The World’s jungles are some of the most spectacular and most hostile environments in the world. They contain vast areas of dense woodland and undergrowth often in intense heat and humidity as well as a vast array of stinging biting and poisonous fauna and flora.
The term jungle describes an area of dense undergrowth and woodland in a tropical area throughout the World. Jungles exist in areas of high humidity and temperature (I have experienced 100% humidity and 115 degrees while in the jungle of the Yucatan Peninsular in Mexico) where the natural vegetation is generally forest. Seasonal variations in temperature and foliage are minimal but some areas have distinct dry and wet seasons with daily rainfall in a wet season being extreme and bringing extra hazards.
Jungle is mostly located in South East Asia and large parts of Central and South America with large areas in Equatorial Africa and Northern Australia. Similar conditions also exist in some Caribbean and Pacific Islands but this is not technically jungle. Dense jungle covers undeveloped river basins and mountain areas and may contain areas of swamp such as mangrove and mountainous areas which can reach over 3,000 meters above sea level. Central Sri Lanka contains examples of such mountainous jungles although much now is tea plantation, these high altitude jungles are still very wet but can have a more temperate climate and even come close to freezing at high altitude at night.
Navigation and movement
Jungles are often very wet with many rivers which can be fast flowing and contain harmful parasites or dangerous Fauna such as crocodiles, snakes and poisonous fish. Bridges are rare and prone to being washed away in flash floods. Heavy rain can produce rapid bank erosion and white water rapids or heavy vegetation can block and slow rivers producing swamps. Most native peoples make use of shallow draft watercraft and use the rivers as the natural highways. When in search of rescue or aid remaining close to a clearly navigable river can be a wise course of action, especially as most settlements will be near such waterways.
Movement overland can be very tiring, dense undergrowth can be near impossible to cut a path through and very exhausting. Many sharp leaved plants can cut clothing or unprotected hands and the slightest cut can quickly become infected in such humid conditions. Navigation is particularly difficult as a clear view of your surrounding is often impossible, normal techniques of compass navigation such as using handrails or taking bearing off terrain features are useless as the dense undergrowth prevents line of sight. Compass navigation is still of use if carried out in a very disciplined way, as it requires the use of pacing and the leap frog technique to keep on a bearing and accurately judge distance travelled. Modern technology can help with the use of a GPS (Global positioning system) also know as satellite navigation. Although such systems can help provide accurate navigation in a jungle environment they are not with some major drawbacks. Firstly deep jungle valleys and dense canopy can actually block the system from getting a signal from enough satellites to pin point your position, this can lead to the system not functioning at all or a loss of accuracy. Secondly most systems rely on batteries, which have a limited life span, which is further reduced in the hot, humid conditions. Trying to obtain the correct batteries from a jungle village would most likely provide the locals with a source of amusement and you with a great deal of frustration. Finally like any piece of modern electrical equipment the jungle is not a friendly environment, heat and humidity can rapidly reduce the working life of any piece of electronic equipment and keeping items dry during a tropical storm or a river crossing can be very challenging.
The high temperature and heavy rainfall results in an almost continual growth of native vegetation. Changes in vegetation type tend to be gradual. Primary Jungle is an area of tall evergreen trees normally in lowland areas with a rainfall above 200cm per year. The high humidity and heavy rainfall causes trees to rot from the inside and some trees may fall without warning. The trees in this type of jungle normally grow up to 60 meters high with branches not appearing below 25 meters on most large trees. Overall light level is about the same as twilight and movement on foot is fairly easy as the dense canopy prevents thick ground level foliage. One problem for rescue is the almost total cover from being seen from the air and any smoke from single fires will be well dispersed by the time it penetrates the high canopy. Secondary Jungle is the result of an area being cleared by fire or logging and then left. Exposure to sunlight results in rapid growth, which can grow 2 –3 meters a year. Heavy ground foliage often including bamboo makes travel arduous and visibility only around 20 meters, some areas will be impenetrable and progress loud and tiring.
Native peoples are well versed in finding food from their jungle environment but for the inexperienced there are many poisonous or harmful plants. Vines and creepers should never be grasped and pulled by the naked hand as many have sharp thorns, or can spilt into extremely sharp fibres, which can cause deep lacerations. Bamboo can split to form sharp stakes when mature and any minor cut can be very serious due to the high risk of infection. Many people will have seen the classic film or TV scene where the hero cuts a vine and then drinks from it, despite this being a common scene it is not a good source of drinking water, if such water is red, yellow or milky in colour it is not safe to drink. Large sections of bamboo can also contain safe drinking water, to test for it tap the section of stem with blade or hard object and listen for a change in tone or sloshing sound, such water is safe to drink. On the other hand many jungle plants are very well adapted to such a damp environment and finding suitable leaves to make a waterproof shelter is often an easy task. Many plant saps contain irritants or toxins, which can be absorbed through the skin, so skin contact with plant sap should be avoided. Fungus is a major source of infections as in the high humidity the human body can become the perfect growing environment for a variety of unpleasant fungal parasites. Care to keep the feet dry using the correct powder is very important if at all possible as fungal foot infections in the jungle can quickly slow a person and turn a healthy one into a casualty.
The image is often of a jungle alive with large and dangerous predators such as big cats, crocodiles and piranha fish. In reality jungles do indeed team with life but the greatest threat comes not from large animals but from invertebrates and smaller poisonous reptiles. Large predators such as Jaguar, Anaconda and crocodiles will rarely attack adult humans although they are to be respected and can be a real risk. Much more dangerous are the vast array of stinging and biting insects which can cause sickness or be carriers for disease such as malaria and yellow fever If scratched mosquito bites can quickly become infected in such conditions draining morale and strength from the person involved. Scorpions, poisonous spiders and even poisonous frogs inhabit some jungles so checking your foot ware for visitors before putting your feet into them in the morning is vital. In some areas soldier ants can be a problems so sleeping should be done in hammocks above the ground, this also offers some protection against snakes and other nocturnal visitors. Larger predators and scavengers can be attracted by waste food and bodily waste so camp hygiene is important. If your party is strong and well armed certain large jungle animals can provide large amounts of fresh meat but such creatures are not easy to hunt and kill, wild boar and pigs are powerful animals and most snakes are edible, an Anaconda can feed a small village but the capture and killing of one is not an easy task. Due to the variety of parasites and climate conditions the consumption of animals that you may find already dead is to be strongly avoided.
Environmental HazardsAs already mentioned jungles are extremely hot and humid places and such conditions can place an enormous strain on the body. Despite the humidity dehydration can be a real problem and although water can be plentiful, clean water may not be. The jungle has a reputation for quickly destroying the fitness levels of the inexperienced, through dehydration, malnutrition, disease and fatigue. River crossings can be extremely hazardous as mentioned above and the simple precaution of wearing a condom (for the male members of the party) can prevent some very nasty parasites entering the body. Psychologically the jungles constant wall of green and low light levels beneath the canopy can seriously affect motivation and the sounds of the nocturnal animals can also be disturbing for those unused to them. All this said many native peoples around the world have learned to adapt and even thrive in such conditions; the jungle is neutral as the title of one famous book states, meaning that it is not your enemy unless you make it so by battling against it. The world’s jungles, of which I have had the privilege to briefly visit a few, are amazing places but any explorer or survivor needs to be fully prepared, physically, psychologically and equipment wise to do well in what is without doubt one of the worlds most hostile environments.