Social Goals and the Valuation of Ecosystem Services. Costanza 2000
A good read, although I disagreed with most things. There are a few interesting statements which I think are worth considering.
First, the paper makes the arguement that valuation of ecosystem services is inevitable, and all choices can be evaluated via projection of relative value (i.e. we choose x over y, therefore x is more valuable than y). I disagree. That is the dominant economic paradigm of our society (both now and historical). But it's not impossible to think of other thought paradigms where this inevitable tradeoff doesn't occur. It's not that choices are not made, but they are not seen in the same light. Therefore, the thought of "inevitable valuation" doesn't even occur. For example, if you don't care between two outcomes, than there's no assumption of value necessary. Or, if you are at state A and are choosing to either transform A to B or leave A alone, you could just consider it a transformation, not a tradeoff.
Building Lego's (should I build an airplane or a boat?) doesn't require a choice between the two based on value, because the inherent thing isn't changed, just altered. The assignment of value is a Western paradigm, and sure, it can be applied to every situation. But so could a paradigm based on choosing whatever option was mentioned first, or options whose title comes first in the alphabet. Those are silly, but they are still options.
I am annoyed with this "let's take this paradigm for granted," because once you start down the valuation path, ecosystems lose. Maybe not today, maybe not tomorrow, but soon... they lose. Today, wetlands purify our water cheaper then we can. But tomorrow, we invent a new technology which purifies water cheaper. All of a sudden, those wetlands have lost value. And putting astetic value (in terms of money) on ecosystems, or even moral value, will only fail in the long run- conservation is a luxury of the rich, as many have said, and people will always choose food over furry friends (and let's be honest, bringing the whole world to our level of luxury won't happen. even if it does, we'll want more, and the problem will begin all over again).
Later, the author says "valuation ultimately refers to the contribution of the item to meeting a specific goal or objective," and "one cannot state a value without stating the goal being served." So without a goal, something has no value? This is a very user-centered view of the world, which is what got us into this mess in the first place.
He argues "the decisions we make, as a society, about ecosystems imply valuations." Sure, according to the paradigm of "everything is a tradeoff between two values." But I think that thought process is what gets us into trouble in the first place. The philosophy of assigning values moves easily into saying "well, this place is nice, but I can make money building condos. I'll just donate to the Sierra club and conserve through them." Thinking in terms of valuation leads to only thinking in the present tense (and one time step ahead). It's all now- you choose between two options now.
Perhaps thinking in terms of place would work better. Thinking in terms of place doesn't assign value (although the valuation paradigm can be imposed on it, of course). Thinking in terms of place assigns consequences. It's not inherently a tradeoff between a human affected environment and a "pristine natural environment," it's just the environment and how it's changed. This leads to longer term thinking- if I do x, and want to do y later, is that possible? How should I structure x so that y is possible in 10 years?
I (being a good Western thinker in the tradition of the liberal arts) assign value unconsciously, as do most people around me. But our society has REALLY screwed up the planet we're supposed to steward- so perhaps that paradigm needs rethinking. I assign great moral value to "unspoiled lands," although even that term implies valuation. But somebody else sees unlimited development, or great beauty in a golf course. The vaguries of human perceptions of beauty are such that eventually, all land will be in control of somebody that thinks it will look better as a community rec center, and our development is far easier carried out then undone. If we rely on valuation to save landscapes, we're going to lose.
Wednesday, January 21, 2009
Climate change and range shifts
Predicting climate-induced range shifts: Model differences and model reliability. Lawler et al, 2006
Modeling! Modeling in R, which is more impressive. This is a great paper- not in terms of being particularly interesting, or revolutionary, but in terms of usefulness. There needs to be more papers like this, a straightforward comparison between modeling approaches using the same data, so relative errors, types of errors, etc can all be directly seen. The researchers take 100 different mammal species present in and around Brazil, and model their current distribution based on nine climate variables and one land cover variable- basically the inputs for most climate change scenarios. Then, they compare the results to actual distributions. Fun.
There are some interesting results. Random forest models were far and away the best. Genetic algorithms were second place, although they had problems with errors of commisson. Other models, like classification trees, GAMs, etc did relatively worse. I'd hypothesize that random forests did better specifically because they sampled from the 10 inputs with replacement, meaning they randomlly added weights to the various factors, so there was an added feature that neural networks and the other machine learning algorithms didn't have.
But, like all models, they have their problems, which follow.....
Prediction of plant species distributions across six millenia. Pearman et al, 2008.
This is a more applied study, where Pearman and friends attempt to model tree species in Europe. For a twist, they model from 6000 BP to now, 6000 BP only, and now only, in an attempt validate future predictions (using past climate records and pollen finds). Their main finding was that some species are modeled quite well, and others not so well- the ones which came out winners are dominant competitors for light. This makes perfect sense, and highlights the main limitation of this study, Lawler's, and most other species distribution models I've seen (and they readily admit to this limitation as well). Light competition is the only way in which most plants experience biotic constraints on their distribution. Most plants don't interact directly, especially these trees, beyond the race for good spots in the canopy. Thus, species which are competitively dominant won't really experience biotic controls on their distribution, because wherever they live, they win. Species which are not competitively dominant will experience this biotic limit to their range, and therefore models which don't take biotic factors into account won't be as accurate.
A second limition is both assume that species are at current equilibria with respect to their distribution. But the Johnstone article (reviewed earlier) indicates that some species are still expanding their range, invalidating this assumption.
Pearman also mentionsthe possibility of rapid niche shifts, which I don't know much about, but which would also invalidate predictions into the future.
Modeling! Modeling in R, which is more impressive. This is a great paper- not in terms of being particularly interesting, or revolutionary, but in terms of usefulness. There needs to be more papers like this, a straightforward comparison between modeling approaches using the same data, so relative errors, types of errors, etc can all be directly seen. The researchers take 100 different mammal species present in and around Brazil, and model their current distribution based on nine climate variables and one land cover variable- basically the inputs for most climate change scenarios. Then, they compare the results to actual distributions. Fun.
There are some interesting results. Random forest models were far and away the best. Genetic algorithms were second place, although they had problems with errors of commisson. Other models, like classification trees, GAMs, etc did relatively worse. I'd hypothesize that random forests did better specifically because they sampled from the 10 inputs with replacement, meaning they randomlly added weights to the various factors, so there was an added feature that neural networks and the other machine learning algorithms didn't have.
But, like all models, they have their problems, which follow.....
Prediction of plant species distributions across six millenia. Pearman et al, 2008.
This is a more applied study, where Pearman and friends attempt to model tree species in Europe. For a twist, they model from 6000 BP to now, 6000 BP only, and now only, in an attempt validate future predictions (using past climate records and pollen finds). Their main finding was that some species are modeled quite well, and others not so well- the ones which came out winners are dominant competitors for light. This makes perfect sense, and highlights the main limitation of this study, Lawler's, and most other species distribution models I've seen (and they readily admit to this limitation as well). Light competition is the only way in which most plants experience biotic constraints on their distribution. Most plants don't interact directly, especially these trees, beyond the race for good spots in the canopy. Thus, species which are competitively dominant won't really experience biotic controls on their distribution, because wherever they live, they win. Species which are not competitively dominant will experience this biotic limit to their range, and therefore models which don't take biotic factors into account won't be as accurate.
A second limition is both assume that species are at current equilibria with respect to their distribution. But the Johnstone article (reviewed earlier) indicates that some species are still expanding their range, invalidating this assumption.
Pearman also mentionsthe possibility of rapid niche shifts, which I don't know much about, but which would also invalidate predictions into the future.
Thursday, January 15, 2009
RS and N (no weeds)
Canopy nitrogen, carbon assimilation, and albedo in
temperate and boreal forests: Functional relations
and potential climate feedbacks
S. V. Ollinger, et al.
Another remote sensing paper, and it continues on with my recent readings in foliar nitrogen. The researchers use AVIRIS (and a little Hyperion, where necessary) to estimate foliar nitrogen levels over a few landscapes in temperate/boreal forests scattered over Canada. I received this paper after emailing S. Ollinger himself about some AVIRIS work he's doing, and he graciously sent me this along with a few thoughts... but back to the paper. They found a strong relationship between measured foliar N and reflectance across most of the NIR spectrum- cool, because that means you can get foliar N estimates from other (read: free) sensors. To quote directly:
"Collectively, these results suggest that we already have a basis
for detecting variation in %N and CAmax of forest canopies at
continental scales by using scaled relationships with albedo
and/or simple measures of NIR reflectance obtained during the
peak period of the growing season."
Then, they tie the N measurements to carbon fixation, using flux towers (through BOREAS sites I assume; I believe that's where the imagery is). All well and good.
My thoughts, to tie into the previous post, are about using this foliar N to potentially address biodiversity levels, potential for invasion, and perhaps even invasion monitoring (I don't know a lot of biogeochemistry, so hopefully I don't say something dumb at this point, but I'll try anyway). Would higher biodiversity sites (in the understory: say vascular plants, or invertebrates, or whatever) also have higher foliar N in the overstory? I would imagine so, given simple things like nutrient availability, more potential niches, etc. Would invasive species be reflected in the overstory N (either via nitrogen fixation themselves, like Scotch broom or sea buckthorn, or by exclusion of other nitrogen fixing plants, see previous post)? To speculate further (what fun!), what would the edge of higher nitrogen zones look like? If you look at the map in the paper, there's a lot of heterogeneity in the foliar nitrogen levels across forests- so... could any sort of meta-population/meta-community dynamics be happening across that edge?
temperate and boreal forests: Functional relations
and potential climate feedbacks
S. V. Ollinger, et al.
Another remote sensing paper, and it continues on with my recent readings in foliar nitrogen. The researchers use AVIRIS (and a little Hyperion, where necessary) to estimate foliar nitrogen levels over a few landscapes in temperate/boreal forests scattered over Canada. I received this paper after emailing S. Ollinger himself about some AVIRIS work he's doing, and he graciously sent me this along with a few thoughts... but back to the paper. They found a strong relationship between measured foliar N and reflectance across most of the NIR spectrum- cool, because that means you can get foliar N estimates from other (read: free) sensors. To quote directly:
"Collectively, these results suggest that we already have a basis
for detecting variation in %N and CAmax of forest canopies at
continental scales by using scaled relationships with albedo
and/or simple measures of NIR reflectance obtained during the
peak period of the growing season."
Then, they tie the N measurements to carbon fixation, using flux towers (through BOREAS sites I assume; I believe that's where the imagery is). All well and good.
My thoughts, to tie into the previous post, are about using this foliar N to potentially address biodiversity levels, potential for invasion, and perhaps even invasion monitoring (I don't know a lot of biogeochemistry, so hopefully I don't say something dumb at this point, but I'll try anyway). Would higher biodiversity sites (in the understory: say vascular plants, or invertebrates, or whatever) also have higher foliar N in the overstory? I would imagine so, given simple things like nutrient availability, more potential niches, etc. Would invasive species be reflected in the overstory N (either via nitrogen fixation themselves, like Scotch broom or sea buckthorn, or by exclusion of other nitrogen fixing plants, see previous post)? To speculate further (what fun!), what would the edge of higher nitrogen zones look like? If you look at the map in the paper, there's a lot of heterogeneity in the foliar nitrogen levels across forests- so... could any sort of meta-population/meta-community dynamics be happening across that edge?
Remote Sensing and Weeds
Remote analysis of biological invasion and biogeochemical change
Gregory P. Asner and Peter M. VitousekMore weeds, this time over to Hawaii for my favorite tree, Myrica faya (I believe it was recently renamed, because I learned it as M. faya and then was told there was a new name, but can't remember it). One of my favorites because the wood isn't super dense, and it's hackable with a machete when doing invasive species control.
Regardless, it's a nitrogen fixing invasive, and the Asner/Vitousek study looks at using foliar N as measured via AVIRIS to detect M. faya prior to it's domination of the canopy. It works, quite well. And for another note, they also found they could detect another invasive, a ginger (and not a fun thing to attempt to control), via water content measurements from AVIRIS- and it's an understory plant. This is a slight vindication for me, since I heard that something like this was possible from Greg in Hawaii, but when taking remote sensing back in Washington later, was told that sensing anything below the canopy wasn't possible. Awsome, it's in print.
This has me thinking: Scotch broom is another invasive species, nitrogen fixing, present in the west and up into BC and Alaska. While I don't think it makes it to the canopy, I wonder if you can detect it's presence via overstory N levels, especially since foliar N seems to be pretty low in most of our forests. The next review has a paper which also inspires that thought....
Fire! Weeds!
Fire and invasive species within the temperate and boreal Coniferous forest of western North America
RJ Harrod, S Reichard - Proceedings of the Invasive Species Workshop, 2000 - jfsp.nifc.gov
Ah, fire. The ubiquitous disturbance that northern forests deal with on a regular basis, and one of the few bringers-of-heterogenity which can be relied on to make things interesting, especially where invasive species are concerned. This paper gives a general overview of the ways that weeds exploit fire for spread, through several potential life strategies. Not a bad review. Of interest are some reviews of fire regimes to kill of invasive species (3 years of early fires to kill yellow starthistle, for instance (although they also mention that early fires are thought to kill Canadian thistle, which in my experience is invincible)).
The later parts of the paper lapse into a discussion of potential influences on the fire regime itself by invasives- namely Bromus tectorums increase of the fire cycle (well evidenced) and spotted knapweeds decrease of the fire cycle (is there evidence for that?).
On another note, I think it might be useful to not think of invasive species as "special," since they invade a post-fire environment just like any other species- it's just that they nearly always win the colonization race, and then (potentially) control the site in perpetuity. Perhaps they are playing with a stacked deck, since they might have gotten some enemy-release help, but the mechanics are often the same.
RJ Harrod, S Reichard - Proceedings of the Invasive Species Workshop, 2000 - jfsp.nifc.gov
Ah, fire. The ubiquitous disturbance that northern forests deal with on a regular basis, and one of the few bringers-of-heterogenity which can be relied on to make things interesting, especially where invasive species are concerned. This paper gives a general overview of the ways that weeds exploit fire for spread, through several potential life strategies. Not a bad review. Of interest are some reviews of fire regimes to kill of invasive species (3 years of early fires to kill yellow starthistle, for instance (although they also mention that early fires are thought to kill Canadian thistle, which in my experience is invincible)).
The later parts of the paper lapse into a discussion of potential influences on the fire regime itself by invasives- namely Bromus tectorums increase of the fire cycle (well evidenced) and spotted knapweeds decrease of the fire cycle (is there evidence for that?).
On another note, I think it might be useful to not think of invasive species as "special," since they invade a post-fire environment just like any other species- it's just that they nearly always win the colonization race, and then (potentially) control the site in perpetuity. Perhaps they are playing with a stacked deck, since they might have gotten some enemy-release help, but the mechanics are often the same.
Monday, January 12, 2009
Long overdue!
It's been a month! Ridiculous. But I've read quite a bit over the break, since Audrey and I stayed in Boulder and most other people didn't- it's been nice and relaxing. I'll just list a bunch of the highlights....
Books: Alaska's Changing Boreal Forest (an LTER book). Stuart Chapin, et al.
Great resource. Balances hard science with good writing, which doesn't seem to be very common in books. Very interesting, especially the parts related to forest and permafrost dynamics. They have quite a bit on successional communities, but nothing on any multiple disturbance sites. Also has some interesting info on fire patterns in Alaska. Quite well cited, no real complaints.
Canada's Boreal Forest, J. D. Henry, Smithsonian Press.
A lighter read, more literary, but still cited and grounded. I read through it expecting a little more ecology, but the strength of the book really lies in the cultural issues associated with resource extraction and climate change. Light enough to read for a break from the LTER book, so it was a nice complement. Not a resource for research, however.
Some papers:
Development of a large area biodiversity monitoring system driven by remote sensing. Duro et al. 2007. Progress in Physical Geography
-More of a project proposal, these folks are trying to get a system set up for monitoring northern Canada (and Alaska, basically) for changes in biodiversity, disturbance patterns, etc. It's not entirely a clear proposal, and it seems more like an idea-sheet than an actual plan at this point. I'm going to reread it and see what else I can get out of it after the first read.
Non-equilibrium succession dynamics indicate continued northern migration of lodgepole pine. Johnstone and Chapin, 2003. Global Change Biology.
-An interesting proposal. They argue that lodgepole pines are still moving north post-glacial period. There's a couple interesting thoughts about this- anthropogenic climate change isn't the driving force behind lodgepole's movements north, and most models are based on static assumptions (the pines live where the pines can live), but if the distribution is moving north and that movement is not tied to a changing climate, then those assumptions are incorrect. (They also assume that plant species migrate individualistically, which I disagree with. Plants migrate according to their local and distributional environment- they move to where they can live. But a plants potential habitat is not just the abiotic factors like temperature and climate, which this paper and most other models assume, a plant's potential habitat must also take into account the biotic factors too. In other words, plants may TRY and migrate individualistically, but their success is tied to a community migrating (or a suitable, but different, community existing elsewhere)). Another issue with their conclusion is the potential for some source-sink population effects going on- there's not any evidence presented which shows that these new stands of lodgepole springing up after disturbance in spruce forests are going to survive, reproduce, and spread the species north- could be a sink population, or a less viable population anyway, leading to a more ragged edge to lodgepole distribution but not necessarily a moving-north distribution.
Extending community ecology to landscapes. Urban, et al. 2002. Ecoscience.
-Decent paper which explores sampling problems related to doing community ecology on a landscape level. All in all, they look into some interesting ways to calculate sample sites and sample number, including randomized ideal with planned sites to match that ideal on a logistically possible level.
Biogeography and landscape ecology. M. Kent. 2007. Progress in Physical Geography.
Landscape ecology: What is the state of the state. M. Turner. 2005. Ann. Rev. Ecol. Evol. Sys.
There were/are many more, but I'll leave those for now.
Any recommendations?
Books: Alaska's Changing Boreal Forest (an LTER book). Stuart Chapin, et al.
Great resource. Balances hard science with good writing, which doesn't seem to be very common in books. Very interesting, especially the parts related to forest and permafrost dynamics. They have quite a bit on successional communities, but nothing on any multiple disturbance sites. Also has some interesting info on fire patterns in Alaska. Quite well cited, no real complaints.
Canada's Boreal Forest, J. D. Henry, Smithsonian Press.
A lighter read, more literary, but still cited and grounded. I read through it expecting a little more ecology, but the strength of the book really lies in the cultural issues associated with resource extraction and climate change. Light enough to read for a break from the LTER book, so it was a nice complement. Not a resource for research, however.
Some papers:
Development of a large area biodiversity monitoring system driven by remote sensing. Duro et al. 2007. Progress in Physical Geography
-More of a project proposal, these folks are trying to get a system set up for monitoring northern Canada (and Alaska, basically) for changes in biodiversity, disturbance patterns, etc. It's not entirely a clear proposal, and it seems more like an idea-sheet than an actual plan at this point. I'm going to reread it and see what else I can get out of it after the first read.
Non-equilibrium succession dynamics indicate continued northern migration of lodgepole pine. Johnstone and Chapin, 2003. Global Change Biology.
-An interesting proposal. They argue that lodgepole pines are still moving north post-glacial period. There's a couple interesting thoughts about this- anthropogenic climate change isn't the driving force behind lodgepole's movements north, and most models are based on static assumptions (the pines live where the pines can live), but if the distribution is moving north and that movement is not tied to a changing climate, then those assumptions are incorrect. (They also assume that plant species migrate individualistically, which I disagree with. Plants migrate according to their local and distributional environment- they move to where they can live. But a plants potential habitat is not just the abiotic factors like temperature and climate, which this paper and most other models assume, a plant's potential habitat must also take into account the biotic factors too. In other words, plants may TRY and migrate individualistically, but their success is tied to a community migrating (or a suitable, but different, community existing elsewhere)). Another issue with their conclusion is the potential for some source-sink population effects going on- there's not any evidence presented which shows that these new stands of lodgepole springing up after disturbance in spruce forests are going to survive, reproduce, and spread the species north- could be a sink population, or a less viable population anyway, leading to a more ragged edge to lodgepole distribution but not necessarily a moving-north distribution.
Extending community ecology to landscapes. Urban, et al. 2002. Ecoscience.
-Decent paper which explores sampling problems related to doing community ecology on a landscape level. All in all, they look into some interesting ways to calculate sample sites and sample number, including randomized ideal with planned sites to match that ideal on a logistically possible level.
Biogeography and landscape ecology. M. Kent. 2007. Progress in Physical Geography.
Landscape ecology: What is the state of the state. M. Turner. 2005. Ann. Rev. Ecol. Evol. Sys.
There were/are many more, but I'll leave those for now.
Any recommendations?
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