Natural Seed Banks

Natural Seed Banks

There are manmade seed banks in the news lately, but nature has had its own seed banks for millions of years.  A natural seed bank is composed of the dormant seeds that lie in soil or sediment that have the ability to germinate and become healthy adult plants once conditions become favorable.  Seedbanks in lakes are found in the sediment, and contain submergent, emergent and floating-leaf plants.

Counterintuitively many aquatic and wetland plants require drought conditions to reproduce sexually via seed.  In terrestrial environments the seedbank can be activated when soil is disturbed through burrowing animals, fire, landslides and other disturbances.  The seed bank of agricultural fields is constantly activated through farming activities.  Fighting weeds in farm fields is a constant battle because the field may contain 1,800 -496,000 weed seeds per square meter! Number of seeds varies widely depending on farming practices and the crops grown.  Not all the seeds are viable though.

Natural Seed Bank

In 2012 a major drought occurred on Lake Puckaway causing a sand bar to be exposed. The exposed sediment must have contained a healthy seed bank because it was quickly colonized by Nut Sedges (Cyperus spp.), Invasive Cattails (Typha spp.), Common Bur-reed (Sparganium eurycarpum), Hardstem bulrush and other species.

Seeds “know” when environmental conditions have become favorable for growth through a combination of natural ques that can include: temperature (both day and seasonal cycles), light intensity, light wavelengths, oxygen concentration, and hormones.  The breaking of seed dormancy is poorly understood for most undomesticated plant species.  However, it is known that temperature plays and import role in most seed germination.  The seeds of many temperate plant species require a period of freezing.  Warmer winters brought on by global climate change could prevent many species from breaking dormancy in the southern portions of their ranges.

Seed Longevity/Viability

For most species we do not know how long seeds remain viable, but we know that viability can vary greatly.  Wild Rice (Zizania spp.) seeds remain viable in the seed bank for only 5-7 years.  In the same seed bank, the American Lotus (Nelumbo lutea) seed may lie dormant for a century before sprouting into a new lotus plant.

The seeds of Hardstem bulrush (Schoenoplectus acutus) are known to remain viable in sediments of lakes and wetlands for 40 years.   They lie in wait for a drought, because they can only germinate and grow on moist soil and sand.  Those seeds may have to last decades before the right conditions occur.  This just one reason why maintaining stable water levels in reservoirs is detrimental to aquatic and wetland plant life.  Reservoirs that have experienced draw downs after decades of having stable water levels may suddenly colonized by species that haven’t been seen in many years because of the seeds that have remained viable in the seed bank.

The maximum amount of time a seed can remain locked away in a seed bank is not really known because it can be difficult to age seeds.  The oldest confermed, naturaly germinated mature seed comes from a 2,000 year-old Judean Date Palm (Phoenix dactylifera) found in Herod the Great’s Palace, but an archeological dig is not a seed bank.   Other seeds germinated have been claimed to be much older, but some of those had to be grown in conditions that can only be created in the lab and not nature.

Seeds become damaged through time from changes in temperature and moisture found under most natural conditions.  Permafrost is probably the best place to find the oldest seeds.  Perhaps as the climate warms and melts the permafrost we will see species that haven’t been encountered in thousands of years, but it doesn’t seem likely.  Eventually the earth’s natural background radiation damages the DNA of the seed’s embryo causing damaging mutations that prevent growth.

Man-made Seed Banks

Today we use seed banks to preserve diversity of agricultural crops and non-domesticated plants.  The huge Svalbard Global Seed Vault in Norway is a so called doomsday vault, because it hold seeds that could provide unique genes if some catastrophe wipes out a species of variety of plant. There are many other seed banks are used by plant breeders and researchers on a continual basis.

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Virginia Ctenucha Moth (Ctenucha virginica)

Close-up of a Virginia Ctenucha moth.

Close-up of a Virginia Ctenucha moth.

The Virginia Ctenucha (Ctenucha virginica) is a moth with dusty gray-black wings and a distinctive small orange head.  The legs and other body parts are black-iridescent blue.  Unlike many moths, the Virginia Ctenucha is easy to see during the day; sitting on flowers, or hiding amongst the foliage.  Their usual habitats are grassy fields and meadows.  The primary food of the larvae are grasses, but the caterpillars also feed on other plants.   The Virginia Ctenucha was the moth that I most frequently encountered as a kid because it is easy to see in the day.  I used to catch a lot of them to feed the constantly hungry bullfrog I had as a pet one summer.

Mating Virginia Ctenucha moths

Mating Virginia Ctenucha moths (Ctenucha virginica) on goldenrod flowers

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For many lakes and streams turbidity is the most important environmental issue effecting individual lakes, but what is turbidity, and where does it come from?

Turbidity is the amount of particles suspended in the water that block light.  These particles can be inorganic soil particles or phytoplankton (algae).

Causes of Turbidity

Some turbidity is natural, in fact if it wasn’t for some particles in the water there would be almost no aquatic life.  However turbidity is often excessive, but where does this extra turbidity come from?

Turbidity Water Samples

In central Wisconsin water moving into Lake Puckaway from the Fox River, collected on the left is relatively clear. As water moves through the lake and exits on the right, it becomes more and more turbid. The main cause of this turbidity is algae followed by resuspension of sediment from wave action and the activities of Common Carp.

Wave caused resuspension of sediment is produced when the energy from waves disturbs to bottom of lakes and rivers.   Shallow lakes and reservoirs are most susceptible to this type of disturbance.  Resuspension of sediment can also be caused by prop-wash from recreational boating, or commercial shipping.

Rough fish like these Common Carp, Bigmouth Buffalo, are over populated on this lake and are being harvested by commercial fisherman. If enough the population is removed there should be water quality benefits, and reduced turbidity. Removing even a moderate amount of fish will have no measurable water quality benefits

Rough fish like these Common Carp, Bigmouth Buffalo, are over populated on this lake and are being harvested by commercial fisherman. If enough the population is removed there should be water quality benefits, and reduced turbidity. Removing even a moderate amount of fish will have no measurable water quality benefits

Activity of bottom feeding fish.  Fish that feed in the bottom sediments are a natural, healthy part of the ecosystem, but as their population grows their collective activity can add up. Bottom feeding fish dig up sediment as they look for their food: plant, invertebrates, or decaying organic matter.  A small population of native white suckers is not going to cause problems, but when the invasive common carp population becomes excessive, they continually disturb the bottom ,releasing both sediment particles and dissolved nutrients that will feed algae growth.

Algal Growth One of the main problems is excessive algal growth in nutrient rich waters.  Phytoplankton need nutrients to grow and if they live in water which has excessive phosphorus and nitrogen these small organism can quickly grow to levels that can block out the light of rooted aquatic plants, produce excessive amounts of oxygen in the day and deplete the oxygen supply at night.

Aerial Algae Bloom

Aerial view of an aquatic plant bed and streaks of algae during an algae bloom.

Erosion from the landscape.  The countryside naturally erodes and makes its way to the sea, but man’s disturbance of the soil for agriculture and construction greatly accelerates the process.  Particles of soil on exposed farm fields are picked up by water and carried into lakes and rivers.  At unprotected construction sites, rain and snowmelt also wash these solids into surface waters.  Often these particles carry nutrient pollution that will lead to excessive algal growth.  The particles can also contain chemical pollutants that can harm aquatic environments.

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Alternative spellings and terms: rip rap, rip-rap, rock armor

Shoreline Rock Rip-rap

Rock riprap can provide some habitat, but trap animals too.

You often see the shores of lakes, ponds, rivers, and other waterbodies lined with piles of rock to prevent erosion, protection for manmade structures, or just to give some sense of order to a shoreline.  These rocks are called riprap.  Rocks are stronger than soil, or sand and so reduce erosion from waves and ice, but they come with a number problems.  Although in landscaping riprap is usually composed of locally available rock, it can be specially formed concrete, or broken up concrete, bricks or other debris from demolition.  Locally they even used old cars at one time!

Waves crashing into concrete and rock riprap

Benefits of Riprap

Not all is bad when it comes to riprap.  In very high energy situations it reduces the erosion of shorelines.  This reduces sediment and nutrients that enter the surface water.  When in the water these pollutants would block light, smother plants and animals and fuel algae blooms.

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Sundew leaves

Drosera rotundifolia, a circumboreal plant.

Circumboreal is a term you may run across in some plant identification books.  It refers to the range of a species, plant or animal.  Circumboreal is defined as a species with a range that circles the boreal (north) portions of the earth. So a species that is circumboreal would be likely to found in Norway, Russia, Alaska, Canada etc.  Many animals such as Moose, and Caribou are circumboreal because of the Bering Land Bridge that formed during the last ice age.   However, these mammals have since evolved into different species or subspecies on the different contents. Just as the land bridge helped exchange animal species between North America and Eurasia many plant species were probably also exchanged.

Some of those plants that have a natural circumboreal range:

Unfortunately many species like Eurasian Water-milfoil (Miriophyllum spicatum) are circumboreal thanks to man’s activities.

Another term sometimes used is circumpolar which refers to a species range around the Earth’s polar region.


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Stormwater Retention Ponds for Wildlife

Stormwater Pond with Native Plants

This stormwater retention pond has been planted with native aquatic plants in the water and its shore and slope has been planted with native prairie plants.

Storm water retention ponds are an important tool that reduces the amount of pollution getting into surface waters, and to lessen the effects of flooding, but they can create good wildlife habitat.  Unfortunately these pond are often sterile, boring features on the urban and suburban landscape.

The basic concept behind a stormwater retention pond is that water coming off of parking lots, buildings and other impermeable surfaces, runs into the ponds where the water has time to evaporate or leach into the ground.  This prevents the water from flooding in areas where it would be a problem for humans.  It also prevents excess water from getting into lake and rivers where it could cause the banks to overflow into homes and businesses.

All of this water coming off of parking lots and the landscape carries pollution with it.  Pollution can be in the form of nutrients, soil particles, and sand, or chemicals such as oil and pesticides.  In a retention pond the particles that could cause turbidity in other surface waters can drop out of the water and collect on the bottom of the pond.  Many chemicals will breakdown over time or in sunlight, and being in a pond gives them a chance to do so.  If there is a chemical spill, or in an agricultural setting, a manure spill the retention pond not only prevents the pollution from getting into waterways, it concentrates the pollution making it easier to clean up. In streams it may be impossible to clean up such a spill.

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Anoxic (no oxygen) Conditions in Lakes and Wetlands

Anoxic conditions in wetlands refer to the lack of molecular oxygen (O2) in wetlands and lakes.  They can arise under a number of conditions.  Most organisms are stressed or killed

Flowers of Silver Maple floating on the water.

The decaying leaves and plants in this floodplain forest can lead to anoxic conditions in the wetland soils.

under anoxic conditions, but there are some bacteria that require anoxic conditions to survive.  Anoxic conditions lead to anaerobic processes (those chemical reactions that occur in the absence of molecular oxygen)

How Anoxic Conditions Arise

I most cases organisms are the cause of anoxic conditions.  They take in oxygen for cellular respiration and release CO2 as part of the chemical process that makes energy for the cell.

One ways anoxia occurs is the overabundance of algae.  It’s true that algae produce oxygen during the daylight hours, but when the sun dips below the horizon these same algae need oxygen to use the energy they created by photosynthesis during the day.  In elementary school it is drilled in our heads that plants produce oxygen and animals use oxygen.  This is really half a lie, because oxygen is just as important to plants as it is to animals, and some plants like Indian Pipe produce zero oxygen.

Anoxia can result quickly in sediments or in other places where there is little or no movement of water, such as in the bottom of deep lakes.  In these stagnant situations it can take 7 hours to diffuse 1 cm.

Many organisms that live in lakes and wetlands have developed adaptations that allow them to survive near anoxic, or fully anoxic conditions temporarily.  Some organisms, shut down their functions for short periods.  Emergent plants will pump oxygen down into their roots, where conditions in the sediment are usually anoxic.  Some fish have the ability to gulp air at the water’s surface.  Many of these adaptations require energy, put them at risk of predation or have some other negative impact to the organism, so anoxia is usually avoided if at all possible.

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Spectacular Night for Northern Lights

On November 1st I received this email from

  • “GEOMAGNETIC STORM WARNING: A high-speed stream of solar wind is about to hit Earth’s magnetic field, prompting NOAA forecasters to estimate an 85% to 90% chance of geomagnetic storms on Nov. 2-3.  This is the same 800 km/s stream that lashed Earth’s magnetic field in early October, sparking strong geomagnetic storms and bright auroras over northern-tier US states.  Visit for more information and updates.
  • TAURID FIREBALLS: The annual Taurid meteor shower is underway and it is lighting up the midnight sky with bright fireballs. Taurid meteoroids are gravelly pieces of debris from Comet Encke that strike our planet’s atmosphere at 70,000 mph.  They pose no danger to people on the ground as they disintegrate entirely high above Earth’s surface every few hours.  If forecasters are correct, the display could continue until Nov. 10th.  Tune into Space Weather Radio for live radar echoes.”

I was very excited.  I checked the forecast to see what the cloud cover looked like, what phase the moon was in, as well as moon rise and set times.  It looked like conditions would be pretty good; few clouds and a waning gibbous moon that didn’t rise for a few hours after sunset.  I figured this would be my best shot at the Aurora Borealis in a longtime, and even if they didn’t show it would still be a good trip.  Then I walked calmly downstairs to see if I could work out the family logistics to allow for a short trip to the Northwoods to see the night sky show.  After about three minutes, the family logistics for the next 20 hours were worked out and all I had to do was charge batteries, pack the car and drive off tomorrow.

Northern Lights Display s

Full Display of the Northern Lights. Purchase this photo of the aurora borealis.  Photo taken with Nikon P7800.

The next day I was ready to go; I had everything I needed to photograph the sky plus a few extra things to do the following morning if I wasn’t too tired.  All I needed to do was to Continue reading

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Harvesting Cattails for Habitat Restoration and Biofuel Production

Invasive cattails are a major problem facing native wetlands in the Midwest.   Hybrid Cattail (Typha x glauca) and Narrow-leaf cattail have taken over large areas of native sedge meadow and shallow marshes.  This cattail invasion has greatly altered wildlife habitat and native wetland and aquatic plants.  One of the ways of reducing the impact and controlling the population of these non-native cattails is cutting and removal of the plant’s biomass.  At Allen’s Marsh, located just outside Oshkosh, Wisconsin we are conducting a small pilot project to use the harvested cattail biomass to produce green electricity through the production of biogass (methane).

Cutting and removal of plant material can be very difficult in wetland areas because of the soft, wet soils, and standing water found there at different times of the year.  Several machines are specifically designed for harvesting plant biomass, most of these are built and used in Europe.  Our harvest was done using a Softrak Cut and Collect System made by LogLogic in the UK.  The Softrak used in the pilot project is owned and operated by Loyola University of Chicago and is being used by them in cooperation with a number of researches throughout the country to investigate the removal of invasive cattail biomass on the environment.  The tracked vehicle works well on dry ground, wet soils, and shallow standing water.

The wetland chosen for this pilot project was Allen’s Marsh.  Like many wetlands in the Winnebago System, Allen’s Marsh is now nearly 100% dominated by invasive cattail species and in desperate need of restoration.  A portion of the marsh is owned by the University Of Wisconsin Oshkosh (UWO) and is where the harvest took place.

Softrak Cut and Collect System Dump Cattail

Softrak Cut and Collect System dumping a load of cattail stems and leaves for late pick up.

At Allen’s marsh the harvester had difficulty cutting low, because of the extremely thick stems and leaves that have built up over the decades.  The harvester pushed these stems over and cut them off about 18 inches (0.5 m) in height, much like a lawn mower would very tall grass.  Cattail marshes, that are cut more frequently would not pose this problem.  I was told Phragmites was less of a problem because that species is less fibrous.

Cattail biomass from this trial run will be taken to the biodigester at the UWO.  There bacteria will break down the cattails and other organic matter mixed in.  The bacteria produce methane as a waste product which is collected and burned to create electricity.  Creating green energy and improving habitat at the same time is win win situation.

Cattail Marsh Harvest Area

Cattail marsh after harvest.

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Blanding’s Turtle – Emydoidea blandingii

Blandings Turtle

Blanding’s Turtle (Emydoidea blandingii) hiding in its shell.

One day while bouncing around in my dad’s truck on the backroads of Wisconsin we came across a strange looking turtle with a high domed shell (carapace) and small, light yellow spots. I thought its head looked snake-like and really cool so we stopped and put it in the back of our rusty old truck.  We took it home and had it for a week or so.  It actually lived in the back of the pickup with a painted turtle for a time because the pickup bed had filled with water.  Later it was moved to a wash basin and one day we had a lot of rain, the basin overflowed and the turtle made its getaway.  That was thirty years ago I didn’t know the Blanding’s Turtle (Emydoidea blandingii) we had found was a threatened species.   I was only eight-years-old and had no idea, and neither did my father, that we had just broken the law.  Even though it’s been three decades since the turtle made its lucky escape, I may still see it again crossing the road one day, because these turtles get old, just how old no one is really sure.

Plastron of Blading's Turtle

The underside, or plastron of a Blanding’s Turtle shell has interesting patterns.

The Blanding’s Turtle is an interesting and fairly unique turtle found throughout the Great Lakes Region.  I tend to think of these turtles as nomadic, traveling from wetland to wetland as the growing season progresses.  Blanding’s Turtles inhabit a wide range of wetlands where there is standing water: swamps, sedge meadows, and shallow marshes.  In these waters they feed on invertebrates, amphibians and plants.


The females must leave the wetlands and head to dry ground to dig their nests in sandy areas with little vegetation.   Sometimes these nesting sites are in farm fields where agricultural practices threaten the ness.  In the nest the mother turtles lay 3-21 eggs. In the nest the nutritious eggs are vulnerable to many mammalian predators such as raccoons, skunks and foxes.  Nest mortality has been noted as being as high as 93%, and when it takes 17-20 years for a female to reach maturity very, very few of her eggs will ever reach breeding age.  When the young turtles hatch the must make the same dangerous journey taken by the mother.  The major difference is the small turtles will be much more vulnerable to predators.  Historically if juvenile Blanding’s Turtles could make it to adulthood they could expect a long life, of up to 70 years!

Threats and Conservation

Any human caused mortality in a long-lived species with a naturally low reproductive rate is a dangerous thing, and Blanding’s Turtles face many man-made mortal dangers.  The most obvious danger to Blanding’s Turtles are cars as they cross roads.  The females must travel to high ground to lay their eggs, and turtles of all ages must move from wetlands when they become dry out either seasonally or during drought events.  The loss of even a small portion of the adult population is significant.

Blanding's Turtle Crossing the Road

Cars are a significant source of mortality of Blanding’s Turtles. I helped this one across before it became roadkill.  Helping turtles across roads is often just as dangerous to people as it is to the turtles.  You could get hit by a car, or scratched or bitten by the turtle you are trying to help.  Use extreme caution.  Also you many not really no which side the turtle was really heading to.

The major threat to the Blanding’s Turtle is habitat destruction and fragmentation.  For more than a hundred years wetlands throughout the Blanding’s Turtle’s current and former range have been drained for agriculture and land development.  The turtles simply have fewer places to live.  Turtles also require upland egglaying areas, and few of those sites are available in a suburb or urban environment.  Many of the remaining wetlands have been fragmented by roads, which leads to another major problem for Blanding’s Turtles, and one that is shared with other wetland inhabitants, the tires of cars and trucks.

The Blanding’s Turtle is under another threat that is shared by many species of turtles as well as frogs.  Many lakes and ponds are reservoirs that are controlled by dams or other water level structures.  Reservoirs are drawn down in the winter, to prevent damage to shorelines by ice and to make room for the meltwater to reduce downstream flooding.  Turtles and frogs are attracted to the mucky shallow waters to hibernate.  If, after they select a spot, the water level is drawn down several bad things may happen.  If the drawdown is severe enough the mud may be exposed.  This will probably always be fatal as the mud will freeze solid and or dry out during the winter.  The second is the ice on the lake will extend down into the mud freezing the turtles.  Third a layer of ice can form over the top of the mud sealing off the turtles’ oxygen supply, causing anoxic conditons.  The turtles may survive the third situation, but their tissues are likely to be damaged from the lack of oxygen.  These problems are amplified during especially cold winters with little snow cover for insulation.  It only takes one harsh winter to wipe out a large portion of the turtle population.  Once again these turtles have a low reproductive rate and it will be difficult or impossible for the population to recover.

Range and Status

The Blanding’s Turtle range is centered around the Great Lakes Region, and Iowa and Nebraska.  Small populations existing in the Dakotas, Missouri.  There is also a separate population covering a small geographic area in New England.  Almost everywhere it lives, the Blanding’s Turtle is considered Endangered or Threatened at the local level.  In Wisconsin it was de-listed as a Threatened species and moved to a protected one of special concern, but I’m not sure why it was de-listed when it is such a vulnerable species.

Blanding’s Turtle Status (not all states listed)

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