Saturday, July 2, 2022

Top of the World, Ma!


I visited Olympic National Park in Washington State last year, and the subalpine meadows on its tall peaks drew us in. The open tree-less spaces, the snow-covered mountain heights in the distance, the ground hugging grasses and forbs. I would not trade this vast panorama for any of the closed humid spaces down below.

This is a place where your soul can soar.

Thursday, June 30, 2022

At My Signal, Unleash Hell: How Invasive Annual Grasses Use Pestilence Against Their Native Perennial Rivals

Taeniatherum caput-medusae (Medusahead Grass) Inflorescence

In previous posts, I touched upon some of the ways invasive grasses manage to overwhelm native populations. 

Usually, this involves having some direct competitive advantage over their rivals. This may include pathogen release (they leave behind all the pathogens that afflict them back in their own native land), some intrinsic competitive abilities, or through some life cycle advantages (for example, as in the diagram below, the ability of Taeniatherum caput-medusae or Medusahead Grass to create flammable litter that prevents competitor germination and clears the rest via frequent wildfires).

How T. caput-medusae (Medusahead Grass) dominates its competitors

Amazingly, however, a new way that invasive annual grasses manage to dominate their perennial native rivals has been discovered. In California, more than 9 million ha of land have been invaded by European winter annual grasses like Avena fatua (Wild Oats), which have usurped the native perennial bunchgrasses. Vast fields of these invasives have paradoxically enough, created the so-called "Golden Hills of California", which have become iconic to that region.

Golden Hills of California

The ability of these invaders to dominate the landscape was thought to be through direct competition with native perennial bunchgrasses, such as Nassella (Stipa) pulchra and Elymus glaucus. But some studies showed that the exotics were in fact poor direct competitors, and other factors were needed to explain their dominance. 

Avena fatua, an exotic and invasive annual grass in California

One of these factors turned out to be a virus!

The barley and cereal yellow dwarf viruses (B/CYDVs) are a family of viruses that are generalized pathogens of grasses, and can cause stunting and slow growth. They travel from host to host via intermediate vectors, which are various species of aphids. The aphids take in the virus from an infected plant when they suck on the phloem, and then transfer it to another plant when they move to new pastures.

Aphids on spikelets of T. caput-medusae (Medusahead Grass)

The invasive grasses compete against their perennial grass rivals by amplifying the population of the aphids, and this in turn significantly increases the pool of infectious viruses. Researchers found that aphids not only were much more attracted to the exotic annual grasses, but that their fecundity increased significantly in the presence of these species. Aphid densities were up to 800 times greater in areas with dense stands of the invasive annual A. fatua, and the infection rate of native grasses with B/CYDV more than doubled! The negative effect of this pathogen on perennial bunchgrasses is more severe than on the short-lived annuals, and this difference is enough to tip the scales of the competition.

By unleashing the viral pathogens against their more vulnerable perennial rivals, A. fatua and other exotic annual grasses have managed to dominate the California landscape. This unusual type of competition (called "apparent competition"), seems to also be available to other exotic annual grasses such as T. caput-medusae, which typically dominate their own areas through more direct methods.

Golden Medusahead Grass carpeting the ground in Oregon

References:

Borer ET, Adams VT, Engler GA, Adams AL, Schumann CB, Seabloom EW. Aphid fecundity and grassland invasion: invader life history is the key. Ecol Appl. 2009 Jul;19(5):1187-96. doi: 10.1890/08-1205.1. PMID: 19688926.

Malmstrom, C.M., McCullough, A.J., Johnson, H.A. et al. Invasive annual grasses indirectly increase virus incidence in California native perennial bunchgrasses. Oecologia 145, 153–164 (2005). https://doi.org/10.1007/s00442-005-0099-z


Sunday, June 26, 2022

The Tree and the Reed: How Wind Affects Grasses


Video above shows Phalaris arundinacea (Reed Canary Grass) being buffeted by wind.

There are many versions of Aesop Fable's The Tree and The Reed, a tale which first appeared in Ancient Greece, and whose moral about pride and humility still resonates to this day. One of the versions goes thus:

A Giant Oak stood near a brook in which grew some slender Reeds. When the wind blew, the great Oak stood proudly upright with its hundred arms uplifted to the sky. But the Reeds bowed low in the wind and sang a sad and mournful song.

“You have reason to complain,” said the Oak. “The slightest breeze that ruffles the surface of the water makes you bow your heads, while I, the mighty Oak, stand upright and firm before the howling tempest.”

“Do not worry about us,” replied the Reeds. “The winds do not harm us. We bow before them and so we do not break. You, in all your pride and strength, have so far resisted their blows. But the end is coming.”

As the Reeds spoke a great hurricane rushed out of the north. The Oak stood proudly and fought against the storm, while the yielding Reeds bowed low. The wind redoubled in fury, and all at once the great tree fell, torn up by the roots, and lay among the pitying Reeds.

The reeds mentioned in these tales were probably a hodge-podge of riverside-living graminoids. The original and most likely species that answers to this name is Phragmites australis (Common Reed), but the term may also refer to other grasses, such as Phalaris arundinacea (Reed Canary Grass), Arundo donaxNeyraudia reynaudiana (Burma Reed), various species of Calamagrostis, as well as a few other assorted members of the Poales. All these plants are herbaceous, with thin leaves that seem to support the central idea of the fable about wind resistance, but the reality is actually more complex. 

It is true that grasses are able to withstand gusts that would topple large trees, but they too can be negatively impacted by continuous strong winds, either due to shaking (seismorphogenic) or rubbing (thigmorphogenic) processes.

Some of the effects of wind include:

  • Increased leaf transpiration, which means grasses lose moisture faster through their stomata. 
  • Decreased leaf extension, which means the grasses produce less leaves.
  • Slower growth rate.
  • Damage to leaf surfaces, including displacement and smoothing of the epicuticular waxes, damage to the cuticle, collapse of epidermal cells and fracture of trichomes.

These effects increase with increasing wind speed, and older leaves are disproportionately affected.

In addition, studies of wind effects on wheat showed that there was significant reductions in grain yield when the grasses were exposed to strong continuous wind. There were less heads per sqm, less kernels per head, and each kernel weighed less than normal. All these negative effects show that Aesop's Fables was not exactly right when it marveled at the invincibility of reeds compared to the more arrogant trees during a storm. 

As an aside, I love seeing grasses swaying and dancing in the wind, especially when they occur in large masses. This is why I decorate my home with lots of ornamental grasses; their movement gives a very attractive active component to the home compared to static bushes and trees. But now that I know the effect of wind on these plants, I'm more careful about wishing for the stronger and damaging winds.



References

Pitcairn, C.E.R., C.E. Jeffree, and J. Grace. 1986. Influence of polishing and abrasion on diffusive conductance of leaf surface of Festuca arundinaceae Schreb. Plant, Cell and Environment 9:191-196.

Russell, G., and J. Grace. 1978. The effect of wind on grasses. V. Leaf extension, diffusive conductance, and photosynthesis in the wind tunnel. Journal of Experimental Botany 29:1249-1258.

Smika, D.E., and R.W. Shawcroft. 1980. Preliminary study using a wind tunnel to determine the effect of hot wind on a wheat crop. Field Crops Research 3:129-135.


Friday, June 10, 2022

Goodbye to an Old Forest Friend


I have mentioned how we like hiking, and more times than not we tend to hike in heavily shaded areas like closed canopy forests. This is mostly because my wife is not usually a fan of walking under the full sun. 

In such places, grasses are not the major component of the understory. They tend to occur in small patches or even in single tufts in the dimly lit ground. Where they tend to occur in masses, the species are usually shade-tolerant aggressive invaders like Microstegium vimineum (Japanese stiltgrass) or Oplismenus undulatifolius (Wavyleaf basketgrass).

But one of the more numerous of the grasses that thrive in the shade is one that I personally find attractive. Dichanthelium clandestinum and its ilk have broad dark green leaves and a habit that you can't help but love.

Beautiful broad and dark green leaves
I encounter it relatively frequently here in the Northeast, and I have stumbled upon it once or twice in Florida.

I also see specimens of this grass close to my home in New Jersey whenever I go for my afternoon walk. They sit alongside the paved path around a nearby lake, and I make it a point to always stop and marvel at the beautiful forms that grace the lakeside and the nearby wooded area.

These are such distinctive critters, and interestingly enough, I see them not only in deep shade, but in brightly-lit areas as well, a testament to the adaptability of this grass.

Spikelets and florets in June
This species also has a somewhat unusual flowering scheme, as I mentioned awhile back in another post. During early summer it produces "normal" flowers which are pollinated when open ("chasmogamous"). Then later in the season, the same individual has closed flowers hidden in the sheaths that will be self-pollinated ("cleistogamous").

Spikelets and florets (macro view) in June

I think this will be my last season in this home, so it saddens me that this will also be the last time I see the D. clandestinum that make their living around the lake. They have been my yearly companions in my jaunts under the shade, and I wish them well. Perhaps someday when I come to visit, I will again walk around the lake path, and say hello to these old friends.

Tuesday, May 31, 2022

Say this 5 times fast: Stenotaphrum secundatum!


 A lawn in a lawn right?

But interestingly enough, the species of grass used to create lawns varies widely as one goes from one region to another in the USA.

In our home in New Jersey, our really old lawn (which I inherited from previous owners) is a mishmash of cool season grasses like Poa pratensis (Kentucky blue grass), Fescue spp, and Lolium spp (eg. Perennial Ryegrass). 

By Kevin Thiele from Perth, Australia

In Florida however, we were confronted by completely different species, those more adapted to the warmer weather all year round. In our case, a rhizomatous and stoloniferous grass called Stenotaphrum secundatum, which has the local name St. Augustine grass (and various other common names around the world).

From a distance, the major difference is probably the lighter color of the lawn. But when you actually look closely the change in habit is very obvious. S. secundatum is a creeper - its stolons or aboveground horizontal stems allowing it to "crawl" along the ground like some green hued centipede. This behavior is quite unlike its cool season brethren in the north, which at best have underground rhizomes. 

I was so taken by this creeping behavior that I potted one, set it down on our lanai, and attempted for a short while to see how far it would stretch along the cement floor in its search for soil. It grew by around 5 cm in 12 days before I had to stop the experiment due to eternal circumstances, but I may repeat the experiment again later.  

Potted grass as it crawls out of the pot and starts to search for soil

The composition of the lawn also affects how it is viewed even from far away sometimes. For example, in the image below, the lighter green areas are S. secundatum, while the dark lot is likely Paspalum notatum (Bahia grass). The border between the two species was amazingly straight most times, although S. secundatum seems to have the more pronounced tendency to encroach onto the other territory. In addition, I noticed various other plant species (aka weeds in lawn parlance, haha) had a harder time establishing themselves in the dense masses of culms and blades and stolons that S. secundatum creates. 

Lawns from high up

A third type of turf grass in the community is a very small, fine leaved species used for the golf areas, and the next time I'm there I'll be sure to take a sample and try to ID it. I know some people are quite ambivalent (or even hostile) towards turf grass, but after being in an HOA community that uses various species to populate the landscape, I have started to become quite interested in the ecology of lawn grasses.

More to come on this perhaps.


Sunday, May 22, 2022

Let Them Grow Cake! Climate Change and The Wheat Crises

by Bluemoose
Triticum  aestivum (common wheat) and a few other species in the grass genus Triticum  (T. durum and T. compactum) are the source of one of the most important staple foods in the world. These grasses are grown in more than 200 million ha of land worldwide, and in 2020 world annual production of wheat stood at 760 million tons. But now an unfortunate combination of climate change and war have threatened our food supply.

Extreme weather events in almost all the wheat producing regions in the world have been causing chaos in the food supply. India, one of the top three wheat exporting countries,  has seen record high temperatures that have severely impacted their crops, so much so that the Indian government just declared limits on wheat export. In China, floods have also potentially compromised wheat supply, and in the EU, US, and Canada various combinations of drought and unseasonably warm temperatures have also threatened wheat crops. Meanwhile, Russia seems relatively unaffected by the extreme weather events going on elsewhere, but the war in Ukraine has limited its role in at least helping to dampen the growing impact of climate change on this year's food supply. Some estimates have declared that the world has only 10 weeks supply of wheat left, and this will be sure to create increases in the prices of bread and other staple foods going forward.

In the end, we owe it to ourselves and to our children to makes sure we address the growing impact of climate change, not only on other species, but on our own, before it becomes too late. 

Monday, May 16, 2022

A Himalayan Miracle: The Terai-Duar Grasslands of India, Nepal, and Bhutan

One-horned Rhino Hiding in the Grass (From Outlook India, by Narendra Bisht)

At the foot of the Himalayan mountain ranges lies a narrow band of grasslands and savannas that is only 25 km wide, but features some of the tallest (non-bamboo) grasses in the world, and are a host to the most amazing animals.

The Terai Grasslands (By Terpsichores and Tom Patterson, US National Park Service)

Not only is this area home to the rare one-horned rhinoceros (Rhinoceros unicornis), but it also boasts a multitude of ungulates (deer and their ilk), as well as the Asian Elephant (Elephas maximus) and the Bengal Tiger (Panthera tigris)!

Elephant (By Yathin S Krishnappa)

I first heard about these grasslands from a nature documentary about biomes (Earth 2: Grasslands, with David Attenborough), which briefly showed gargantuan Asian elephants, who were themselves dwarfed by tall grasses that almost hid them from sight. The area was not named, but I was curious about it. Through the miracle of google I finally managed to pinpoint the location as the Terai-Duar grasslands, which spans three countries (India, Nepal, and Bhutan), and is maintained by annual flooding during the monsoon season, and not only by fire or grazing. 

The grasses that serve as the foundation of this system include Saccharum spontaneum (called kans grass and talahib where I grew up), which can grow up to 4 meters tall and more. Another equally tall grass in the place is Cenchrus purpureus, which appropriately enough is sometimes called elephant grass (but which is called Napier grass most times, and which I encountered in southern Florida). The terai also has stands dominated by the much shorter Imperata cylindrica, the same cogon grass that dominates in many other regions of the world. I found it interesting that many tourist and even nature sites kept calling them the tallest grasses in the world, even though bamboos of course can get much much taller.

Cenchrus purpureus dwarfing even a school bus in Florida City

I once mentioned I get really nervous about being alone in a shaded closed canopy forest, where my over active imagination always thinks there is some predator lurking in wait behind the next tree trunk. But being submerged in these tall grasses must be equally scary, something that Stephen King explored in his novelette In the Tall Grass. In this case, the fact that the Terai grasslands are home to the Bengal Tiger probably has something to do with my anxiety.

Bengal Tiger in the Grass (by PM Dhakate)

Nevertheless, the Terai grasslands are firmly in my bucket list of places to visit. But like many old growth grasslands, most of the Terai has been converted to agricultural and other human uses, mainly due to its rich soil. In fact, the region is one of the most endangered in the world. Fortunately, there are some major parks that seek to protect the grasslands, including Shuklaphanta National ParkChitwan National Park, and Bardia National Park in Nepal, and Dudhwa National Park in India.

Be sure to visit and be amazed by this fantastic place the next time you are in that area!

Friday, May 6, 2022

Book Review: The Death of Grass by John Christopher

by ISFDB

I admit that I probably would not have read this before my interest in the Poaceae.

I am an ardent science fiction reader, but this post-apocalyptic novel was published in 1956, and I tend not to read older SF. Nevertheless, once I started reading it, I found to my surprise that it was actually quite interesting, although some of the language and viewpoints of the characters were quite dated and made me cringe and roll my eyes.

The story involves the spread of a virus named Chung-Li, which devastates rice crops in China, causing mass starvation. Although confined at first to rice, the virus soon develops variants which attack all members of the grass family. Caught in the backdrop of this ecological catastrophe, a mild mannered British man named John and his family try to safely make it to his brother David, who has started growing potatoes in a farm that is sheltered in a well protected valley. On the way they pick up various other people who can help them, and John slowly transforms into a hardened survivor who will stop at nothing to protect his family.

The Chung-Li virus devastates rice crops

The author does a very good job of emphasizing the importance of the grass family to the very fabric of our lives. Not only does he show the disintegration of governments and societies when the virus expands worldwide, but at various points in the narrative, the characters note the disastrous consequences of the loss of grasses because these make up the vast majority of our food.

"Yes," John said, "wheat is a grass, too, isn’t it?"

"Wheat," David said, "and oats and barley and rye – not to mention fodder for the beasts."

In addition, the author is thoughtful enough to mention the scientific name of the grass family, and even goes so far as to throw in the taxonomic nomenclature of some grass  genera and tribes. 

Roger went on: "The appetite of the Chung-Li virus was for the tribe of Oryzae, of the family of Gramineae. Phase 5 is rather less discriminating. It thrives on all the Gramineae."

"Gramineae?"

Roger smiled, not very happily. "I’ve only picked up the jargon recently myself. Gramineae means grasses – all the grasses."

John thought of David. "We’ve been lucky."

"Grasses," he said, "that includes wheat."

"Wheat, oats, barley, rye, that’s a starter. Then meat, dairy foods, poultry. In a couple of years’ time we’ll be living on fish and chips – if we can get the fat to fry them in."

Wheat is also affected, by Bluemoose

The disappearance of grasses not only impacts the entire food chain that enables civilization, but it also impacts the surroundings, as noted by one of the protagonists:

‘They frightened me. I hadn’t understood properly before quite what a clean sweep the virus makes of a place. Automatically, you think of it as leaving some grass growing, if only a few tufts here and there. But it doesn’t leave anything. It’s only the grasses that have gone, of course, but it’s surprising to realize what a large amount of territory is covered with grasses of one kind or another.’

Although the author has done his botanical homework, he seemingly stumbles at certain points in the narrative. For example, as rationing starts to take its toll on the country, some children complain about the rationing of sweets.

"Potato-cakes,’"John said, "and the empty tin circulating along the tables for you all to have a sniff. Very nourishing too." 

Davey said: ‘Well, I don’t see why they’ve rationed sweets. You don’t get sweets out of grass, do you?’

But of course, most sugar is actually derived from sugarcane (Saccharumn officinarum), which is also a grass!

Overall, I found the novel interesting and entertaining, and the author does not shy away from describing the savagery of man when civilization collapses. In one of the Stephen King novelettes, the phrase "arc of descent" is used, and I think that phrase is quite apt in describing the way the protagonist in this book evolves from beginning to end. 

If you have the time and inclination, give it a go. An electronic version (kindle) is available from amazon.com, and probably from other booksellers worldwide.

Enjoy!

Dying maize/corn


Thursday, April 28, 2022

When Kangaroos Came Down from the Trees

by Rileypie

Kangaroos are marsupials, that unique group of mammals that originated in the Americas, then crossed Antarctica 55 million years ago to end up in Australia by around 25 million years ago. Although kangaroos do not belong to a single species, but to several related species in the family Macropodidae, the group is characterized in the mind of the public as all having disproportionately large hind legs and a propensity to hop along the savannas that it inhabits.

But people today would probably not even recognize the ancestors of these iconic mammals, which were opossum-like critters that spent their lives up in the trees and first ate fruits and then tree leaves. The prevailing view at one time was that the kangaroos did not move down from the trees until around 15-5 million years ago, when growing aridity in Australia caused them to gradually evolve to have the attributes we see in them today.

Modern kangaroos loiter about in their grassland home (by By AWS10)

But a new study disputes that theory.

Researchers studied the teeth of more than 1600 kangaroo specimens, both from modern kangaroos and their fossil ancestors. They focused on the crown height and wear on the teeth, which gave them an indication of what the animals ate. Animals that eat relatively soft foods such as leaves and fruit do not have high crowned teeth, and the wear on the teeth is much less than if the animal ate something abrasive such as grass. This is because grasses are filled with silica bodies called phytoliths, which make eating them akin to eating sand, and the high crowned teeth is an adaptation towards eating such tough food.

Modern Tree Marsupial, who remained in the trees, by By Fred Hsu

When these researchers looked at the changes in teeth from the ancestors of kangaroos to their modern counterparts, they found that the change in dentition (from low crowned to high crowned teeth) and explosive radiation of kangaroo species did not happen as the land first grew arid (15-5 million years ago). Instead, this change only happened 3 million years ago, when C4 grasses started pushing back the trees and forests to create the grasslands and savannas that are now so prevalent in that continent.

This tight correlation between the expansion of grasslands in Australia and the evolution of the kangaroo as we know it today again highlights the importance of our old growth grasslands to the rise of so many iconic and magnificent animals. 

In fact, without the grasslands, our own ancestors would not have done the same thing as the kangaroos did, and we might still be lounging lazily in the treetops today, our minds bereft of the keen intelligence that (allegedly) is a hallmark of Homo sapiens.

Reference:

Couzens AMC, Prideaux GJ. Rapid Pliocene adaptive radiation of modern kangaroos. Science. 2018 Oct 5;362(6410):72-75. doi: 10.1126/science.aas8788. PMID: 30287658.

Monday, April 18, 2022

The Mysterious Origin of Andrews Bald in Great Smoky Mountain National Park

View at Andrews Bald using Panorama setting of Phone Camera

Lying just an hour and a half walk away from one of the most popular tourist destinations in Great Smoky Mountains National Park is a large grassy area that sits atop a mountain. Since it is still below the timberline, all around this open expanse are tall spruce and fir trees, which provide a very shaded environment for hikers who venture out from Clingman's Dome and want to do the 2.5 km trek to this somewhat anomalous area.

The hike itself is moderately easy and quite peaceful, although the almost continuous upward incline on the way back was somewhat strenuous. Recent upgrades to the trail provided nice steps and above-ground planks at certain points that allowed us to move quickly over the sometimes muddy ground.

Narrow boardwalks and steps provide sure footing for hikers

After about an hour and a half we finally burst into the open air and gazed upon an amazing grassy meadow that covered about 1.6 hectares of the mountain top. The change from the dark forested interior to the sunlit top was fairly dramatic, and many people had draped themselves over the lawn-like ground close to the opening, although it was only April and most of the grasses had yet to green and were a dry golden color.

We had finally arrived at Andrews Bald, which at 1800 meters (1.8 km), is the highest so-called "bald" in the Great Smoky Mountains National Park.

Wooden path emerges from forest into Andrews Bald

These "balds" are grassy meadows below the timberline which are found in the southern Appalachian Mountains, and the origins of most are shrouded in mystery. The dominant grass is usually Danthonia compressa, but other grasses such as redtop (Agrostis alba), timothy (Phleum pratense), Canada bluegrass (Poa compressa), Kentucky bluegrass (P. pratense), and red fescue (Festuca rubra) may also be found.

The trail continues, with a view to other parts of the Great Smoky Mountains

Some researchers believe Native Americans originally cleared the areas as hunting grounds or lookouts, and there are historical records that seem to indicate that settlers cleared some of the balds for grazing. There are even some who postulate that the balds had been originally founded by prehistoric herbivores, and then maintained by human hands thereafter.

Whatever the case, there is no doubt that the balds had been used as grazing land during the 1800s. The cattle and sheep that were herded up onto these ridgeline areas during the summer months kept the land open, but after the formation of the national park and the cessation of grazing in the 1930s, trees and shrubs have been slowly reclaiming the land.

Andrews Bald, with visitors (dots on far left) sunning themselves on the golden Springtime grass

A quick look at historical satellite imagery from Google Earth shows that Andrews Bald went from being around 2.5 ha in size in 1995 to around 1.6 ha in 2017 (see image below), and if grazing continues to be excluded from the area, then it is probably inevitable that the bald will continue to shrink in the future. 

But for now, visitors can continue to enjoy the relatively open vista possible in Andrews Bald. It may not be the vast green expanse that it used to be, but I still highly recommend it if you ever visit Great Smoky Mountains National Park.

Area of the meadow shrunk from 2.5 to 1.6 ha from 1995 to 2017

Thursday, April 14, 2022

Rushes are Round: Finding Luzula in Great Smoky Mountain

Although this site is focused on the Poaceae, the other members of the order Poales can oftentimes be mistaken for grasses. This is especially true for members of the families Juncaceae (rushes) and the Cyperaceae (sedges), which are sometimes even given common names that mistakenly identify them as grasses. 

In this case, there is an old adage that might help people separate the three. It goes:

Sedges have edges. Rushes are round. Grasses are hollow. What have you found?

OR

Sedges have edges, rushes are round, Grasses have nodes all the way to the ground.

So, if the stems have corners and edges (roll a stem between your thumb and forefinger), then it's likely what you just thought was a grass is actually a sedge, and if the rounded stems are not hollow and have no nodes spaced along their length, then you probably have a rush.

This rhyme helped me during a hike along the Grotto Falls trail in Great Smoky Mountain a couple days back, when I spied some graminoids near the edge of the wet path that had lots of spiky inflorescence at the top. They were notable because this early in the season, almost none of the grasses had any reproductive structures out yet, 

This particular specimen seemed to be a grass on first look, but when I took macro shots of the flowers and felt around the stems, I decided I was probably mistaken. I could not find any solid nodes along the stems (although granted, this early in the season, everything was still pretty low to the ground), and the round stems seemed to have a solid interior.

Now, I am horrible at identification, but I believe what I found on that day was Luzula multiflora, or the common wood rush, a member of the Rush family. The long white hairs on the leaves and stems indicates it belongs to genus Luzula, and the multiple flowers on variable length stalks separates it out from L. acuminata.

It is a circumpolar species but is listed as relatively scarce in this national park, so if I identified it correctly, then I was quite lucky to see it during that hike!

Long white hairs that is typical of Luzula spp.


Sunday, April 3, 2022

Spreading the New Concept of Alternative Biome States (ABS) to Save Our Old Growth Grasslands

Old-growth grasslands are grass-dominated open biomes which are ancient (some are tens of millions of years old), have high endemism and diversity (they are more diverse than rainforests at some scales), and are slow to reassemble once they have been degraded (more than a millennium according to studies). This ecosystem is one of the most endangered in the world, and misguided efforts to fight climate change by mass tree plantings can only hasten their demise.  

One of the major impediments to the widespread acceptance of the concept of ancient grasslands among the general public is the outdated notion that there is only one natural climax community. This wrong idea that ecological succession is a ladder-like process and that closed canopy forests (e.g. rainforests) are the ultimate goal in nature is deeply entrenched in the public consciousness. It promotes the wrong notion that all grasslands are simply forests that are waiting to happen, and are thus exempt from our protection and conservation.

It must be replaced by the more accurate paradigm of Alternative Biome States (ABS).

African Tropical Grassland (Savanna), by Gossipguy)

What are Alternative Biome States?

New research has shown that open old growth grasslands are a natural alternative to dark shaded forests, and that they can maintain themselves without any human intervention over thousands and even tens of millions of years. Neither grasslands nor forests are the "ultimate" expression and final state of natural succession. Instead, an area whose climactic and soil characteristics can theoretically support both grasses and trees alternates between the two stable biome states depending on other, more local factors.

North American Temperate Grassland (Osage Plains Prairie in Missouri), by Pat Whalen
What local factors keep the two biomes stable over time?

Grasses have harnessed two local factors to help push back forests. Some species have evolved with natural fire, while other grass species have partnered with large herbivores (e.g. elephants, bovids like antelopes, buffaloes, bisons, etc). Both of these "allies" can kill or weaken trees, as well as tree seedlings and saplings. This keeps the grassy biomes sunlit and open, which is the optimum environment for many sun-loving members of the Poaceae.

On the other hand, the dark humid interior of forests is not a welcome environment for most grasses. C4 grasses in particular grow best under the wide open and sunlit skies, and the high humidity and lack of wind also helps keep grass-induced fires from penetrating the inhospitable interior of the forest.

These counteracting forces on both sides stabilize the alternative biomes and allow each one to flourish.

South American Tropical Grassland (Cerrado), by Eliane de Castro)
How are these biomes switched from one state to the other?

Although old growth grasslands and forests are naturally stable over potentially long periods of time, strong perturbations can be enough to tip them over to the alternative state. 

For example, one or two strong forest fires in a region plagued by drought could be enough to quickly turn a closed canopy forest to an open ecosystem, as fire-adapted grasses and other plants colonize the resulting gaps in the forest. This can create a strong feedback mechanism whereby the gaps are widened as the flammable vegetation contributes to more fires going forward, with large herbivores following the grasslands to help keep the trees out.

This scenario created the great savannas in Africa as early as 15 million years ago, when C4 grasses started pushing back the forests to create new and sunlit open landscapes. Evidence of the rise in grass-fueled fires during this period of grass expansion is etched in charcoal deposits, as well as in the phylogeny of savanna-living underground trees, whose lineages increased in response to the rise of the new open biome. It was also around this time when the ancestors of large iconic megafauna like antelopes and other mammalian herbivores radiated into many more species to fill the new ecosystem.
 
The opposite transition from forest to grassland is usually more gradual, but just as inevitable. If fire and mammalian herbivores are somehow excluded from open ecosystems in areas whose climate and soil can support both biomes, then trees will gradually shade out the grasses and other smaller sun-loving plants. 

African Tropical Grassland (Savanna), by Bjørn Christian Tørrissen
What can you do?

Champion and spread the new paradigm of Alternative Biome States (ABS) as a replacement for the outdated concept that ecological succession is a one directional process towards shaded closed canopy forests. The elevation of open ecosystems as a natural alternative to forests will help protect and conserve our ancient and biodiverse grasslands and the countless other plants and animals that live there.

North American Temperate Grassland (Konza Prairie in Kansas), by Jill Knutson Hauko
 References

Pausas JG, Bond WJ. Alternative Biome States in Terrestrial Ecosystems. Trends Plant Sci. 2020 Mar;25(3):250-263. doi: 10.1016/j.tplants.2019.11.003. Epub 2020 Jan 6. PMID: 31917105.

Tristan Charles-Dominique, T. Jonathan Davies, Gareth P. Hempson, Bezeng S. Bezeng, Barnabas H. Daru, Ronny M. Kabongo, Olivier Maurin, A. Muthama Muasya, Michelle van der Bank, and William J. Bond (2016). Spiny plants, mammal browsers, and the origin of African savannas. PNAS DOI: 10.1073/pnas.1607493113

Thursday, March 31, 2022

What happens when an invasive grass parks itself in your parking lot

I had to laugh when I saw this parking lot island invaded by Imperata cylindrica (cogon grass). 

It really wasn't funny, but it does illustrate the problem faced by people who suddenly find masses of cogon grass in their property.

Parking Island with Cogon Grass
Intact Parking Island Flora (with an understory of ornamental grasses and short shrubs)
The persistent rhizomes make it hard to permanently eliminate the species once it encroaches en masse in an area. In this case, I imagine a piece of rhizome (or less likely, a seed?) managed to get into the soil during some activity, and over the years the grass spread throughout the island. Whereas the invaded island was almost entirely covered with the invasive species, the rest of the parking islands with intact flora had healthy looking shrubs and ornamental grasses in them. 

Maintenance crews may have simply pulled individual blades out (which would have done nothing to solve the problem), or perhaps even shrugged in defeat and hoped that the invader would somehow blend in with the rest of the plants.

Shrubs (red arrows) being engulfed by Cogon Grass
Unfortunately, by delaying any aggressive actions against the invader, they simply allowed it to strengthen its grip on the area, and since cogon grass grows very fast and slowly engulfs other plants around it unless it can be shaded out (impossible in this case due to the open nature of the island) the island now sticks out like a sore thumb when compared to the other islands in the parking lot.

The lesson of this story is that when an aggressive invasive shows itself in an area, don't delay in confronting it or you'll end up paying a much larger price later.