Campaigns Against Invasive Species, part one

I have been posting almost exclusively about invasive species for four months now. If you have made it this far, I salute you. It is neither the most exciting nor the most encouraging topic, but it is the journey I am on (for whatever reason), and I am pleased to have you along.

In the battle against invasive species, citizen awareness and participation is imperative. The public and private sectors can try as they may, but if individual citizens are acting in ways that help introduce or spread invasives, then much of this effort can be for naught. Thus, campaigns to educate the public are regularly launched.

One popular way to spread the word is through video. Often, the goal of these videos is to both educate and entertain. Some achieve this better than others, while some are downright dull or simply baffling. Speculating on the effectiveness of these videos is not the purpose of this post. Rather, I just thought I would take a break from the usual text heavy posts and share a few videos that I found interesting and/or entertaining. If you have a favorite invasive species video, please share it in the comment section below.

Invasive species explained:

Introducing Bob Noxious from Invasive Species of Idaho:

And here is the particularly creepy, Vin Vasive, from USDA APHIS:

Invaders! in British Columbia:

In Namibia, “Cacti must die!”:

Eco Sapien and the story of Japanese knotweed in the UK:

What happened when American minks, brought to Europe for the fur trade, escaped into natural areas?:

Michigan’s Department of Environmental Quality explains how invasive species spread:

Pennsylvania’s Wild Resource Conservation Program teaches kids about invasive species:

MinuteEarth‘s take on invasive species:

Also, check out these five TEDx talks:

Invasive Species vs. The Global Economy

As humans have spread across the globe, other species have followed. The domestication of animals and the advent of agriculture helped speed up this process, but species have been traveling around with humans long before that. Presently, our ability to move species from one corner of the globe to another is unprecedented. As more countries join the global economy, the risk of outsider species establishing themselves in uncharted territory increases. Species introductions via globalization are not likely to decrease, and so the question must be asked: Are we, as a global community, equipped to address this?

A review published in Nature Communications in August 2016 warns that “most countries have limited capacity to act against invasions.” The authors come to this conclusion after analyzing available data about invasive species across the globe and developing a “global, spatial forecast for emerging invasions throughout the twenty-first century.” National responses to invasive species were assessed based on reports to the Convention on Biological Diversity (CBD).

As part of the 2011-2020 CBD Strategic Plan for Biodiversity, nations or states that are parties of the CBD agreed to work towards a series of goals called Aichi Biodiversity Targets. Target 9 addresses invasive species: “By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated and measures are in place to manage pathways to prevent their introduction and establishment.” The authors of the review found that, while most countries have made progress on identifying and prioritizing some of the most prominent and threatening invasive species, “current management practices only target a handful” and “prevention of introduction and establishment lags far behind progress towards the reactive CBD goals.”

Biological invasions are expected to remain high across the globe; however, regions with a high Human Development Index (HDI) face different threats compared to regions with a low HDI. Due to increasing levels of international trade, high-HDI regions will continue to be threatened by introductions via pet and plant imports. Climate change and the coinciding biome shifts and changes in fire frequency are expected to aid in the establishment and perpetuation of invasive species in these regions.

Low-HDI regions have historically been less threatened by invasive species compared to high-HDI regions. As these regions join the global economy, they risk experiencing a much higher level of species introductions. Many of the planet’s biodiversity hotspots are found in low-HDI regions, making these hotspots more vulnerable to invasions as the potential for introductions increases. The authors found that the threat of introductions is at its highest in regions where “high levels of passenger air travel overlap with agriculture conversion.” Low-HDI regions are more limited in their capacity to respond to invasions compared to high-HDI regions and are more vulnerable to food shortages when invasive species disrupt agriculture.

“High risk in low-HDI countries could arise from coincidence between intensifying agriculture sectors and high levels of passenger air travel that is likely to transport arthropod pests. … Low-HDI countries could prioritize screening of passenger baggage for live plants, fruits or vegetables, which could host crop pests and pathogens.” – Early, et al. (2016) – photo credit: wikimedia commons

The authors state: “The intensities and global patterns of introduction and disturbance are changing more rapidly today than at any time during human history.” Introductions are not projected to slow in high-HDI regions, and low-HDI regions will be increasingly threatened as species already well established in high-HDI regions expand their reach. This is grim news, but it also presents an opportunity. Through cooperation and data sharing, our understanding of invasive species can greatly increase, and regions with greater access to resources can share such things with less fortunate regions. This is the hope of the authors as well: “We urge increased exchange of information and skills between regions with a wealth of invasive alien species experts and low-HDI countries that have less expertise.”

For more information about this review, go here. For more information about global trade in the modern era, check out the new podcast Containers.

What Is a Plant, and Why Should I Care? part four

What Is a Plant?

Part one and two of this series have hopefully answered that.

Why should you care?

Part three offered a pretty convincing answer: “if it wasn’t for [plants], there wouldn’t be much life on this planet to speak of.”

Plants are at the bottom of the food chain and are a principle component of most habitats. They play major roles in nutrient cycling, soil formation, the water cycle, air and water quality, and climate and weather patterns. The examples used in part three of this series to explain the diverse ways that plants provide habitat and food for other organisms apply to humans as well. However, humans have found numerous other uses for plants that are mostly unique to our species – some of which will be discussed here.

But first, some additional thoughts on photosynthesis. Plants photosynthesize thanks to the work accomplished by very early photoautotrophic bacteria that were confined to aquatic environments. These bacteria developed the metabolic processes and cellular components that were later co-opted (via symbiogensis) by early plants. Plants later colonized land, bringing with them the phenomena of photosynthesis and transforming life on earth as we know it. Single-celled organisms started this whole thing, and they continue to rule. That’s just something to keep in mind, since our focus tends to be on large, multi-cellular beings, overlooking all the tiny, less visible beings at work all around us making life possible.

Current representation of the tree of life. Microorganisms clearly dominate. (image credit: nature microbiology)

Current representation of the tree of life. Microorganisms clearly dominate. (image credit: nature microbiology)

Food is likely the first thing that comes to mind when considering what use plants are to humans. The domestication of plants and the development of agriculture are easily among the most important events in human history. Agricultural innovations continue today and are necessary in order to both feed a growing population and reduce our environmental impact. This is why efforts to discover and conserve crop wild relatives are so essential.

Plants don’t just feed us though. They house us, clothe us, medicate us, transport us, supply us, teach us, inspire us, and entertain us. Enumerating the untold ways that plants factor in to our daily lives is a monumental task. Rather than tackling that task here, I’ll suggest a few starting points: this Wikipedia page, this BGCI article, this Encylopedia of Life article, and this book by Anna Lewington. Learning about the countless uses humans have found for plants over millennia should inspire admiration for these green organisms. If that admiration leads to conservation, all the better. After all, if the plants go, so do we.

Humans have a long tradition of using plants as medicine. Despite all that we have discovered regarding the medicinal properties of plants, there remains much to be discovered. This one of the many reasons why plant conservation is so important. (photo credit: wikimedia commons)

Humans have a long tradition of using plants as medicine. Despite all that we have discovered regarding the medicinal properties of plants, there remains much to be discovered. This is one of the many reasons why plant conservation is imperative. (photo credit: wikimedia commons)

Gaining an appreciation for the things that plants do for us is increasingly important as our species becomes more urban. Our dense populations tend to push plants and other organisms out, yet we still rely on their “services” for survival. Many of the functions that plants serve out in the wild can be beneficial when incorporated into urban environments. Plants improve air quality, reduce noise pollution, mitigate urban heat islands, help manage storm water runoff, create habitat for urban wildlife, act as a windbreak, reduce soil erosion, and help save energy spent on cooling and heating. Taking advantage of these “ecosystem services” can help our cities become more liveable and sustainable. As the environmental, social, and economic benefits of “urban greening” are better understood, groups like San Francisco’s Friends of the Urban Forest are convening to help cities across the world go green.

The importance of plants as food, medicine, fuel, fiber, housing, habitat, and other resources is clear. Less obvious is the importance of plants in our psychological well being. Numerous studies have demonstrated that simply having plants nearby can offer benefits to one’s mental and physical health. Yet, urbanization and advancements in technology have resulted in humans spending more and more time indoors and living largely sedentary lives. Because of this shift, author Richard Louv and others warn about nature deficit disorder, a term not recognized as an actual condition by the medical community but meant to describe our disconnect with the natural world. A recent article in BBC News adds “nature knowledge deficit” to these warnings – collectively our knowledge about nature is slipping away because we don’t spend enough time in it.

The mounting evidence for the benefits of having nature nearby should be enough for us to want to protect it. However, recognizing that we are a part of that nature rather than apart from it should also be emphasized. The process that plants went through over hundreds of millions of years to move from water to land and then to become what they are today is parallel with the process that we went through. At no point in time did we become separate from this process. We are as natural as the plants. We may need them a bit more than they need us, but we are all part of a bigger picture. Perhaps coming to grips with this reality can help us develop greater compassion for ourselves as well as for the living world around us.

Tomato vs. Dodder, or When Parasitic Plants Attack

At all points in their lives, plants are faced with a variety of potential attackers. Pathogenic organisms like fungi, bacteria, and viruses threaten to infect them with diseases. Herbivores from all walks of life swoop in to devour them. For this reason, plants have developed numerous mechanisms to defend themselves against threats both organismal and environmental. But what if the attacker is a fellow plant? Plants parasitizing other plants? It sounds egregious, but it’s a real thing. And since it’s been going on for thousands of years, certain plants have developed defenses against even this particular threat.

Species of parasitic plants number in the thousands, spanning more than 20 different plant families. One well known group of parasitic plants is in the genus Cuscuta, commonly known as dodder. There are about 200 species of dodder located throughout the world, with the largest concentrations found in tropical and subtropical areas. Dodders generally have thread-like, yellow to orange, leafless stems. They are almost entirely non-photosynthetic and rely on their host plants for water and nutrients. Their tiny seeds can lie dormant in the soil for a decade or more. After germination, dodders have only a few days to find host plants to wrap themselves around, after which their rudimentary roots wither up. Once they find suitable plants, dodders form adventitious roots with haustoria that grow into the stems of their host plants and facilitate uptake of water and nutrients from their vascular tissues.

A mass of dodder (Cuscuta sp.) - photo credit: wikimedia commons

A mass of dodder (Cuscuta sp.) – photo credit: wikimedia commons

Some plants are able to fend off dodder. One such instance is the cultivated tomato (Solanum lycopersicum) and its resistance to the dodder species, Cuscuta reflexa. Researchers in Germany were able to determine one of the mechanisms tomato plants use to deter dodder; their findings were published in a July 2016 issue of Science. The researchers hypothesized that S. lycopersicum was employing a similar tactic to that of a microbial invasion. That is, an immune response is triggered when a specialized protein known as a pattern recognition receptor (PRP) reacts with a molecule produced by the invader known as a microbe-associated molecular pattern (MAMP). A series of experiments led the researchers to determine that this was, in fact, the case.

The MAMP was given the name Cuscuta factor and was found “present in all parts of C. reflexa, including shoot tips, stems, haustoria, and, at lower levels, in flowers.” The PRP in the tomato plant, which was given the name Cuscuta receptor 1 (or CuRe 1), reacts with the Cuscuta factor, triggering a response that prohibits C. reflexa access to its vascular tissues. Starved for nutrients, the dodder perishes. When the gene that codes for CuRe 1 was inserted into the DNA of Solanum pennellii (a wild relative of the cultivated tomato) and Nicotiana benthamiana (a relative of tobacco and a species in the same family as tomato), these plants “exhibited increased resistance to C. reflexa infestation.” Because these transgenic lines did not exhibit full resitance to the dodder attack, the researchers concluded that “immunity against C. reflexa in tomato may be a process with layers additional to CuRe 1.”

photo credit: wikimedia commons

photo credit: wikimedia commons

A slew of crop plants are vulnerable to dodder and other parasitic plants, so determining the mechanisms behind resistance to parasitic plant attacks is important, especially since such infestations are so difficult to control, have the potential to cause great economic damage, and are also a means by which pathogens are spread. It is possible that equivalents to CuRe 1 exist in other plants that exhibit resistance to parasitic plants, along with other yet to be discovered mechanisms involved in such resistance, so further studies are necessary. Discoveries like this not only help us make improvements to the plants we depend on for food, but also give us a greater understanding about plant physiology, evolutionary ecology, and the remarkable ways that plants associate with one another.

Additional Resources:

Maize Anatomy and the Anatomy of a Maze

Commonly known as corn throughout much of North America, maize is a distinctive emblem of the harvest season. It is one of the most economically important crops in the world (the third most important cereal after rice and wheat) and has scads of uses from food to feed to fuel. The story of its domestication serves as a symbol of human ingenuity, and its plasticity in both form and utility is a remarkable example of why plants are so incredible.

The genus Zea is in the grass family (Poaceae) and consists of five species: Z. diploperennis, Z. perennis, Z. luxurians, Z. nicaraguensis, and Z. mays. Maize is the common name of Zea mays subsp. mays, which is one of four Z. mays subspecies and the only domesticated taxon in the genus. All other taxa are commonly and collectively referred to as teosintes.

The domestication of maize, apart from being an impressive feat, has long been a topic of research and a challenging story to tease apart. The current understanding is that maize was first domesticated around 9000 years ago in the Balsas River valley in southern Mexico, the main progenitor being Zea mays subsp. parviglumis. It is astonishing how drastically different in appearance teosintes are from modern day maize, but it also explains why determining the crop wild relative of maize was so difficult.

Teosinte, teosinte-maize hybrid, and maize - photo credit: wikimedia commons

Teosinte, teosinte-maize hybrid, and maize – photo credit: wikimedia commons

Teosintes and maize both have tall central stalks; however, teosintes generally have multiple lateral branches which give them a more shrubby appearance. In teosinte, each of the lateral branches and the central stalk terminate in a cluster of male flowers; female flowers are produced at the nodes along the lateral branches. In maize, male flowers are borne at the top of the central stalk, and lateral branches are replaced by short stems that terminate in female flowers. This is where the ears develop.

Ears – or clusters of fruits – are blatantly different between teosintes and maize. To start with, teosinte produces a mere 5 to 12 fruits along a short, narrow cob (flower stalk). The fruits are angular and surrounded in a hard casing. Maize cobs are considerably larger both in length and girth and are covered in as many as 500 or more fruits (or kernels), which are generally more rounded and have a softer casing. They also remain on the cob when they are ripe, compared to teosinte ears, which shatter.

Evolutionary biologist, Sean B. Carroll, writes in a New York Times article about the amazing task of “transform[ing] a grass with many inconvenient, unwanted features into a high-yielding, easily harvested food crop.” These “early cultivators had to notice among their stands of plants variants in which the nutritious kernels were at least partially exposed, or whose ears held together better, or that had more rows of kernels, and they had to selectively breed them.” Carroll explains that this “initial domestication process which produced the basic maize form” would have taken several hundred to a few thousand years. The maize that we know and love today is a much different plant than its ancestors, and it is still undergoing regular selection for traits that we find desirable.

Female inflorescence (or "ear") of Zea mays subsp. mays - photo credit: wikimedia commons

Female inflorescence (or “ear”) of Zea mays subsp. mays – photo credit: wikimedia commons

To better understand and appreciate this process, it helps to have a basic grasp of maize anatomy. Maize is an impressive grass in that it regularly reaches from 6 to 10 feet tall and sometimes much taller. It is shallow rooted, but is held up by prop or brace roots – adventitious roots that emerge near the base of the main stalk. The stalk is divided into sections called internodes, and at each node a leaf forms. Leaf sheaths wrap around the entirety of the stalk, and leaf blades are long, broad, and alternately arranged. Each leaf has a prominent midrib. The stalk terminates in a many-branched inflorescence called a tassel.

Maize Anatomy 101 - image credit: Canadian Goverment

Maize Anatomy 101 – image credit: Canadian Government

Maize is monoecious, which means that it has separate male and female flowers that occur on the same plant. The tassel is where the male flowers are located. A series of spikelets occur along both the central branch and the lateral branches of the tassel. A spikelet consists of a pair of bracts called glumes, upper and lower lemmas and paleas (which are also bracts), and two simple florets composed of prominent stamens. The tassel produces and sheds tens of thousands of pollen grains which are dispersed by wind and gravity to the female inflorescences below and to neighboring plants.

Female inflorescences (ears) occur at the top of short stems that originate from leaf axils in the midsection of the stalk. Leaves that develop along this reduced stem wrap around the ears forming the husk. Spikelets form in rows along the flower stalk (cob) within the husk. The florets of these spikelets produce long styles that extend beyond the top of the husk. This cluster of styles is known as the silk. When pollen grains land on silk stigmas, pollen tubes grow down the entire length of the silks to reach the embryo sac. Successful fertilization produces a kernel.

The kernel – or fruit – is known botanically as a caryopsis, which is the standard fruit type of the grass family. Because the fruit wall and seed are fused together so tightly, maize kernels are commonly referred to as seeds. The entire plant can be used to produce feed for animals, but it is the kernel that is generally consumed (in innumerable ways) by humans.

There is so much more to be said about maize. It’s a lot to take in. Rather than delve too much further at this point, let’s explore one of the other ways that maize is used by humans to create something that has become another feature of the fall season – the corn maze.

Entering the corn maze at The Farmstead in Meridian, Idaho

Exploring the corn maze at The Farmstead in Meridian, Idaho

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corn-maze-5

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Grasshoppers – More Friend Than Foe?

Major outbreaks of grasshoppers can be devastating. A plague of locusts of biblical proportions can decimate crop fields and rangelands in short order. Clouds of grasshoppers moving in and devouring every plant in sight makes it easy to see why these insects are often seen as pests. Even small groups of them can do significant damage to a garden or farm. Yet, grasshoppers and their relatives have great ecological value and are important parts of healthy ecosystems. Love them or hate them, they are an essential piece of a bigger picture.

Grasshoppers are in the order Orthoptera, an order that includes katydids, crickets, wetas, and a few other familiar and not so familiar insects. Worldwide, there are more than 27,000 species of orthopterans. These insects mostly feed on plants; many are omnivorous while others are exclusively herbivorous. They are most commonly found in open, sunny, dry habitats like pastures, meadows, disturbed sites, open woods, prairies, and crop fields. Most insects in this order are fairly large, making them easy to identify; yet they don’t seem to receive the same level of human attention that charismatic insects like bees and butterflies do. In Field Guide to Grasshoppers, Katydids, and Crickets of the United States, the authors defend this diverse group of arthropods: “Grasshoppers often are thought of as modest-looking brown or green insects, but many species in this family are brightly colored, and some of the most dull-colored species rival butterflies in beauty when they spread their wings in flight.”

photo credit: wikimedia commons

photo credit: wikimedia commons

The voracious appetite of grasshoppers and their preference for plants can influence ecosystems in many ways. Certain plants may be favored over others, which affects the diversity and distribution of plant communities. Grasses are a particular favorite, despite being high in hard to digest compounds like lignin, cellulose, and silica. As grasshoppers consume vegetation – up to their body weight per day – digested materials return to the soil where soil dwelling organisms continue to break them down. In this way, grasshoppers and their relatives are major contributors to nutrient cycling. Returning nutrients to the soil results in increased nutrient availability for future plant growth. In fact, one grassland study found that despite short-term losses via grasshopper herbivory, plant growth was enhanced in the long-term due in part to accelerated nutrient cycling.

Because grasshoppers are such prolific consumers, their robust bodies are loaded with nutritious proteins and fats, making them a preferred food source for higher animals. Reptiles, raccoons, skunks, foxes, mice, and numerous species of birds regularly consume grasshoppers and related species. While many adult birds feed mostly on seeds and fruits, they seek out insects and worms to feed their young. Nutrient-packed grasshoppers are an excellent food source for developing birds. Humans in many parts of the world also find grasshoppers and crickets to be a tasty part of their diet.

Grasshoppers provide food for other invertebrates as well. The aforementioned field guide refers to the fate of grasshoppers and certain species of blister beetles as being “intimately linked,” because the larvae of these blister beetles feed exclusively on grasshopper eggs. Several species of flies and other insects, as well as spiders, also feed on grasshoppers and other orthopterans.

grasshopper on blade of grass

In short, grasshoppers play prominent roles in plant community composition, soil nutrient cycling, and the food chain. When grasshopper populations reach plague proportions, their impact is felt in other ways. From a human perspective, the damage is largely economic. However, their ability to thoroughly remove vegetation across large areas can be environmentally devastating as well, particularly when it comes to soil erosion and storm water runoff. The USDA’s Agricultural Research Service considers grasshoppers “among the most economically important pests” and cites research estimating that they are responsible for destroying as much as 23% of available range forage in the western United States annually. A paper published in the journal, Psyche, references a period between 2003-2005 in Africa where locusts were responsible for farmers losing as much as 80 to 100% of their crops.

This level of devastation is relatively rare. In Garden Insects of North America, Whitney Cranshaw states that of the more than 550 species of grasshoppers that occur in North America, “only a small number regularly damage gardens…almost all of these are in the genus Melanoplus.” Like most large, diverse groups of organisms, many grasshopper species are abundant and thriving while others are rare and threatened. Human activity has benefited certain species of grasshoppers while jeopardizing others. In general, grasshopper populations vary wildly from year to year depending on a slew of environmental factors.

Differential grasshopper (Melanoplus differentialis) - one of the four grasshoppers that Whitney Cranshaw lists as "particularly injurious" in his book Garden Insects of North America. (photo credit: www.eol.org)

Differential grasshopper (Melanoplus differentialis) – one of the four grasshoppers that Whitney Cranshaw lists as “particularly injurious” in his book Garden Insects of North America. (photo credit: www.eol.org)

A plague or outbreak of grasshoppers is a poorly understood phenomenon. It seems there are too many factors at play to pin such an occasion on any one thing. Warm, sunny, dry weather seems to favor grasshopper growth and reproduction, so drought conditions over a period of years can result in a dramatic increase in grasshopper populations. But drought can also limit plant growth, reducing the grasshoppers’ food supply. Natural enemies – which grasshoppers have many – also come into play. It seems that just the right conditions have to be met for an outbreak to occur – a seemingly unlikely scenario, but one that occurs frequently enough to cause concern.

Grasshoppers and fellow orthopterans are fascinating insects, and their place in the world is worth further consideration. For an example of just how compelling such insects can be, here is a story about crickets from Doug Tallamy’s book, Bringing Nature Home:

“Male tree crickets in the genus Oecanthus attempt to lure females to them by making chirping songs with their wings. The loudest male attracts the most females, so males often cheat a bit by positioning themselves within a cup-shaped leaf that amplifies the song beyond what the male can make without acoustical help. Each male chews a hole in the center of his cupped leaf that is just large enough to accommodate his raised wings during chirping. This ensures that the sound projects directly from the center of the parabolic leaf for maximum amplification.

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Biodiversity Dips When Japanese Rice Paddies Go Fallow

Large-scale farms that generally grow a single crop at a time and are managed conventionally are, by design, lacking in biodiversity. Abandoning such farms and allowing nature to take its course should, not surprisingly, result in a dramatic uptick in biodiversity. Plant colonization of abandoned farmland (also referred to as old field succession) is well studied and is regularly used as an example of secondary succession in ecology textbooks. The scenario seems obvious: cease agriculture operations, relinquish the land back to nature, and given enough time it will be transformed into a thriving natural community replete with diverse forms of plants and animals. This is an oversimplification, of course, and results will vary with each abandoned piece of land depending on the circumstances, but it generally seems to be the story. So what about when it isn’t?

Rice farming in Japan began at least 2400 years ago. Rice had been domesticated in China long before that, and when it eventually arrived in Japan it shaped the culture dramatically. For hundreds of years rice was farmed in small, terraced paddies in the mountains of Japan. Dennis Normile writes about these traditional, rice paddies in a recent issue of Science. He describes how they were found in villages “nestled in a forested valley” accompanied by vegetable plots, orchards, and pasture. Today, farms like these are “endangered,” and as they have become increasingly abandoned, plants, insects, and other wildlife that have historically thrived there are suffering.

Since the 1960’s, a combination of factors has resulted in the decline of traditional rice farming in Japan. For one, large scale farming has led to the consolidation of paddies, which are farmed more intensively. Diets in Japan have also shifted, resulting in a preference for bread and pasta over rice. Additionally, Japan’s population is shrinking, and residents of rural areas are migrating to cities. Traditional rice farmers are aging, and younger generations are showing little interest in pursuing this career.

Red rice paddy in Japan - photo credit: wikimedia commons

Red rice paddy in Japan – photo credit: wikimedia commons

Demographic and dietary concerns aside, why in this case is the abandonment of agriculture imperiling species? The answer appears to be in both the way that the rice paddies have been historically managed and the length of time that they have been managed that way. Agriculture, by its very nature, creates novel ecosystems, and if the practice continues long enough, surrounding flora and fauna could theoretically coevolve along with the practice. When the practice is discontinued, species that have come to rely on it become threatened.

Traditional rice paddies are, as Normile describes, “rimmed by banks so that they can be flooded and drained.” Farmers “encouraged wild grassland plants to grow on the banks because the roots stabilize the soil.” The banks are mowed at least twice a year, which helps keep woody shrubs and trees from establishing on the banks. In some areas, rice farming began where primitive people of Japan were burning frequently to encourage grassland habitat. Maintaining grassland species around rice paddies perpetuated the grassland habitat engineered by primitive cultures.

As rice paddies are abandoned and the surrounding grasslands are no longer maintained, invasive species like kudzu and a North American species of goldenrod have been moving in and dominating the landscape resulting in the decline of native plants and insects. Normile reports that the abandoned grasslands are not expected to return to native forests either since “surrounding forests…are a shadow of their old selves.”

Additionally, like most other parts of the world, Japan has lost much of its natural wetland habitat to development. Rice paddies provide habitat for wetland bird species. On paddies that have been abandoned or consolidated, researchers are finding fewer wetland bird species compared to paddies that are managed traditionally.

The gray-faced buzzard (Butastur indicus) is listed as vulnerable in Japan. It nests in forests and preys on insects, frogs, and other animals found in grasslands and rice paddies. It's decline has been linked to the abandonment and development of traditionally farmed rice paddies. (photo credit: wikimedia commons)

The gray-faced buzzard (Butastur indicus) is listed as vulnerable in Japan. It nests in forests and preys on insects, frogs, and other animals found in grasslands and rice paddies. Its decline has been linked to the abandonment and development of traditionally farmed rice paddies. (photo credit: wikimedia commons)

All of this adds fodder to an ongoing debate: “whether allowing farmland to revert to nature is a boon to biodiversity or actually harms it.” Where agriculture is a relatively new practice or where conventional practices dominate, abandoning agriculture would be expected to preserve and promote biodiversity. However, where certain agricultural practices have persisted for millenia, abandoning agriculture or converting  to modern day practices could result in endangerment and even extinction of some species. In the latter case, “rewilding” would require thoughtful consideration.

The thing that fascinates me the most about this report is just how intertwined humans are in the ecology of this planet. In many ways humans have done great harm to our environment and to the myriad other species that share it. We are a force to be reckoned with. Yet, the popular view that we are separate, above, apart, or even dominant over nature is an absurd one. For someone who cares deeply about the environment, this view has too often been accompanied by a sort of self-flagellation, cursing myself and my species for what we have done and continue to do to our home planet. Stories like this, however, offer an alternative perspective.

Humans are components of the natural world. We evolved just like every other living thing here, and so our actions as well as the actions of other species have helped shape the way the world looks. If our species had met its demise early in its evolutionary trajectory, the world would look very different. But we persisted, and as it turns out, despite the destruction we have caused and the species we have eliminated, we have simultaneously played a role in the evolution and persistence of many other species as well. We must learn to tread lightly – for the sake of our own species as well as others – but we should also quit considering ourselves “other than” nature, and we should stop beating ourselves up for our collective “mistakes.” It seems that when we come to recognize how connected we are to nature we will have greater motivation to protect it.

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