Lost and found (12 May 2016)

Back in 1995, the Las Cruces District Office botanist, Laird McIntosh, was out botanizing on the east side of the Organ Mountains, in Rock Springs Canyon. He collected a few plants, one of which was an inconspicuous little member of the carrot family (Apiaceae) that he identified as Spermolepis echinata. At that time, Spermolepis echinata was the only Spermolepis known to occur in this part of New Mexico. Another one, Spermolepis divaricata, was known to occur in Eddy County, in the southeastern corner of the state. Since Eddy County is outside of Las Cruces District, I will ignore the plants of Eddy County in the following. In any case, here’s his specimen:

That specimen sat in the New Mexico State University Herbarium (NMC) for 15 years or so. Then Guy Nesom, of the Botanical Research Institute of Texas, decided to study Spermolepis. He got specimens on loan from most of the major herbaria in the southwestern U.S., including NMC. He published the results of his research in 2012, and you can read his paper here. Nesom made a few changes in the taxonomy of Spermolepis, two of which are relevant to us. First, he concluded that Laird McIntosh’s specimen was a new species, which he named Spermolepis organensis. That lone plant on the sheet was the only known individual of this species when Nesom published his work. Second, he separated Spermolepis echinata into two species: Spermolepis echinata and Spermolepis lateriflora. All the New Mexico specimens–except Laird’s from Rock Springs Canyon, of course–were assigned to Spermolepis lateriflora. Now Spermolepis echinata, which we had thought to be the only Spermolepis in Las Cruces District, was not known to occur anywhere in New Mexico.

Here’s what Spermolepis lateriflora looks like:

There are a couple of clear differences between Spermolepis lateriflora and Spermolepis organensis. The fruits of Spermolepis lateriflora have hooked hairs, while those of Spermolepis organensis are glabrous. Spermolepis lateriflora has sessile umbels, while Spermolepis organensis has pedunculate umbels. So, morphologically it’s clear enough. However, naming a new species based on a single specimen is a bit risky. Maybe this was just one odd individual rather than a species.

Following the publication of Nesom’s paper, a few New Mexico botanists went out to look for Spermolepis organensis at Rock Springs Canyon where Laird McIntosh collected it. Ken Heil and Dave Anderson went out there in 2013. I joined them for another search in 2014. Jeanne Tenorio and I looked for it again in 2015. None of us found it. We found a few Spermolepis, but nothing with the glabrous fruits of Spermolepis organensis. Repeating the search was on my to-do list this year, but I was beginning to suspect Laird’s plant was just a one-off with anomalous morphology.

Before I got the chance to go out and look for Spermolepis organensis, I was out on the northeast side of the Organ Mountains, a couple of miles north of Rock Springs Canyon, to collect seeds. A friend of mine, Gregory Penn, joined me. We made a Seeds of Success collection of Phacelia coerulea. I’m allergic to this species, and it causes rashes very much like poison ivy. Most people have no reaction to Phacelia coerulea and other members of the genus, but a lucky few of us do. In hindsight, doing a seed collection of it was a bad idea. Of course, it’s not just hindsight. I knew it was a bad idea at the time and did it regardless. In any case, before we started collecting seeds, only a few steps out of the truck I noticed that Spermolepis was abundant. Some of it was Spermolepis lateriflora, but I knew immediately that some of it was not. There were many plants that had no hooked hairs on their fruits. I wasn’t sure these were Spermolepis organensis, though. Perhaps I was mistaking another genus for Spermolepis. For instance, perhaps they were Cyclospermum leptophyllum, another inconspicuous little carrot. So I took some photographs and collected some specimens. Both Spermolepis lateriflora and this other little carrot were abundant throughout the area where we collected Phacelia coerulea.

After reviewing Nesom’s work and looking at my specimens under a dissecting microscope, I became certain the plants without hooked hairs on their fruits were indeed Spermolepis organensis. So, Laird’s plant was not an oddball. Spermolepis organensis is out there, easily identifiable from morphology, and locally abundant. Our earlier fruitless searches, I guess, resulted from looking for them when moisture conditions weren’t quite right. Or perhaps it only occurs sporadically at Rock Springs Canyon, and is more reliably found a bit to the north. In any case, here’s what it looks like:

Once I knew we had found Spermolepis organensis, I decided I needed to go back out there, look at more of them, collect a few more specimens so I could send duplicates to various regional herbaria, and visit a few more sites to get a better idea of its distribution in the area. I was also hoping to get some more pictures, of both Spermolepis organensis and Spermolepis lateriflora, but it was very windy. I went back another week later for pictures and it was, again, very windy. Oh well. I eventually got some decent pictures in spite the wind. During these revisits of the area, I noticed that there seem to be three Spermolepis species out there. One, with sessile umbels and hooked hairs on the fruits, is Spermolepis lateriflora. One, with pedunculate umbels and glabrous fruits, is Spermolepis organensis. The third has pedunculate umbels and hooked hairs on the fruits. I collected specimens of all three and, again, I needed to review Nesom’s work and look at my specimens under a dissecting microscope. It turns out that the third Spermolepis is Spermolepis echinata. Here’s what it looks like:

I guess this is the story of how a plant that was identified as Spermolepis echinata, but wasn’t, led in a roundabout way to the discovery of Spermolepis echinata in New Mexico. Our knowledge moves forward, more or less, but takes a few odd turns and relies on some happy accidents along the way.

Where I’ve been in the past year (19 Jan 2016)

Last year about this time, my post was a map of where I’d been in the past year. I couldn’t think of a better idea then, and I can’t think of one now, so here we go again.

I’ve highlighted the counties of the Las Cruces District Office in red. Each of those blue dots is a place where I’ve taken a picture and recorded what plants were there. About a third of those dots are places I visited as part of my CLM internship, the rest are mostly recreational botanizing. I continue to move slowly towards my goal of having been everywhere in southwestern New Mexico, but do not anticipate achieving that goal any time soon. That’s good. If I thought I knew what was going on, I would be wrong and it would be time to move elsewhere. For instance, at this time last year I had visited 174 of the LCDO’s 608 grazing allotments. Now I have visited 250 of them. So, closing in one half-way for that particular metric. In the last few weeks I’ve decided to wander around northwestern Luna County for no particular reason. It’s nice out there.

And, recently, I came across a mysterious Cylindropuntia. I couldn’t identify it, so I sent the pictures out to folks who might. According to Marc Baker, it is Cylindropuntia davisii, a species I had not seen before that has been very rarely recorded in southwestern New Mexico.

It’s kind of an unpleasant little cactus, but interesting. And, repeating a theme from my earlier posts here… you wouldn’t find it unless you’re walking around out there for a while, and why would you do that? Well, why not?

Fun with Sphaeralcea (30 Dec 2015)

Sphaeralcea is, in many ways, a wonderful genus. It is found throughout the western United States, it’s pretty, pollinators like it, herbivores like it, it germinates well and is easy to cultivate, and thus it is one of the few native genera that is readily available commercially for restoration use. However, if you’ve tried to identify them you are probably painfully aware that, although the genus is very easy to identify, species within it are an awful muddled mess. Part of the problem is that, despite how ubiquitous and important Sphaeralcea is, taxonomists have avoided it like the plague. There has been no significant taxonomic research on Sphaeralcea since 1935. At that time, of course, there were relatively few herbarium specimens available and taxonomic techniques were rather crude, consisting essentially of “stare at plants for a long time and guess”. That approach seems to work dramatically better than it has any right to, and is still used, but in many genera it just won’t get you there.

I don’t have any insight to provide in solving the problem of Sphaeralcea taxonomy, so this is mostly just a plea for some hapless graduate student to sink into this particular mire. I do have some photographs and a pdf, though.

One of the Sphaeralcea I’ve been confused by this season is shown below. I had hoped to collect seed of this species, but phenology did not cooperate.

Those of you who are familiar with Sphaeralcea will probably think that this looks an awful lot like Sphaeralcea coccinea. That’s what I thought, too, and I’ve misidentified these in the past as Sphaeralcea coccinea. However, the anthers are dark and there is a well-developed epicalyx, neither of which is compatible with that species. Other possibilities that might come to mind are Sphaeralcea digitata, Sphaeralcea grossulariifolia (this was my next best guess once I decided it wasn’t Sphaeralcea coccinea), or Sphaeralcea laxa. However, there are various features, which I won’t go into here, that will eventually lead you to believe it cannot be any of those species. What will not occur to you, or at least didn’t occur to me, is that this could be Sphaeralcea hastulata, a species that has narrow, shallowly lobed leaves and pale anthers. But that is, apparently, what it is, at least in recent floristic works.

My plants are a very good match for the type specimen of Sphaeralcea pumila, a species named by Wooton and Standley back in 1909. You can see that type specimen here. Since 1909, that species has been moved to Sphaeralcea subhastata subsp. pumila, then Sphaeralcea subhastata var. pumila, and more recent floras will simply list Sphaeralcea subhastata, and by inference Sphaeralcea pumila along with it, as a synonym of Sphaeralcea hastulata without any further explanation. So, my plants are the same taxon as the type of Sphaeralcea pumila, therefore they are Sphaeralcea hastulata even though they don’t look like it and won’t go there in the key. Part of the problem here is that, as I mentioned before, there hasn’t been any significant taxonomic research on Sphaeralcea in the last 80 years. The best published work on the genus is still Thomas H. Kearney’s “The North American Species of the Genus Sphaeralcea Subgenus Eusphaeralcea“, published as an issue of the University of California Publications in Botany in 1935. Kearney calls this plant Sphaeralcea subhastata subsp. pumila. I tried for a little while to figure out why someone decided to dump Sphaeralcea subhastata and all its subspecies into Sphaeralcea hastulata, but I didn’t get anywhere. This is what happens to genera that go without research, subsequent botanists poke around a little, move some names, and generally muddy the waters in a piecemeal fashion, and there’s rarely any clear, easy-to-find record of who made what decision and why. However good or bad the last big treatment of the genus was, over time our understanding gets worse. And, of course, Kearney’s 1935 work isn’t carried by too many libraries (New Mexico State University’s library system doesn’t have it) and isn’t available online. Luckily, you can still buy old copies for a reasonable price. Some out-of-print botanical works are exorbitantly expensive, but I found Kearney’s for $20 or so, which isn’t too bad. Since it is still the best taxonomic treatment of Sphaeralcea in North America, I bought a copy and turned it into a pdf. I can never get paper books to be where I need them, when I need them. Pdfs are easier, I just stick them on my phone. If you like you can download it here. I’ll see if I can get it onto Biodiversity Heritage Library, too, but it isn’t there yet. It’s amazing how much you can find online these days. Also, I checked, and this work is not under copyright.

Can we find rare plants? (13 Nov 2015)

Well, yes, we can find rare plants. The question really is: How many of the rare plants that are present in an area can we find? That doesn’t fit as well in the post title box, though.

One of the nice things about studying plants is that they are much more cooperative than animals. They don’t hide from you, run away, have large home ranges, or migrate. For those of us trying to survey them and map their populations, this is convenient. Nonetheless, not all plants are easy to find. There is basically a spectrum of survey-friendliness in plants. At one end, we might have something like Sequoia sempervirens: it’s big, easy to spot and easy to identify, and it lives for a very long time. At the other end, we might have something like Euphorbia rayturneri: it’s tiny, hard to spot, you can’t ID it without a hand lens, and it’s ephemeral. You can’t really find it at all unless weather conditions are right, and even under ideal conditions it’s going to be difficult to pick out from any distance or distinguish from the other prostrate spurges that are common in the area. Most plants, particularly in desert areas, are going to have at least one of these characteristics that make surveys difficult. So, today I’m going to give a brief example using one of the species I’ve already discussed several times on here: Peniocereus greggii var. greggii. For a desert plant, it’s reasonably large, generally 1 to 3 feet high. It’s easy to identify. It’s pretty long-lived. It is hard to spot, however. Here’s a large plant, pretty unobscured:

And here’s what you’re more often dealing with–a cactus hiding inside a shrub:

So, let’s suppose you’re surveying an area to ensure that some upcoming project won’t harm our peniocerei. What kind of detection rate is achievable? And, given that detection rate and some understanding of the density and spatial patterns of Peniocereus greggii var. greggii populations, how many individuals can we expect to harm simply because we couldn’t find and avoid them? Those are difficult problems and, instead of trying to answer them in any kind of rigorous fashion, I’ll just provide some anecdotes. We have three populations of Peniocereus greggii var. greggii that were thoroughly surveyed back in 2012, and for which previous CLM interns began a monitoring study in 2013. They’re just about our best case for high detection rates.

This year, my interns and I went out and remeasured plants in two of these populations (Steins and Swallow Fork). In the third (Big Cat), I went out back in May with several other botanically-inclined folks kind of poking around (I was just hoping to find plants in flower, and luckily I did!). In all cases, we found new plants. In the Big Cat population, three of us were wandering around for two or three hourse, mostly checking on previously-known individuals. We found ten new plants in an area where 32 were previously known. For the Swallow Fork population, we found 12 new individuals where 26 were known previously. In the Steins population, we found 58 new individuals, where 113 were previously known. So these put very approximate upper bounds on the detection rate in previous survey, somewhere around 67%. I’m sure if we had done full surveys in each of these areas, we would have kept finding more individuals, so the actual detection rate is probably substantially lower. Now here’s the interesting thing: many of these new individuals we found were right next to previously known plants! It was fairly common, in all three populations, for us to be looking for one of the previously GPSed plants, have a little trouble finding it, and stumble across another plant a few meters away. In all but a couple of cases we were eventually able to find the original GPSed plant, so it’s not just some kind of GPS error. Here are a couple of maps of of portions of the Steins and Swallow Fork populations to illustrate–notice the scale at bottom left, we’re dealing with pretty small areas:

Often, the previously known plants were in worse shape and harder to find than the “new” plants. So, how did the original survey crew find those beatup, unhappy plants while often missing a big healthy Peniocereus a few meters away? Well, they almost certainly didn’t. There’s a very simple explanation that wouldn’t have occurred to me. Drs. Ed and Beth Leuck mentioned to me about a year ago that Peniocereus greggii var. greggii that they’ve been monitoring seem to die back to the ground every now and then, particularly after flowering. Oh yeah, I forgot to mention: these guys have big honking tubers. So they can die back to ground level, then pop back up next year. This is very odd for a cactus. It’s also pretty odd for a tuberous plant. Most tuberous plants, at least in our climate, don’t have woody above-ground stems that persist for a few years. So we’re dealing with a tuberous cactus that has somewhat ephemeral stems. After the stems die back, they are incredibly difficult to spot. You can be within a meter of a GPSed individual and still poke around for five minutes until you find that one dead stem that isn’t like the others. So, as a cactus, you would think that one of the things Peniocereus greggii var. gregii has going for it is that you’re dealing with a long-lived plant that is basically going to be where it is and be findable over long periods of time. Nope. So that moves it a notch or two away from the survey-friendly end of the plant spectrum. I guess the moral of the story here is just that, even though plants are easier to keep track of than animals, they’re still kind of a pain. And most plants are probably going to have some weird quirks like Peniocereus, you just won’t know about the quirks until you’ve spent some time with a particular species.

Now a few miscellaneous pictures.

Is it a legume? No, it’s a spurge, Phyllanthus abnormis!

And here’s a Pituophis catenifer sayi who was not pleased to see me:

Also thinking about fire (12 Oct 2015)

Unlike many folks in the BLM and in the CLM intern program, I live in a place that basically doesn’t burn. Natural fires are extremely rare in the Chihuahuan Desert, although relatively common in the nearby mountains (mostly USFS lands) and occasionally dropping down to the higher, pinyon/juniper portions of the Las Cruces District Office. There are sometimes anthropogenic fires, particularly along the interstates, but these are generally quite small. Neighboring Fort Bliss occasionally starts unintentional fires in the Organ Mountains. We’ve done some prescribed burns, and can generally get a good blaze going up in the pinyon/juniper. Prescribed burns at the lower elevations, in the Chihuahuan Desert that makes up most of LCDO, haven’t been as successful. The more densely-vegetated draws can burn OK, but otherwise the landscape just doesn’t seem to have the fuel load to carry a fire. So far as I can tell, natural fires are basically unknown. We don’t know if they ever played an appreciable role in Chihuahuan Desert ecology or how the landscape reacts to a natural fire. Interestingly—and diametrically opposed to the prevailing view that fires reduce or exclude woody plants while promoting grasses—the few studies on the effects of prescribed burns in the Chihuahuan Desert indicate that the opposite is true. Our grasses are less resilient to fire than our shrubs. So all that’s the long way of saying that I was a bit excited when one of my interns and I drove out to a seed collection site at Aguirre Spring on the northeastern side of the Organ Mountains… and saw this on the way:

This is, to our understanding, a natural fire ignited by lightning. There was a big thunderstorm system on 3 Oct 2015, but this area did not receive rain. This fire burned a pretty small area, 70-80 acres, and went out when the rain arrived the next day. So far as I can recall, this is the only natural burn on LCDO land that I’ve seen in the 11 years I’ve been in Las Cruces. So, we postponed the seed festivities a bit and I got some photo points—that one above, and these two:

For each, I’ve got the photo and a list of all identifiable plants within a 10 m radius. Hopefully I’ll be able to revisit these over the next few years and see what happens. And, no, the third one didn’t burn. We can pretend it’s a control.

Here’s a view of the whole burn area, seen from the Aguirre Spring picnic area:

So that’s probably not too exciting to most of you: “Yup, that’s a little burn.” To me, though, it’s pretty awesome. I have a rare chance to watch the response to a natural fire in a place that basically doesn’t burn.

Once we got to poking around at seeds around Aguirre Spring, we found that one of my nemeses thus far, Setaria leucopila, actually had seeds. I mentioned in my last post that I’d checked multiple populations of this species that had well-developed, mature inflorescences, but no seeds that I could find (not “very few”, but “none”, “nada”, “zilch”, “bupkus”). Well, this one still had an unimpressive seed set rate, about 1 in 10 fertile florets actually contained a caryopsis. But there’s plenty of it up there, so we collected around 400,000 of those fertile florets and we should be OK. Here’s the collection site:

And here’s Setaria leucopila:

Fertile florets (top) and caryopses (bottom; grass terminology: a caryopsis is a fruit with a single seed and the ovary wall highly reduced and adherent to the seed; non-agrostologists usually just call the whole thing a “seed”):

I enjoy photography and particularly like having an excuse to take macro photographs of plant bits that we don’t usually see. So I’ve been appreciating the SOS dictum to take pictures of the seeds we collect. I probably go a bit overboard. Also, some of these grass caryopses are pretty hard to separate out from the fertile florets. It’s fun, though. Here are some of my other seed pictures:

Aristida adscensionis:

Bothriochloa barbinodis:

Bouteloua aristidoides:

Chloris virgata:

Pectis papposa:

Sphaeralcea emoryi:

I guess that’s about it. Seed collection is winding down here. We could probably do more of it, but we’ve met the 2015 collection target and made a few collections that go into fiscal year 2016. There’s one more I want to try for in a couple of weeks, but mostly we’ll be back to looking at Peniocereus greggii var. greggii until my interns leave at the beginning of November. I’ll leave you with a pair of photographs. The one on top is from the New Mexico State University archives, Oct 1912. I took the one on the bottom on 19 Sep 2015.

The monsoon that ain’t (12 Sep 2015)

I have been woefully derelict in my blog-writing duties but have a little free time today, so here it goes. My interns have been here since the beginning of June (yes, I’m an intern with interns) and this is my first time collecting seeds. So here’s the gist of my experience so far: the natural world is uncooperative. In southern New Mexico, our usual rainfall pattern is that it is very dry (average monthly rainfall 0.25″ to 0.7″ in Las Cruces; driest month: March) February through June, wet during the monsoon season, July through September (1.4″ to 2.2″ per month; wettest month: August), and pretty dry October through January (0.5″ to 0.9″ per month). This year, here’s what we’ve got in Las Cruces: January 1.13″; February 0.04″; March 0.34″; April 0.44″; May 0.8″; June 0.71″; July 2.41″; August 0.96″. There’s been a lot of variation within the Las Cruces District, but most places have shown a similar pattern: wetter than average in June and/or July, drier and hotter than average in August. What this means for me is that the early summer rainfall got lots of plants going and then August, which is supposed to be wetter and a bit cooler, was instead abnormally hot and dry. So most of those plants that were happy in July are either maturing earlier than you’d expect or going crispy. Those that are maturing early and look like they have good mature infructescences that ought to have lots of seed are often proving to have just empty husks when you start cutting things open. Setaria leucopila, for instance, hasn’t had a single well-developed seed in any of the fertile florets I have checked from several populations. Pleuraphis jamesii and Panicum obtusum likewise haven’t yielded any seed, and seed set rates for Bouteloua eriopoda, Bouteloua curtipendula, and Bouteloua gracilis are, thus far, so low that they may not be collectable even in large, dense populations. The odd rainfall also changes plant community composition. A site dominated by Enneapogon desvauxii last year, for instance, is dominated by Gutierrezia sphaerocephala this year and there is hardly an Enneapogon there to be found. Machaeranthera tanacetifolia, which I didn’t include in our target list because I have never seen it in sufficient abundance for a seed collection, is the dominant plant over a few patches of several square miles each. We’ve also been having some problems with herbivores, both domesticated and wild. A lovely population of Ipomopsis longiflora from which we had hoped to collect was decimated by, I think, rabbits. Sporobolus flexuosus that looked great in late June was mowed down by cattle in July, although the 5% or so of plants that escaped grazing to produce seed were, hopefully at least, enough for a decent collection. Although some of this is rather obnoxious, there’s a good side, too. Due to early maturation, we’ve made more seed collections than I would have expected by now and are at something like 23 of our intended 36 collections. And, although the target species list I made back in March or so has suffered and is by now wildly inaccurate, other species that are desireable for restoration or reclamation seeding have stepped in to fill the gap. I didn’t think we would be able to collect Bahia pedata, Baileya multiradiata, or Machaeranthera tanacetifolia, but we’ve made two collections of each. Enough of that, here are some pictures:

Interns, Jeanne Tenorio:

And David Morin:

Bahia pedata:

Baileya multiradiata:

Machaeranthera tanacetifolia:

And some insect friends encountered in the field; first, Odontoloxozus longicornis (a fly):

Murgantia histrionica (a bug):

Diabrotica undecimpunctata (a beetle):

More rare plant surveys (13 May 2015)

Since my last post here, we did three weeks of plant surveys, of which I missed the middle week while visiting the National Native Seed Conference in Santa Fe. The conference was fun, but wandering around in the desert is better, so that’s what I’m going to talk about. Luckily, the crew did fine without me, although one window at our office did suffer the assault of a trailer hitch. I did the same thing to a post at a hotel last year, but the post just needed to be put back on its footing while the window requires a bit more intervention. Gist being: be careful backing up in those big pickups, OK? (And BLMers getting new vehicles: maybe they don’t all need to be huge pickups. Sometimes we need ’em; more often, they’re a hindrance in the field as much as in town.)

Anyhoo, here’s the gist from the recent stint of rare plant surveys: We found rare plants! Specifically, about 85 Pediomelum pentaphyllum and about 40 Peniocereus greggii var. greggii. We also got to see some of the varying results of previous herbicide treatments. These treatments are intended to restore grassland by removing shrubs that have become more abundant due to grazing. Sometimes, it works admirably–especially at a little higher elevations where we’re near the current shrub / grass transition zone or in places where grazing pressure has dropped down towards sustainable levels. Sometimes, it’s basically a wash, neither better nor worse. Sometimes, removing shrubs just gives invasives a chance to take over. I think we’re getting better at doing more “best case” and fewer “worst case” herbicide treatments, but when you spend a couple days out around one of the worst case scenarios–basically, tumbleweed heaven–it erodes optimism and belief in progress somewhat. Luckily, I think Las Cruces District is ahead of the curve on putting monitoring plots in place so that we can learn from our mistakes and move towards the holy grail of Adaptive Management. Mistakes are unavoidable in land management; if we’re doing it right, we don’t repeat them.

Enough of that, here are some pictures!

Pediomelum pentaphyllum habitat:

And Pediomelum pentaphyllum:

Peniocereus greggii var. greggii habitat:

And Peniocereus greggii var. greggii:

Also, Crotaphytus collaris fuscus:

If you were paying attention on the Peniocereus greggii var. greggii photos, you noticed that they have flower buds. I’m headed out shortly to find them with flowers, so that I can get pictures of this species’ ephemeral but spectacular stage in which it does not look like a dead stick.

In other news: I looked for a very rare species (Spermolepis organensis) and didn’t find it. Two papers from my academic days are about to be published, which will result in five new species in New Mexico. I head off to seed collection training in California next week, and rangeland health training not long after. The rangeland health training is, luckily, near Moab–which means I can drive up and botanize en route. If I can drive, I do; if I can take a couple extra days to poke around on the way, I do that as well. Why go somewhere awesome and not dedicate some time to wandering around? (Just don’t forget important items at your campsite, because you’ll have to backtrack and retrieve them–did that a couple weeks ago, and not for the first time. Hopefully the last. Probably not the last.)

Also, Shameless Plug for Commerce: That little yellow thing in one of my Peniocereus greggii var. greggii photos is the Bad Elf GNSS Surveyor. It’ll send 1-meter accuracy locations to an iPhone, iPod, iPad, or probably other Bluetooth devices. It isn’t cheap but it’s cheaper than a Trimble (even if you have to buy the iDevice to go with). The available apps are better than ArcPad, too. Trimble wins only if you need submeter, have a big pile of cash handy, and don’t mind a dramatically worse user experience. I am not associated with Bad Elf in any way other than as an enthusiastic customer. My assessment is not that of the Chicago Botanic Garden nor of the BLM.

CLM: Fun with aerial imagery (2) (6 Mar 2015)

Hello, world!

Continuing from the last post, let’s look at Prosopis glandulosa shrubland and some associated plant communities from the ground and from the air. Once you’ve seen enough of it in both contexts, you can start interpreting soil types and associated species from aerial imagery. This has important land management implications. In the Las Cruces District, we have a rare plant (Pediomelum pentaphyllum) that occurs primarily in a subset of Prosopis glandulosa shrubland (a subset which is, luckily, identifiable from the air!). Also, the diversity of associated species and abundance of perennial grasses–both important indicators of the likelihood of success in herbicide treatments intended to restore grassland after grazing has led to an increase in shrubs and loss of grass–can also be predicted from aerial imagery. Double-checking in the field is still critical. However, you can’t be everywhere so, ideally, you check on the ground as much as you can, take photos and notes, and correlate that with aerial imagery to extrapolate to the rest.

So, here’s what Prosopis glandulosa shrubland looks like in its purest form–which usually occurs with little associated plant diversity, very low abundance of perennial grasses, and a relatively firm clay-loam (or loamy clay, or perhaps just clay; I’m not a dirtologist) surface soil.

On the ground:

Same site from the air:

And another example (which you may recognize from my last post), on the ground:

Same site from the air:

One thing you may notice from both of those photographs is that there is obvious evidence of rills caused by water erosion. This is a good indicator that there is little or no surface sand. In the second example, the exposed petrocalcic horizon along the small road is more evidence of this. The lack of surface sand is a good indication that there is probably little plant diversity at these sites and, especially, few perennial grasses. Sometimes–although not as often–very low-diversity Prosopis glandulosa shrubland occurs at sites that do have surface sand, as seen in the following example. The loose surface sand is very obvious in the field, but also identifiable in aerial imagery by the lack of any rills or gullies caused by water erosion.

On the ground:

Same site from the air:

In the first and third examples shown so far, we are looking at Prosopis glandulosa coppice dunes. In this plant community, each Prosopis glandulosa has raised soil around it. It is not clear (to me, at least) to what extent the raised soil of each coppice dune is the result of deposition (soil deposited around each shrub, mostly or entirely by soil particles in wind) and to what extent it is the result of erosion (from both wind and water) in the spaces between the dunes. I suspect that, in most cases, we have a little of each. Most Prosopis glandulosa shrublands in the Las Cruces District have at least some coppice dune tendencies, but you will find Prosopis glandulosa shrubland on fairly level ground without any notable accumulation of soil around the shrub bases. The second example above is intermediate between these two extremes. The following is at the duneless extreme.

On the ground:

Same site from the air:

That form of Prosopis glandulosa shrubland tends to have higher associated plant diversity and more perennial grasses than coppice dunes that lack surface sand, as seen by the big, healthy Muhlenbergia porteri at that site. Prosopis glandulosa also tends to be smaller and more upright in this context. Of course, Prosopis glandulosa shrubland does not always occur in a fairly pure form. Often there are other shrubs or perennial grasses in the interspaces. At the following site, Gutierrezia sarothrae is fairly abundant in the spaces between Prosopis glandulosa, and is visible in the aerial imagery as much smaller dark blobs.

On the ground:

Same site from the air:

Usually, smaller blobs mixed in with the big, obvious Prosopis glandulosa are a good indication that you’re dealing with something more interesting and diverse than just Prosopis glandulosa shrubland. This is not always the case, as in the following example.

On the ground:

Same site from the air:

A few of the smaller blobs in the aerial image are Atriplex canescens or Gutierrezia sarothrae, but most are Prosopis glandulosa–just younger and smaller individuals. So instead of plant community diversity, they indicate demographic diversity in a single dominant species. More often, smaller blobs are other species. So, here’s an example of mixed Prosopis glandulosa and Larrea tridentata, with a few sprinkles of Gutierrezia sarothrae.

On the ground:

Same site from the air:

Prosopis glandulosa is also often found with Pleuraphis mutica, usually in fine-textured soils without any surface sand, as in the following.

On the ground:

Same site from the air:

Or, one might find Prosopis glandulosa mixed with Pleuraphis mutica and Gutierrezia sarothrae, as follows.

On the ground:

Same site from the air:

In cases like the two above, I would assume that we are looking at places that were formerly Pleuraphis mutica grassland with few or not Prosopis glandulosa. In the Las Cruces District, Gutierrezia sarothrae and Gutierrezia microcephala are probably the most reliable indicators of recent grazing pressure. However, although they can expand dramatically after relatively high grazing pressure, these Gutierrezia species are not particularly long-lived. Prosopis glandulosa, on the other hand, is usually a very long-lived indicator of grazing pressure. Pleuraphis mutica rarely occurs in areas with much surface sand and is relatively easy to identify from aerial imagery, so its presence is a good indicator of fine-textured, relatively sandless soil. I would also guess that these sites have relatively stable soils; Prosopis glandulosa associated with Pleuraphis mutica rarely has well-developed coppice dunes and usually has relatively few of the rills and gullies typical of pure Prosopis glandulosa shrubland on fine-textured soils.

OK, let’s move on to Prosopis glandulosa in areas that have loose surface sand. These are usually higher-diversity sites with more perennial grass. The grass at these sites in the past was probably Bouteloua eriopoda; now it is more likely to be Sporobolus flexuosus. Below is an example of Prosopis glandulosa shrubland with relatively sparse Sporobolus flexuosus.

On the ground:

Same site from the air:

Other shrubs usually associated with Prosopis glandulosa on these sandier sites are Artemisia filifolia, Atriplex canescens, Psorothamnus scoparius, Yucca elata (not exactly a shrub, but we don’t have another good word for it) and, less often, Lycium pallidum or Sapindus saponaria. Below is an example of Prosopis glandulosa with both Atriplex canescens and Sporobolus flexuosus.

On the ground:

Same site from the air:

And the following is Prosopis glandulosa with Psorothamnus scoparius. Most of the smaller blobs in the aerial imagery are Psorothamnus scoparius, but a few are just younger, smaller Prosopis glandulosa. The two have very similar morphology as seen in aerial imagery, with Psorothamnus scoparius looking an awful lot like typical Prosopis glandulosa coppice dunes, but much smaller.

On the ground:

Same site from the air:

Occasionally, you can also find almost Psorothamnus scoparius shrubland with few or no Prosopis glandulosa, as seen in the following example.

On the ground:

Same site from the air:

At the high-shrub-diversity end, you might see Prosopis glandulosa, Artemisia filifolia, Atriplex canescens, and Yucca elata all at the same site, as follows.

On the ground:

Same site from the air:

Occasionally, you will even see Prosopis glandulosa mixed with Bouteloua eriopoda grassland–the plant community it has probably replaced at most of these sandy sites.

On the ground:

Same site from the air:

Once you get the hang of some of this, I think you can often get a pretty good guess of the composition, surface soil characteristics, and history of a site with Prosopis glandulosa from aerial imagery. However, everything related to the landscape (and especially, in my opinion, the New Mexico landscape) is incredibly complicated. There are exceptions to everything and thousands of rabbit-holes to go down, both literally and figuratively, in understanding the land. Ideally, this post would go on for at least another 50 pages… but I think neither I nor any readers have the patience for that.

CLM: Fun with aerial imagery (1) (9 Feb 2015)

One of the basic challenges of any land management agency is figuring out what’s out there. The BLM Las Cruces District manages 5.4 million acres of public land. Although I do my best to get outside and visit as much of it as I can, that’s a lot of land to cover. There are many GIS layers we can use to get around this problem and understand what’s happening on the landscape in areas we can’t personally visit and experience, but one of the most informative is aerial imagery. Trying to understand aerial imagery is also, in my opinion, just about the most challenging and entertaining thing you can do with maps! My basic process in training myself to understand aerial imagery is to stare at maps for a while, guess what I’m looking at, and then go outside and see if I’m correct. Sometimes this is part of my job, sometimes this is just what I do for fun. Once you get a good sense of the relative scale of the different shrubs, what grasses to expect in what context, and the like, you can get a surprising amount of information from aerial imagery and, in reference to Stillman‘s recent post on this blog, sometimes you can even make out the stems of ocotillo from aerial imagery! Of course, there are still many things you can’t understand without being out on the ground.

There are also various programs that implement basically the same approach in an automated computational framework. LANDFIRE, for instance, produces vegetation maps by taking vegetation plot data and then running GIS wizardry to interpolate and classify all of the areas between the plots. That’s useful, but not nearly as much fun. So here are some examples of what plant communities look like in aerial imagery vs. what they look like on the ground. I’m anticipating doing a few more posts like this, hence the “1″ in the title of this post.

In the Las Cruces District, most of our vegetation is grassland or shrubland. Our two most abundant shrubs are Larrea tridentata (creosote bush) and Prosopis glandulosa (honey mesquite). Many of our grasses, especially Dasyochloa pulchella and Muhlenbergia porteri, are typically abundant hidden within either of these, or in the interspaces of shrubland rather than occurring as grassland. Our most abundant perennial “grassland” grasses include Pleuraphis mutica (tobosa), Scleropogon brevifolius (burrograss), Sporobolus flexuosus (mesa dropseed), and Bouteloua eriopoda (black grama). We also have a few ubiquitous annual grasses that sometimes form annual grasslands, most notably Aristida adscensionis (sixweeks threeawn). This is what they look like:

Larrea tridentata shrubland, on the ground:


Same site from the air:


Larrea tridentata shrubland, on the ground:


Same site from the air:


Prosopis glandulosa shrubland, on the ground:


Same site from the air:


Prosopis glandulosa shrubland, on the ground:


Same site from the air:


Pleuraphis mutica grassland, on the ground:


Same site from the air:


Pleuraphis mutica grassland, on the ground:


Same site from the air:


Scleropogon brevifolius grassland, on the ground:


Same site from the air:


Scleropogon brevifolius grassland, on the ground:


Same site from the air:


Sporobolus flexuosus grassland, on the ground:


Same site from the air:


Sporobolus flexuosus grassland, on the ground:


Same site from the air:


Bouteloua eriopoda grassland, on the ground:


Same site from the air:


Aristida adscensionis grassland, on the ground:


Same site from the air:


In that last aerial image, you might notice that Aristida adscensionis is basically invisible in aerial imagery, but looks like a thick carpet on the ground. The aerial photograph might have been taken in a dry year, or during the middle of summer when most of the annual grasses have dried up and blown away, or Aristida adscensionis might just be too diffuse to ever be visible in aerial imagery–it tends to form fairly uniform stands that don’t offer a whole lot of contrast. Yucca elata, on the other hand, is fairly sparse but stands out prominently in the aerial imagery–that’s what most of the dark blobs are, and in a few you can tell from the shadows that you are indeed looking at relatively tall, narrow plants (at least, if you click & open the full-size image!). The smaller dark speckles in there are a mixture of sparse perennial grasses (Sporobolus airoides and Sporobolus flexuosus), perennial forbs (mostly Croton pottsii), and small shrubs (Ephedra trifurca, some small, young Prosopis glandulosa) but not very intelligible in the aerial imagery. In the next post, I think I will dive into the various flavors of Prosopis glandulosa shrubland.

All aerial imagery is via Google, using screenshots from Gmap4.

CLM: Where I’ve been in the last year (13 Jan 2015)

A brief post this month. As we begin a new year, I decided to create a map of where I’ve been in the last one. Well, OK, I also included a few places I’ve visited so far this year; close enough. So, here it is:

I’ve highlighted the counties of the Las Cruces District Office in red. Each of those blue dots is a place where I’ve taken a picture and recorded what plants were there. About half of those dots are places I visited as part of my CLM internship, the other half are mostly recreational botanizing with a few trips that were part of my old job, before I started my internship, thrown in. I am steadily moving towards my goal of having been just about everywhere in southwestern New Mexico, but it’s a big place and I don’t think I’m going to run out of destinations any time soon. I’ve been here a decade and have still only visited 174 of the LCDO’s 608 grazing allotments, for instance. One of the things I’m really enjoying about working with the BLM is that it gives me a good excuse to go to a lot of places most botanists would never bother with. For instance, wandering around in mesquite shrubland for a few weeks is not very high on the priority list for most botanists, but I enjoy it and now I have more reason to do it. Looking at this map, I’m also remembering that I need to put more labels and legends on maps. Perhaps some people don’t immediately recognize, say, the outline of Otero County. Oh well.

In the coming year, I think I’ll start posting about plant communities and interpretation of aerial imagery. Examining aerial imagery and trying to figure out what you’re looking at is one of the most enjoyable mental puzzles out there, in my opinion, and also on my list of “fun things I get to do more often with the BLM”. Admittedly, I already spent what most would probably consider an unfathomable amount of time staring at maps!