Tag Archives: Mycorrhiza

The Role of Microbes in the Tropical Rainforest

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OLYMPUS DIGITAL CAMERAThe Role of Microbes in the Tropical Rainforest

Have you ever wondered how a Tropical Rainforest can sustain itself, without fertilizers and maintenance from Humans?

Well the organic layer, in which the trees are rooting, is in most cases just 30 to 50 cm thick on average and because the sub-soil frequently consists of Rock, Clay Mineral (Kaoline) or a layer not suitable for rooting, the roots, except for crevices,  are mainly growing horizontally. The trees are depending on its others support. Still the full-grown rainforest does not need the help from Humans. Humans are doing harm to the rainforest, most of the time due to poor knowledge of the processes, which are taking place above and more so below the soil. The Amazon forest is according to some scientist 110 million years old, while others estimate it to exist 450 million years. The 110 million would coincide with the time the American continents drifted to the west, until it bumped into the Pacific Plate forming the Andes Mountains/Rocky Mountains. See: 180 million years ago the supercontinent Pangea began to break up into two continents, Laurasia and Gondwanaland, at Nature.org. At the same time, the Atlantic Ocean was formed. I believe the 110 -150 million is about right, although some flora and fauna compare with that of Africa and Europe for that matter.

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Cross section of a nodule. See the membrane between the vascular system of the tree and the nodule

The rainforest depends on processes in symbiosis with microbes, like Mycorrhizae (root fungi) and Rhizobacteria (root bacteria), which are predominantly endophytic (living in the host). Among the heterogeneous tree population are species belonging to the Leguminosae, a major group of plant families. These plants are of the utmost importance, due to the major need for Nitrogen, which they acquire out of the air in gaseous form (N2). The absorption of Carbon Dioxide (CO2) from the air also needs the help of the microbes and Nitrogen to convert it to nutrients for the forest, while releasing Oxygen in the air. The air consists of 78% Nitrogen (N2) and 21% Oxygen (O2). The remainder are various gases of which Carbon dioxide (CO2) forms the majority.

Mycorrhiza!

Root fungus in symbiosis with the plant

Here comes the symbiosis with fungi and bacteria. The trees, forming nodules in their rooting systems, secrete flavonoids to attract bacteria. Most of the bacteria live inside those nodules and convert the Nitrogen gas into compounds, which are readily available for uptake by the roots, such as Nitrates (NO3), Nitrites (NO2) and Ammonia (NH3). The trees are pumping these converted compounds in the soil for the benefit of all plant life, including the fungi. The processes in the forest also depend on some macro organisms; to decompose large trunks and other dropped phytomass. To name a few, beetles, caterpillars larvae, birds etc.

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rhizobacteria

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Nodules in the root system of the tree

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Rhizobacteria in the rootzone

The fungi are transporting nutrients through the tree and between the trees so even those, not exposed to the sun, can benefit from the nutrients obtained through Photosynthesis by others. They are also forming shields around the hair roots, to keep them moist and aid in the absorption of nutrients. They further improve the soils keeping the aggregates together and forming bridges. This functions as absorption complexes to regulate the Air and Water Household in the rooting zone and protect against erosion. It is amazing the cooperation between all the species.

Fungi and bacteria, producing more nutrients for the trees, decomposing the leaves and branches, which fall on the forest floor. At given times certain genera of fungi, belonging to the Basidiomycetes, produce recognizable fruiting bodies like Mushrooms, small and large, which are popping out of the ground or growing on the lower trunks. The start of new growth without sufficient microbes results in a very dense vegetation with a few species and poor growth for many years.
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REFORESTATION – IS THIS REALLY A PROBLEM?

Fauna, Flora, Natural Resources, , , , , , , , , , , , ,

REFORESTATION –
IS THIS REALLY A PROBLEM?
Tree crusher

Introduction

When the company, I worked for, issued an order to start a reforestation project for all the mined out areas, I was very excited and immediately concentrated my thinking on how to manage this gigantic charge to do the best we can, especially with the not so great results from an effort done in the late sixties and begin seventies. The first thing came to mind was, what is really essential to successfully reforest an Amazon Rainforest.

It is important to have some knowledge about the virgin forest. It is amazing to see how the Amazon Rainforest grows. The organic layer in the top soil, which is ever recycling is in fact very thin, between one and two feet. The rooting is practically horizontal, as the rocks or in some places an underlain clay mineral (kaolin), prevent deeper rooting, except for the incidental occurrence of crevices in those rocks. It is due to the earlier mentioned recycling processes, the forest can sustain itself, with all heterogeneous  vegetation.

The planning

Everybody who is planning to undo these natural processes, by clearing an area, without making a plan beforehand, how to restore the jungle after whatever activity he plans to develop, is looking for serious trouble. The jungle is only capable to sustain itself due to this very process of recycling and support between the various trees in this heterogeneous tree population. The latter becomes immediately evident, when a part of the jungle is cleared, as the trees at the rim one by one start to fall down by itself as the support is missing. This goes especially for those trees, which were not rooted deeply enough due to the structure of the subsoil, which in most cases is hard rock or consist of the clay mineral “kaolin”.

Consider what to do before starting to clear the land. Make an extensive plan with saving of organic matter at a large scale in mind. In the example of the mine, we planned to push the trees to the areas outside the area to be mined or to be mined on a later date. The humus layer, although thin, ought to be stockpiled for later use, at a convenient area, preferably in some shadow. The significance of this procedure, will be illustrated next. If the mined out areas become available deep rip the kaolin floor and introduce the trees reduced to wood slivers, mixed with the original topsoil/humus. In the meantime, special crews with knowledge of the species, gather seedlings from the neighboring jungle adapt them in makeshift nurseries. Finally contract locals to plant the adapted seedlings in the rainy season and monitor the growth during the first one and a half year. Make sure to include a large number of leguminous species.

Execution of the plan

Issuing orders not to burn was an absolute must. This was, in detail discussed with nearby communities and with all the workers of the company, explaining that burning, not only means a loss of the needed organic matter, but also emit tremendous amounts of pollutants in the air for a long period. Imagine the resistance, with a habit of centuries of slash and burn practices. Close supervision remained an absolute must in the first year to spot violations of the order. I must say that, in general, the message did clearly convince workers and community very well. To convert all the organic matter, it was necessary to purchase a mobile tree shredder to diminish the trees to very small sized chips or slivers.

As in the meantime the mining process advanced and the mined out areas became available the haul trucks were diverted to the extra charge to haul this crushed tree material and the humus to those areas, mixing the two. The benefits of the humus will be explained now. The freshly crushed  trees are not suitable as substrate for the new growth, as they are not yet decomposed, to serve as nutrients. To speed up this process the humus serves as a catalyst, introducing the microbes, to help with that.

Once the mixed organic matter was spread out over the previously deep ripped kaolin of the mined out floor, it had to be covered, by introducing the new plants, which were gathered` by special crews in the nearby standing jungle. The plantlets were moved to makeshift nurseries, to re-adapt them Then came up a new process, these small seedlings from the jungle needed to be planted.

As in most tropical rural areas all planting is done by women, so the plan included contracting the women from the villages, to do the populating of the newly prepared reforestation areas. This became a real success. In a matter of less than two years, the new growth reached a height of some 15 – 20 feet, helped by a rainfall of average 2500mm annually and plenty of sunshine in between.

The thinning of the densely planted areas is then only a task of nature. Competition and other laws of nature do their work and the new jungle is a fact, practically on autopilot. In very few cases, a cutlass will help to make it perfect.

Evaluation

Comparing this process with the previously reforested areas, a major improvement was evident, accomplished by a very coordinated effort from all staff and workers. The goals of reestablishing the Rainforest, could only be reached due to this fact. The new growth will have to sustain itself again with an organic layer of approximately two feet and support of its neighboring trees.

As a special note, it should be said, that also the future habitats of the fauna species, should be included in the plan, by scattering some trunks through the area to provide some shelter. It will not, and did not, take long for these species, to go into the reforested areas, once the height of the trees will thin the undergrowth and give access to them to continue their natural processes of roaming, hunting, eating and taking care of their new offspring. A Rainforest is not complete, without the fauna, crawling, running or flying from one habitat to the other. Later this fauna will also reintroduce epiphytes.

This was a short description of an otherwise very complicated plan and execution, but I may say, with at the end, a very satisfying experience. If the planning is done right, the answer must be, Reforestation Is Not A Problem. Let us Save our Natural Resources http://alturl.com/9sznc
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