Too much soil can affect plant growth

Literature research

To what extent do soil and vegetation (hedges) influence each other?

Abstract

At many roadsides, inside and outside a town, you can see hedges. But what functions does a hedge have? In this literature review I would like to outline some of these functions in relation to soil and their interactions.

There is a multitude of interactions between vegetation and soil, only a few of which are really known. The mutual influences should, however, be taken into account when interfering with nature. If, for example, a hedge is to be planted on the edge of a field, one should first compare the positive and negative effects of the hedge on the field at this location and then decide whether a hedge is suitable at this location or not.

In this literature search, some of the interactions are presented in order to provide a general overview. However, no third factors that support the effects are included, only the factors soil and vegetation, whereby the vegetation is mainly hedges.

Keywords: hedge; hedgerow; vegetation; soil; Interactions; effect

introduction

During our excursion week in November 2018 in Bornum, Lower Saxony, we had the opportunity to talk to three farmers who own fields on a hedge. This hedge was not planted by the farmers, but was created by overgrowing a dirt road. During the conversation, I got the impression that the farmers were not happy about this hedge, as part of their yield is lost through the hedge. In addition, they are not allowed to remove the hedge, but still have to take care that it does not grow too far out into the field. This led me to the question of which positive and negative effects a hedge can have and in which locations a hedge makes sense.

So I decided to collect general information about the interactions between soil and vegetation in this literature search and to present it in a bundled way, thus giving an overview of the advantages and disadvantages of, above all, hedges. In doing so, I also take a look at agriculture, as I am mainly referring to the soils of arable land, as these can be used to better understand and observe the effects of the hedge.

When it comes to vegetation, I focus on the hedge, as our project deals with the importance of the hedge for the environment and the general effects of hedges.

method

At the beginning of the literature research I got an overview of the existing literature on hedges and soil by using the terms “hedge; Vegetation; Ground; Interactions ”(in German and English). After that, I gathered the articles that included the terms and examined them for information about the interactions. I went through several steps in this process. At first I just looked at the titles of the articles and then read through the abstract. If the abstract continued to cover the topic, then I have read the entire article.

The following table shows the sources that were used most to answer the question:

Literature title + author

Central content

source

"The role of hedgerow in soil functioning within agricultural landscapes" (Holden, J. et al., 2019)

Soils under the hedge are less compacted and have a lower bulk density

Web of Science

"Interactions between plants and soils" (Kainz, W. et al., 2003)

Soils influence the plants that appear on the vegetation cover; Plants influence the humus content of the soil

Internet research

"Hedges. Significance for nature, landscape and agriculture "

Pros and cons of a hedge

Internet research

"Fundamentals of Soil Science" (Kaupenjohann, Prof. Dr. M.)

Moles loosen the soils; Earthworms bring organic matter into the depths of the soil

ISIS platform of the Technical University of Berlin

Result and discussion

In general, one can say that hedges have a variety of ecological functions, as they provide and represent, for example, the habitat for many plants, but also for invertebrates, reptiles, amphibians, birds and small mammals.

The animals living on the hedge also have an influence on the soil, as burrowing soil animals such as moles loosen the soil, while soils that earthworms have digged through still carry organic matter deep down (Kaupenjohann, Prof. Dr. M .).

In addition, the soils under a hedge are less compacted, as the soil is not trampled on by people, among other things, and have a lower bulk density (Holden 2019), which means that the soil on the surface can be drier. On the other hand, a soil with a low bulk density is good for root formation and the animals.

In addition, the hedge is also important for agriculture, because it offers, for example, wind protection for the adjacent field as well as protection from snow drifts and prevents soil erosion, which makes it easier for the farmer to plant something in the field and to make a profit .

Furthermore, the hedge promotes the formation of dew, in which the moisture adheres to the leaves, and prevents evaporation by casting shadows, whereby the soil moisture is stabilized and the hedge can remain in the location for longer. This is very important because soils under hedges are usually drier, as they are usually not watered, which prevents them from drying out.

In addition, the plant forms a protection above the soil surface, which reduces the impact of precipitation and surface runoff and also regulates the water balance.

In addition, the hedge creates a balance between the ground temperature and the air temperature close to the ground, which means that fewer temperature extremes occur and the microclimate is regulated. This is caused by the fact that the air temperature cools down at night and only slowly warms up again during the day near the hedge, which means that there is not so great a difference between the soil temperature and the air temperature close to the ground.

Soils have different properties, such as soil type and texture, as well as the availability of nutrients and water. These properties create different framework conditions for the plants, with which the soil influences the emerging plant community of the vegetation cover (Kainz et al. 2003).

The relationships between plants and soils are changeable and can be altered by climatic fluctuations, changes in soil properties triggered by the plants, and changes in use, vegetation and landscaping controlled by humans. Thus the relationship and the mutual influences between the plants and the soil are constantly changing.

In the relationship between the plant cover and the soil development, a distinction is made between three conditions (Kainz et al. 2003):

In the first state, there is a soil with harmonious vegetation, which means that the soils are constant in their horizon sequence under given site conditions and carry a vegetation cover.

In the second state, the soil has a disharmonious vegetation, which means that the soil reveals current changes in the horizon sequence under given site conditions and their soil structure and soil vegetation do not correspond.

In the third condition, soils are present whose formation conditions differ from today's site conditions, so that the soils no longer correspond to what would probably be formed under the current site conditions.

Under given site conditions, a natural equilibrium is established in the flow of matter. However, changes in the plant cover can disturb this balance and lead to lasting changes in the soil properties. Since the vegetation is also shaped by other factors, such as the climate, the water balance and the animals, this can also change easily, which could lead to a relatively quick disturbance of the equilibrium.

Another influence of plants is that they help determine the shape of the humus, since dead plant and root remains are the starting material for the humus and the soil reaction is influenced by the vital activity of the plants and the formation of humus (Kainz, W., 2003).

Another point is to increase the yield of the field adjacent to a hedge. However, it must be taken into account that the yield is reduced directly next to the hedge on the edge of the field, as there is competition between the hedge and the plant grown in the field. In addition, it must be taken into account that, depending on the type of soil and the plant cultivated, different increases in yield can occur.

In addition, the hedge could be used by the farmer as an alternative cultivation area, since a different type of plant can be planted there than the field crop. This gives the farmer the opportunity to sell another product, which means that he is no longer dependent only on the field crop, but has an alternative if the price of the field crop is reduced, for example.

Although field trees are smaller than hedges, they still have ecological functions similar to hedges and, on the one hand, structure the landscape and provide a habitat for some animal and plant species.

In addition, hedges and field trees offer a privacy screen, which means that they are also planted in cities and in front of properties and thus still have an aesthetic function.

conclusion

In general, one can say that there are a number of effects between soil and vegetation, which are constantly changing and are also influenced by many other factors.

In addition, a hedge has many positive effects, which in my opinion outweigh the negative aspects. However, the location must also be taken into account, as growing a hedge is not suitable in some locations and the soil at these locations does not create the appropriate framework conditions for the hedge.

In the end, I have to say that there are not many scientific articles and more on the interactions between soil and vegetation, but that often a third factor is taken into account, which makes it difficult to find substantiated information on just the two factors. In addition, some of the articles deal with soils in certain places, which means that they are not generally applicable and therefore not always helpful.

Bibliography

"The role of hedgerow in soil functioning within agricultural landscapes"

  • Kainz, W .; String, P .; 2003

"Interactions between plants and soils"

  • Kaupenjohann, Prof. Dr. M; Wessolek, Prof. Dr. "Fundamentals of Soil Science; Technical environmental protection; Technical University Berlin"

"Hedges. Significance for nature, landscape and agriculture "

  • www.naturtipps.com/hecken_feldgehoelze.html