Nomad blackboard: The Jungle vs the desert

On this blackboard, the differences between two completely opposite habitats found very close to each other in the garden are shown, along with the strategies that allow plants to thrive in them.

On the one hand, we have the desert. Deserts are located in geographical regions where solar radiation is very high. In other words, in places where the sun directly impacts the land for most of the year, without clouds to block it. Solar radiation is energy that transforms into heat, which warms the landscape. In the desert, ambient humidity is low because it almost never rains, with an average of 100 to 300 mm of rain per year (for reference, the Mediterranean averages 400 to 600 mm/year). Within an ecosystem, water acts as a thermoregulator, capable of cooling it because it can absorb heat without significantly raising its temperature. Since water is scarce in these regions, temperatures cannot decrease. The substrate is characteristically sandy and rocky, with the ability to heat up very quickly and cool down just as rapidly. At night, the heat stored in the ground during the day radiates upward, and since there are no clouds, nothing blocks this energy, resulting in very cold desert nights. Nonetheless, some plants, such as cacti, are able to survive in these conditions. The resulting vegetation community is sparse and patchy, and due to its morphology, it does not provide enough shade to cool the ecosystem. Adaptations, such as spines, highly developed superficial root systems, and water-storing mechanisms, have enabled plants to survive in this arid subtropical climate. Without these adaptations, plants would not be able to endure such harsh conditions.

To grow and maintain this type of vegetation, the garden has positioned the cacti in areas where solar radiation is very high, where temperatures are slightly higher, and where the substrate is sloped to allow water to drain away, preventing the cacti’s roots from becoming waterlogged.

On the other hand, we have the jungle. In the jungle, there is abundant daily rainfall, with an average of 2000 mm per year. This results in high environmental humidity and a significant availability of water in the ecosystem. When it rains, some of the water is intercepted by the tree canopies, while the rest reaches the soil. The vegetation in the jungle is so abundant and dense that it leaves almost no exposed soil, causing water droplets to collect on top of the leaves. However, since the leaves are very flexible, most of the water eventually drips down to the ground, with only a small portion being retained. Once the water reaches the ground, the roots absorb it and transport it to the plant. After the plant metabolizes it, the water is evaporated during photosynthesis. Temperatures are consistently stable, averaging around 20 ºC. Although the jungle receives high solar radiation and could technically be hotter, the climate has its own mechanisms for cooling. Firstly, the abundant clouds block much of the sun’s radiation. Secondly, the high humidity means there is a lot of available water to absorb the heat. These two factors together support the growth of dense and lush vegetation, which organizes itself in layers. The tallest trees provide shade for the other plants, which is essential because they wouldn’t survive under direct sunlight. However, since plants need sunlight for photosynthesis, they have evolved adaptations to ensure they get the necessary exposure, such as climbing abilities, epiphytism (the ability to grow and develop on another organism or surface), and large leaves. Without these adaptations, these plants wouldn’t thrive in the subtropical humid climate. To grow and maintain this type of vegetation, the garden has placed these plants on a pergola, a shaded area, alongside companion plants that provide additional shade. Additionally, they are watered more frequently to mimic the conditions of their natural habitat.

To conclude, and in response to the initial question, it is the different climates of these environments that dictate the climatic conditions (temperature, sunlight, rain), which in turn limit the presence of certain vegetation communities.

The vegetation in the desert is entirely different from that in the jungle, and each has its own set of adaptations that allow it to thrive in its respective climate. Therefore, the plants found in the desert are not the same as those in the jungle; each has specific needs that enable it to thrive where those requirements are met.