GPS vs. GPS

There has been some buzz on the blogs about the possibility of smart phones replacing more standard recreational grade GPS devices. This article in the NY Times suggests that the smartphone is beginning to displace the GPS receiver as a convenient way for drivers to get directions to unknown destinations.

Next might be the use of smart phones for non-driving uses of the recreational GPS devices, like geocaching, or science education.  We will be releasing our OakMapper device for the iPhone in September, and will likely be better able to comment on the comparison.

Indigenous mapping network at UC Berkeley

Our friends from DataBasin are on campus on Monday. Kai Henifin is a Cultural Ecologist/GIS Analyst with the non-profit organization Conservation Biology Institute, the developers of DataBasin. Kai will be speaking about "Incorporating Indigenous Knowledge to Improve Conservation through Data Sharing" as part of the Berkeley Indigenous Mapping Network. For more info on the event.

We have some interesting cross-overs with CBI and DataBasin: we added our SOD data to DataBasin recently (see image at left); and CBI have a nice modeling project looking at fisher in the southern Sierra that Reg and Rick are using in their SNAMP work.

Interesting sources of data for science: commerce and construction for ecological trend analysis

In the early 1800s, Canadian fur traders began to notice dramatic fluctuations in snowshoe hare (Lepus americanus) and Canadian lynx populations (Lynx canadensis). Almost 100 years later, ecological researchers were able to use pelt sale data generated by the Hudson’s Bay Company to document an interrelated rise and fall in hare and lynx populations. Today, we understand even more about this classic and frequently cited example of predator–prey cycles, and have identified large-scale factors, including climate, as playing an important role in regulating these populations and their interactions. But it was the novel use of commercial records that got scientists started on their work. This piece excerpted from our article on webGIS.

Now, in the same spirit, comes this article in PERS recently, and it prompted me to start collecting studies on interesting and non-traditional sources of data for hinting at or validating ecological trends. Download Full Article (members only)

The article: Wal-Mart from Space: A New Source for Land Cover Change Validation by Potere et al. The authors use the location and opening dates for 3,043 Wal-Mart stores as a means for validating land-cover change-related products at medium (28.5 m) to coarse (250 m to 1 km) resolutions throughout the conterminous United States. Since Wal-Marts are large, nearly everywhere, and have been built throughout the remote sensing record (1962 to 2004), they prove to be good data set for examining land cover change. A very interesting and creative approach.

Update on Friday, July 24, 2009 at 8:39AM by Maggi

Add to this list: espionage. Last week, thanks to the U.S. intelligence community, researchers saw pictures that will allow them to model the breakup of sea ice at a level of detail they never imagined. Science article.

Costs & benefits of lidar

I am collecting information on the costs and benefits of lidar primarily in forest research/management. Since lidar is still in the research phase in many forest applications (although there are some operational aspects to the technology), we get questions about the relative costs of lidar vs. fieldwork. I am collecting information here.

There is more information on the cost-benefits of lidar for topographic mapping and construction. See for example the blog from Merrick. State-wide mapping (e.g. NC), coastal mapping and floodplain mapping clearly see a benefit in increased accuracy and coverage from using lidar over more traditional surveying methods. See an example here from the USGS; Greg Snyder also has some nice graphics in a presentation at ASPRS available here.

For forestry applications, however, there is less information on the relative costs of lidar vs field capture. Tree attributes such as height, dbh (diameter at breast height), height to live crown, species, age, location, basal area, volume, biomass growth and leaf area index have been measured in the field in forest plots for over 100 years. Many of these attributes can be measured directly using LiDAR data, and some can be inferred from lidar data. Stand attributes such as age, trees per hectare, mean diameter and height, dominant height, volume per hectare, form factor, annual increment per hectare and growth have also been estimated from individual plot data for some time. Again many of these can be measured from processed LiDAR data. Accuracy, which is usually estimated by comparing ground data from a series of plots with lidar values, varies with species, density, topography, lidar equipment. For example, in our SNAMP project, preliminary analysis shows r2 of 0.78 for tree height, and 0.65 for dbh. A clear technical advantage of lidar is the ability to completely inventory the forest, instead of collecting a sample of plots that might not be representative of forest heterogeneity. The derived data products that come from lidar can easily be used at multiple scales (and resolutions) as direct inputs to fire models and environmental niche models. The field plot-based approach requires interpolating between these sampled plots to generate a continuous surface.

But as for costs, there are few solid comparisons. The cost of lidar includes aquisition, field data collection, and processing, which includes software and hardware as well as personnel.  These can add up.  Most comparisons of lidar vs. field alone concentrate on the technical advantages highlighted above. One exception is Renslow et al. (2000) who claim that for a typical even-aged, managed forest of 500,000 acres where in each year, 2% of 10,000 acres (200 acres) are sampled to determine what management steps are needed, cost savings with lidar would be $15,400 annually.  I think this is overly optimistic, as it only includes 2 weeks for analysis.  Our SNAMP analysis (albeit over a much larger area) takes considerably longer.

So, in proto-conclusion, I think the advantage of lidar is clearly in its accuracy and coverage, and these outweigh any cost savings that a fast and cheap field campaign might provide.  Still, I will come back to this topic later with more analysis from our SNAMP project.

Location, location, location

Two interesting articles from Wired via the Map Room.

1. Wired magazine's tips on getting better GPS reception.
2. Clive Thompson's article Future of the Web: Location, Location, Location asks: How is the return of geography (via location-aware cell phones et al) going to change our lives?

Mapping virtual trees and buildings

From a series of news releases (all text, no pics, alas): UK aerial survey specialist Bluesky has launched a brand new digital map layer accurately modelling the location and extent of trees and their proximity to buildings. Designed as a tool to aid insurance assessors, property developers and Local Authority Planners, ProximiTREE details the exact spatial location and height of individual trees together with the circumference of its canopy. From this information a determination can be made of the root extent and the potential impact on either existing or proposed properties.

They plug this product for its use in avoiding building subsidence, but in fire-prone Cali, we could use it to look at defensible space and risk.

They also provide a range of good downloads, including sample data and software for your enjoyment.

Science Editor-in-Chief

I know this is late: blame my routine end-of-semester office paper clean-up (late again). This comes from last year, when Bruce Alberts took over Science. He says in his first editorial: New science will be needed on our crowded planet to protect our environment, to insure our health, and to provide sufficient water and food for humanity.  I think that is true, and sounds a lot like the CNR's mission statement.

New Remote Sensing Journal

I just received an announcement about a new journal for RS folks, succinctly named Remote Sensing. It is a new open access journal of the remote sensing process, from instrument design and signal processing to the retrieval of geophysical parameters and their application in geosciences. Remote Sensing is published under the leadership of Prof. Dr. Wolfgang Wagner from the Institute of Photogrammetry and Remote Sensing (I.P.F.), Vienna University of Technology (TU Wien), Vienna, Austria. Check it out.

iPhone apps for environmental science

Having just set up a HOBO weather station over the weekend (ain't she pretty?), and being dismayed at having to use my windows computer to control it, I wondered about other ways to monitor the environment.  Amazingly, but perhaps not surprisingly, there are many new iPhone apps out there for us to investigate. 

For example: the recent NPR study about soil moisture monitoring via the iPhone is interesting. The sensors themselves are very expensive, but are monitored via an iPhone app.

Also: this new Wind Meter app, which I am going to test at lunch today. Seems fun, but a far cry from a real anemometer.

And of course: we will soon be releasing our OakMapper iPhone app.

Sudden Oak Death Science Symposium Highlights

I thought I'd post some highlights from the SOD Science Symposium, currently running in Scotts Valley, CA.

Dave Rizzo presented new disease information since the first isolations (9 years ago this week!) in 2000 to today. Some highlights include:

• Across California, there has been filling in of existing areas of the disease, but new areas of confirmation of note:
  
  • furthest north in CA is 45 miles north of Redway, CA; confirmed from stream baiting, and is associated with a nursery. No terrestrial confirmations. In Mendocino, another river baiting example north of Fort Bragg; no terrestrial confirmations.
• There are some exciting management projects ongoing, from preventative treatment to large-scale management.

Alan Kanaskie talked about the Oregon situation. Highlights include:

• Tanoak is critical for SOD in Oregon;
• Monitoring in OR depends on aerial surveys, field surveys and stream baiting. With these methods, they are confident that ramorum only exists in the known quarantine area. However, they are getting rare PCR confirmations out of steam baiting in new watersheds, but they have not been able to replicate with culture, nor have they found any newly infected trees in those watersheds.
• They are confident their management approach is working to slow the spread, and compares a map of Humboldt and Curry counties; in Humboldt, things look worse than in Curry.

Sandra Denman from Forest Research in UK gave an update on Pr in Europe: still mainly a nursery problem, but some interesting facts include:

• Coutries reporting Pr in Europe in 2000 were few, and only 4 countries had outdoor outbreaks; in 2008: 19 countries report Pr in nurseries, and "burgeoning" reports of outdoor outbreaks across western and southern europe.
• In the UK, Pr has been found in 600 nurseries in UK. In outdoor outbreaks, rhodies are the main problem, and outside outbreaks on trees are associated with these ornamentals.
• First use of "kerfuffel" in a science presentation that I have heard.
• P. kernoviae is also important in UK; and last year Pk was found in the Republic of Ireland for the first time.

Clive Brasier, from UK Forestry Commission, talked about P species and increased invasions due to international trade, and weak international biosecurity. Before 2000, about 20% of P sp were threats to forests; since 2000 (with 50+ new P species named), about 60% are threats to trees and forests. He guesses there might be 100-500 unnamed P. species out there that could be invasive in forests. They are now hypothesizing that Pr came from Japan and/or Taiwan.

For more on Sudden Oak Death, check out the OakMapper site, and other oakmapper posts on this blog.