This flood of antibiotics released into the environment--sprayed on fruit trees and fed to the likes of livestock poultry and salmon among other uses--has led bacteria to evolve Hollis writes.
In the 1960s mathematicians William Tutte and Crispin Nash-Williams separately developed theories about structures called edge-disjoint spanning trees
A spanning tree is a subgraph--or a graph-within-a-graph--in which all of the nodes are connected by the smallest number of edges.
A set of spanning trees within a graph are called edge-disjoint if they do not share any of these connecting lines.
If a network contains three edge-disjoint spanning trees for example information can flow in parallel along each of these trees at the same time meaning three times more bandwidth than would be possible in a graph containing just one tree.
The higher the number of edge-disjoint spanning trees the larger the information flow Ghaffari says.
The results of Tutte and Nash-Williams show that each graph contains almost as many spanning trees as its edge connectivity he says.
MD chair of the Cedars-Sinai Department of Pediatrics and director of the Division of Neonatology.
The above story is provided based on materials by Cedars-Sinai Medical center. Note: Materials may be edited for content and length h
#Slippery bark protects trees from pine beetle attacktrees with smoother bark are better at repelling attacks by mountain pine beetles
The findings published online in the journal Functional Ecology may help land managers make decisions about which trees to cull and
which to keep in order to best protect forested properties against pine beetle infestation. The current mountain pine beetle epidemic has spread across 3. 4 million acres in Colorado
since the outbreak was detected first in 1996. The tiny beetles which are about the size of a grain of rice bore into the pine bark.
The trees fight back by exuding pitch which pushes the beetles back out of the tree. Large-scale and continuous beetle attacks can kill the tree.
Doctoral student Scott Ferrenberg who led the study said he first began to suspect that bark texture might affect the survival of trees
while he and Jeffry Mitton a professor of ecology and evolutionary biology were walking through a stand of high-elevation limber pines.
They noticed that surface resin a residue of fighting off a beetle invasion was common only on patches of rough bark.
We found trees that had both textures on the same stem and when the tree was attacked it was on the rough surfaces Ferrenberg said.
We thought the beetles were either choosing to avoid the smooth surface or they just couldn't hang onto it.
To determine which was the case the researchers tested how well the beetles could hold onto different bark textures.
They placed each of 22 beetles on a rough patch of bark and on a smooth patch.
and Jeffrey Kane of Humboldt State university in California found that a second physical characteristic of a tree also helps predict how resistant the pine is to beetle infestation.
The team discovered that trees that had survived beetle attacks had more resin ducts than trees that were killed.
The number of resin ducts differed between trees of the same age and in general younger trees had more resin ducts than older trees.
The number of resin ducts--which is related to the trees'ability to pitch out the beetles--is counted easily by taking a small core of the tree.
There are very practical applications Ferrenberg said. These two traits are very easy to see on the tree.
Because young trees tend to have smoother bark as well as more resin ducts the research also suggests that land managers should consider cutting down some older trees
when mitigating properties to resist beetles. This contradicts the approach that has been historically common for fire management Ferrenberg said.
The common approach for fire is to cut all the small trees. But if you want to defend a small amount of land against bark beetles that may not be the best strategy.
In a study to appear in the December 22 issue of the journal Nature the team constructed an evolutionary tree of more than 32000 species of flowering plants--the largest time-scaled evolutionary tree to date.
By combining their tree with freezing exposure records and leaf and stem data for thousands of species the researchers were able to reconstruct how plants evolved to cope with cold as they spread across the globe.
Some plants such as hickories and oaks avoid freezing damage by dropping their leaves before the winter chill sets ineffectively shutting off the flow of water between roots
Other plants such as birches and poplars also protect themselves by having narrower water transport cells
and stem data onto their evolutionary tree for flowering plants they found that many plants were equipped well for icy climates even before cold conditions hit.
As a next step the researchers plan to use their evolutionary tree to find out how plants evolved to withstand other environmental stresses in addition to freezing such as drought and heat.
This small shark can fit in the palm of your hand and is recognized by interesting clusters of brown or white spots in polygon configurations all over its body.
if a tree doesn't fall in China can you hear it elsewhere in the world?
The plant is a small understory tree found only on the main island of New caledonia in the South Pacific.
This group includes tomato apple and legumes as well as timber trees such as oak and poplar. As an evolutionary outsider to this diverse group the Amborella genome allowed the researchers to estimate the linear order of genes in an ancestral eudicot genome
since it split from the rest of the flowering plant tree of life. For example DNA sequences that can change locations
One way to slow climate change is to increase the number of trees On earth as they through photosynthesis take up the greenhouse gas carbon dioxide converting it to carbon products
but has an excellent climate for tree growth and thus has a high potential for carbon stocking through forests.
Since the emerald ash borer was first found feeding on trees in southeastern Michigan in 2002 this Asian invader has been responsible for the death of 30 million trees in the northeastern U s. and Canada.
In Chicago where the emerald ash borer is already destroying trees 17 percent of the street trees are ash--85000 trees with an estimated 300000 more ash trees on private property.
and into Michigan so that we could follow the decline of trees and the impact on the ecosystem Flower said.
and nuthatches were feeding on the emerald ash borer. They hoped that unlike other exotic invasive species which run amok in new regions because of the lack of predators to keep them in check the emerald ash borer might meet its match in native predators--bark foraging birds like the woodpecker and nuthatch.
This kind of bio-control would be as or perhaps more efficient than other methods to slow the spread of this pest said Flower.
and may cause harm to trees and other fauna and the introduction of an ash borer predator from its native range in Asia might bring with it a host of new problems he said.
One of the ways a predator can respond to a new abundant food source according to Flower is a functional response:
the woodpeckers alter their behavior in a way that allows them to find emerald ash borers more efficiently
When emerald ash borer larvae emerge from eggs laid on the tree they burrow in
and eat their way through the phloem layer of the tree the vascular system that delivers water and nutrients from root to branch.
The insects create characteristic serpentine galleries that cut this vascular system starving the tree. Eventually mature adults exit the tree to start the process again.
A section of trees in the stand behind the school was cut down for examination each year for two years.
The students searched for and painted all the holes they found in the bark of each tree--a different color each for large round woodpecker holes for the characteristic crescent-shaped holes mature emerald ash borers
make exiting a tree and for holes made by other insects. Paint seeped through to dye the stem beneath
and after the bark was stripped the students could identify woodpecker holes that penetrated into emerald ash borer galleries
or into holes made by other bugs. The students tracked the fate of each bug that had been in the tree.
Instead of relying on a statistical estimate of the insect population and thus the food source available every bug and its fate were accounted for.
This was looking at woodpecker foraging at a fine tree-by-tree scale said Flower.
Their results proved that woodpeckers were indeed choosing to prey on emerald ash borers--eating 85 percent of the emerald ash borer in an infested tree.
In a related study researchers at Cornell tracked the movement of emerald ash borer from Detroit
and the white-breasted nuthatch the important bark foraging birds in this region increased as the emerald ash borer increased.
and the nuthatch to have an impact on the population of the emerald ash borer said Whelan.
Very little is known about emerald ash borer habits in its native environment its natural predators
Woodpeckers won't save a tree once it's infested but they may save the forest.
The research suggests that the woodpeckers are likely slowing the spread of emerald ash borer.
While estates are mandated by law to maintain tree plantations on at least 10 percent of their own land this law is enforced rarely justified by the national strategic importance of the tobacco industry.
but collect and carry vegetation--often grasses flowers fir needles and herbaceous forbs such as lupine alumroot and yarrow--to their homes to make haypiles for winter use.
and undergraduates conducted the study on two talus slopes--each about 3. 5 acres--surrounded by a forest of Douglas fir western red cedar and bigleaf maple near the Gorge Trail near Wyeth Ore.
The scientists surveyed the abundance of lichens mosses ferns grasses sedges rushes forbs shrubs and trees along the two rockslides.
and Livesixty percent of the pikas'diet by dry weight came from moss at both sites with the rest from grasses lichens ferns forbs shrubs and some fir needles.
and fir needles high in phenol to preserve the food cache through the winter. Yet in both places the haypiles equaled about three ounces per animal per day of annual snowpack also showing the low-elevation pikas didn't need to prepare for winter as much because of the availability of their year-round salad bar.
#Significant advance reported with genetically modified poplar treesforest geneticists at Oregon State university have created genetically modified poplar trees that grow faster have resistance to insect pests
The trees are one of the best successes to date in the genetic modification of forest trees a field that is much less advanced than GMO products in crop agriculture.
and pulp industries and in an emerging biofuel industry that could be based on hybrid poplar plantations.
Commercial use of such trees could be done with poplars that also had been engineered to be sterile
so they would be unlikely to spread their characteristics to other trees researchers said. Development of male sterile trees has been demonstrated in the field
which can be used for male varieties of poplar. Female sterility has not yet been done but should be said feasible they.
However it is unclear if regulatory agencies would allow use of these trees with sterility as a key mitigation factor.
In terms of wood yield plantation health and productivity these GMO trees could be said very significant Steven Strauss a distinguished professor of forest biotechnology in the OSU College of Forestry.
Our field experiments and continued research showed results that exceeded our expectations. And it is likely that we have underestimated the value these trees could have improved in growth and production.
A large-scale study of 402 trees from nine insertion events tracked the result of placing the cry3aa gene into hybrid poplar trees.
The first phase was done in field trials between 1998 and 2001 and in 14 years since then study continued in a clone bank at OSU to ensure that the valued traits were retained with age.
All of the trees were removed or cut back at the age of two years before they were old enough to flower
and reproduce in order to prevent any gene flow into wild tree populations researchers said. With this genetic modification the trees were able to produce an insecticidal protein that helped protect against insect attack.
This method has proven effective as a pest control measure in other crop species such as corn
Insect attack not only can kill a tree it can make the trees more vulnerable to other health problems said Amy Klocko an OSU faculty research associate.
Hybrid poplar trees which are grown usually in dense rows on flat land almost like a food crop are especially vulnerable to insect epidemics the researchers said.
and targets a wide range of insects rather than only the insects that are attacking the trees.
A number of the GMO trees in this study also had improved significantly growth characteristics the researchers found.
Compared to the controls the transgenic trees grew an average of 13 percent larger after two growing seasons in the field and in the best case 23 percent larger.
Some of the work also used a drought-tolerant poplar clone another advantage in what may be a warmer and drier future climate.
The research was supported by the Tree Biosafety and Genomics Research Cooperative at OSU. Annual crops such as cotton and corn already are grown routinely as GMO products with insect resistance genes.
Trees however have to grow and live for years before harvest and are subjected to multiple generations of insect pest attacks.
Some genetically modified hybrid poplar trees are already being used commercially in China but none in the United states. The use of GMO trees in the U s. still faces heavy regulatory obstacles Strauss said.
Agencies are likely to require extensive studies of gene flow and their effects on forest ecosystems
Strauss said he advocates an approach of engineering sterility genes into the trees as a mechanism to control gene flow
Agoutis eat tree seeds. Ocelots eat agoutis said Patrick Jansen research associate at the Smithsonian Tropical Research Institute and assistant professor at Wageningen University.
Scientists compared daily activity patterns of agoutis between parts of forest with contrasting abundance of palm seeds.
and establish a new tree. Hungry agoutis plant trees but may never see the fruit of their labor--a fascinating feedback loop.
Story Source: The above story is provided based on materials by Smithsonian Tropical Research Institute. Note: Materials may be edited for content and length.
#Economically valuable sweet-gum trees: Taxonomy and nine new combinationsthe sweet-gum family Altingiaceae is a small group of wind-pollinated trees that produce hard woody fruits that contain numerous seeds.
This widespread tree family has been puzzling botanists for a while due to its complicated taxonomic structure and the morphological similarities between the different genera
which makes their separation and description a challenge. Best known for their biogeographic intercontinental disjunction between E Asia
and Semiliquidambar are nested within Liquidambar. A new taxonomic synopsis published in the open access journal Phytokeys formally transfers all Altingia and Semiliquidambar taxa to Liquidambar
which has nomenclatural priority and provides a new analysis including nine new combinations. Traditionally classified into members with a predominantly temperate distribution (Liquidambar) those with a largely tropical to subtropical distribution (Altingia) are presented also in the new study including the taxonomic enumeration and distribution of 15 recognized species based on studies of 1500 specimens
from 24 herbaria throughout the distributional range of the taxa. Despite the difficulties in their taxonomy sweet gum trees are in fact widely distributed and well known due to their varied uses by people.
They are valued for their high quality timber and they produce fragrant resin (styrax). Some species are cultivated also as ornamentals
and Liquidambar chingii is listed as near-threatened by the IUCN. Story Source: The above story is provided based on materials by Pensoft Publishers.
#Cellulose nanocrystals possible green wonder materialthe same tiny cellulose crystals that give trees and plants their high strength light weight and resilience have now been shown to have the stiffness of steel.
Cellulose could come from a variety of biological sources including trees plants algae ocean-dwelling organisms called tunicates
and ecologists from Switzerland Norway and the US debuts in applying existing methods of tree-ring research (dendrochronology*)to analyze annual horn growth rates of the Alpine ibex (Capra ibex**)
and tree nuts but Liam drank soy milk for months before his anaphylactic reaction. After drinking a cup of soy milk as he had done regularly for months Liam immediately started coughing vomiting developed hives all over his body
and dry pine forests in particular. Although nitrogen deposition remains small in Northern europe even a slight rise in long-term deposition could change the competitive relationship of vascular plants by promoting the dissemination
According to long-term monitoring by the Finnish Forest Research Institute (Metla) tree felling is still the key factor in changes to forest floor vegetation.
These consist primarily of pine and eucalyptus. The sawmill industry provides work for around 35 per cent of the population in South australia's Green Triangle region.
The report can be found online at: http://www. dmitre. sa. gov. au/manufacturing works/programs and initiatives/cellulose fibre chain initiativestory Source:
Above all globalization and perhaps climate change bring not only more foreign plants and invertebrates to these shores but also--more worrying by far--new pests and diseases especially of trees such as the recent ash chalara.
which were common in the past rather than insisting on uprooting every existing tree. We might replicate some of the modes of exploitation other than grazing
It is spread by a tiny insect called the Asian citrus psyllid that feeds on the trees leaving bacteria that starve the tree of nutrients.
Infected trees produce fruits that are unsuitable for sale as fresh fruit or for juice and most die within a few years.
The disease has affected already millions of citrus trees in North america. Gabriel's team's work will be outlined in a research paper that will be published in February in the journal Molecular Plant-Microbe Interaction.
and crushed tissue from the veins of infected citrus trees where the organism was concentrated most highly.
The team had to separate the tree DNA from that of the bacterium. DNA comprises four nucleotides
In the battle against greening UF/IFAS researchers have tried everything from working on ways to eradicate the psyllid to grafting trees that show better resistance to greening.
Frederick Gmitter a citrus breeder and faculty member at IFAS'Citrus REC said his research team has found new experimental rootstocks that seem to be supporting healthier trees--even ones with citrus greening.
In addition his team is studying escape trees which are trees that remain unscathed even when surrounded by thousands of infected tress.
Story Source: The above story is provided based on materials by University of Florida Institute of food and agricultural sciences. Note: Materials may be edited for content and length.
These ephemeral secondary forests may contribute little to tree-biodiversity conservation according to a new report by scientists at the Smithsonian Tropical Research Institute in Panama.
From the perspective of conserving tree species this doesn't work. Even 30-year-old forests have a very low percentage of the reproductive trees essential to long-term species survival.
Perhaps the most extensive of its kind in the tropics van Breugel's study suggests that forests subjected to regular human disturbance may undergo profound long-lasting tree biodiversity loss.
Whereas fallow forests can have a surprisingly high tree-biodiversity a large proportion of tree species only occur as seedlings and saplings.
They do not reproduce before the forests are cleared again. A tree only contributes to the conservation of its species
when it arrives at a site establishes grows and reproduces said van Breugel. The research was conducted on the Smithsonian's 700-hectare Panama canal Watershed Experiment a long-term research site designed to quantify ecosystem services provided by different land uses.
And to what extent can short-lived secondary forests in dynamic agricultural landscapes contribute to the conservation of a high diversity of tree species?
which they counted more than 52000 trees palms and lianas. To the authors'knowledge this was the first metacommunity study of its kind ever conducted in the tropics.
In the study plots researchers found 324 tree and shrub species about 55 percent of Agua Salud's suite of approximately 600 tree species. They estimated relative reproductive size thresholds
If left undisturbed secondary forests may regain levels of tree diversity similar to those of mature forests
and remnant trees as it did in this case. The research underscores the importance of protecting old forests to maintain the tree diversity for which the tropics are famous.
In the long term we might see a distinct shift in the functional composition of human-altered landscapes said van Breugel.
On the other hand many shade-tolerant trees are dispersed poorly grow slowly and depend on forest-bound species for pollination and dispersal.
and colleagues conducted on short-term testosterone spikes among Tsimane hunters follows previous studies examining similar increases resulting from chopping down trees--another physically demanding task that is critical to successful farming and food production.
which in turn enhance performance during physically active production strategies such as tree chopping for farming or hunting.
#Better protection for mangroves with models for successful seedling establishmentseedlings of mangroves do not have an easy time to get established.
Human intervention in coastal areas and climate change also make life difficult for mangrove seedlings.
Thorsten Balke studied the conditions that enable mangrove seedlings to be successful. On 18 december he will defend his Phd thesis at Radboud University.
Geographer Thorsten Balke studied the establishment of mangroves: how do the seedlings get to the tidal flat and
what factors ensure their growth to become a successful mangrove forest? To answer these questions he carried out experiments in Singapore and New zealand.
The dangers of high tide What is the biggest danger for mangrove seedlings? High tide. Due to the currents and waves that accompany high tide sedimentation
tidal periods in which the conditions are ideal for the establishment and further development of mangrove seedlings.
'We now understand both the optimal conditions for successful establishment of a mangrove forest and the optimal location and optimal time to sow mangroves'explains Balke.'
'Policymakers can take these factors into account when restoring mangroves. Moreover with this information we can create scenarios to predict the consequences of climate change on mangroves.'
'The results of Balke's models emphasise that the most important factor for successful restoration is not planting seedlings
but improving the growing conditions for the seedlings. For example in Indonesia mangrove rehabilitation projects are being developed using brushwood groynes to counteract erosion
and enable mangrove seedlings to develop. Balke:''All my publications are open source so that everyone in the world can use this information freely.'
'Story Source: The above story is provided based on materials by Radboud University Nijmegen. Note: Materials may be edited for content and length h
#Pine plantations provide optimum conditions for natural forests to develop underneath themif there is any native forest in the vicinity tree fern
and herbaceous species typical of these forests penetrate under the pine plantations without any need for action.
and Ecosystem Services group in its research carried out on the pine plantations of Bizkaia.
Nowadays mixed native forests in other words the ones in which the predominant species is the oak (Quercus robur) occupy no more than 3%of the surface they could occupy in Bizkaia
As they are trees with a longer turnover because they grow more slowly than pine plantations their management produces fewer disturbances in the system explained Ametzaga.
Intervention necessary to achieve restaurationas a result of the crisis affecting forestry there are many pine plantations at the end of their turnover.
In the last years of pine plantations as there has been no clearing thinning out or pruning the seeds arriving from the adjoining forests thrive in the conditions provided by the pine trees.
We have seen that on the whole typical trees and ferns and some herbaceous species are the ones that adapt to that environment best she added.
In view of these results Ametzaga proposes that in some areas pine plantations can be used to encourage the native forest by taking advantage of ecological succession.
What is more the older or more ancient the plantations are the richer the forest that develops from them is
To equate the species composition to that of native mixed forests it will be necessary to undertake adaptive management involving the gradual removal of the pine trees
Part of that evidence comes in the form of a single dried-out leaf from a larch tree that grew thousands of years ago.
The researchers know that the glacier had remained previously unchanged for a very long time--in part because of the preserved larch leaf
They identified the leaf as belonging to Larix decidua or the European larch. Carbon dating determined it to be around 2600 years old.
when this particular larch tree grew though it was not far from his resting place. The leaf supports the idea that prehistoric ice is still present at the highest elevations of the region Gabrielli said.
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