Ecological concepts

Ecological concepts - natural versus managed forest by Paul Veenvliet

Natural versus managed forest

Even here in Slovenia, where over 60% of the country is covered with forests, natural forests are very, very rare.
 
A natural forest is not necessarily a place without people, instead, it is a place where the forest is not used in any way. Trees can grow undisturbed, and, even more important, trees can also die undisturbed. Once the forest is mature, over 20% of the trees can be either dead or dying.
 
When a tree dies, the decaying wood nourishes the forest in many ways and the open place in the canopy provides light for other trees to grow. In a natural forest, a fallen tree is not an economic loss, but an opportunity.
 
Natural forests are an inspiration. A place to dream. And a place to carefully, quietly visit. In such a forest, it feels like we are inside a church of nature, and we should behave accordingly.
 
In a managed forest, the largest and most valuable trees are cut and removed, which means that there are few or no dead trees left.
 
Some trees are damaged at the base when stems are pulled out of the forest with heavy machinery. There are few trees with holes: nestboxes are put up to provide birds with alternative nesting places.
 
Humans are no longer mere visitors, but actively shape the forest in many ways; which is why I depicted a hunter who carries a gun.

Natural forest

  • Vector art
  • Concept for a book
  • 25 January 2021
Ecological concepts - how hydropower plant impact by Paul Veenvliet

The impact of a dam on a river ... and on us!

How a dam changes a river. These drawings show all kind of effects, but mostly how dams affect us directly: 

Because of the rapidly changing water levels both below and above the dam, rivers become unsafe for recreation: it is a myth that dams can be good for tourism: in fact, dams exclude people!

Dams “catch” sediments which normally move downstream with the flow of the water. Below the dam, sediments still flow downstream, but no new ones are added from above. As a consequence, the river becomes ever deeper below the dam, which in turn lowers the groundwater in a wider region. This affects agriculture, drinking water availability and nature. 

Because of the stagnant water in the artificial lake, water quality deteriorates, both in the lake and downstream. I showed this as a different water colour (green algae bloom) and toxic bubbles in the lake.  In the long term, this will affect drinking water quality as well. 

Because of the lowered groundwater level, the last old river meanders disappear (many are in fact already destroyed long ago, for other reasons). This greatly affects wildlife. 

The impact of a dam on a river ... and on us!

  • Vector art
  • Made to explain the human impact on nature in support of project ZA SAVO.
  • January 2021

za savo logo

Link to the project

 

Ecological concepts - the environmental problem by Paul Veenvliet

A major environmental problem explained

How European food production alters the world more than we want to know …

A considerable part of animal food for the European bioindustry comes from South America. In South America, soy and grains are grown on huge fields, in places where there used to be forest and small-scale agriculture.

European animal products, especially dairy, is exported all over the world, where it floods the market and outcompetes local small farmers, who cannot produce for a similarly low price. 

The animal faeces containing “South American nutrients” stays in Europe, where it causes significant environmental damage (acid rain, nitrogen pollution, overfertilization). 

At the same time, European small scale farmers have a problem to compete with this industry as well.

Much of European farming is no longer about feeding the people of Europe. It is about economics and making sure people from the rest of the world start to buy as many European products as possible.

It is about time to re-think European agricultural policy … 

A major environmental problem explained

  • Vector art
  • Made to explain the human impact on nature.
  • December 2020
Ecological concepts - impact of a dam on migratory fish by Paul Veenvliet

The impact of a dam on migratory fish

Many fish migrate downstream and upstream in rivers throughout their lives. They spawn in shallow, oxygen-rich headwaters and grow to a large size in the deep parts of the river, or even in the sea.

Dams interrupt these movements. This is only partly compensated by the construction of fish passages for several reasons: 

  • Artificial lakes in front of dams represent an unsuitable habitat for many riverine fish, and this might be as big a barrier as the dam itself. These lakes are eutrophic with stagnant water which is often turbid because of an algae bloom.
  • Upstream migrating fish have their path blocked by strong water currents but do not get sucked into electricity generators. Instead, they can search for a way around and eventually may find the fish passage. However, there is no good reason to assume that downstream migrating fish have the idea to try to find a small passage rather than just move downstream with the current, and eventually get sucked into electricity generators of a power plant.  
  • Some fish species, like sturgeons, are unable to pass through most fish passages. This is because fish passages are generally designed for middle-sized fish with a strong swimming ability like salmonids and riverine cyprinids. 
  • The downstream habitat is altered as well because the downstream flow of gravel is interrupted. Gravel is “trapped” in the artificial lake and new gravel does not reach the lower parts of the river. At the same time, the water keeps transporting gravel away below the dam. This leads to a gradual deepening of the river which changes the habitat and reduces river dynamics. 

Some fish, like trout, can survive in above-dam parts of a river, even when their overall populations are much reduced. 

Other fish species, like sturgeons, need to be able to migrate through the entire river in order to survive. Even a single dam can mean that these fish go extinct in the entire river. 

The impact of a dam on migratory fish

  • Vector art
  • Made to explain the human impact on nature.
  • December 2020
Two drawings depicting a pond before and after the introduction of carp.

The impact of carp

Carp are among the most popular fish for sports fishing, consumption fish and ornamental fish worldwide. However, they have a pronounced impact on their surroundings, especially when they are stocked at high densities. Carp change the ecology of ponds by: 

  • Eating plants – this alters the habitat for invertebrates and many fish species. Also, plants filter out nutrients from the water, which reduces nutrient availability for algae. In this way, dense aquatic plants can outcompete algae. 
  • Eating small invertebrates including water lice – these invertebrates eat algae. A lack of small algae-eating invertebrates increases the growth of algae. 
  • Searching for food in the water bottom – this stirs up mud, which effectively dissolves nutrients in the water, which are naturally present in the bottom. This increases the availability of nutrients for algae. 

Combined, this means that carp change the habitat in a pond from clear water with underwater plants, to murky green water (“algae bloom”) without underwater plants. Many fish and invertebrates depend on clear water and underwater plants: these species disappear from a pond with carp. Without them, also their predators cannot survive. This way, carp change a pond from species-rich to species-poor. 

The impact of carp

  • Vector art
  • Made to explain the human impact on nature.
  • November 2020
Ecological concepts - the difference between an intensive and extensive meadow by Paul Veenvliet

Fertilizing a meadow

The left picture shows a traditional meadow, which is mown once a year. There are many different plants, which obtain the scarcely present nutrients (the red circles) in different ways underground: grass has dense roots near the surface, parsnip has a long, deep-reaching taproot, an orchid grows in symbiosis with a fungus and rattle draws nutrients from the grassroots. The multitude of plants combined with the sunlit, open ground between the plants provides a habitat for many animal species, of which I have depicted a small copper butterfly, a field cricket and a quail.

The picture on the right shows the situation that arises after intensive fertilization. There are many nutrients (the red circles), not only in the surface layer but also deeper in the soil, out of reach of the plant roots. Eventually, some of these nutrients wash out to the groundwater and end up in our drinking water (where some are carcinogenic …).

The excess of nutrients means that only the fastest-growing plants survive = grass. This grass grows so fast that it can be mowed five or more times a year. The dense grass is moist and cooler (hence the blue water droplets in the grass), combined with the low diversity of plants and the intensive use, means that virtually no animals in this meadow can survive. The grass itself becomes susceptible to diseases: this is the orange colour caused by traces of a rust fungus.

Fertilizing a meadow

  • Vector art
  • Made to explain the human impact on nature.
  • November 2020