But 1st tortoises and turtles a fascinating bunch giant come up a ghost tortoises can weigh up to 300. 00 kilos sadly many species of these reptiles are in decline only 3 yangtze giant soft shell turtles are thought to still exist and thats even though a lot of these creatures have a very long life spans some live more than 200 years and was from what Tom Valentine wanted to know more. How do sea turtles find their way back to their place of birth. To look ahead turtles are globetrotters following ocean currents they can travel more than 100 kilometers a day with their aerodynamic shape them paddle like feet they are in bursts able to exceed speeds of 25 kilometers an hour. They have to come up to breathe every few hours. Because they have lungs not gills and they go ashore to lay their eggs. Every few years a female sea turtle returns to the beach where she herself hatched digs a hole and deposits a clutch of around 100. 00 eggs in it. Then she leaves the nest and returns to the sea. After a few weeks the babies hatch and follow a light source such as moonlight reflected on the water to reach the ocean. That later return as adults is known as natal homing. But how do sea turtles find their way back from flowers and of kilometers away. One theory is that they navigate by sensing our planets Magnetic Field using it as a g. P. S. System of sorts. A long term study in eastern florida show that the pattern of nesting places of loch ahead sea turtles moved in tandem with subtle shifts in the earths Magnetic Field lines. But is a home beach necessarily a safe one unfortunately not gulls im crows steal the eggs right out of the nest once the baby turtles reach the sea hungry crabs and fish await them. Tourism also upsets the delicate cycle of egg laying and hatching only one in a 1000 hatchlings is likely to survive to adulthood. So why do sea turtles go back to that birth place to nest one hypothesis is that the females assume theyll find favorable conditions if they return to the beach where they themselves were hatched the logic being if it worked for me why shouldnt it work for my offspring. Everything is interconnected the ideas of visionary german researcher and explorer alexander from humboldt continue to influence us today born 250 years ago on september 4th 769 he traveled the world in search of new experiences and insights he recorded his 5 year journey in central and south america in his diary luckily he invented a waterproof ink so his writings even survived a shipwreck on the orinoco and we can still read them today. The last in our series retracing alexander from humble to footsteps takes us to one of the longest rivers in south america the orinoco. When i came to understand i was 19 years old and it was amazing to see all these forests and so then you can see the whole thing jumping on the water and i fall in love with it with all. So i decided to put my life to study the dolphins on the system of the very noble. This trembling of the air this solitude this wild expanse of the river transports the traveler into adventurous nature. This was a front on both describe the orinoco river. On his Research Expedition he spent 2 and a half months following the mighty waterway documenting its every twist and turn. For the explorers from europe the endless wilderness on land and in the water was a source of continuous wonder and unexpected dangers. Nobody back home expected home both to return alive from his or a no go expedition. Now if you want to do an expedition the scientists make. The research. And you know they have the basic wittman to do that and not the trouble of trying to rob to the continent if you knowledge about these so we we have a lot of things to learn to steal from home will then endurance the passion the real city and i think this guy is an example for us to put some goals and go behind them. Biologist for an undertow he has a Research Camp here its the base for the International Expeditions he leads across the entire river network. Covering an area of almost 1000000 square kilometers we already know called base in is one of the largest ecosystems in south america. Scientists come here to study its astonishing diversity of species both in the river itself and in the forests that line at. The base an area that is home to 250 different species of mammals and over 100 reptiles finding the animals is no easy task for the researchers many of the creatures are nocturnal and move territory several times a year. Baker cross a native daughter on grew up here. He sets up cameras in the forest fitted with motion sensors that are to study the behavior of the animals over a period of months. When it has come and i think at the end we can install these camera traps at various heights and this camera records everything that happens here up to a height of 40 or 50 centimeters or it enables us to record larger animals such as jaguars tapirs and copy barbarous well now lead the camera here for at least 3 months in. A few kilometers upstream we are a no go squeezes its way through a maze of cataracts. The outsiders rapids are an ecosystem in their own right nutritious algae grow on the rugged granite rocks a feast for the fish that pass through here. Over a 1000 different species live in the waters of the orinoco and many of them exclusive to the river. T. V. But you know if this place is dangerous you know about it if you dont know the river well you could overturn and drown in the rapids you know what you had to a young man drowned over there recently in a given i thought that that that. But a gallon oh yes that ive been fishing here for 40 years my father used to bring me here when i was a kid but i mean i wanted to teach my son but hes lost interest in fishing i mean no no no no no look at anybody. For centuries people here lived off the riches of the orinoco to this day there are still families that move from shore to shore many of them from venezuela they settle wherever there are currently the most fish to catch but the ecosystem here is out of balance increasing river traffic and dam construction have had a disruptive effect on the natural course of the are you know. We as a human we need to change your minds and take care of these places the rivers are unprotected in most countries you protect sometimes the land but the water the a few examples in latin america of government say ok lets protect the rivers and and bikini of Vehicle Systems or a livelihood of many people are the rivers we we need help to reverse for Healthy People and healthy biodiversity. Increasingly human activities are encroaching on the rivers ecosystems. This prompted for an undertow he go to buy land here a few years ago and turn it into a reserve. Plant and animal species are able to gradually recover here protected from deforestation poaching and environmental pollution. If they are long a total. Big conflict a very wealthy a with the leaves on the bottom. And if it involves. If they are a lot of time theyre underwater you know of a Shallow Water and they would be. With this note. And then still in the water looking for it to play and when the fish bites they have missed. Extensive conservation zones help to ensure that a growing number of animals returned to the riverside areas as footage from the camera traps confirms. Each of the animals has its own individual pattern enabling the researchers to come and track their behavior. One major success for the reserve is the return of the jaguar to the rain forest the big cats have been under threat due to the loss of their habitat to make way for crop and livestock farming included in my. Hand they are not the only species to are found a new home in the reserve. It was in the questions. Of the ecosystems everything. In good conditions but now not trouble because everything happening so quickly now they get a vision of the. Fast so if we dont want to lose these species and we need to do Something Like this prevent conservation and to support as well the national parks. The coffin of animal sounds on the orinoco lead to sleepless nights for on board but also to a pioneering concept the animal world peace is a constant struggle in which species numbers are constrained by mutual competition. And there are more than 2 centuries later there equilibrium has been disturbed the animals biggest enemy today is a 2 legged species. During his travels along the orinoco humboldt also confirmed that there was a link between the orinoco and amazon River Systems the real. On his journey through the rain forest he wrote you find yourself in a new world in wild and untamed nature nowadays there are few places left on this planet undisturbed by human activity. Devastating fires have been raging in the amazon rain forest for weeks such huge blazes are unusual here. The high humidity and the last vegetation usually prevent flames from spreading but in the past few years things have changed the world. Largest rain forest has become more vulnerable to drought due to Climate Change. Many of the current fires were caused by humans. Loggers use fire to clear underbrush and dried Indigenous People from their land. Farmers set blazes to gain land for their cattle and to grow crops but the soil itself isnt all that fur tile is the intact forest ecosystem that so efficiently recycles nutrients the amazon is a reservoir for 150 gigatons of Carbon Dioxide and now the fires are releasing huge amounts of c o 2 into the atmosphere. Astronaut nuka parmitano observed the forest fires in the amazon from the International Space station and photographed the thick smoke trails. These red dots give an impression of the number of fires burning on a single day their impact on the rain forest is devastating in comparison the problem in Southern Africa seems far worse. But the blazes seen here are for the most part savanna fires grasslands need the flames to renew themselves old grass burns fertilizing the soil and making way for new growth. On facebook we asked you to tell us what you think about forest fires have you ever been affected by one. K. P. Pandy from india writes fire is a good servant if its controlled but a bad master if its beyond control forest fires and Global Climate change are a vicious circle global communities need to break this cycle by promoting Renewable Energy technologies and reducing deforestation and forest degradation folio from ecuador post the fires in the amazon are nothing compared. The 1000 time bigger devastation the forest has undergone over the past 40 years the fire is the desperate cry of a jungle that has been mutilated by the interests of multimillionaires and a few government beneficiaries it has turned the eyes of the world to the rain forest before she disappears. And. Lets start a movement everyone should plant at least one tree if its chopped down will plant a new one. Thanks for your comments. There are more than 4000000000. 00 hectares of forest worldwide they cover 30 to 40 percent of the earths surface. The most densely forested countries are russia brazil canada the us and china more than half of the planets woodlands are located there but for decades forests have been disappearing at an alarming rate Climate Change pests and fire do less damage than humans who continue to flee are foreigners to create farmland. And thats even though forests can help prevent mudslides and stop soil erosion. Forests protect. Carbon dioxide around 10 tons per hectare of land and they produce oxygen for us to bring. Their home to 80 percent of all land welling animal and plant species the trees collect huge quantities of water whatever reaches the forest floor is stored there or is filtered as it seeps away. Forests can cool the air in cities by up to 8 degrees celsius acting like a huge air conditioning system but not every species of tree has the same cooling properties. In the future what types of forest will best stand. To Climate Change. This to city was woodland next to an old spruce plantation has a special function to help combat Climate Change. But will it really outperform the spruces. Researchers in austria using these devices to study the spruce and maple trees. They want to know if one of the 2 woodlands remains cool in the summer how much particulate matter the trees fell to from the air and how well they grow during the hot dry summer up to now a little data like this has been collected. These sensors measure the temperature a lot intension analyzes the data so far he has no concrete findings but he has developed a hypothesis the. Maple trees have much deeper roots and spruce trees do so in dry weather like weve had this summer the roots can tap more water from the ground and draper as the water on the surface of the layers and thereby effectively cool all surrounding air. That makes the decision was forest a better Economic System the surrounding area and communities benefit from the fresh air and cooler air. For more than 40 years ranger patent has been concerned with devising the best kind of woodland to cope with hot and dry summers. Here and of area in southern germany the bark beetle has destroyed vast swathes of spruce trees. Now paddle is restructuring the woodland he and his colleagues are planting wild fruit trees deciduous trees indigenous to the forest. We need clean water we need healthy air with low levels of particulates and we need protection against erosion. Every forest should provide that so we have to manage our woodlands well and take care of. His idea is to plant particular types of forests for particular functions the 1st is the energy forests. Fast growing populous that can be used in the local wood chip power plant for heating under lettre city. I. Stefan vic cop a would Energy Expert is examining how much biomass can be produced by poplar trees. Theyll still produce shoots from their roots or stumps after theyre felled thats why one tree can be harvested several times each sector of Poplar Forest can produce the equivalent of around 5000 liters of heating oil per year the trees also cleanse the atmosphere absorb Greenhouse Gases and help ensure clean drinking water. Point 2 meters thats a fair amount for an 11 year old tree. 50 percent of germanys energy is used to produce heat and ward is ideal for that purpose we can burn it with a very high yield support for. The scientists to researching how much wood and how much bark the popular generated and how much energy can be produced from it in the ideal. Case only the wood would be used for Power Generation the park produces more fine particulate the researchers are working on new harvesting methods leaving the bark behind in the forest along with the leads to rot and feed the soil with nutrients. Back in the climate protection forest which planted 25 years ago the researchers are still comparing the deciduous and spruce forests. And is examining whether the trees grew during the hot summer months 1st he looks at the maple tree. Or curve you see the circumference. Expanded by 15 millimeters 45 millimeters in diameter. And how well did the spruce grow. A bit more than one millimeter in diameter much. After. Until now heat was regarded as the crucial factor in determining a trees growth here in germany but more and more attention is switching to the importance of water following recent heat waves trees can grow only when they get enough water. And only then can the forest in turn help make rain as they grow trees release water vapor through the leaves. And makes sense. As a cloud seeds water vapor is the posited on the turpins creating raindrops and rain. Without the water vapor would needlessly evaporate into the atmosphere. Findings show that the city was forests cope with a lot of dry summer months better than the old spruce forests. I hope we can turn things around in time and we need to futureproof our forests so they can keep providing us with fresh and clean water. If our old one is right why are they i only need a few ok to help do you have a science question that youve always wanted answered it like were happy to help out send it to us as a video text ovoid smell if we answer it on the show post thank you a little surprise as a thank you can i just ask. You find as i do w dot com slash science or drop us a line at d w underscore site tech on facebook d w dot science. Thats all for now next time we focus on food and ask could algae provide a sustainable alternative to me. Tune in to find out more see you then. Does it make guys domain and aggressive selfcentered. Does that make them friendlier more sociable maybe even sometimes. Testosterone. Is a means a lot more complex than you would think the 1st thing. You discovered in the making of them are. Welcome to the girl max new dr chan. Good line of story. With exclusive inside. The must see concerning parts culture to ensure a. Place to be for curious minds. Do it yourself networkers. So subscribe and dont miss our. Earth. Home of species. A home worth saving and. Oh good those are big changes and most start with small steps but global ideas tell stories of creative people and innovative projects around the world. To such good news to manage solutions and reforestation. Current interactive content teaching the next generation about environmental protection. Using the channels available to inspire people to take action and most are turning to build something new for the next generation. As the environment series of global 3000. 00 on t. W. And online. Where is home. When your family is scattered across the globe. Its a good to. Turn back to the roots cattlemen of the bush family from somalia live around the world the money needed urgent assistance and. The family starts october any on d w. This is d w news coming to you live from hong kong prepares for another weekend of prodemocracy demonstrations but there could be harsh consequences for those caught up in the clashes with police we meet a young man due to go on trial the pace is a daunting jail sentence if found guilty also coming up whats broken i know how to fix it and im going to lead the fight to get it done to get us the leading democratic president ial hopeful shares the same debate stage for the 1st time clashing health care education