David and Goliath – a story of bark beetles

Bark beetles (Scolytinae) are small beetles a few millimeters in size. Their larva develop under tree bark eating the phloem, xylem, and cambium layers. Certain species cause extensive forest damage by killing healthy trees, while others only impact weakened individuals. The eating patterns (called galleries) and the trees’ defensive reactions cause disturbances in the nutrient and water cycling within the trunks. The trees literally dry to death.

Bark beetles can be detected by the gallery patterns they leave on tree trunks. These patterns are species-specific, and often very beautiful. The patterns can be used to recognize infestations and begin warding off the worst damage. Then again, the gallery patterns cannot be seen until the tree bark falls off.

Bark beetles also have a secret weapon: wood-staining fungi. This group of fungi includes several species that damage wood or cause serious diseases to trees. Bark beetles and wood-staining fungi have developed various relationships such as the ambrosia beetles that spread certain fungi species into their galleries to farm them for food. Wood-staining fungi benefit from the bark beetles transporting them to new trees, and have developed exceptionally sticky spores that attach to adult beetles as they are preparing to disperse. Bark beetles also benefit: the fungi weaken new tree individuals, giving adult bark beetles the opportunity to infest and lay their eggs in these trees.

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A possible wood-staining fungus is spreading beneath the bark of a birch infested by the birch bark beetle. ©Stella Thompson

It’s hard to believe that tiny beetles and even more minuscule fungi can kill gigantic trees. Situations where a bark beetle or fungi spreads to a new geographical region among lumber are particularly devastating. The new host trees have no immunity or defense mechanisms against this new organism and the alien species spreads like wildfire.

Dutch elm disease is a prime example of this. Ophiostoma ulmi, a fungus killing elm shoots spread from Asia initially to Europe and then, fueled by the post-World War I reconstruction boom, from Europe to North America in lumber. European elm species coped with the disease slightly better than their North American cousins. European elms also died, but the spread of the disease around Europe took several decades and finally the outbreak waned. 10–40% of the elms died, depending on the country in question. The situation was very different in North America. The American elm (Ulmus americana), a very popular urban and ornamental tree, formed large forests in the eastern areas of the continent. It narrowly escaped extinction through active eradication and education measures such as campaigns forbidding the transportation of firewood outside infected states. Unfortunately, a new, much more virulent fungus (Ophiostoma nova-ulmi) causing Dutch elm disease spread to Europe and North America during the 1940s. This fungus has caused the near annihilation of elms from several European countries. As of yet Finland has mostly been spared by the disease, but this may change with a warming climate that allows beetles belonging to the Scolytus genus that carry Dutch elm disease to overwinter in more northern regions. These beetles are already found on the northern coast of Estonia and in the Stockholm area of Sweden. The birch bark beetle (Scolytus ratzeburgi), commonly found in Finland, does not spread Dutch elm disease as it has specialized in solely utilizing birch trees.

However, the birch bark beetle spreads the Ophiostoma karelicum -fungus. Trappings

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The presence of birch bark beetles can be detected by their unique eating patterns. ©Stella Thompson

conducted during 2008 and 2009 for a study carried out in Norway, Finland, and Russia revealed the prevalence of O. karelicum: every single birch bark beetle individual carried the fungus, which was also found in each of the beetle’s galleries that were searched. The life cycle and ecology of O. karelicum is very similar to the fungi spreading Dutch elm disease, and the commonness of the fungus and the birch bark beetle means a very high risk of the disease spreading to e.g. North America. The birch species native to North America would most probably have no resistance to the disease.

On the other hand, pitch canker (Gibberella circinata) is a fungus spread by bark beetles, originating in North America, which has now spread to Europe where it causes pine mortality. The Scots pine (Pinus sylvestris), native to e.g. Finland, is especially susceptible, but the disease has not spread as far north as Scandinavia yet.

To make these dynamics even more complicated, several mite species have also been shown to transport or act as the primary hosts of wood-staining fungi. These mites are in turn spread by bark beetles. The relationships and interactions between these three organisms are still poorly understood.

The disease resistance of tree species can be increased through cultivation. American elm cultivars more resistant to Dutch elm disease have been found, and their disease resistance has been further enhanced through cultivation. These cultivars are most probably the reason that elm forests still exist today in North America, although the age and size composition of these forests has changed considerably with the death of the old and large trees. Biological and chemical disease control is also a possibility: fungicides can be injected into live trees to stop the spread of specific diseases. Six fungicides combating Dutch elm disease are currently on the market in the US.

Similar control measures can most probably be developed against O. karelicum. However, widespread injection campaigns are difficult to implement. In the US, Dutch elm disease is mainly controlled by injecting individual ornamental or urban trees. Injection control as an effective eradication measure requires more development before it becomes a feasible tool for preventing damage caused by alien species.

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Crawlers and fliers – how to study forest insects

Studying insects is interesting yet challenging. Determining individuals to the species level

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The presence of birch bark beetles can be detected by their unique eating patterns. ©Stella Thompson

nearly always requires capturing them first, although some species, such as the birch bark beetle (Scolytus ratzeburgi), can be identified by the unique pattern they leave on tree trunks. However, it is almost always necessary to use various types of traps to capture individuals if identifying the insect species present at a certain site is the main objective of a study. For example, butterflies are trapped during the night using light traps, and the occurrence of certain protected species can be confirmed using feromone traps that use synthetic lures as bait. Traps can be dug into the ground, lifted high up into tree canopies, or attached to the insides of hollow tree trunks.

As my PhD research I am assessing how beavers affect forest beetle populations. I have several research questions:  do beaver-induced flood zones have different beetle species assemblages than other areas, do the increased moisture and sunlight conditions in the flood zone affect species assemblage, and do beaver areas advance or hinder potential forest pest or protected species. My research combines a game species with widespread effects on its surroundings and forest beetles, several species of which have become scarce and require protection. Beaver-induced flooding and the species’ habit of felling tree trunks may locally disturb forest owners, but my study is looking into whether beavers’ actions facilitate or disturb forest pests. Combining game and insect research is cool, and generates new information on which to base decision-making for future protection measures, beaver population management, and even for using beavers as a natural tool for restoring degraded wetlands and forests.

Window traps are widely used for determining the insect assemblages of sites. Window traps cannot be used to capture specific insect groups, because all sorts of invertebrates ranging from flies to pseudoscorpions and wasps to beetles creep or fly into them. Window traps are very simple: the trap is attached to a tree trunk or set to hang between two trees. Insects crawl or fly into the plastic plexiglas frame and then fall through the funnel into a liquid-filled container at the bottom. The container is filled halfway with water, dishwashing fluid, and salt. The dishwashing fluid prevents the insects from regaining flight, consequently drowning them. The salt helps preserve the insects until the trap is emptied out, which happens about once a month. I have 120 traps spread out at several sites, so every summer I collect about 600 samples.

Unfortunately other creatures may sometimes end up caught in the window traps. So far I have inadvertently captured a few common lizards and a bat. This is always disappointing, because an individual dying for nothing does not advance research or science in any way. In the same way it is frustrating if you unintentionally set up a trap on a tree trunk that an ant colony uses as its route. Hundreds or even thousands of ants may drown in the window trap. As my own study focuses on beetles, I cannot utilize the ants in any way. At least this does not happen very often.

After the trap container has been emptied the gathered sample is sifted through using tweezers and a microscope, to separate the insect groups that I am interest in. Next the individuals are determined to the necessary level. Sometimes determining the family level is enough, but if making conservation decisions or gaining new information on certain species is the goal, it is usually necessary to determine individual insects to the species level. How this is done depends on the order in question, e.g. beetles are often recognized by their ankles and genitals.

Occasionally you come across data deficient species, i.e. species that are not well known or understood. Species, genera, and families are determined using identification keys, which are sometimes incomplete. For example, currently the best key for identifying Finnish rove beetles is in German, and for several families the most complete keys are in Russian. So I’m currently kind of happy that I studied German in middle and high school. I guess next I should begin uncovering the secrets of Russian vocabulary.

Let’s ban lead shot!

The use of lead shot and sinks is a global phenomenon. Only the past decades has

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Grouse species also suffer from the harmful effects of lead shot. ©Stella Thompson

increased our understanding of the negative effects that toxic lead shot inflicts on ecosystems. As an example, birds die of lead poisoning after eating lead shot. They mistake the ammunition for sand or grit, which they use to aid their digestion. The birds’ gizzards and stomach acids dissolve the shot, causing lead to accumulate in their bones. As little as two lead shots is enough to directly cause the death of a mallard-sized animal.

During the 1980s, the US Fish and Wildlife Service (USFWS) conducted a study on the effects of lead exposure on water birds such as waterfowl. Diving ducks were found to be most susceptible, but lead shot was also commonly found in dabbling ducks, geese, and swans. Long-term monitoring by the USFWS also uncovered negative effects on bald eagle (Haliaeetus leucocephalus) populations, and since then, several studies have found harmful effects to numerous animal groups around the world, e.g. bears, deer, predatory birds, doves, loons, and frogs. International studies also associate lead shot with increased lead concentrations in people who regularly consume game.

A federal ban on using lead shot for waterfowl hunting was issued in 1991 in the US. Since then, 34 states have decreed tighter state-wide bans, e.g. California completely banned the use of lead shots in the home ranges of the California condor (Gymnogyps californianus), and by July 2019 California will completely ban lead shot in all forms of hunting, the first state to do so.

But what is the European Union’s game plan concerning lead shot? A total ban has been proposed, but the motion is currently only a thought, and we are still miles away from actual progress. Several countries in the EU have issued various types of bans, e.g. the lead shot has been prohibited in wildfowl hunting in Finland since 1996. The US also seems far from a federal ban.

So what’s the big deal, why are we not stepping up and pushing forward?

Not everyone has been satisfied with the disappearance of affordable, high quality, and gun-safe lead shot. The lead shot ban has caused a great deal of debate and criticism over the years. Many are hoping to weaken the ban in waterfowl hunting to only concern certain shallow wetlands or very important rest areas along migration routes. Those opposing the ban have based their arguments on several propositions formed in the 1990s, which have since been scientifically proven incorrect:

 

Claim 1: Lead shot is not dangerous, because it is believed to rapidly sink to the bottom of wetlands, where waterfowl cannot reach it.

After initiating the partial lead shot ban in 1991, the USFWS began long-term monitoring of its affects. Lead shot –induced mortality in mallards dropped by 64% in the six years following the ban. And this is a dabbling duck species, which according to studies should not even suffer the most from lead poisoning. The impacts that the ban has had on diving duck populations, which find their nutrition from the bottom mud layer of wetlands, or on small duck species are probably even more pronounced. Lead poisoning additionally causes e.g. reproductive problems, which can lead to long-term population declines even without directly killing all individuals. For example, a French research group found that female teals carry shot in their gizzards more frequently than males do, wherefore females had worse survival rates than males. A study in the US relates 17–46% of the mortality of loons directly to lead shot, while the same estimates for swans and bald eagles are 31% and 12%, respectively. The lead shot ban is estimated to annually save 1.4 million waterfowl in the States alone. In Canada, the lead concentrations found in the bones of water birds lessened by 50–70% following a ban. An although loons are not hunted as game, their population declines due to lead shot and sinks should be taken in to consideration when considering the fate of toxic lead shot.

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Both teal and mallards suffer from lead poisoning, which besides causing death also causes behavioural abnormalities. This makes individuals more susceptible to hunting. ©Veli-Matti Väänänen.

Claim 2: Alternative shot types (mainly steel, vismuth, and zinc) are inefficient and expensive.

A 2015 study in the US compared the effectiveness of lead shot and two types of steel shot in the hunting of mourning doves (Zenaida macroura). No differences were found in aim, the number of injured escapees, hunter satisfaction, or realized quarry numbers. Necropsies of shot doves revealed no differences in the numbers of through-body shots or average strike depths. Steel shot was therefore found to be accurate enough for dove hunting. A poll study found nearly 80% of US hunters to prefer steel to lead shot, or at least consider the two equally effective. Initially the steel shot sold in several countries tried to mimic the qualities of lead shot. The resulting low muzzle velocities and large ammunition size led to poor hunting success. Higher quality steel shot is currently widely available, but the damage caused by poor shot quality was immediate, and is the only reason why steel shot still carries a bad reputation. Many people tested steel shot once or twice, and returned to illegally using lead shot despite the bans.

Steel shot was additionally about four times as expensive as lead shot when the ban was issued in the US, but rising demand has caused their prices to drop significantly. The same would probably occur in many European countries, where demand to increase.

 

Claim 3: Hunting with alternative ammunition increases the numbers of wounded animals. This has been suggested to happen because of the ineffectiveness of non-lead shot and hunters being unaccustomed to lighter weight ammunition.

The USFWS annually conducts a poll inventorying e.g. the numbers of total hunted quarry and injured escapees. During the 1950s and ‘60s, the number of injured escapees was about 20%, but initially grew to about 24% after the partial led shot ban. However, a few years later numbers dropped down to initial levels, as hunters became used to the new shot. During the last years the level has dropped to 14%. The study conducted on mourning dove hunting success also did not reveal any differences in the numbers of injured escapees. So if European hunters are still performing worse after lead shot bans in their countries, they should perhaps consider looking in the mirror and wondering what’s wrong with their aim.

 

Claim 4: The lead shot ban has decreased realized duck quarries, e.g. because hunting and hunting success have lessened.

To date, there is no scientific proof to back either of these claims. But on the contrary, waterfowl populations have decreased markedly during this same time period due to disagreeable habitat change. Could this, by any chance, be the actual reason for diminishing quarry sizes? Especially as assessments and research show that hunters have in fact not obeyed the lead shot ban very widely. For example, 90% of Finnish hunters are still estimated to use lead shot in waterfowl hunting. About 70% of the ducks shot in Britain carry lead shot in their bodies. This means that the use of steel shot cannot have decreased duck quarries, because steel shot simply isn’t being used.

However, one actual problem is that steel shot cannot be used in certain older shotguns. This has probably slightly lessened the duck hunting enthusiasm of some elderly hunters.

 

Unfortunately, the European Commission wants to focus on only lessening the amounts of lead found in wetlands. The EU has ratified the UN’s Convention on the Conservation of Migratory Species of Wild Animals, so we should be rid of lead shots within three years. Therefore it is fairly questionable that a total ban is currently not being discussed in more detail. A few EU nations, e.g. Denmark and Holland, have executed a total ban, thus preventing the use of lead shot in any forms of hunting. Nothing appears to be happening in the US either. Despite the encouraging results on the number of lead poisoning incidents dropping dramatically, the effectiveness of partial bans is just too weak. An overview from 2015 by the University of Oxford estimates that 50 000 to 100 000 birds die annually from lead poisoning in Britain alone. According to the Finnish Food Safety Authority and the Finnish Museum of Natural History, every third white-tailed sea eagle (Haliaeetus albicilla) death is directly related to lead poisoning. Partial bans are ineffective and their execution cannot be properly monitored. A total ban would also create pressure to develop shot that would work well with older shotguns. Now is the time to finally completely ban lead shots.

 

Additional information

on lead poisoning occurring in several bird species

http://link.springer.com/article/10.1007/BF00119051

http://www.nwhc.usgs.gov/disease_information/lead_poisoning/

 

on the mourning dove study

http://onlinelibrary.wiley.com/doi/10.1002/wsb.504/full

 

on the effects of lead on teals

http://www.sciencedirect.com/science/article/pii/S0006320707001346

Golden eagles deter foxes, facilitate forest grouse

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Top predators can have surprising effects on ecosystems. Golden eagle @Sari Holopainen

The effects of top and mesopredators on lower levels of food webs have been researched from many perspectives, but less focus has been given to the roles that avian top predators play on mid-sized mammalian predators. The cascade effects of raptors, which concurrently affect several trofic levels, have also gained little attention. However, researchers at the University of Turku have observed how the golden eagle (Aquila chysaetos) affects pine marten (Martes martes) and red fox (Vulpes vulpes) populations, along with the cascade affects induced on black grouse (Tetrao tetrix) and hazel grouse (Tetrastes bonasia) populations.

Golden eagles hunt black grouse, red foxes, and pine martens. When the opportunity arises they will also catch hazel grouse, but because of their smaller size and habitat preferences (thick forests), hazel grouse are better protected from golden eagles, which prefer open territory when hunting. The researchers initially hypothesized that the golden eagle would locally lessen the numbers of red foxes and pine martens, thereby causing a positive affect on the two grouse species.

However, the truth is not quite as simple. Pine marten and red fox densities actually increase in areas with large numbers of golden eagle. One possible reason behind this surprising result could be the large prey populations available for all three predators in these areas, along with the partially overlapping habitat preferences of pine marten and golden eagle. On the other hand, pine martens avoid open territory, possibly because of the non-lethal deterrent effect that golden eagles exert on pine marten.

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Top predators can have surprising effects on ecosystems. Golden eagle @Sari Holopainen

But the story doesn’t end here: high densities of golden eagles still does have an effect, as larger numbers of young hazer grouse and black grouse are present at these sites. The golden eagle may therefore facilitate the grouse by lessening the numbers of mesopredators in their territories through the deterrent effect. This would lead to less predation and egg eating by the pine marten and red fox. In other words, red fox and pine marten avoid golden eagles so effectively, that the two grouse species benefit from their weakened predation performance. A similar protective effect has also been observed with the goshawk (Accipiter gentilis).

Increasing golden eagle territory and offspring densities cause decreasing numbers of black grouse, but this does not occur with hazel grouse. The small size of the hazel grouse most likely protects it from golden eagle predation. The black grouse, on the other hand, favors open territory. Golden eagles therefore appear to have a protective effect on juvenile hazel and black grouse individuals, while threatening adult black grouse.

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Black grouse lekking @Stella Thompson

The cascade effects directed at these grouse species do not appear to change with fluctuating pine marten and red fox densities. The presence of other mesopredators, e.g. raccoon dogs (Nyctereutes procyonoides) and the American mink (Neovison vison), has been suggested as the reason for this. The effects of these other mesopredators were not assessed during the study.

The golden eagle affects mesopredator behavior without affecting their population densities. A similar deterrent effect has previously been observed from white-tailed sea eagles (Haliaeetus albicilla) on the American mink, and golden eagles most probably also deter minks and raccoon dogs. The eagles additionally deter the movements of other potential egg thieves such as corvids.

Wolf population management – problems in every direction

The wolf is currently quite the hot potato in Finland. In fact, wolves are such a burning topic, that finding neutral information on the current state of the species and on hunting it can be difficult.

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Wolf pup in Polar Park, Norway. © Sari Holopainen

Wolves form packs of several individuals to optimize their ability to hunt moose and deer, their staple food. A pack is run by an alpha pair, or a male and female wolf that have mated for life. The other individuals in a pack do not produce offspring, and young individuals may wander between packs to find mates or raise their position in the hierarchy. Alpha pairs are what keep a pack together.

The wolf is designated an endangered (EN) species in Finland, and strictly protected in the European Union (EU). The Finnish wolf population grew during the early 2000s, due to increased protection and additional individuals moving in from Russia. This increased both the incidence of damage caused by wolves (e.g. to hunting dogs) and the number of wolf sightings around human habitation, leading to dissatisfaction in wolf conservation measures and increased poaching. The wolf population began declining in 2007 due to widespread poaching, which in turn angered conservation organizations and the EU. Since then the wolf population size has seesawed back and forth, and confrontations between various interest groups have escalated.

To alleviate the wolf conflict, the Finnish Ministry of Agriculture and Forestry decided to implement a two-year trial wolf hunt in 2015–2016, aimed to control the population. The effects of the cull will be evaluated after this period. The trial cull is based on a wolf management plan, which attempts to incorporate both the requirements of people living in wolf territory and that of wolf conservation. The management plan is territory-based, meaning all actions are planned per wolf pack and territory.

The management plan determines the smallest viable wolf population as 25 breeding pairs. The Natural Resources Institute Finland (Luke) will produce an estimate for the country’s total wolf population, and based on this evaluation the Ministry determines the largest yearly quota that can be culled using population control permits. However, this quota does not automatically have to be reached.

Population control permits are granted for hunting young individuals, which most likely have the smallest impact on the vitality of a pack. These permits can also be granted for hunting problematic individuals that e.g. repeatedly enter yards or come close to humans. Population control permits can only be granted to target wolf packs that produce litters, or in special conditions on packs in areas where the species has a stronghold. In addition to population control permits, wolves can also be hunted with special permits granted for damage control or by law enforcement. These two permit types are granted only when dealing with problem wolves.

Wolf population fluctuations and management will continue to cause problems in the future. Various interest groups have lost trust in each other and in the Ministry’s wolf management plan. Accommodating both the protection and management of an extremely endangered top predator is very difficult in a situation where said species also causes damage to and fear in certain interest groups. Additionally, protecting the Finnish forest reindeer (Rangifer tarandus fennicus), another extremely endangered species, requires straightforward action plans in terms of the wolf. Population levels of the Finnish forest reindeer are believed to have suffered because of the dense wolf population in the district of Kainuu.

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Wolf in Polar Park, Norway. © Sari Holopainen

The complete protection of the wolf, a management regime in practice at the beginning of the 2000s, obviously failed to work. The population grew initially, but was quickly bulldozed by unsustainable poaching. The population decreased up to 15% a year between 2006 and 2010. The population was approximately 250–270 individuals at the end of 2006, but by the end of 2007 the level had dropped to 200. Complete protection of the species crossed a line in Finnish society, after which poaching was used as an excuse for preventing future damage – a situation that should not be allowed to form. Returning to a similar conservation model would require intensive intervention to stop poaching.

The two-year trial cull was completed at the end of February. Luke evaluated the Finnish wolf population at 220–245 individuals prior to the trial period in 2015. Two hunting seasons later, in March 2016, population levels were estimated at 200–235 individuals. When looking solely at these numbers, the cull has managed to keep the population fairly level. However, 43 wolves were shot during the two-year cull, and over half of these (24) were over two-year-old individuals. It is easy to see that the cull has not met its goal of only targeting young individuals. In fact, a staggering 21% of the culled individuals were alphas. And this level may still increase once age determination is complete for all the culled individuals. Such a high number is unsustainable in terms of future hunting management.

Culling each of these alphas has either caused the weakening or disbanding of a pack, leading to higher numbers of individuals or small groups of wolves roaming around unable to optimize their hunting. This is exactly the way to create more problem wolves that willingly come close to human habitation or begin killing hunting dogs. Additionally, several worrying cases have surfaced, where wolves have intentionally been driven towards habitation or have been deliberately wounded to gain more population control or damage control permits for hunting these “problem individuals”. The goal of the wolf management plan is to uphold a viable population in Finland, but at this current rate, the trial wolf cull also appears to have failed.

What next? The future of the wolf cull will be determined during the fall of 2016. The wolf is obviously a species that causes so many societal conflicts, errors in management, and people taking the law into their own hands, that we need to question whether the wolf should remain a species that can be hunted by the general public. Nevertheless, the wolf population does need both management and protection in the future. Perhaps Finland should consider a model where wolf hunting is carried out solely by the (game) authorities. The population control process could remain the same as before, which would allow the cull of problematic individuals and the regulation of pack sizes. But the professional skills of the proper authorities would ensure that overreactions and the killing of alpha individuals could be prevented, which in the long-term could help stabilize the whole population and mitigate wolf-human conflicts.

Protecting one of the largest economies in the world

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Shallow waters of the Baltic Sea © Stella Thompson

Implementing the Red List of Ecosystems (RLE) has kicked off to a good start. I introduced this fairly new conservation method in a previous blogpost (https://encounterswithwildlife.wordpress.com/2015/09/30/the-red-list-of-ecosystems-assessing-the-extinction-risk-of-ecosystems/). So far trial studies have been conducted in cooperation with IUCN on all continents apart from Africa and Antarctica. Several countries (e.g. El Salvador, Costa Rica, Marocco, Senegal) have additionally completed or nearly completed drafts for the RLE assessment of their ecosystems. Norway, Finland, and Australia are furthest in the task of implementing RLE categories and criteria into their national nature conservation standards and biodiversity legislation. A quick look at the different ecosystems encompassed so far reveals that various mires, wetlands, shore environments, coral reefs, and temperate and boreal forests are fairly well represented.

The Southern Hemisphere in particular has stepped up in the concrete utilization of RLE in assessing the health and collapse risk of ecosystems. Through a series of 13 studies, Australian researchers have determined that RLE is a functional tool for classifying and assessing various ecosystems. This has concurrently revealed several practical measures for promoting ecosystem conservation. Within the next couple of years the assessments will be extended to include all ecosystems in Australia. Factors most strongly weakening the health of Australian ecosystems have been gathered together. It is hardly surprising that climate change plays a large part, impairing ecosystems from rainforests to oceans and deserts to dry meadows. However, each ecosystem faces unique challenges at its own pace. This supports the all-round utilization of RLE. We cannot kid ourselves that conserving a few currently unwell ecosystems would be sufficient, but we must also take into consideration the probable changes that will occur in presently healthy or nearly healthy ecosystems in the near future. The future viewpoint should unquestionably be included in national RLE assessments.

A concurrent armament race seems to be ongoing concerning marine conservation; during 2015 at least four countries announced plans of founding the largest marine conservation areas in the world. The Kermadec nature reserve in the Pacific waters of New Zealand will span 240 000 mi2 (620 000 km2), while Great Britain is planning three protection zones in the Pacific and Atlantic Oceans with a combined area of 695 000 mi2 (1 8000 000 km2). Palau ratified the establishment of a 193 000 mi2 (500 00 km2) nature reserve, and Chile declared intentions of founding a marine sanctuary in the waters of Easter Island, covering 243 200 mi2 (630 000 km2). Complete RLE assessments should be conducted on each of these soon-to-be-founded zones, to find the areas that would most benefit from improvement. Assessments have indeed been planned for some of the reserves.

Marine conservation is geared towards securing important growth, spawning, reproductive, and feeding areas. Protecting specific ecosystems, e.g. underwater volcano chains, and securing fishing possibilities are also paramount. A recent WWF report (downloadable at http://wwf.panda.org/wwf_news/?244770/Ocean-wealth-valued-at-US24-trillion-but-sinking-fast) calculates the combined economic value of oceans at $24 trillion. The products and services attainable from oceans is valued at $2.5 trillion. If they were an independent nation, the world’s oceans would be the seventh largest economy on the globe, ranking between Great Britain and Brazil. However, the WWF report concludes that the biodiversity of oceans has decreased by nearly 40% during 1970–2010 due to climate change, seawater acidification, and overfishing. Currently two thirds of our fishing waters have been completely utilized. Most of the remaining areas are over- rather than underexploited. The economic value of oceans is presently dwindling rapidly as marine ecosystems weaken and collapse.

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Fishing boats on the Atlantic Ocean © Stella Thompson

The oceans and seas have long been the Wild West of our planet, where utilization and downright exploitation are permitted with little or no rules (the so-called “tragedy of the commons”). Legislation lags behind the current situation, but founding enormous nature reserves is an excellent way to uphold ocean ecosystem health, at least from the viewpoint of reducing raw material overexploitation. But even huge conservation zones are not sufficient to control the negative effects of climate change.

Marine sanctuaries are an indication of how much we can do to uphold and maintain ecosystem health, especially when national authority and decision-making is combined with international cooperation. Unfortunately the similar protection of land ecosystems is proving more difficult because of intense land use and strict land ownership. The above-mentioned four marine sanctuaries will have a total surface area of approximately 75% of the surface area of the European Union. Conserving such a massive land area would be demanding. International cooperation is the only way forward when dealing with these challenges.

 

More on the planned marine sanctuaries:

http://www.theguardian.com/world/2015/sep/29/new-zealands-new-ocean-sanctuary-will-be-one-of-worlds-largest-protected-areas

http://www.theguardian.com/environment/2015/feb/10/conservationists-call-for-uk-to-create-worlds-largest-marine-reserve

http://www.theguardian.com/environment/2015/oct/22/palau-approves-huge-pacific-marine-sanctuary

Beavers restore the dead wood of boreal forests

Dead wood is a necessary element for numerous species living in the boreal zone. It functions as a food resource, nesting space or growth substrate for several mammals, fungi, insects, and birds. Dead wood is produced through two main mechanisms: senescence and disturbances e.g. forest fires or wind damage. A controlled forest has less ageing trees and disturbances, and currently up to 90% of Fennoscandian forests have been influenced by forest management. The recent drop in dead wood levels due to intensive forest management across the globe has concurrently led to dead wood-dependent (= saproxylic) species becoming rare as well, which weakens food webs and ecosystem functionality. Managed forests may only contain a few cubic meters of dead wood per hectare, while dead wood levels in old-growth forests and forests influenced by disturbances can rise up to hundreds of cubic meters per hectare.

Beaver, the ecosystem engineer © Sari Holopainen

Beaver, the ecosystem engineer © Sari Holopainen

Strong disturbances are less frequent in moist lowland areas of the boreal zone, where dead wood is mainly created as single trees die due to competition and ageing. However, beavers act as wetland ecosystem engineers, raising floodwaters through the damming of water systems. These floodwaters kill surrounding shore forests due to oxygen deprivation, thus creating significant amounts of dead wood into the habitats. In certain cases the flooding may kill entire forest stands. Beavers can therefore be considered the main natural disturbance factor of lowland forests.

Beavers require wood for food and as a building material for their nests and dams. Foraging for woody materials causes the resource to run out within a few years, forcing the beavers to move location. The process of flooding and dead wood creation begins again in a new area, thus producing a continuation of dead wood hotspots into the landscape. Eventually after several years the beavers can return to a previously inhabited location, which will be then be repeatedly subjected to their engineering. These hotspots may be very important to dead wood -dependent species, especially as they uphold a network and continuous supply of different-aged dead wood.

Calculating dead wood levels at a beaver flood - spot the researchers! ©Mia Vehkaoja

Calculating dead wood levels at a beaver flood – spot the researchers! ©Mia Vehkaoja

Despite an overall decrease in dead wood levels, certain types of dead wood have become rarer in the boreal forest than others. Currently the rarest forms are standing dead trees (snags) and deciduous dead wood. Both have declined more rapidly than other types due to forest management actions and attitudes. Beavers create a broad range of dead wood types (e.g. downed wood, stumps and coniferous dead wood), but they particularly aid in the production of snags and deciduous dead wood. This is good news for many saproxylic species, as these organisms are often strongly specialized, utilizing very specific dead wood types.

The dead wood produced by beaver-induced flooding is also very moist, which may affect the wood-decay fungi species that begin colonizing the dead wood. For example, sac fungi are more tolerant of wet conditions, and may therefore outcompete Basidiomycetes at beaver sites. This in turn will lead to differing invertebrate communities that utilize sac fungi instead of Basidiomycetes. Very different dead wood –dependent species assemblages may therefore be formed at beaver sites compared to fire areas of clear-cuts. The interactions of these species are currently poorly understood.

The beaver offers a possibility for all-inclusive ecosystem conservation compared to the conservation of single species. The species could be used to produce dead wood and restore the shore forests of wetlands.

Our research group has recently published an article concerning the impacts beavers have on boreal dead wood. The article can be accessed from http://www.sciencedirect.com/science/article/pii/S0378112715005757

Calculating dead wood levels at a beaver flood - spot the researchers! ©Mia Vehkaoja

Calculating dead wood levels at a beaver flood – spot the researchers! ©Mia Vehkaoja