Today I want to share with you a fascinating story from Science Daily on how the invasive reed Phragmites australis manages to suppress other wetland plants by taking advantage of the biochemical activities of native plant roots and native microbes in the soil.  Apparently, “Phrag”, as it is known to those of us who are all too familiar with it, releases larger-than-usual amounts of compounds called gallotannins, which are initially harmless.  BUT, when enzymes produced by microbes in the root zone of the soil (as well as by the roots of some native wetland plants) get hold of the gallotannins, they convert them to toxic gallic acid.  The gallic acid actually destroys the structural integrity of plant roots by breaking down the tubulin protein that helps keep the roots rigid.

Unlike many other examples of allelopathy, the chemicals secreted by the invasive Phragmites don’t do the damage themselves, but take advantage of enzyme activity already present in the soil of native plant communities!  How fortuitous for the invader!  What isn’t known yet is how the invasive strains of Phragmites are themselves able to resist damage from gallic acid present in the soil.  Research like this is revealing that complex underground warfare between plants is much more common (and more fascinating) than we once thought!

The research, conducted by investigators at the University of Delaware, was published in the December 2009 issue of the journal Plant Physiology.  You can download the full PDF here.

For more information on Phragmites, the threats it poses to wetland ecosystems, and its identification and control, check out the Plant Conservation Alliance’s Phrag page or download a free copy of my publication, Mistaken Identity?  Invasive Plants and their Native Look-alikes: an Identification Guide for the Mid-Atlantic.

What’s the issue? In short, the Farm Services Agency is accepting public comments on the environmental impact of two possible policy alternatives for the Conservation Reserve Program, an important mechanism for protection of wildlife habitat and biodiversity on working farms.

Here’s a little background.  The CRP (Conservation Reserve Program) is a land retirement program administered by the Farm Services Agency (FSA), and implemented by the USDA Natural Resources Conservation Service (NRCS).  Basically, the government pays eligible farmers an annual rental rate for taking cropland or certain marginal pastureland out of production and keeping it that way for the life of the CRP contract (10-15 years).  In addition, farmers receive a cost-share assistance payment for “practices” they install on the enrolled acres, including wildlife habitat plantings, erosion control, riparian buffers, etc.

With more than 33 million acres enrolled in CRP nationwide, the program has become an important tool for conservation of biodiversity in agricultural landscapes.  Grassland birds, insect pollinators, quail and other upland game birds, and many additional species use CRP land.

Now, however, the number of acres enrolled in CRP is likely to be threatened by the economic reality of our times.  With corn and cellulosic biofuel production receiving considerable economic and political support, CRP rental rates are unlikely to be high enough for farmers to maintain land in the program.  The “opportunity costs” of CRP, i.e. the potential earnings for biofuel production, are increasing.  I wrote about this issue in a previous post, Biofuels and Habitat Loss, which also provides further background on CRP for those of you who are unfamiliar with the program.

At the same time that biofuels are threatening to reduce CRP acreage via economic competition, FSA is considering (see Alternative 2 below) reducing the CRP acreage enrollment cap from 32 million acres (the cap authorized in the 2008 Farm Bill) to 24 million acres, a full 25% reduction.  Alternative 2 also cuts the acreage cap for so-called targeted enrollment programs by a combined 50%.  These programs include state partnerships like the Conservation Reserve Enhancement Program (CREP) and State Acres for Wildlife (SAFE), as well as Continuous CRP, as well as special initiatives.  All of these programs are enhanced versions of CRP that allow targeted enrollment for particular wildlife species or habitats, including species of conservation concern.

Alternative 2 would also nix plans for a separate pollinator habitat practice under CRP.  This is challenging because it means that standard cost-share rates for existing practices would have to be used for pollinator habitat creation, a practice that is generally significantly more expensive (due to high plant materials costs) than other traditional conservation practices.

You can review the public meeting slide presentation prepared by GeoMarine, Inc. here. The following comparison of alternatives is taken from this presentation.

I just spoke with an FSA representative who informed me that, while the two alternatives are currently being presented as two discrete alternatives covering all the provisions, those providing comments should feel free to voice support for either alternative in each provision.  In other words, if you agree with Alternative 1 for several provisions, but Alternative 2 for a few other provisions, you can state that in your comments.

Please take a few minutes to provide your comments on this important issue at the comment page on the GeoMarine, Inc. web site.  Wildlife that depends on our agricultural landscapes is depending on you to make your voice heard.

As much as we all love eagles, we must bear in mind that the recovery of the Bald Eagle has been an overwhelming success and that the species is once again common across large areas of its breeding range.   Because of this, conflicts between human activity and eagles are on the rise.

When the Bald Eagle was delisted, the Endangered Species Act provisions could no longer be applied (including the provisions that allowed limited “take” or disturbance under the ESA).  The Bald and Golden Eagle Protection Act, which has been on the books since 1940, was left in place, but while this act prohibited disturbance, it provided no permitting mechanism for allowing “takes” for unavoidable disturbance.  This might have been okay when Bald Eagles were truly rare, but it has now become a real problem.  The rule states:

Many actions that are considered likely to incidentally take (harm or harass) eagles under the ESA will also disturb or otherwise take eagles under the Eagle Act. Until now, there was no regulatory mechanism in place under the Eagle Act to permit take of bald or golden eagles comparable to incidental take permits under the ESA. This rule adds a new section at 50 CFR 22.26 to authorize the issuance of permits to take bald eagles and golden eagles on a limited basis. The regulations are applicable to golden eagles as well as bald eagles. We will authorize take of bald or golden eagles only if we determine that the take (1) is compatible with the preservation of the bald eagle and the golden eagle and (2) cannot practicably be avoided. For purposes of these regulations, ‘‘compatible with the preservation of the bald eagle or the golden eagle’’ means ‘‘consistent with the goal of stable or increasing breeding populations.”

-Federal Register Vol. 74, No. 175 Friday, September 11, 2009. Rules and Regulations. 46837.

It is worth noting that the original USFWS proposal for this rule in 2007, during the Bush administration, interpreted the statutory mandate of “compatible with the preservation of” as being fulfilled by adhering to a national standard of 0.54% or less annual decline in populations.  Thus, the change to a goal of “stable or increasing” populations in the final rule is a significant turnabout for the agency, and one that makes much more sense for the long-term conservation of eagles.

The permitted take of Bald Eagles will initially be capped at 5% of estimated annual productivity, a conservative figure to be sure.

Also, while the Times article pointed out that, unlike Bald Eagle populations, Golden Eagle populations are declining, it failed to mention that permitting under the new rules for Golden Eagles would be very limited, at least initially.

For golden eagles west of 100 degrees West longitude, including in Alaska, we will initially implement this rule only insofar as issuing take permits based on levels of historically authorized take, safety emergencies, and take permits designed to reduce ongoing mortalities and/or disturbance. Future projects seeking programmatic permits would need to minimize their own take of golden eagles to the point that it is unavoidable and also reduce take from another source to completely offset any new take from the new activity….  For golden eagles east of 100 degrees West longitude, we will not issue any take permits unless necessary to alleviate an immediate safety emergency. We do not have enough data on rates of golden eagle mortality in the eastern U.S. to issue programmatic take permits.

-Federal Register Vol. 74, No. 175 Friday, September 11, 2009. Rules and Regulations. 46840.

Additionally, the new rules create a permitting process for the take of active and inactive eagle nests.  Take of an active nest would only be allowed in the rare case of “genuine safety concerns” such as nests at airports, or unstable nest trees that may threaten to fall on a residence.  Inactive nest take permits, however, could be issued “when necessary to ensure public health and safety”, or when the nest interferes with the operation of a human-engineered structure (such as a nest built on a crane).  Finally, an inactive nest take permit may be issued when the activity provides a net benefit to eagles or otherwise mitigates the impact of the take.  This provision could allow, for example, an unavoidable take of an inactive nest in an eagle territory, in exchange for the donation of a conservation easement protecting the habitat on the remainder of the territory.

In general, the new regulations seem sound and conservative, a good balance of conservation science and understanding of the growing need to conduct human activities in close proximity to eagles.  If you would like to read all of the details for yourself, you can read the entire 45-page final rule as recorded in the Federal Register.  The new rule goes into effect on November 10, 2009.

Lined Orbweaver, Mangora gibberosa
Family: Araneidae

The Lined Orbweaver is a common spider that is widespread throughout the eastern United States.  In the southeast, it is especially abundant in grassy pond pine (Pinus serotina) savannas like the one shown below.

Strung among the grasses throughout the savanna are small, white, silken rings that are conspicuously evident against the sea of yellowish-green vegetation. Upon closer examination, the white ring is at the center of a larger orb-web, the rest of which is invisible from a distance. The white part of the web is called the stabilimentum, a structure found in the webs of many species of orb-weavers (Araneidae).

The purpose of the stabilimentum has been debated among arachnologists for a long time. Hypotheses range from prey attraction to camoflauge for protection from predators to warning signals that keep megafauna from accidentally destroying webs.  Phylogenetic work suggests that web-decoration with stabilimenta evolved several different times in many araneid lineages (Scharff & Coddington 1997).

My personal observations of the Lined Orb-weaver indicate that, in this species, one use of the stabilimentum is as a refuge from potential predators. When the web is approached closely or bumped, the spider quickly runs to the opposite side of the web from the intruder and hides behind the stabilimentum, which is sized perfectly to conceal the body of the spider.

How well this works, however, is open to debate. Bruce et al. (2005) tested the visibility of stabilmentum silk to birds and bees. They found that in one of their study species, the chromatic contrast between the spider and the silk was significant enough that the stabilmentum probably provided inefficient camoflauge from avian predators at close range.  It’s also possible that, since they are visible to bees and other insects, the small, discoid stabilimenta of the Lined Orb-weaver may attract prey to the web by mimicking flowers.

Whatever their adaptive significance, the sight of dozens of these small, silken rings dotting the vegetation is a fantastic experience for the naturalist willing to look closely. The spider responsible for the web is pretty cool-looking as well!

For a nice review of the literature on this topic, check out Matt Bruce’s web site on web decorations.

Citations:

Bruce, M.J., Heiling, A.M., Herberstein, M.E. 2005. Spider signals: are web decorations visible to birds and bees? Biology Letters 1: 299-302.

Scharff N, Coddington J.A. 1997. A phylogenetic analysis of the orb-weaving spider family Araneidae (Arachnida, Araneae). Zool. J. Linn. Soc. 120: 355–424.

The pinkish-violet blossom of spotted knapweed.

I first noticed knapweed blooming on our wildlife sanctuary property in Pennsylvania about five years ago, at the same time that I started to seriously consider the possibilities for habitat management on the site.  Knapweed control was one of my first projects on the property.  Since I knew that mowing was counter-productive (causing the plants to flower at a lower height), I decided to pull the knapweed by hand.  I’ve repeated the process for four years, and have eliminated spread of the plant while steadily reducing the seed bank at the main introduction site.  Because spotted knapweed seedlings assume a low-growing rosette form during their first year and don’t bolt and bloom until their second year or later, I’ve been able to track my success by noting a significant reduction in rosettes (a few dozen this year compared to countless hundreds during the first year of two of treatment).

Unfortunately, Spotted Knapweed is a highly favored bee plant, used heavily by native bumblebee species.  It’s always emotionally taxing for me to pull, bag and dispose of the knapweed with bumblebees crawling all over the blossoms as I work.  This brings me to one of my take-home messages in invasive species control and restoration: in degraded habitats, native species often rely heavily on invasive plants because the diversity of native plants has been reduced.  It is important to know what native insect and wildlife species rely on the invasive plant you are removing.  Then, when planning a restoration, try to plant (or enhance habitat for) native plants that provide resources at the same time of year as the invasive.  In my case, I’m working on restoring some meadows that will hopefully make up for (from a bee perspective) the eventual disappearance of my knapweed stand.

Spotted knapweed is an invasive plant, but is used extensively by native bumblebees

Since I’ve been working on this population for several years with a good deal of success, I thought I’d share a brief description of my spotted knapweed manual removal method.

Here are a few important points:

1. Get a good digging tool – I have tried various things – heavy clawhammers to grab and yank roots, various hand tiller/weeder/fork type things, etc.  I’ve recently settled on a well-balanced, heavy-duty, and inexpensive digging tool  (see the photo below) that I picked up at the friendly neighborhood home improvement warehouse.
2. Pull plants during their bloom period and before they’ve gone to seed.  Be sure to bag and dispose of the plants in a landfill, to avoid dispersing seed or root fragments.  A good rain just before (or even during) pulling makes the job much easier.
3. Be patient when pulling and learn to stop and dig more when you feel that the root is about to snap.  Pieces of root left in the ground will sprout the following year.
4. Don’t dig right at the base of the plant – you risk cutting through the root, which often twists to one side or another a few inches down.  Instead, loosen the soil about 5-6 inches from the base of the plant.

Here’s the process illustrated:

This is my tool of choice: a beveled, pointed blade on one end (used the most) and a straight blade on the other. The pointed blade sinks well into the shale soils where my infestation occurs.

Many stems usually radiate from a single root crown of older Spotted Knapweed plants. It's important to gather all the stems up to get a good grip on the plant for pulling.

Strike the ground about 5-6" from the base of the plant and loosen the soil, prying up with the tool while pulling straight up on the plant. Pulling at an angle makes it more likely that you'll break the root.

The root system should pull up cleanly if you loosen the soil enough and slowly pull upward on the plant.

The root crown can be quite broad on robust plants, or much smaller with fewer fibrous roots on stressed plants.

Please let me know if you have had success with other spotted knapweed control methods.  I have considered trying Milestone, a selective herbicide that is supposedly quite effective on both knapweed and thistles.  So far, I haven’t needed to resort to spraying though, since manual removal has been working well and at this point only takes me about a day each year to complete.  Now if only I could eliminate my crown vetch, smooth brome, and reed-canary grass this easily!

A prescribed burn in progress on a conservation property in New Jersey. Photo (c) 2009 Matthew Sarver

All that changed on July 14th 2009, when Pennsylvania Governor Ed Rendell signed House Bill 262, establishing the Prescribed Burning Practices Act.  Introduced by Rep. Gary Haluska, the new law authorizes the state Department of Conservation and Natural Resources to establish standards for the conduct of prescribed burns in the state.  The state will begin regulating burning practices by certifying burn managers and requiring state approval for burn plans.  In exchange, the law limits the criminal and civil liability of landowners and burn managers, so long as the regulatory process is followed:

No owner of property who contracts with or authorizes a prescribed burn manager to conduct or permit a prescribed burn on the property pursuant to the requirements of this act shall be subject to civil or criminal penalty for damage or injury caused by the fire or resulting smoke, unless negligence is proven.

- PA House Bill 262

The passage of this law is a major step forward in facilitating the use of prescribed fire as a management tool on private conservation lands in the state.  I hope to be able to use fire to manage the grasslands at my own wildlife sanctuary property in southwestern Pennsylvania at some point in the future.

Another exciting step forward is the establishment of The Pennsylvania Prescribed Fire Council, an organization created “to promote the exchange of information, techniques, and experiences of the Pennsylvania prescribed fire community, and to promote public understanding of the importance and benefits of prescribed fire.”

PPFC has named Matt Boss of The Nature Conservancy as the Council’s first Training Coordinator.  You can join the effort to promote prescribed burning in Pennsylvania by becoming a member of PPFC.

Members of the search team paddle Bayou DeView in winter of 2004. (Photo L Morgens)

A new documentary film on the Ivory-billed Woodpecker search and controversy, Ghost Bird, recently had its US premiere at the Maine International Film Festival.  Jeff Wells posted the trailer on his Boreal Bird Blog, and I thought I’d share it here for your enjoyment.

This past season’s systematic search activity by Cornell’s mobile search team was the final effort after five years of field work, according to a recent article in the Cornell Chronicle.  The recent search yielded no Ivory-bills, but lots of ecological data on difficult-to-access natural communities in south Florida.