to put numbers to the impact of practices.

Baldocchi, D., & Peñuelas, J. (2019). The physics and ecology of mining carbon dioxide from the atmosphere by ecosystems. Global Change Biology, 25(4), 1191–1197.

Bàrberi, P. (2019). Ecological weed management in Sub-Saharan Africa: Prospects and implications on other agroecosystem services. In Advances in Agronomy (1st ed., Vol. 156).

Bogenschneider, K., Day, E., & Parrott, E. (2019). Revisiting theory on research use: Turning to policymakers for fresh insights. American Psychologist.

Burivalova, Z., Allnutt, T., Rademacher, D., Schlemm, A., Wilcove, D. S., & Butler, R. A. (2019). What works in tropical forest conservation, and what does not: Effectiveness of four strategies in terms of environmental, social, and economic outcomes. Conservation Science and Practice, in press(March), 1–15.

Cui, Y., Booth, D. B., Monschke, J., Gentzler, S., Roadifer, J., Greimann, B., & Cluer, B. (2016). Analyses of the erosion of fine sediment deposit for a large dam-removal project: an empirical approach. International Journal of River Basin Management, 15(1), 103–114.

Gonzalez, P., Wang, F., Notaro, M., Vimont, D. J., & Williams, J. W. (2018). Disproportionate magnitude of climate change in United States national parks. Environmental Research Letters, 13(10), 104001. Retrieved from

Grill, G., Lehner, B., Thieme, M., Geenen, B., Tickner, D., Antonelli, F., … Zarfl, C. (2019). Mapping the world’s free-flowing rivers. Nature, 569(7755), 215–221.

Renzi, J. J., He, Q., & Silliman, B. R. (2019). Harnessing Positive Species Interactions to Enhance Coastal Wetland Restoration. Frontiers in Ecology and Evolution, 7(April), 1–14.

White, E. M., Lindberg, K., Davis, E. J., & Spies, T. A. (2019). Use of Science and Modeling by Practitioners in Landscape-Scale Management Decisions. Journal of Forestry, 117(3), 267–279.



p.s. If you'd like to keep track of what I write as well as what I read, I always link to both my informal blog posts and my formal publications (plus these summaries) at

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