Guadua

The guaduas, cañazas or tacuaras (Guadua spp.) are a genus of plants of the bamboo subfamily, of the poaceae family.

In 1806 it was described by Alexander von Humboldt and Amadeo Bonpland who saw this plant in Colombia and called it Bambusa guadua, then in 1822 it was classified by Carl Sigismund Kunth as Guadua angustifolia. It is considered one of the most representative native plants of the Andean forests.

This resource was used since ancient times by the primitive inhabitants of the Andes, and is still used today, especially in the central-western region of Colombia.

The origin of the word guadua is not known for certain, although some specialists believe that it could be Venezuelan. These versions emerge from the variants "guadúas", "guafa" with which this plant is known in this country. And the term "guasdua" is also often used as the city of Guasdualito, in Venezuela, reminds us.

Territorial distribution

From the tropical zones of Mexico to the south in Argentina, except for Chile and the Caribbean islands, guadua grows in all Latin American countries and in many Asian countries. In Argentina the genus Guadua is represented by G. chacoensis, G. trinii, G. ramossisima and G. paraguayensis. The term tacuara is used in the Río de la Plata to name reeds of Asian origin, such as Phyllostachys aurea.

Use

Its use is so old that, according to the book 'New bamboo construction techniques' (1978), in Ecuador bamboo imprints have been found in constructions that are estimated to be 9,500 years old.

Suspension and cable-stayed bridges of impressive engineering precision, powerful boats as well as flutes, quenas and marimbas, were made by the Incas with this resource during the pre-conquest period, and after it during the colony, the species was in charge to protect the Indians and even small towns from the Spanish siege by hiding them behind their thickets.

Colombia, Ecuador and Panama are the countries in the Americas with the greatest tradition of use, in fact in these areas there were the largest extensions of the species on the continent.

In Colombia, guadua has been subjected to great deforestation pressures; Extensive existing areas have gone to small wooded patches located on the banks of rivers and in the humid forests of the mountain slopes, especially in the departments of Quindío, Risaralda, Caldas, Tolima, Valle del Cauca, Cundinamarca and Santander. Guadua is a plant from the bamboo family, which brings great benefits to the land and to people, since almost all the elements of a house can be built with it. It develops very quickly, takes 4 to 6 years to mature, and begins its decomposition process at approximately 10 years of age.

During the Spanish conquest and, much later, the Antioquian colonization of old Caldas, guadua was an important material used in the construction of their houses, household utensils, hunting tools, livestock and agriculture, and even aqueducts.

And Fernando Calzadilla Valdés, in his work Por los Llanos de Apure points out that the lances used by the riders of the patriot army in the southern campaign were made with guasdua canes, a light material and very hard, which could be used as a spear in combat to cause havoc among the royalist population ()

Use

Use is a silvicultural practice for the maintenance and improvement of guadual. It can be defined as a silvicultural practice that seeks to create favorable conditions in the guadual, which implies the improvement of natural regeneration and structural composition, which ensure maximum sustainable yield. Harvesting not only aims to obtain the maximum possible income from the resource.

In the guadua forests, the succession process can be considered as progressive when its management shows the guadua in biological equilibrium, contrary when there is some alteration or deterioration in its structure, product of a natural or artificial intervention, in case in which is considered that the guadual begins to present a regressive succession, which can cause its complete disappearance.

To avoid the above, it is necessary to know and differentiate each and every one of the elements that make up the guadual. Its knowledge allows technical uses, in addition to knowing its dynamics within the productivity process of guadual.

Among the causes that cause the so-called regressive succession of the guadual is non-management, since if the guaduals are not used they tend to degrade due to excess of individuals at a certain time and/or due to a decrease in the biological or dynamic activity of the guadual.

Because of the above, the bamboo trees must be intervened periodically to regulate the living space of their individuals and to favor a greater appearance of regrowth or shoots. In Colombia, research has been carried out on technical exploitation because the vast majority of forests are very dense due to lack of management, or heavily intervened by anti-technical exploitation.

It is necessary to determine for each site, the cutting cycle or cutting period to elapse between one use and another, and the cutting intensity, that is, the quantity and type of individuals to be extracted on each occasion, this being what It properly constitutes the technical management plan of a guadual.

With the technical use, the aim is to obtain a balance in the forest, in the environment and through it, obtain income according to the sustainable management of the resource.

The management plans are based almost exclusively on the number of adult or “made” guaduas reported by the stock inventory, that is, the importance of the stand is limited to the number of usable guaduas.

Commercial uses are based mainly on the thinning system, determining the number of stems in percentages according to the state of each guadual tree and the cutting age, posing as the ideal, when the guadua changes color, because it goes too far. from green to yellow, being invaded by lichens that give it an ash, whitish or “rucia” hue, this coloration occurring at approximately 5 or 6 years of age of the stem.

To know the use, it is necessary to know a series of technical concepts that will help to make more rational use.

Basic concepts of use

Vegetative cycle

It is the time elapsed from the appearance of the regrowth continuing with all its vegetative phases until the total inactivity of the plant or the drying phase of the stem.

Turn

It is the time elapsed from the appearance of the regrowth until the moment it is used as guadua.

Pause or step time

It is the time that the guadua remains in a certain vegetative phase, before passing to an immediately higher phase.

The technical uses are based on the extraction of a certain percentage of mature or "made" only, which implies knowing very well the development phases of a guadual, easily distinguishable at the field level, namely:

• Rebrote or renew: This first phase of development of the guadual includes from the appearance of the rebrote until it reaches its maximum height, without the presence of apical or higher branches; sometimes there are basal branches or hooks. In this phase the stem is always covered by caplinar leaves or "capachos" both in its basal or scissor part, and in its apical or superior part. The nudes are intense green and have two white bands in each knot, called nodale bands, composed of pubescence (pelusa). Rebrotes should never be cut.

• Youth guadua or "biche": in this phase, the stem removes all its caplinar leaves from its top and preserves the basal. There are spike branches and the foliage of the plant gradually grows. The nudes are intense green and the nodal bands are still clearly appreciated. The stems in this phase should not be cut either.

• Adult, mature, or "made" guadua: the stem is covered with lichenous stains, the nodal bands are stopped and some mosses appear in the knots, there are no rubber leaves anywhere in the stem and the guadua acquires its highest degree of resistance. The white color is called "Guaduas Rucias" and are usually found inside the guadual. They're the only guaduas that can be used.

• Dry guadua: there is no presence of foliage and the stems are ocher or pale yellow. The guaduals should not be allowed to reach that state because of it, the stems lose their resistance and also the generation of chusquins or rebrotes is being prevented.

Mowing Cycle

It is the time elapsed between two successive uses on the same forest. This depends on the possibility of the guadual. The main thing for cutting a guadua is to take into account the changes of the moon, so it is advisable to cut it on the waning moon since this exerts pressure on the water, taking it to its root and thus the guadua is in better condition for its use. We must also take into account the white spots that appear from top to bottom.

Possibility

It is the volume or number of guaduas that can be used in a given period seeking to ensure maximum sustainable yield. The possibility depends on the desired product, the structural composition, the dynamics in natural regeneration, the shift, the pause time and the area to be used.

Technical management plan

The technical management plan is made up of the cutting cycle, cutting intensity and harvesting techniques.

Harvesting techniques

To extract any amount of stems from a guadual tree, it is essential to obtain a harvesting license and take into account that harvesting must be supervised by competent professionals. ^{[citation required]}

Once the development phases of the guadual are known, sampling is carried out, where the number of individuals (stems) is counted for each development phase. This work is carried out through sampling plots of 10 m x 10 m x 10 m square.

The number of stems to be thinned is subject to technical studies that determine the intensity or cutting index.

The use of the stems should be aimed at the mature ones, but within this phase the most advanced ones should be selected, analyzing the already mentioned characteristics.

Knowing the number of mature or "made" per hectare, a percentage of this type of guaduas can be extracted. The utilization index is generally 35% of mature guaduas. Greater uses imply physiological imbalances of the guadual and susceptibility to overturning of regrowth and young guaduas caused by storms, strong winds, gales and storms.

Thinning must be done uniformly throughout the entire area of the guadual and the cuts of the stems must be made at the height of the first or second node and flush. Cuts that leave a concavity or "well" should be avoided, which favors water deposits that cause rotting of the plant.

All diseased, dry standing or dry split stems should be cut. The crown with its branches and other non-usable parts of the guadua must be chipped and spread evenly inside the guadua, since its decomposition generates organic matter. When the intervention is carried out near streams or water tanks, it is necessary to avoid throwing waste that hinders its free flow.

Cutting the stems at dawn between 3:00 and 5:00 a.m. implies obtaining them with lower moisture content and lower concentrations of carbohydrates, therefore more resistant to attacks by insects and fungi. All the cut stems should be left inside the guadual in an upright position for approximately 20 to 30 days, then they are preferably dried in the shade.

Stem cuts should be made flush with the first or second node, avoiding hollow spaces in the stump that favor water deposits and consequent rotting of the rhizome.

Uses of Guadua in construction

For centuries^[when?] guadua has traditionally been used as a construction material, and now, due to the current trend of searching for materials for sustainable development, this plant has gained space in construction. From houses in rural areas built with bahareque in which the framework is built with guadua canes, even for export in projects developed in countries where this plant does not exist. Houses have also been built with mixed techniques.^{[citation needed]}