Imagine a soccer-field-sized area of forest in chilly Alaska. It has around 40 different plant species. Now, compare that to about 70 species in the milder climate of England and a whopping 300 in the lush Amazon rainforest. This pattern of biodiversity isn’t just limited to small patches of land; it extends to entire countries. For instance, England boasts 1,500 plant species, while tropical Guyana has even more. The incredible diversity found in tropical rainforests is rivaled by another unique ecosystem: the scrubby, fire-prone shrublands of western Australia and southern Africa. Although these shrublands might not seem as grand as rainforests, they are home to an equally impressive variety of species.
Both tropical rainforests and shrublands owe their rich biodiversity partly to their nutrient-poor soils, which are low in essential nutrients like nitrogen and phosphorus. These nutrients are crucial for plant growth. Interestingly, the world’s top biodiversity hotspots are found in areas with nutrient-poor soils. It might seem logical to assume that richer soils would support more species, but in nature, as in human society, having abundant resources doesn’t always mean everyone benefits equally.
In ecosystems like meadows, forests, and wetlands, we often see larger plants but fewer species where soil nutrients are abundant. Fast-growing species quickly absorb most of the extra nutrients, allowing them to grow rapidly. This growth advantage helps them access more water and sunlight, leaving slower-growing species with fewer resources, which may lead to their decline. On the other hand, poor soils don’t provide enough nutrients for fast-growing plants to dominate, allowing a wider variety of species to coexist.
This pattern is also evident in human societies. In poorer countries, there tends to be a greater number of small businesses, while wealthier nations often have fewer but larger companies. However, poor soil isn’t the only factor contributing to high diversity. Environments frequently affected by harsh weather or catastrophic events often have poor soils and fewer plant species.
Time is another crucial factor for high diversity. Glaciers regularly reshape ecosystems and create new soil, but our high-diversity rainforests and shrublands have remained undisturbed for millions of years. This stability has allowed their inhabitants to evolve a wide range of strategies for surviving in nutrient-poor conditions. As a result, we see tall, diverse rainforests thriving in wet, nutrient-poor soils and scrubby, diverse shrublands flourishing in dry, nutrient-poor soils.
The human landscape follows a similar pattern. The highest cultural and linguistic diversity, along with the greatest number of businesses, is found in regions with stable climates where humans have lived the longest and where economic resources are limited. In this sense, some of the poorest places on Earth can also be considered the richest in terms of diversity.
This exploration of biodiversity is supported by the Kwongan Foundation at the University of Western Australia, which is dedicated to conserving Australia’s remarkable biodiversity. To learn more about the ecology of the hyper-diverse Kwongan ecosystem, you can explore “Plant Life on the Sandplains in Southwest Australia” or visit the Kwongan Foundation online. A special thanks to the Kwongan Foundation for making this educational content possible.
Explore an interactive map that highlights global biodiversity hotspots. Analyze the correlation between soil nutrient levels and species diversity in different regions. Discuss your findings with peers and consider how these patterns relate to the concepts discussed in the article.
Research a specific ecosystem, such as the Amazon rainforest or the shrublands of western Australia. Prepare a presentation that explains how nutrient-poor soils contribute to biodiversity in your chosen ecosystem. Highlight any unique species and their adaptations to the environment.
Participate in a debate about the impact of resource distribution on biodiversity. Argue whether nutrient-rich or nutrient-poor environments are more beneficial for sustaining diverse ecosystems. Use examples from the article to support your position.
Design a hypothetical field experiment to test the effects of soil nutrient levels on plant diversity. Outline your methodology, including how you would measure biodiversity and control variables. Share your experimental design with classmates for feedback.
Investigate a region with high cultural and linguistic diversity. Compare its environmental and economic conditions to those described in the article. Write a short essay discussing the parallels between ecological and human diversity in this context.
A soccer-field-sized patch of forest in frigid Alaska has about 40 different species of plants, compared with about 70 in temperate England and 300 in the Amazon rainforest. These biodiversity differences hold true for entire countries as well: England has 1,500 plant species, while tropical Guyana has even more. The super-diversity of tropical rainforests is only matched by another type of ecosystem on Earth: scrubby, fire-prone shrublands found in western Australia and southern Africa. While these shrublands may not appear as majestic as tropical rainforests, they host similarly impressive numbers of species.
However, both ecosystems owe their enormous diversity, in part, to their soils, which have critically low supplies of nitrogen and especially phosphorus—nutrients essential for plant growth. The leading biodiversity hotspots in the plant world are, quite literally, nutrient-poor. Logically, it seems that richer soils should support more species, but in nature, as in human society, having plenty of resources doesn’t necessarily mean that everyone benefits equally.
In meadows, forests, and wetlands around the world, we often find larger plants but fewer species where soil nutrients are highest. Fast-spreading species absorb most of the extra nutrients, allowing them to grow rapidly, which in turn enables their roots to access more water and their leaves to capture more sunlight. As a result, slower species receive less of these resources and may die out. Conversely, poor soils do not provide enough nutrients for fast-growing plants to thrive, allowing a greater variety of species to coexist.
This pattern can also be observed in human society, where there tends to be a greater number of small businesses in poorer countries, while fewer larger companies dominate in wealthier nations. However, poor soil isn’t the only factor contributing to high diversity; environments frequently affected by harsh weather or catastrophic events often have poor soils and fewer plant species.
Another major factor for high diversity is time. Glaciers regularly reshape ecosystems and create new soil, but our high-diversity rainforests and shrublands have remained undisturbed for millions of years, allowing their inhabitants to evolve a wide variety of strategies for surviving in nutrient-poor conditions. This has led to the development of tall, diverse rainforests in wet, nutrient-poor soils and scrubby, diverse shrublands in dry, nutrient-poor soils.
The human landscape appears to follow a similar pattern, with the highest cultural and linguistic diversity, as well as the greatest number of businesses, found in climatically stable regions where humans have lived the longest and where economic resources are limited. Thus, in some ways, the poorest places on Earth can also be considered the richest.
This episode of MinuteEarth is supported by the Kwongan Foundation at the University of Western Australia, which promotes the conservation of Australia’s remarkable biodiversity. To learn more about the ecology of the hyper-diverse Kwongan ecosystem, check out “Plant Life on the Sandplains in Southwest Australia” or visit the Kwongan Foundation online. Thank you to the Kwongan Foundation for making this MinuteEarth video possible.
Biodiversity – The variety and variability of life forms within a given ecosystem, biome, or the entire Earth, often used as a measure of the health of biological systems. – The Amazon rainforest is renowned for its high biodiversity, hosting millions of different species of plants and animals.
Ecosystems – Communities of living organisms in conjunction with the nonliving components of their environment, interacting as a system. – Coral reefs are complex ecosystems that support a wide range of marine life.
Nutrients – Substances that provide nourishment essential for the growth and maintenance of life. – Nutrients from decomposed organic matter enrich the soil, promoting plant growth in forest ecosystems.
Species – A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. – The introduction of invasive species can disrupt local ecosystems and threaten native biodiversity.
Soils – The upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles. – Healthy soils are crucial for sustainable agriculture and maintaining ecosystem services.
Conservation – The protection, preservation, management, or restoration of natural environments and the ecological communities that inhabit them. – Conservation efforts are essential to protect endangered species and their habitats from further decline.
Rainforests – Dense forests rich in biodiversity, found typically in tropical areas with consistently heavy rainfall. – Rainforests play a critical role in regulating the Earth’s climate and are home to a vast array of species.
Shrublands – Vegetation dominated by shrubs, often found in regions with a Mediterranean climate. – Shrublands provide important habitats for wildlife and are adapted to withstand periodic fires.
Evolution – The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth. – The theory of evolution explains the adaptation of species to their environments over time.
Diversity – The state of being diverse; variety, especially in the context of biological systems where it refers to the range of different species and genetic variability within a population. – Genetic diversity within a species is crucial for its ability to adapt to changing environmental conditions.
