September 2023 science summary

 Hello,

I had high hopes to do more reading this month but international travel and getting sick got in the way. So here are just two articles for some light summer reading.

If you know someone who wants to sign up to receive these summaries, they can do so at http://bit.ly/sciencejon (no need to email me).

RANGELANDS AND SOIL C:
Provencher et al. 2023 models the potential carbon gains (and costs) to restore degraded rangelands (remotely sensed) in UT and NV (and some of OR, ID, and CA). The restoration sometimes involves herbicide to kill invasives and always involves: seeding w/ native perennial plants, excluding grazing for only 3 years from pixels that were seeded (grazing resumes after 3 years), and ending fire suppression. They found that invasive annual species like cheatgrass are more common than other analyses have found (Fig 8). See Table 3 for the key results: sequestration rates were very low in two sites (compared to less arid ecosystems) and modest in a third. Overall they ranged from 0.022 - 0.730 t CO2e / ha / yr (0.6-20 g C / m2 / yr). The best case scenario is in UT where ~$66 / ha delivers ~0.73 t CO2e/yr (+-50%), or ~$90 / t CO2e / yr (comparable to reforestation). Conversely the other ranches would be >$3,000 / t CO2e / yr. But selecting sites likely to be favorable to carbon accumulation could help make the case for ecological restoration (with empirical data needed if one wanted to sell carbon credits). And there is a LOT of degraded rangeland globally, so there's room to scale. To make carbon trading feasible in the Intermountain West, making this kind of seeding cheaper and more successful is important. 

INVASIVE SPECIES:
I couldn't resist reading Clark et al. 2023 right away despite my sad backlog. I once had a native plant garden guy tell me "at best non-native plants offer no value to pollinators and other wildlife, and most are harmful." Obviously false as an absolute! But how do they compare? Clark looked at 10 species in a Connecticut forest and found some invasive species (like honeysuckle) had more bugs (mass and protein) than the average for natives, but others (Japanese barberry) had fewer bugs. But birds seemed to forage both equally. It's a tiny study and I wish they hadn't pooled all native species, but I do like a study that counters "it depends!" to a truism in conservation.

REFERENCES:

Clark, R. E. (2023). Are native plants always better for wildlife than invasives ? Insights from a community-level bird- exclusion experiment.

Provencher, L., Byer, S., Frid, L., Senthivasan, S., Badik, K. J., & Szabo, K. (2023). Carbon Sequestration in Degraded Intermountain West Rangelands, United States. Rangeland Ecology & Management, 90, 22–34. https://doi.org/10.1016/j.rama.2023.05.004


Sincerely,
 
Jon
 
p.s. This is a photo of a fountain at a mini golf course in Wildwood, NJ

October 2018 science journal article roundup

Greetings,

Here is a short set of articles on potato cultivation, groundwater, and cattle and rangelands.

If you know someone who wants to sign up to receive these summaries, they can do so at http://eepurl.com/diB0nr

POTATO CULTIVATION:
Drakopolous et al. 2016 found that reduced tillage for potatoes led to 13% lower yields (smaller tubers) but also led to higher quality and nitrogen efficiency. The quality boost wasn't enough to offset yield loss and result in net economic benefit from reduced tillage.

Myrick 2016 is a masters thesis investigating adoption (and abandonment) of a potato variety resistant to late blight (C-88) in Yunnan, China. They found smaller farmers and those closer to cities were less likely to grow it, although they noted access to seed is very limited so decisions may largely be driven by which varieties extension agents promote. The appendix has some interesting (and at times, conflicting) data on farmer perceptions.

GROUNDWATER:
Jasechko et al. 2017 makes two important points about groundwater. The first is that between 42-85% of groundwater in the upper 1 km of the ground is over 12,000 years old, as is more than half the water pumped from deeper than 250m (highlighting challenges with pumping out "fossil" water which will be very slow to recharge). The other is that while the water is very old,  half of the wells showed contamination with tritium (a radioactive isotope mostly present in the environment from nuclear weapons and testing, showing relatively recent contamination). In other words, groundwater which took millennia to recharge and get clean is being contaminated more rapidly.
You can read a blog about this one: http://www.bbc.com/news/science-environment-39715738

RANGELANDS / CATTLE / REMOTE SENSING:
Reeves and Baggett 2014 developed a relatively simple way to assess rangeland degradation using remote sensing. Essentially they compare rangelands to reference conditions (all rangelands within similar ecological classifications), and found relatively little degradation (with degradation trends almost undetectable). They list several reasons for this in the discussion, but from other work in this space I've read it seems that estimating grassland productivity and degradation remotely is fundamentally challenging and limited (especially without field data to calibrate on), and NDVI is not an ideal tool for grasslands for several reasons. Caution could be taken before assuming relatively simple remote sensing estimates of grassland condition are accurate and actionable.

Reeves et al. 2017 predicts how climate change will affect cattle in the western U.S., considering forage (quantity, interannual variability, and vegetation types) and hear stress. They expect more forage in the north, less woody plants and more grass (in general), more variation in forage quantity year to year, and more heat sress (starting 2020-2030), which taken together means more vulnerability of cattle in most places (especially in the Southwest). In northern areas, the impacts of heat stress are expected to offset the benefits of more forage (with some exceptions). The two top maps in Figure 3 has a good summary of net impacts on cattle by 2060 and 2100, with yellow to red indicating negative effects, and green to blue indicating positive ones.

REFERENCES:
Drakopoulos, D., Scholberg, J. M. S., Lantinga, E. A., & Tittonell, P. A. (2016). Influence of reduced tillage and fertilization regime on crop performance and nitrogen utilization of organic potato. Organic Agriculture, 6(2), 75–87. https://doi.org/10.1007/s13165-015-0110-x

Jasechko, S., Perrone, D., Befus, K. M., Bayani Cardenas, M., Ferguson, G., Gleeson, T., … Kirchner, J. W. (2017). Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination. Nature Geoscience, (April), 1–6. https://doi.org/10.1038/ngeo2943

Myrick, S. N. B. (2016). An Economic Impact Assessment of Cooperation-88 Potato Variety in the Yunnan Province of China. Virginia Polytechnic Institute and State University.

Reeves, M. C., & Baggett, L. S. (2014). A remote sensing protocol for identifying rangelands with degraded productive capacity. Ecological Indicators, 43, 172–182. https://doi.org/10.1016/j.ecolind.2014.02.009

Reeves, M. C., Bagne, K. E., & Tanaka, J. (2017). Potential Climate Change Impacts on Four Biophysical Indicators of Cattle Production from Western US Rangelands. Rangeland Ecology and Management, 70(5), 529–539. https://doi.org/10.1016/j.rama.2017.02.005


Sincerely,

Jon

p.s. as a reminder, you can search all of the science articles written by TNC staff (that we know of) here http://www.conservationgateway.org/ConservationPlanning/ToolsData/sitepages/article-list.aspx