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Old 04-21-2013, 04:23 PM   #1
A Bee's Best Friend
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Default Biodiversity and fighting invasive species

A diversity of plant species increases the diversity of creatures both above and below ground and increases the number of soil microorganisms. This increase in biodiversty within a community helps combat invasive species and increases ecosystem services. The more we learn the more we understand that invasives on a local level disrupt ecosystem services provided by high diversity, and put species at greater risk of disease and local extinction. Gloria

Global plant diversity still hinges on local battles against invasives, study suggests

The research helps to explain seemingly contradictory findings in the scientific literature, but what does it mean for people who have been hacking down honeysuckle in their backyards and brushing their boots before entering conservation areas to avoid bringing in garlic mustard?
Is it worth whacking invasives or not?
"Emphatically yes," Knight says. "Invasive species are a serious threat," Knight says, "and if we're going to deal with them we need the cooperation of the public. Invasive plants have negative impacts on plant communities at smaller scales -- the scales that are crucial for necessary ecosystem services, like water management and nutrient cycling."
Take that bush honeysuckle choking Missouri's natural areas, for example. It was seeded by birds carrying honeysuckle berries from backyards. To prevent it from turning beloved nature preserves into shrub monocultures, people must remove it from their yards or choose not to plant it in the first place.
Microbial diversity determines the invasion of soil by a bacterial pathogen

Natural ecosystems show variable resistance to invasion by alien species, and this resistance can relate to the species diversity in the system. In soil, microorganisms are key components that determine life support functions, but the functional redundancy in the microbiota of most soils has long been thought to overwhelm microbial diversity–function relationships. We here show an inverse relationship between soil microbial diversity and survival of the invading species Escherichia coli O157:H7, assessed by using the marked derivative strain T. The invader's fate in soil was determined in the presence of (i) differentially constructed culturable bacterial communities, and (ii) microbial communities established using a dilution-to-extinction approach. Both approaches revealed a negative correlation between the diversity of the soil microbiota and survival of the invader. The relationship could be explained by a decrease in the competitive ability of the invader in species-rich vs. species-poor bacterial communities, reflected in the amount of resources used and the rate of their consumption. Soil microbial diversity is a key factor that controls the extent to which bacterial invaders can establish.

Our results demonstrate that plant diversity impacted
ecosystem processes by modifying the composition and
function of heterotrophic microbial communities in
soil. Many of the responses that we observed could be
explained by greater plant production (i.e., detritus production)
associated with higher levels plant diversity,
which are likely to result from niche complementarity,
positive interactions, and greater resource capture in
the most species-rich experimental plant communities
(Tilman et al. 2001). This appears to have fostered
greater rates of microbial respiration at higher levels
of plant diversity, but not when this process was normalized
for differences in plant production. The pattern
of gross N mineralization roughly matched the increase
in microbial respiration, suggesting that greater microbial
activity is one mechanism behind the increase in
N mineralization. However, when N mineralization was
adjusted for differences in plant production, there was
still a significant relationship with plant diversity, indicating
that greater rates of decomposition were not
the only mechanism at work.
Although the exact mechanisms causing greater rates
of N mineralization remains to be determined, plant
diversity altered microbial community composition and
function, which, in turn, increased the supply of soil
N to plants and contributed to greater productivity in
the most species-rich experimental plant communities.
They also demonstrate that the response of soil microbial
communities can be an integral component of plant
diversity’s influence on ecosystem function. Feedbacks
between plant and microbial communities control ecosystem
productivity, and our results demonstrate that
plant species richness is an important factor influencing
this biotic interaction.
"Half Earth Quest" Edward O. Wilson

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Old 04-23-2013, 11:49 AM   #2
A Bee's Best Friend
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So if all this is true how do the invasives get a toehold to begin with?
Population increases have caused so much disruption over such large areas that almost no land is exempt.
Agriculture alone even without the chemicals used has been a large culprit. For so long science did not comprehend the extensive damage being done and farmers thought they could add anything missing. But cost began to be a major factor sending everyone to look for answers.
Developers have done a fair share of ecosystem disruption, as have mining and logging companies going to more and more extremes to extract the many natural resources needed to keep producing all that consumers demand.

All this is a little overwhelming but as a simple gardener I can seek to understand the earth's processes and try not to get in the way.
"Half Earth Quest" Edward O. Wilson

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Old 04-25-2013, 04:27 PM   #3
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Biodiversity Crisis: The Impacts of Socio-Economic Pressures On Natural Floras and Faunas
Science Daily
Apr. 16, 2013

Biodiversity crisis: The impacts of socio-economic pressures on natural floras and faunas
excerpt from above:
It is well understood that the survival of a substantial and increasing number of species is put at risk by human activity via e.g. habitat destruction, environmental pollution or introduction of alien species. Accordingly, the most recent global IUCN Red List classifies 31% of the 65,518 plant and animal species assessed as endangered. However, the temporal scale of cause-effect relationships is little explored. If extended time lags between human pressure and population decline are common, then the full impact of current high levels of anthropogenic pressures on biodiversity will only be realized decades into the future...
The tendency of man's nature to good is like the tendency of water to flow downwards.
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