Wolves bring aspen back to Yellowstone

Aspen (Populus tremuloides) was a major species in Yellowstone, but over the twentieth century populations declined and there was little regeneration. While elk were initially blamed for this lack of regeneration, changing policies by the Park Service led to a change in this policy:

Until 1968, Park Service officials contended that an unnaturally large elk population, which had built up in Yellowstone during the late 1800s and early 1900s, had severely damaged the park’s northern winter range, including aspen (Populus tremuloides) communities. However, agency biologists now hypothesize that elk and other ungulates in Yellowstone are “naturally regulated,” being resource (food) limited, and that the condition of the ecosystem today is much like it was at park formation (Houston 1982; Despain et al. 1986). Elk influences on Yellowstone’s vegetation are now thought to be “natural” and to represent the “pristine” condition of the park.
According to the Park Service, Yellowstone is not now nor has it ever been
overgrazed, and all previous studies to that effect are wrong (Houston 1982).

[Kay, Charles E. 2001. Long-Term Aspen Exclosures in the Yellowstone Ecosystem. USDA Forest Service Proceedings RMRS-P-18.]

This conclusion was challenged by available evidence. For example, Kay showed the change in herbivore exclosures between 1946, 1963 and 1987 (images from Kay, 2001). The aspen clone is bisected by the exclosure's fence. While the two portions of the clone seem fairly similar in 1963, by 1987 the portion of the clone that was protected from herbivores has spread considerably.

William Ripple and Eric Larsen found* that the aspens had stopped regenerating in 1920, about the same time that wolves were eliminated from Yellowstone. However, there were questions on the role that wolves might play in regulating the elk population.

To this end, Ripple and Robert Beschta** looked at the level of browsing and the height of aspen saplings in areas with and without logs (which can provide cover for wolves). In both upland and riparian sites, aspen saplings were taller when downed logs were present.

The reintroduction of wolves has allowed allowed aspen to return to riparian areas (although not, so far, in upland areas). Willows and cottonwoods also returned - more quickly than the aspen, which are a preferred browse for elk. While populations reductions have played a role, so has the 'ecology of fear'.

*Ripple,W.J., Larsen, E.J., 2000. Historic aspen recruitment, elk, and wolves in northern Yellowstone National Park, USA. Biological Conservation 95, 361–370.
**Ripple, W.J., Beschta, R.L., Restoring Yellowstone’s aspen with wolves, Biological Conservation (2007), doi:10.1016/j.biocon.2007.05.006

Story at Science Daily.

Can organic agriculture sustain current levels of food production?

A recent report by Ivette Perfecto, Catherine Badgley and others at the University of Michigan suggests the organic agriculture is capable of sustaining or increasing current levels of food production globally.

Organic farming can yield up to three times as much food as conventional farming on the same amount of land—according to new findings which refute the long-standing assumption that organic farming methods cannot produce enough food to feed the global population.

According to the press release, the authors found that organic agriculture, which they define as "practices referred to as sustainable or ecological; that utilize non-synthetic nutrient cycling processes; that exclude or rarely use synthetic pesticides; and sustain or regenerate the soil quality", can maintain current levels of production in developed countries, and as much as triple production in developing countries.

The original article was published in Renewable Agriculture and Food Systems. There's a more detailed review at New Scientist and a two-part story(part 1, part 2) at OrganicAuthority.com.

H/T Meteor Blades at dKos.

Open access in botany journal

The Journal of Experimental Botany has provided open access to papers if the authors' institutions subscribe to the journal. Other authors who want their papers to be freely accessible will have to pay the full cost of publication which is estimated at £1500/$2800/€2250.

Over the last three years the journal has conducted an experiment in which they made about 30% of their papers freely available. They have found that these papers are more widely cited:

Early indications show that OA publication increases impact as full text downloads are, on average, 17% higher and citations 14% higher than for those publications kept under subscription control.

H/T Chronicle of Higher Education News Blog.

Ceiba pentandra: dispersal, vicariance and press releases

Ceiba pentandra (the silkcotton, kapok or ceiba tree) has a broad distribution including across the Neotropics and Africa. A cultivated form is grown across a wider range for kapok fibres. The trans-Atlantic distribution of C. pentandra has attracted attention for a long time - based on the fact that there are nine species in the Neotropics and only one in Africa, it has generally been assumed that it is a Neotropical species that dispersed to Africa. How it got there has long been a question.

EurekaAlert! published a press release attributed to the National Science Foundation about a paper published in Molecular Ecology concerning the trans-Altantic distribution of Ceiba pentandra, the silk cotton or kapok tree. The paper* considers three mechanisms by which the species could have come to be present on both sides of the Atlantic: Gondwana vicariance, Boreotropical dispersal (and subsequent vicariance) and long-distance dispersal.

In the case on Gondwana vicariance, the distribution would reflect the fact that South America and Africa were connected (as parts of Gondwana) until 96 million years ago. In the case of Boreotropical dispersal, the species would have colonised Africa about 35 million years ago through a then warmer North America and Europe, only to be lost from those areas as the climate warmed. Both of these would be expected to produce deep divergence between African and South American C. pentandra populations. On the other hand, if long-distance dispersal across the Atlantic took place more recently, the divergence would be smaller.

The paper found evidence for recent dispersal. The authors noted that:

Ceiba pentandra has the weakest phylogeographical structure yet reported for a widespread rainforest tree species. Apart from the cluster of sites in Western Ecuador having a variant psbB-psbF haplotype, there was no cpDNA variation across Mesoamerica, the Amazon basin, and West Africa. In fact, this study found less cpDNA variation across three continents than some rainforest tree species exhibit within putative breeding populations in French Guiana and Brazil (Hamilton 1999b; Dutech et al. 2000; Latouche-Halle et al. 2003) or among sample sites at regional scales in French Guiana and across Mesoamerica (Caron et al. 2000; Cavers et al. 2003).

In this regard, C. pentandra is by no means unique - several other species have been found that have recently crossed the Atlantic, including Symphonia globulifera, which apparently colonised the Americas from Africa.

One thing that bothers me is the press release. It opens with

Celebrated in Buddhist temples and cultivated for its wood and cottony fibers, the kapok tree now is upsetting an idea that biologists have clung to for decades: the notion that African and South American rainforests are similar because the continents were connected 96 million years ago.

It’s obvious that whoever wrote the press release didn’t spend much time looking at the paper. While the issue of Gondwanan roots is considered, it’s by no means a new idea. At the same time, it’s a fairly limited suite of trees that are shared between the two areas, and evidence of recent trans-Atlantic dispersal by a few species does not “[upset] an idea that biologists have clung to for decades”. That’s nonsense.

* Christopher W. Dick, Eldredge Bermingham, Maristerra R. Lemes and Rogerio Gribel. Extreme long-distance dispersal of the lowland tropical rainforest tree Ceiba pentandra L. (Malvaceae) in Africa and the Neotropics. Molecular Ecology (OnlineEarly Articles). doi:10.1111/j.1365-294X.2007.03341.x

H/T Agricultural Biodiversity Weblog.

[Crossposted from my Wordpress blog]

Biofuels

ScienceDaily has an article today about a new biofuel based on wood chips which can be blended with biodiesel and petroleum diesel. It's based on pyrolysis of wood chips in an oxygen-free environment, and yields charcoal as a waste product. It's supposed to be nearly carbon-neutral (as long as the forests are being replanted), and actually carbon-neutral if the charcoal can be added back to the soil as a fertiliser (presumably since the carbon in charcoal is pretty much out of circulation forever).

Link to the paper is here.

Of course, the thing that pops into my head is the question of how much land is available for growing trees. Will a wood-based biofuel lead to further deforestation - like the Brazilian forests that were cleared to plant Eucalyptus to produce charcoal for an iron smelter? Will it shorten the rotation time on current forest plantations? Will it lead to pressure to convert natural and semi-natural areas to tree monocultures? Will it compete with land for food production? Obviously we can't continue to depend on fossil fuels indefinitely, but alternative fuels seem to raise as many questions as answers.

The impact of farming on biodiversity

Globally, the demand for food is expected to double by 2050, which could require the conversion of an additional 10 billion hectares of natural ecosystems to cropland. With 37% of the available land already under agriculture, agroecosystems represent an important component of global biodiversity. Since agricultural intensification is usually associated with biodiversity declines, being able to estimate the effects of land use change on biodiversity is an important tool for land management. In the latest issue of Science, Butler et al. were able to use six historical measures of agricultural land use change to successfully explain population changes in 57 bird species over the a forty-year period.

New developments in biofuels

Syngenta is working on a genetically engineered corn variety which contains amylase, an enzyme required to break starch down into sugars, a necessary step in fermenting corn into ethanol. Monsanto and Pioneer Hi-Bred are looking at ways to develop corn varieties which are better for ethanol production.

Despite this interest, corn is unlikely to meet the fuel needs of the US. Instead of starch, many people are looking to cellulose as a source of feedstock for ethanol production. Ceres and the Noble Foundation are looking at switchgrass in Oklahoma, while Mendel Biotechnology is looking at Miscanthus, a Chinese grass. (Read article)

Plant defense against bacteria

Usually thought of as unwitting participants in the infection of plants by bacteria, it appears that stomata actually play an active role in fighting bacterial infection. New work by Maeli Melotta and Bill Underwood in the lab of Sheng Yang He at Michigan State University shows that stomata close when bacteria are placed on the leaf surface. However, bacteria which infect plants produce coronatine, a phytotoxin which forces the stomata to open (read press release)

Did pollination evolve before flowers?

It has generally been assumed that pollination originated with flowering plants. However, a study by Nils Cronberg et al. suggests that the process of having animals act as intermediaries in plant reproduction may have arisen long before flowering plants. Not only do springtails and mites move sperm between antheridia and archaegonia, fertile plants attract five times as many of these microarthropods and do sterile ones. (Read article in Science News, or original paper in Science)

Biologist charged with destroying non-native plants

Biologist Robert van de Hoek is charged with six misdemeanours for killing non-native plants (a Ficus tree and Myoporum shrubs) in one of the largest coastal wetlands in Southern California

To prosecutors, Robert "Roy" van de Hoek is a vandal with pruning shears. To supporters of native California shrubs and trees, he's a martyr. Once again, he's in court.

"Trimming and landscaping isn't done without authorization from government agencies," said Frank Mateljan of the city attorney's office.

(Read article)

New tallest living thing

A new contender for the title of "tallest living thing" has been discovered in Redwood National Park near Eureka, California. Standing 378.1 feet (115 m) tall, the Coast Redwood nicknamed Hyperion stands 8 feet (2.4 m) taller than the previous champion, the Stratosphere Giant, in Humboldt Redwoods State Park. (See article)

How to grow plants on Mars

Plants that could grow on Mars would need to be able to tolerate conditions outside the range experienced by plants on Earth. One source of such genes is extremophiles living in Antarctica and in deep ocean vents. University of North Carolina plant physiologist Wendy Boss and microbiologist Amy Grunden propose that transfering stress-tolerance genes from extremophiles to plants may allow them to grow in Martian conditions (See article).

Barcoding algae

In a paper in the August issue of the American Journal of Botany, Robba et al. discuss the use of mitochondrial cyctochrome c oxidase subunit 1 (cox1) for barcoding Red alge, which are difficult to indentify solely on the basis of morphology. They found that they were able to discriminate species on this basis, and suggested that it might be a useful tool. (See article)

Miracle tree in Haryana

While neem is often considered a "miracle tree" for all its useful products, but a neem tree in Jagadhri in Harayana is being seen as miraculous for another reason. The tree is oozing a milk-like substance which people believe will cure them of their ailments. (Read more)

Bt brinjal

The Indian Genetic Engineering Approval Committee has set up a panel to review health and environmental concerns related to Bt brinjal (otherwise known as eggplant, aubergine or melongene). These crops express genes from the bacterium Bacillus thuringiensis, making them toxic to certain lepidopteran and coleopteran species. (Read more)

Jack Fisher, Botanist

The St. Petersburg Times has a nice little bio on Jack Fisher of the Fairchild Tropical Botanic Garden. (Read more)

Bringing back extinct plants from herbarium specimens?

Forgotten inheritance: The 150-year-old herbarium of the University of Namur in Belgium is being catalogued for the first time. Among the discoveries is a specimen of Bromus bromoideus, Brome of the Ardennes, a grass endemic to Belgium which went extinct in the 1930s. The European Native Seed Conservation Network is apparently trying to bring the plant out of extinction using stored seed. The article doesn't make it clear whether they expect to get viable seed from the 1852 specimen. (Read more)

Asian Soybean Rust

Soybean Rust worries farmers: Despite the title of the article, apparently farmers in Indiana aren't worried about Asian Soybean Rust yet, and it doesn't pose a threat at this point in time. However, there's potential for it to spread north if there is a wet spring and summer in the Gulf states, where Asian Soybean Rust currently exists. (Read more)

Forensic Botany

A nice little article on Forensic Botany from the Nueces County Record Star.

"Botanical evidence has been used as early as the 1930's but is often not used to its full potential because the area of botany is overlooked by many people," said Galloway. "One of the earliest cases using botanical evidence to solve a crime was the Lindbergh baby kidnapping trial, where a ladder found at the crime scene was traced back to the suspect. One of its rungs was matched with wood found in the suspect's shop. Tool marks found on the wood also corresponded with the suspect's tools."

Corridors and plant species richness

Corridors Increase Plant Species Richness at Large Scales: The utility of corridors in fragmented landscapes has has been controversial since the 1980s. They became popular elements of landscape management plans, but there is little empirical evidence supporting their utility. A recent study in Science found that:

habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species.

This supports the idea that corridors have conservation value (see Damschen et al.'s paper)