Archive for month: May, 2024

Biodiversity – The Series

The three main aspects of biodiversity are species diversity, the genetic diversity of a species and the diversity of habitats in a region. We cover all those aspects in dedicated articles. In this one, we take a closer look at how important it is to have multiple habitats in a given area.

What does habitat diversity mean?

Habitat diversity is a metric of how many different habitats are present in a given area. For example, an area where a naturally flowing stream separates a woodland fringe from a meadow may have a high structural diversity. A large arable field without hedges or wildflower strips, on the other hand, does not have a high diversity of habitats. A high diversity of habitats automatically increases the species diversity of the area, as each of these biotopes has its own biocoenosis and therefore a single area can be colonized by more species.

Loss of habitats

Humans bear the main responsibility for the destruction of habitats through the use of natural resources, air, light and water pollution, noise pollution, intensive agriculture, industrial production and the progressive urbanization of landscapes. Other influential human activities include mining, deforestation and trawling. Eutrophication, the excessive input of nitrogen and phosphorus into ecosystems and the atmosphere, has a global impact. In the long term, this nutrient input leads to nutrient-poor habitats losing their unique and species-rich character and becoming increasingly similar to other locations.

However, abiotic environmental factors can also (indirectly) contribute to the destruction of habitats. These include geological processes such as volcanism, climate change, and the spread of invasive species.

Invasive species take over habitats

Habitat destruction in an area can lead to a shift in local biodiversity from a mix of generalists and specialists to a population consisting mainly of generalists. Invasive species are often generalists because they can survive in a much wider variety of habitats than specialists. If these invasive species, which are particularly prolific, colonize ever larger habitats in an area, there is less and less room for the few specialists originally native to the area. As a result, the so-called extinction threshold of the specialists shifts ever further into a fatal direction – and the probability of their extinction increases.

Loss of biodiversity

Habitat destruction is the biggest driver of species loss and the loss of genetic diversity within species. And this is not just about the loss of large and popular animals such as the giant panda. Species such as nematodes, mites, earthworms, fungi and bacteria carry out many of the processes that are essential to human life, such as purifying air and water, and they too disappear when their habitats are destroyed. At a higher level, plants not only provide structural diversity and protection against erosion, but also energy and nutrients, which are then processed by other creatures in the food chain.

Example: Deadwood

A “well-tended and tidy” (managed) forest is often one from which wood is harvested before it can die. However, this means that the forest habitat is missing something that was originally an integral part and has been able to develop and optimize itself over thousands of years – a hotspot of biodiversity: under the bark of dead trees, starch, sugar, vitamins, proteins, amino acids and cellulose are waiting to be decomposed by longhorn beetles and bark beetles, wood wasps and thousands of often highly specialized insects and fungi. Their bore dust, excrement and moulting residues attract new wood colonizers – by the way, different ones in lying than in standing dead wood. Bats, owls and dormice use dead wood as a hibernation camp or roost, while other organisms – plants, fungi, woodlice, mites and worms – complete the decomposition process. What remains is a large amount of humus, the perfect basis for new growth.

Biodiversity

The example of deadwood shows impressively that countless habitats and processes have already been changed and destroyed so quickly by humans that entire groups of organisms have become extinct or their survival is acutely threatened. However, knowledge of the interrelationships and daily efforts to preserve and restore habitats can make the difference between preserving a diversity of habitats, of species and the diversity within these species in your own town, village or garden.

This article was featured as a story in the Flora-Incognita app in spring 2024. In this plant identification app, you can find exciting information about plants, ecology, species knowledge, and tips and tricks for plant identification. Check it out!

Biodiversity – The Series

The three main aspects of biodiversity are species diversity, the genetic diversity of a species and the diversity of habitats in a region. We cover all those aspects in dedicated articles. In this one, we take a closer look at the aspect of species diversity.

Species diversity

The term species diversity describes the number of biological species in a given area. This applies to small areas as well as large ones: a single tree in the Amazon, an entire mountain range, a political state, or even just a grid cell in a city. Typically, the species diversity of such an area is divided into specific groups such as plants (or just trees), mammals, fish, insects – depending on the question or topic.

How many species are there?

In 2006, around 2 million species were scientifically described. This contrasts with estimates of 5 to 20 million species that actually exist worldwide. It is very difficult to give precise figures for these two, as different groups of organisms have different criteria for species delimitation, and modern classification methods also include genetic information. There are also a large number of synonyms, and most species are very small and live in areas that are not easy to reach. Nevertheless, around 12-13,000 new species are scientifically described every year.

Why is species diversity important?

Nature is crucial for our survival as it provides us with important ecosystem services such as food, medicines, water regulation and recreational opportunities. It also helps to regulate the climate, and each species plays a unique and important role. The absence of a species can lead to the disruption of complex ecological cycles. For example, the extinction of insect species can have a negative impact on birds that feed on these insects and on the pollination of plants (including crops).

What threatens species diversity?

First and foremost is the destruction of habitats through construction, clearing, or modification, e.g., through intensification of soil cultivation. Many species-rich habitats are nutrient-poor, as a few dominant species spread quickly on nutrient-rich sites. The input of nitrogen and phosphorus from pollutants poses a threat to these habitats. Finally, invasive species can also have a lasting impact on existing ecosystems by disrupting the complex interactions between the species that occur there and successfully displacing established species. Above all these factors is climate change, which is altering many established processes so rapidly that the adaptability of many species cannot keep pace.

How can species diversity be protected?

Restoring or maintaining diverse habitats is the most important measure for preserving species diversity – or at least slowing its decline. Examples include restoring floodplain landscapes along rivers, allowing standing and lying deadwood in forests, thinning dry grasslands, extensive year-round grazing, flowering strips with native wild herbs and shrubs on agricultural land and stopping the drainage of moors. But our own actions can also have an influence: Wild corners in the garden, partially mowing of meadows, use of peat-free soil, participation in work to remove invasive plants or political and educational work are valuable building blocks for the preservation of species diversity.

This article was featured as a story in the Flora-Incognita app in spring 2024. In this plant identification app, you can find exciting information about plants, ecology, species knowledge, and tips and tricks for plant identification. Check it out!