Riparian Restoration: More important than ever with climate change

For people in the conservation/restoration community, trying to deal with climate change is a tough assignment.  Years and years of training and conventional wisdom preaches the value of restoring habitat to a 'pristine' state.  In the U.S., that usually translates into Pre-European settlement.  However, the reality is that the pre-settlement environment may simply no longer exist.  Even if those conditions do exist, there's no guarantee that it is even possible for those ecosystems to be recreated (some species may now be extinct or extirpated, or those genotypes may be extirpated, or the particular sequence of events that allowed those ecosystems to persist may never again occur).

Getting past the goal of pristine restoration is not easy, in part because what goals are you going to use instead of pristine?  Obvious (to many research ecologists) is the use of various ecosystem services or functions as replacement goals.  Equally obvious is the conservation of particular endangered species.  However, doing this without realizing the rapidity with which environmental conditions are changing is likely to result in poor results.

Seavy et al. (2009; full cite below) recently published a paper in Eco Restoration that discusses some of these issues in relationship to the restoration of riparian areas.  They further argue that restoring riparian areas will provide benefits beyond the boundaries of the areas being restored.  Specifically, they argue that restoring riparian areas will improve overall ecosystem resilience in the face of changing climate.  Resilience (as defined by the authors) refers to the ability of an ecosystem to withstand disturbance without changing 'state', recover after disturbance, and the way an ecosystem responds to gradual changes.  Resilience is a tricky concept (over a large enough time scale, every ecosystem is in constant flux), but for timescales relevant to wildlife management, this is probably a useful idea.

Essentially, Seavy et al. (2009) argue that restoring riparian areas is likely to improve the ecosystem resilience of surrounding areas because 1) riparian areas are naturally very resilient, 2) riparian areas improve connectivity between ecosystems (aquatic and terrestrial; along longitudinal migration corridors), 3) riparian areas are natural thermal refugia, and 4) there are lots of flood-related benefits to "natural" riparian areas. So lots of benefits, but achieving those benefits (in spite of major climate change) will require some fancy work.  For instance, restoration plantings typically use seeds from species on-site or nearby.  However, if environmental conditions are likely to change, then those species (or those genotypes) may not be successful, and noxious or non-native species would have the opportunity to invade.

Ok, so that all sounds really good.  Some issues:

1)  There's a real emphasis in this paper on riparian woodlands, but there are some places where woodlands are rare, or absent entirely.  Should we plant woodlands along areas that haven't had them historically?  I don't know, but I don't know if we should, or if we should even encourage it.

2)  The authors talk about riparian areas being naturally resilient, but this is only really documented for persistence in the face of hydrologic variability (flood and, to a lesser extent, drought).  I'm not aware of any literature documenting any particular resilience of riparian ecosystems to disturbances related to temperature, invasive species, pollution or eutrophication.

3)  The primary benefit, that I can see, to prioritizing riparian restoration above other areas, is the reality that you are benefiting both terrestrial and aquatic habitats at the same time.  However, I think this ignores the integrated nature of watersheds.  I suspect that if you improve the non-riparian terrestrial components of a watershed, you're going to have similarly dramatic (if potentially different) positive effects on streams.  I guess I'm not convinced that it is a good idea to make riparian restoration a priority without consideration of what else is going on in the watershed.

Having said that, the paper does make a compelling case that riparian areas are really important, and that we need to adjust how we restore them, and that some important questions need to be answered if we are going to be effective at restoring these ecosystems in the future.

Summary:

Restoration of riparian areas will likely provide a lot of benefits in light of the rapidly changing global climate, even beyond the strict borders of these areas.  However, different techniques need to be employed to realize these benefits.

Seavy, N., Gardali, T., Golet, G., Griggs, F., Howell, C., Kelsey, R., Small, S., Viers, J., & Weigand, J. (2009). Why Climate Change Makes Riparian Restoration More Important than Ever: Recommendations for Practice and Research Ecological Restoration, 27 (3), 330-338 DOI: 10.3368/er.27.3.330

Aquatic Invasive Species and the Effectiveness of Education and Outreach

Apparently my friends from Notre Dame are continuing to publish at a feverish rate, because I keep stumbling onto their papers.  The latest is by Rothlisberger, Chadderton, McNulty and Lodge, and is all about aquatic invasive species (full cite is below), and I think this paper really throws into question the value of education and outreach.

There are a lot of big questions out there regarding invasive species (IS).  IS cause all kinds of economic damage and are a big cause of native species being threatened.  Yet this is a very artificial classification structure for biota.  Invasive species aren't defined by their evolutionary history or morphology, but rather by the impact they have on human-centric ecosystem services.  I think that has caused a lot of confusion in the way we research the subject.  However, I'm just rambling a bit here, the focus of this paper is a lot more pragmatic.  Essentially this paper looks at how aquatic IS are being spread by boats.  And man, it looks like they could be spread really easily.

Essentially, we know that boats moved around by recreational boaters are causing IS to be moved around.  As a result, there are all kinds of efforts out there to prevent that from happening.  For the most part, those efforts center on 2 approaches:  1)  Educate the public and 2) boat inspections.  95% (maybe more) of the effort goes into the first of these categories.

And this is where it all goes wrong.

There probably isn't anywhere in the country that has been more inundated by the 'prevent the spread' of invasive species message than the Great Lakes Region.  Since the 1930s, the Great Lakes have been subject to an increasingly devastating series of invasions by non-indigenous species.  This has devastated economic and environmental interests throughout the region.  So the residents of Wisconsin and Michigan (particularly those who are targeted by these educational efforts) should be more aware of the problems and what they can do to help than anyone else.

And yet they don't seem to be all that aware or all that interested in doing much.

"68% of transient boaters did not always was or dry their boat when moving it overland between waterways...27% did not always remove aquatic weeds they saw attached to their boat and trailer."  p 125 (Rothlisberger et al. 2010)

I'm reminded of a talk I saw at NABS '08 by the state malacologist of Missouri.  Missouri did a similar survey with a bunch of boaters, and got similarly miserable responses (most people had never heard of IS or zebra mussels in particular, and didn't realize they could do anything to help prevent their spread).  These respondents were then asked what the state should do.  The responses were things like put ads on TV, put ads in magazines, put up signs at boat ramps, etc.  After going over these responses, the malacologist sighed heavily and brought up the next slide:  That's what Missouri had just spent millions of dollars doing over the previous X number of years.  Sometimes you just can't win.

There's more in this paper.  For instance, the authors also tested the effectiveness of the boat inspection and wash stations.  For some of the smaller organisms (crustaceans and seeds), visual inspection just wasn't very effective.  Even a high-pressure wash was only about 90% effective at removing these organisms, and according to the methods, even a ten-minute delay was enough for boaters to become unwilling to participate in a high-pressure wash.

The authors also quantified the amount and type of material being moved around by these recreational boats.  On average, they found 37 species per boat, indicating a large potential for this vector to be spreading invasive species.

Summary:
Despite massive educational efforts over the past 20 years, a majority of boaters don't seem to be taking the basic steps necessary to prevent the spread of aquatic invasive species.  Additionally, it now seems clear that these boats do possess the ability to transport a significant variety of aquatic organisms (although it isn't clear how long these species would remain viable out of the water).

Rothlisberger, J.D., Chadderton, W.L., McNulty, J., & Lodge, D.M. (2010). Aquatic invasive species transport via trailered boats:  What is being moved, who is moving it, and what can be done American Fisheries Society, 35 (3), 121-132

Organic matter processing and retention

I've already mentioned one of the papers from the big 25th anniversary issue of JNABS.  I've now read a handful of these papers, and they continue to be very interesting and a little bit annoying.  Why are they annoying?  Well, I like the review aspect of the papers, I don't like the "JNABS played X role in the development of X concept", because, really?  Who the hell cares?  This is a perfect example of the sometimes egocentric nature of scientists:  It isn't enough for something to be discovered or understood.  It must be clear that this person discovered or understood something.  And by extension, this society contributed this to science.  I know that the incentive structure of the entire scientific community is geared towards rewarding this kind of attitude, but that doesn't make it right.  If anything, it makes it more wrong.

But I digress.  Let's focus on "A review of allochthonous organic matter dynamics and metabolism in streams" by Tank and others (2010; full cite below).  Actually, because I know all these authors, I'm going to list out the others:  Emma Rosi-Marshall, Natalie Griffiths, Sally Entrekin, and Mia Stephen.  Frankly all these people are awesome, and so I fully expected this paper to be awesome.

I was not disappointed.

There is a hell of a lot of interesting stuff in here.  Lets bring out some of the highlights:

• There have been a hell of a lot of leaf-decomposition studies.  Essentially, inverts and microbes are the big players, with other factors influence the effectiveness of those two main players.  Some of those other factors:  Pollution (by reducing invert populations/diversity and sometimes increasing microbial activity, temperature, and leaf species (even different hybrids have different decomp rates).
• Biomonitoring using leaf decomposition (at least combined with invert measurements) might be a good way to measure ecosystem health or "stream integrity".  There are a lot of papers cited here that I'll have to read at some point (assuming I can get access).  
• Although production to respiration ratios (P/R ratios) have often been used to determine allochthnous versus autochthonous production (whether or not a stream is heterotrophic or autotrophic), this is a more complicated assessment than was first believed (although the authors here don't fully explain why).
• People have tried a lot of different things to measure organic matter retention:  using leaves, sticks, logs, particle analogs (waterproof paper cut into squares), plastic strips, wooden dowels, etc.  Why?  Because most small streams have energy budgets dominated by terrestrial inputs (at least, most small streams that have been studied).  Getting estimates of in-stream retention of little stuff (dissolved or just fine particles) has been a lot more difficult. 

As I said, there's a hell of a lot here, and I'm in no way going to reproduce all the interesting stuff here.  Those are just a few highlights.  However, it is worth pointing out that this kind of research is a natural extension of some of the oldest 'modern' ecological studies that have ever been done.  What do I mean by modern?  I mean studies integrating abiotic and biotic components to understand large-scale phenomena.  Maybe 'modern' isn't the right word...how about awesome?

Summary:

This paper offers a pretty comprehensive overview of organic matter dynamics in streams, including decomposition, metabolism, and budgets.  Prior to doing any research on this topic, I would recommend reading through this to get a good historical perspective.

Tank, J.L., Rosi-Marshall, E.J., Griffiths, N.A., Entrekin, S.A., & Stephen, M.L. (2010). A review of allochthonous organic matter dynamics and metabolism in streams Journal of the North American Benthological Society, 29 (1), 118-146 : 10.1899/08-170.1

The bizarre history of rangeland management research

As with the paper from last Friday, today's paper comes from "Ecological Restoration", one of the few journals that is delivered, in print, to our office. So yeah, I've been reading through it.

This paper is by Sayre (2010; full cite below) and is basically about how the cultural and scientific beliefs of those living in the desert southwest have shaped the way that restoration has occurred there. Southwest refers to southwestern US (Arizona, New Mexico, etc.).

The paper is really a historical essay more than anything else, and so I'm not sure if it really qualifies as 'science'. However, it was really interesting. Basically, Sayre points out that three really big-picture things have dominated the way people have managed this part of the country:

1. The "Natural" aesthetic laid out by early-20th century writers, specifically John Van Dyke.
2. The belief that rangeland could be managed for and by livestock grazing (which depended on believing Clements' "climax community" theory).
3. The unwillingness of (virtually) anyone to look at fire as a management technique.

That's a pretty amazing list. The desert aesthetic laid out by Van Dyke was popularized by his book (Desert), and turned out to be primarily a documentation of a massive drought. So the ideal that so many people believed in was really a landscape already heavily degraded by overgrazing and drought. The climax community theory that Clements promoted, and that was so popular in ecology for the early part of the 20th century, has been shown time and time again to be a poor representation of what is actually happening. And finally, fire has now been shown to be one of the most important factors in maintaining grassland communities.

So people pretty much got that all wrong, which isn't surprising. What is surprising is how long people have clung to those false theories.

The basic idea was that the grasslands would restore themselves if you just 'leave them alone'. What everyone wanted was for the grasslands to be as rich and abundant as they were in 1874. Unfortunately, the southwest grasslands were probably maintained by a more dynamic equilibrium (periodic fire, flood, and drought keeping the native grasses abundant and undesirable species [like mesquite] rare). Even worse, it took these scientists the better part of a century to figure out that all three of those factors above were wrong.

The net effect of all this poor management and questionable science is apparently quite astounding (I haven't visited myself).

"The Nature Conservancy estimates 84% of perennial grasslands in the Apachean Highlands bioregion has been invaded by shrubs; three-fifths of this area is deemed by The Nature Conservancy to be beyond restoration, either because there is insufficient grass to provide the fine fuels needed to carry a fire (which would be necessary to set back shrubs), or because non-native grasses dominate to such an extent that fire, although possible, would not appreciably help the native grasses." (Sayre p 26)

Holy cow.

There's also some discussion in this paper about whether the goal of restoration should be the historical conditions of an area or something else, but that discussion is less fleshed out. I'm under the impression that the author sees no a priori reason to believe historical conditions should necessarily be the ideal.

Summary:

About a century of poor management in the desert southwest (USA) is directly attributable to the widespread adherence to a series of unfounded beliefs. As a result, large portions of this area are unlikely to ever be restored to 'pristine' or desirable conditions.

Sayre, N. (2010). Climax and "Original Capacity": The Science and Aesthetics of Ecological Restoration in the Southwestern USA Ecological Restoration, 28 (1), 23-31 DOI: 10.3368/er.28.1.23

State Use of NRDA (why Florida is pretty awesome)

One of the oddities of state and federal government is the sheer number of regulatory authorities that go unused. For example, the Clean Water Act grants the EPA broad authority to protect the nation's waters. The EPA then actually delegates permitting for the CWA to the Corps of Engineers and state agencies (in many cases). As far as I can tell, many of the authorities embedded in the Clean Water Act are rarely or never invoked. As a result, a lot of bad stuff happens that would have been prevented if a more strict interpretation of the CWA were followed.

An even better example of this is the National Resource Damage Assessment (NRDA) process. This is a program to force those who pollute to pay the costs necessary to restore what they have damaged by polluting. I'm actually completely clueless on what law this stems from, but it looks as if the federal efforts are lead by the Department of the Interior (or maybe the EPA?). However, in some capacity, states are able to use this legal structure to recoup the costs of restoring habitats from polluters.

Except they aren't doing that. At least, that's according to a paper I stumbled upon recently by J. Faass (2010; full cite below). In this report, Faass surveyed a bunch of state agencies and found that most (25 of 42 surveyed) rarely or never pursued NRDA compensation for impacts to natural resources. Why?

"When asked why they routinely forgo NRDA, some survey takers cited as major obstacles the cost, time, and resources needed...as well as the potential liability. Others cited a lack of manpower or political will." (Faass, pg 34)

This is fairly crazy (after all, this legal structure was important enough for elected officials to put into place, why would we assume it would be ignored). However, it isn't completely unexpected. There is a decreasing amount of resources devoted to state agencies and increasing number of responsibilities. In most state and federal cases, NRDA is a complicated, site-specific process (involving a lot of research and investigation and court appearances). According to conventional wisdom, it is a real pain.

However, what's interesting is just how easy this problem is to solve, and the fact that Florida has basically done it. Unlike every other state, Florida uses NRDA for every oil spill (or other spill) that occurs in coastal areas. Basically, they have a simple formula (and I do mean simple) that any of their field personnel can use in response to a reported spill. Plug in number, draw a polygon on a map, and bang dollar value is spit out. Hand the bill to the polluter and move on.

There are some problems (e.g., costs are fixed by law and have remained unchanged since 1993), however, the use of a known scheme and set of criteria circumvent a number of tricky legal and ethical problems, and make it a routine process.

The biggest criticism I see of the program from this article is that they haven't actually spent the money exclusively on restoration, and they haven't spent any at all since 2001. With federal NRDA cases that's a huge no-no (you must spend only on restoration in federal cases). The reason they haven't spent any of the money since 2001 is purely political:

"...interviewees noted that a legislative appropriation would be necessary to access the money...reluctance [to solict such an appropriation] is due in part to the fact that the balance of the fund has remained below $1 million...and to fears that once awareness of the money has been raised, it could conceivably by diverted to cover non-restoration-related expenditures." (Faass p 37)

Man, that totally sucks, but it is a problem seen in lots of agencies. Once it is realized this source of money exists, it will be exploited for something completely unrelated to its intended purpose.

Summary:

Florida uses a simple formula to assess NRDA damages, making them capable of recovering restoration money from a far greater proportion of the damaging spills that occur in coastal areas.

Faass, J. (2010). Florida's Approach to Natural Resource Damage Assessment: A Short, Sweet Model for States Seeking Compensation Ecological Restoration, 28 (1), 32-39 DOI: 10.3368/er.28.1.32

A hierarchical framework for assessing environmental impacts of dam operation

The effects of impoundments are big one for people working in aquatic ecosystems. In Kansas, a large number of dams are still being built (and a lot more are in the discussion stages). So I am constantly trying to understand more about the effects of dams and the impacts they have on upstream and downstream aquatic ecosystems. I was recently forwarded the an article by Burke, Jorde and Buffington (2008; full cite below) entitled "Application of a hierarchical framework for assessing environmental impacts of dam operation: Changes in streamflow, bed mobility and recruitment of riparian trees in a western North American river."

Essentially the authors are starting from the direct effects of an impoundment and extrapolating out what the effects would be on downstream channel morphology and flow, and subsequently downstream biota. In this case, this hierarchy has been laid out in general terms in a previous paper (Jorde et al. 2008). Basically first order stuff is what causes the second order stuff, and the third order stuff is caused by the first and second order stuff, and so on, and so on.

In this study, the first order stuff is the hydrology, the second order stuff is "channel hydraulics" and bed mobility, and the third order stuff is the recruitment of cottonwood trees. Channel hydraulics seems to be referring to the depth and discharge of the streams being investigated. The entire study is of the Kootenai River (a trib of the Columbia River), which includes two dams: The Corra Linn Dam (built in the 1930s on a naturally occurring lake) and the Libby Dam (finished in 1974). Both dams are ostensibly dual purpose: hydropower and flood control. In addition, there were lots of levees constructed along the reach.

Basically the authors compared 3 time periods: Before all the dams, before the Libby Dam, and After the Libby Dam. Apparently the Libby Dam is the subject of some controversy, which is why it is getting such special attention.

Let's start with the first order effects. They are actually pretty dramatic, but then again, this is why the dams were built. These are the effects we expected when humans built the dam.

This if Figure 6 from the Burke et al. paper. What we're looking at is the difference between the discharge pre-Libby and post-Libby (the other dam doesn't seem to have as much of an effect as the Libby dam). See the big negative values for the spring? That's the spring snowmelt being intercepted by the dam. The big positive values? That's when they are releasing that snowmelt (in the winter!). Considering the importance of hydrology to all kinds of ecosystem properties in streams, that's a big impact.

Now, what does that mean for the second-order effects? Well, I'm not going to sample the figures of this (which are huge and beautiful but take some time to process), but what changes a lot is the water velocity and the wetted width. Instead of periods of extremely high velocity followed by periods of extremely low velocity, you get prolonged periods of more moderate velocity. This is especially true in the first 80-100 km downstream of the dam, where the stream is still relatively steep.

As for third order effects: Well, the authors use cottonwood recruitment as their parameter, which is an interesting choice. I have never really thought of cottonwood trees as a particularly good indicator species, but maybe they used it because the data is available. And boy, the data seems to be available. Basically, for a cottonwood seedling to become established, there have to be:

1. High flows to clear out some barren ground so the seeds have somewhere to establish.
2. Slowly lowering water levels so enough soil moisture is retained to promote growth in the seedling.
3. Flows that rise only to within a particular band above baseflow
4. A minimum number of flood events to prevent mortality through the year.

Sound complicated? Actually, not really does it? Regardless, all that data is either known or can be calculated. In fact, it was calculated as part of the second order effects. So all the authors had to do was model this to create estimates of the 'potential' for cottonwood recruitment.

What they found is post-Libby, there isn't much recruitment occurring at all, and even pre-Libby but post-Corra Linn, recruitment was probably pretty rare. By contrast, the historic conditions probably had a very high potential for recruitment. Oddly enough, this was particularly true for dry years. Mechanistically, the model is being a little confused at this, because you need wet years to scour out open patches. Still, this model is basically suggesting recruitment isn't happening much at all post-Libby. A fair amount of empirical work seems to back up this result.

There's a lot more detail here that I won't go into. The whole goal of this paper seems to be to point out how to mechanistically link the known, 1st order effects of an impoundment to the downstream biotic responses. I think this is actually pretty successful, although I'd like to see it used on more interesting biotic response variables than just cottonwood recruitment (diversity indices spring to mind as a potential example). One thing that is really needed for such studies, however, is good historical discharge data. The USGS maintains several hundred gaging stations all over the country, but they've been continually forced to shut those down as budgets are cut.

This is an approach that I think is useful for a variety of other research as well (i.e., agricultural activities, etc.) just because it starts at the basic, well-understood mechanistic level and works up.

To Summarize:

The authors document the first, second, and third order effects of dam construction on the Kootenai River. They demonstrate a strong effect of two dams on the hydrology, channel morphology and hydraulics, and the recruitment of cottonwood trees in the downstream reaches. This approach could be a useful framework for investigating other effects of impoundments when primary impacts are known.

-

Jorde, K., Burke, M., Scheidt, N., Wlcker, C., King, S., Borden, C. 2008. Reservoir operations, physical processes, and ecosystem losses. In: Habersack, H., Piegay, H., Rinaldi, M. (Eds.), Gravel-Bed Rivers VI: From Process Understanding to River Restoration. Elsevier, pp. 607-636.

Burke, M., Jorde, K., & Buffington, J. (2009). Application of a hierarchical framework for assessing environmental impacts of dam operation: Changes in streamflow, bed mobility and recruitment of riparian trees in a western North American river Journal of Environmental Management, 90 DOI: 10.1016/j.jenvman.2008.07.022

Nitrogen, Phosphorus and Organic Carbon (The Big Three)

I'm a stoichiometry kind of guy (even if I've been relatively unsuccessful lately), and stoichiometry seems to revolve around N, P and C. And really, mostly just N&P. As a result, I've been thinking a lot about how the terrestrial and upstream watershed affects the N, P, and C in receiving waters. So, for instance, if you change the proportion of wetlands, how is the ratio of these nutrients going to change? In this vein, I wrote a paper (still in review) that looks at the relationships between watershed characteristics and dissolved, inorganic N&P in streams (in Michigan and Wisconsin). Sounds like fun right? Yes.

In that context, I was surprised to stumble upon a paper recently that I hadn't previously been aware of that seemed to look at something very similar. I'm referring to Saunders, McClain and Llerena (2006) "The biogeochemistry of dissolved nitrogen, phosphorus, and organic carbon along terrestrial-aquatic flowpaths of a montane headwater catchment in the Peruvian Amazon." I was specifically intrigued by the reference to sampling nutrients along transects. So I hit up my sources for subscription-only publications, and I soon had my hand on the paper.

The paper isn't at all what I was expecting, although it was incredibly interesting. I was expecting longitudinal transects along stream networks. Instead, the authors investigated transects from the upland down to the stream (see Fig 1 from the paper below).

Although this isn't what I was expecting, this is really interesting. Basically, the authors measured the nutrient concentrations in groundwater as it moved from these upland areas down into the stream. There's a lot of interesting data in here, but big-picture, what they found is that nitrogen tends to be high in the upland areas (both organic and inorganic) and then decreases as it moves down into the stream. By contrast, phosphorus is low in the upland areas, but much higher in the stream.

This seems to support a general trend observed in the tropics: In-stream inorganic nitrogen is really low, and fairly constant. Based on this study, it appears that this is driven by the fact that as soil/groundwater is passing through the riparian and hyporheic zones, all the inorganic nitrogen is being stripped out. That's an oft-repeated story (my first encounter was Pusch et al. 1998; pdf), but it is interesting that this seemed to be generally true for the organic nitrogen as well.

I also find it interesting that P behaved in almost the exact opposite way. I actually have a hard time reconciling this. If water coming in to these riparian areas is low in P and high in N, then I would anticipate the biota holding onto that P, since they are presumably P-limited. The opposite seems to be the case, with N being stripped out of the water and P actually increasing. This might indicate that a big part of this story is abiotic (i.e., stuff is sorbing to surfaces in the riparian areas).

Also interesting is the fact that nutrients were just really different in the terrestrial and aquatic areas. Money quote from the authors:

Spatial trends in nutrient stoichiometry highlighted a clear divergence in the nutrient composition of terrestrial and aquatic hydrologic compartments along the Wara transects.

- Saunders et al. p 2559

I have a few quibbles with the paper. The nutrient concentrations are given in graphical form, but nutrient ratios are not provided. Also, the authors froze their DOC samples! I found that freezing could change the DOC concentration slightly (it changes the absorbance a lot), but I don't know the mechanism by which that happens. As a result, I never freeze DOC samples. Without knowing the mechanism, it is pretty difficult to really know how big of a problem this is. I've seen a lot of other authors do this though, so maybe I'm missing some methodological papers that investigated this.

Summary:

Great paper, easy to read and well-written. Documents the pretty dramatic differences in nutrient composition that can occur over a relatively short lateral gradient.

Pusch, M., D. Fiebig, I. Brettar, H. Eisenmann, B.K. Ellis, L.A. Kaplan, M.A. Lock, M.W. Naegeli, and W. Traunspurger. 1998. The role of micro-organisms in the ecological connectivity of running waters. Freshwater Biology 40:453-495.

Saunders, T., McClain, M., & Llerena, C. (2006). The biogeochemistry of dissolved nitrogen, phosphorus, and organic carbon along terrestrial-aquatic flowpaths of a montane headwater catchment in the Peruvian Amazon Hydrological Processes, 20 (12), 2549-2562 DOI: 10.1002/hyp.6215

Landscape approaches for the study of aquatic ecosystems

Well, I'm trying to read a paper a day (this can be really hard with 2 kids and a job that doesn't encourage it), and today I randomly pulled up this paper: Johnson and Host "Recent developments in landscape approaches for the study of aquatic ecosystems" (full cite below).

Let's just say that there's a lot here.

Basically, this paper is part of a big-time retrospective done by J-NABS in celebration of their25th anniversary (they are all open source, so by all means download away). I'm a big fan of NABS, and I love the journal. Virtually every article in this special issue holds some real interest to me. This Johnson and Host paper might be among the most relevant, because I am currently working on a Catchment Stoichiometry special issue for Freshwater Bio (whether or not it is successful or not is unfortunately still up in the air).

Regardless, this paper has a ton of great information. Essentially, the authors are reviewing the landscape approaches used in aquatic ecology and updating some of the more recent reviews on terrestrial aquatic linkages (with a particular emphasis on J-NABS contributions).

There's so much here that I don't really know how to summarize it for easy digestion. The authors really focus in on watershed scale studies (i.e., how do watershed properties affect the aquatic properties), and of course those kinds of studies have exploded in the last 15-20 years as both recognition of this level of biological organization has expanded and the tools available to do the research have become widely available. Aerial photography, combined with fairly sophisticated computer software (i.e., ESRI's ArcGIS software) have become available to many, many researchers. As a result, many many phenomena have been investigated with varying levels of success (e.g., species distributions and diversity, water chemistry, water velocity and temperature, habitat distribution, etc.).

Unfortunately, there are still some real challenges. Practically speaking, not a lot of people are speaking the same language in this field yet. Even within this paper, I was occasionally confused by changing terms, or at least terms that seemed to be very similar (catchment vs. watershed is explained; habitat versus reach I must have missed). More theoretically, there is a lot of difficulty in trying to figure out the most appropriate scale for investigating some phenomena, and sometimes as a result, the mechanistic connections between observed relationships is not always clear (in some cases it is just plain confusing).

Most or many of the landscape studies done on aquatic ecosystems are attempting to determine the extent or effects of various anthropogenic stressors. However, the authors point out that anthropogenic disturbance itself is definitely confounding our ability to distinguish what is happening. Some impacts may have lag times, others may so homogenize the landscape that important relationship cannot be seen. The authors also stress that future research will need to integrate landscape/catchment level data with local data (i.e., point source samples) better, because an abundance of local data is becoming available. Being able to manage and analyze these huge, integrated datasets seems like a formidable problem (perhaps one that Morpho can assist with?).

Maybe the biggest take-home message on the future of landscape studies of aquatic ecosystems is summarized here:

We need: 1) robust statistical and sampling techniques to discrim- inate among multiple stressors (e.g., climate and land use) and among anthropogenic and natural stressors, 2) mechanistic and empirical models linked to multi- sensor systems, 3) cross-sensor integration to expand the temporal and spatial density of data collection, and, 4) sustained communication between researchers and managers to ensure rapid deployment of mitigation and adaptation strategies.

Seems pretty simple, but very difficult.

Summary:

Overall a great paper that provides a wealth of information on how and what has been done with regards to landscape studies in aquatic ecosystems. I would deem this paper essential for anyone doing work on aquatic-terrestrial linkages.

Johnson, L.B. and G.E. Host (2010). Recent developments in landscape approaches for the study of aquatic ecosystems Journal of the North American Benthological Society, 29 (1), 41-66 : 10.1899/09-030.1