Question

Why do deserts and arctic tundra support a much smaller biomass of animals than do tropical forests? Why do most animals in a tropical rain forest live in its trees?

Short answer

Limited resources in deserts/tundra lead to less biomass; tropical forests support more due to abundant resources. Most animals live in trees for safety and food.

Step-by-step solution

Understanding Biomass Distribution

Deserts and arctic tundra are known for their extreme climates—hot and dry in deserts, and cold in tundra—with limited water resources and poor soil quality. These conditions result in limited plant growth and diversity, leading to less food availability for herbivores and consequently fewer predators.

Tropical Forest Climate Support

Tropical forests maintain a warm climate and abundant rainfall, creating a rich environment supportive of dense vegetation. This abundance of plant life provides extensive food resources, allowing for a larger biomass of animals.

Resource Availability in Tropical Forests

The rich diversity of plant species in tropical forests provides numerous niches and resources, which supports a greater variety of animals. This contrasts with the limited niches available in deserts and tundra due to harsher conditions.

Adaptations of Arboreal Lifestyle

In tropical rainforests, the dense canopy of trees offers protection from predators and easier access to food resources, such as fruits and leaves. Most animals, such as monkeys and birds, have adapted to life in the trees to take advantage of these resources and space, avoiding the dense and competitive forest floor.

Key concepts

Tropical Rainforest Adaptations

Tropical rainforests are teeming with life, immensely supported by their unique environment. These areas are known for constant warmth and high levels of rainfall, creating one of the most biologically rich environments on Earth.
The variety and density of plant life result in a complex ecosystem of overlapping niches. In response to this abundance, many animals in tropical rainforests have developed adaptations that allow them to thrive in the trees, forming an arboreal lifestyle. For example, the dense canopy structure provides both food and protection from predators. Monkeys and birds are particularly adept with their grasping limbs and strong tails, which help them navigate and thrive in these towering ecosystems. These adaptations are crucial as the forest floor is often fiercely competitive with limited resources, pushing life upwards into the trees.

Desert and Tundra Climates

Deserts and tundras are known for their harsh environmental conditions, yet they host life forms uniquely adapted to survive in these extremes. In desert climates, the intense heat and scarcity of water make it difficult for life to exist. Water conservation is a key survival strategy here, with plants like cacti storing water within their tissues, and animals such as camels having specialized systems to retain moisture.
In contrast, tundra environments are cold with a short growing season, supporting vegetation such as mosses and small shrubs that are well-suited to withstand frost and minimal sunlight. Both ecosystems have limited resources, resulting in a much smaller biomass compared to tropical rainforests. The poor soil quality and temperature extremes restrict plant growth, which in turn limits the food supply for herbivores and the predators that depend on them.

Plant and Animal Diversity

The diversity of plants and animals varies greatly between ecosystems due to differences in climate, resources, and habitat structure. Tropical rainforests boast high biodiversity due to favorable climates and an abundance of resources. This environment supports numerous plant species, creating various niches for a wide range of animal species.
However, in deserts and tundras, the extreme climates and limited resources result in less diversity. Here, only species that have specific adaptations can survive. For instance, desert animals often have nocturnal behaviors to escape the heat, while tundra species develop insulating features like thick fur to tolerate the cold. The variance in diversity across these ecosystems highlights the importance of adaptations. Each species' characteristics enable it to exploit available resources, permitting survival in its respective environment.