Blurs

Trees are usually associated with moderate climates: sufficient rainfall, tolerable temperatures, fertile soil and a reasonably long growing season. Yet trees grow in places that seem to violate almost every rule. Some survive where winter temperatures plunge far below freezing. Others cling to mountainsides where the growing season is measured in weeks. Some endure intense drought, salt spray, volcanic soils or repeated fire. There are forests close to the Arctic Circle, trees growing on isolated volcanic islands and individual trees that have survived for thousands of years. They aren't anomalies in the sense of being impossible. They are examples of just how far evolution can push a plant's ability to survive. What Makes a Place Too Harsh for a Tree? Trees have several fundamental requirements. They need water, but too much water can be just as problematic as too little. They need carbon dioxide and sunlight for photosynthesis. They require nutrients and a stable enough grow...

Across the hills of central Laos sit thousands of enormous stone jars. They were deliberately carved and transported by people whose culture remains only partly understood.  They are associated with ancient funerary practices, yet their precise purpose and the society that created them still contain unanswered questions. But something rather unexpected has happened to these ancient monuments. For roughly two thousand years, some of the jars have been collecting rainwater. Leaves have fallen into them. Organic matter has decomposed. Algae and microorganisms have colonised them. Nutrients have accumulated. Oxygen levels have changed. In effect, the ancient jars have become miniature ecosystems. And scientists now think they can be used as something even more unusual: a set of natural experiments that have been running for around 2,000 years. A monument hiding an experiment The Plain of Jars is one of Southeast Asia's great archaeological mysteries. Thousands of large stone vessels ar...

Look at a satellite image of Earth today and it is tempting to think we understand its major landscapes. Forests occupy certain regions. Deserts occupy others. Grasslands stretch across broad areas. Ice dominates the poles. But today's Earth is only a snapshot. The planet has been through countless versions of itself. There have been periods when enormous areas that are now deserts were covered in vegetation. Forests have existed near the poles. Sea levels have risen and fallen dramatically. Glaciers have advanced across continents. Warm climates have extended much farther towards the poles. And ecosystems have appeared, expanded, fragmented and disappeared. Some of these vanished worlds were enormous. Some may have covered areas comparable to modern continents. Their plants, animals and ecological relationships were eventually transformed or destroyed. Yet the question remains: How much of Earth's ancient forest history has effectively disappeared? And could some of the ecosys...