Shade

Shade out the bullshit, and the grass will be left in the dark.
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Introduction

One of the biggest challenges of reforestation, which you know if you’ve read other pages on this website, is GRASS.

Grass is an extremely competitive plant that steals nutrients, water, space, sunlight, and energy from the other innocent plants around it who just want to grow up like normal plants and trees.

The two most effective ways to battle this vegetative demon and other noxious weeds are by creating shade and establishing a ground cover.

The Healing Canopy: Benefits of Forest Shade

In this bustling world where concrete jungles dominate so many landscapes, the soothing shade of a forest canopy offers a much-needed refuge. Beyond its aesthetic appeal, the canopy of a forest plays a very important role in maintaining ecological balance and offering a myriad of benefits that often go unnoticed, including suppressing grass, creating transpiration, and regulating temperatures and humidity.

Suppression of Undergrowth

Walk into a dense forest, and you’ll notice the serene tranquility that envelops you. The shade of the canopy overhead not only provides relief from the scorching sun but also suppresses the growth of grass and underbrush. This suppression of undergrowth is essential for the health of the forest ecosystem.

By reducing competition for resources such as sunlight, water, and nutrients, a robust forest canopy enables specialised flora to thrive, creating a diverse and balanced environment without the detriment of grass – the demon of the earth.

Transpiration and the Water Cycle

One of the most vital functions of a forest canopy is transpiration – the process by which plants release water vapour into the atmosphere. The shade provided by the canopy helps to regulate this process by reducing excessive evaporation of water from the soil surface.

As trees transpire, they not only cool the surrounding air but also contribute to the formation of clouds and precipitation. This, in turn, sustains local water cycles, ensuring a steady supply of freshwater to ecosystems downstream.

Temperature Regulation and Humidity Control

Step beneath the leafy canopy of a forest, and you’ll immediately feel a drop in temperature. The dense foliage acts as a natural shield, blocking out the harsh rays of the sun and creating a cooler microclimate. This temperature regulation is essential for both flora and fauna, providing them with a suitable habitat to thrive.

Additionally, the canopy helps maintain humidity levels by reducing moisture loss through evaporation. This controlled humidity is beneficial for plant growth, soil fertility, and overall ecosystem stability.

So How Do We Make Shade?

The most effective way to create shade will change through the different stages of maturation of the forest. When starting from barren grassland with no appreciable shade, fast-growing pioneer plants are most important in order to create the most shade possible as quickly as possible. Other trees will be planted in the shelter of these pioneers, and over time, these other trees will form a canopy of their own, and the age of the pioneer plants will pass. Once this longer-term canopy has established, any gaps can be filled with more long-term plants; the amount of sunlight required by the pioneers will no longer be available. By accepting the gradual transition from pioneers to old-growth forest, we align our efforts with the natural succession process.

Fast-Growing Pioneer Plants

These are the first line of defence against the grass. Don’t get too attached to them, as there WILL be casualties. Their mission is to get SOMETHING growing taller than the grass and depriving it of sunlight, and any other useful functions are secondary. Diversity is also not a major concern at this stage; the long-term plants that grow to replace these pioneers will diversify the forest, so for now, plant whatever is most effective at suppressing the grass. The plants most suitable for the job will vary depending on the local conditions, but in general, they should have as many of these traits as possible:

Some Examples

Native Amazonian pioneer shrubs such as Senna alata and Solanum quitoense × sessiliflorum can grow like weeds in recently cleared areas where the soil has been disturbed, so broadcasting seeds after digging out the grass can be a simple way to get some shade growing quickly, even immediately around where long-term trees will be planted. The most effective shade, however, comes from the larger leguminous pioneer trees. The most suitable of these trees fix nitrogen (or rather, their bacterial buddies do), they grow rapidly, they develop a dense evergreen canopy of medium/large leaves from an early age, and they reliably sprout back after being cut or otherwise damaged. The genus Inga is an excellent option distributed through most of the Amazon (with an abundance of seeds readily available), but every region should have at least one such native tree available, so don’t discount your local weed species!

If reforesting with native trees only, Cecropia can be planted sparingly or allowed to grow on its own, but we do NOT recommend planting it in a fruit forest setting. Despite its large leaves and rapid growth, its canopy is too sparse to adequately suppress grass, and its great height makes it susceptible to falling over in a storm, usually on the fruit trees. Unfortunately, Pourouma cecropiifolia is very similar.

With the understanding that these pioneer plants are temporary, we can plant them close together for maximal shade within a target area, and we can thin them out when it comes time to plant long-term trees. They also lend themselves well to alley croppingnoun: the practice of planting rows of one or more support species between rows of fruit trees or other “production” crops for the purpose of shade, erosion control, chop-and-drop, et cetera and chop-and-dropnoun: the practice of pruning a plant repeatedly, especially coppicing or pollarding in order to provide mulch, providing both shade and an abundance of mulch. Inga edulis is among the most effective chop-and-drop species for the Amazon, and any Musa can also function as chop-and-drop when the fruits are harvested. In areas with a dry season (such as Pará), other vigorous leguminous trees such as Gliricidia sepium have the potential to replace Inga edulis if planted densely enough, though many of these may lose their leaves in the dry season, making heavy mulching of longer-term trees a life-or-death necessity, as these will have no additional protection until the rains return.

Flemingia macrophylla is a widely-adapted shrub used for chop-and-drop, and its mulch is of excellent quality, but it is too delicate when small, and even at maturity it does not cast sufficient shade over a wide enough area to do much against the grass surrounding it. Coppiceverb: to cut back (a tree or shrub) to a stump near ground level in order to control height and encourage a more bushy habit with multiple smaller stems growing from the stump or roots it for mulch only, and shade the grass by other means.

The Role of Mulch

Mulch is no substitute for shade in the long run, as it will require frequent replacement in order to continue to suppress the grass, but it is very useful for stalling the grass and keeping the soil protected until the canopy grows, feeding the trees in the process. Its importance in this regard cannot be overstated. We have a dedicated page about it.

Long-Term Canopy Cover

Unlike the fast-growing pioneers, these plants are not merely weapons of grass destruction but engineers of a forested future, destined to secure the canopy for posterity, which requires that they reach their full potential. Guard them well from all manner of creeping gymnospermic filth, and no choppy-choppy other than pruning to shape.

In many mature forests, the dense shade and aggressive surface roots of the mature trees will suffice to protect the forest from grass, their fallen leaves a self-replenishing mulch, the leguminous among them recycling nitrogen in perpetuity. This self-sustaining ecosystem is the ultimate goal of reforestation, the aspiration of every forest given suitable conditions, the pinnacle of arboreal culture, a sanctity that grass cannot defile. Some trees that form the canopy of an old-growth forest cannot even re-grow on open ground; their young seedlings MUST have the shade, mycelium, humidity, and stable temperatures of the forest in order to survive. These must be planted in areas where the demons have already been fully exorcised.

The long-term keepers of woodland peace are a diverse bunch. Even palms have their place in the canopy, but the most effective shade comes from multiple layers of leafy growth, which is the specialty of the dicotyledons. Shrubs can fill open spaces near the forest floor. For the provision of various layers of shade from above, trees reign supreme, their achievements unmatched in all of botany. These traits are especially desirable for the long-term shade-givers:

  • long-lived
  • large leaves
  • dense evergreen canopy
  • low-branching habit
  • aggressive surface roots (to resist invasion from belowground as well)
  • allelopathy

If it’s not a tree, it is immediately questionable.

Some Examples

Matisia cordata straddles the line between pioneer and long-term canopy. It grows reasonably quickly, forms a multi-tiered evergreen canopy of large leaves, has plenty of surface roots which can grow quite large, and exudes growth inhibitors to complement its own shade. It should not be planted on exposed slopes due to its mostly shallow root system, but in flat or sheltered locations, it can be an excellent option. (Do not grow it in its native Amazon primarily for the fruit, as the native insects often damage them. Harvesting undamaged fruits should be a bonus.)

Although it can be a bit slow to establish itself (and is therefore an excellent candidate for heavy mulching), Artocarpus odoratissimus is all but unstoppable once it rises above the height of the grass and its growth takes off, at which point it becomes one of the fastest long-term canopy trees. Its large leaves begin to shade the grass into oblivion at just a few years old, and it dominates the forest at maturity, its dense shade working together with its aggressive surface roots to completely suppress any graminaceous invaders. Artocarpus sericicarpus is very similar, but it takes longer to get established, and its canopy does not become sufficiently dense until it’s a bit older. Artocarpus altilis is extremely fast-growing for a non-leguminous fruit tree, with even more vigorous surface roots, but its large leaves are often too few and far between to completely shade the ground below.

To reforest a pasturised landscape where some native trees remain but cast insufficient shade, or to fruiterrarise an open woodland ravaged by loggers, low-branching trees such as Sandoricum koetjape or Dacryodes edulis can fill in the lower canopy. The former grows taller (but withstands strong wind) and requires more sunlight, while the latter can grow beneath an established canopy and in poor soils. Both provide dense evergreen foliage comprised of fairly large compound leaves, and both tolerate periods of drought and monsoonal rains. For those patiently tending a fruit forest, a more delicate option is the “duku” race of Lansium domesticum, which requires a sheltered and humid location in the equatorial lowlands and ideally some shade for the first few years. It matures very slowly and does not tolerate drought nor flood nor wind nor cold, and its shallow root system benefits from very heavy mulching, but it can grow in leached soils with a high water table. It rewards the patient fruiterrarist with a dense and very low-branching evergreen canopy filled with racemes of large, juicy, aromatic berries.

Litsea garciae is a bit of a unique case. It cannot tolerate cold, so it is completely unsuitable for the far southern Amazon or higher elevations, and it also cannot tolerate long droughts or extreme winds, precluding its use at the exposed edges of the eastern Amazon. In the sheltered and rainy lowlands, however, its dense and fairly low-branching canopy of very large leaves and its extremely aggressive surface roots make it a fortress of dicotyledonous supremacy. In the typical ultisol and oxisol clays of the Amazon basin, it grows at an unremarkable rate but eventually finds its place among the layers of the forest, quashing any uprisings below, so long as the soil is sufficiently fertile to maintain a full canopy of leaves (and the leaf-cutter ants don’t get to it). In loose alluvial soils with constant access to the water table, it becomes a ferocious and all-consuming monster of a tree, growing rapidly to its full size, its dense network of lateral roots sucking up all available topsoil and mulch while strangling (perhaps even poisoning) all vegetation around it… and then it dies, the ultimate kamikaze grass killer. Keep out of reach of children. (Your results may vary.)

In Closing

The shade of a forest canopy is not just a visual spectacle; it’s a self-sustaining lifeline for the delicate balance of nature. From suppressing undergrowth to facilitating transpiration and regulating temperatures and humidity, the canopy plays a multifaceted role in supporting biodiversity and ecological resilience.

As we continue to appreciate the wonders of nature, let us strive to conserve and recreate these beneficial forest canopies for generations to come by preserving the forests we still have and reforesting areas that have been destroyed by humans for other uses.