The Science of Leave No Trace
Diving deep into the scientific basis of why practicing Leave No Trace is so important.
If you’re an outdoors(wo)man, you’ve likely heard of Leave No Trace (LNT). If you’re regularly going to enjoy the outdoors, you HAVE to know LNT through and through. There’s so many great resources out there to help you learn about LNT. My hope here is to provide a new level of perspective with my expertise. I have a bachelor’s degree in biology and have worked on many ecological research projects. I don’t know it all but I want to impart some of my knowledge to show you why LNT is so important. I’m going to dive into the science of LNT but for those who haven’t heard of LNT yet, here’s the basics:
Pack out what you pack in. This especially applies for garbage! If you eat a granola bar on the trail, make sure the wrapper leaves in your bag. This could even apply to forgetting stuff. Obviously you don’t try to do that but make sure to scan the area one extra time before you leave.
Leave the spot better than you found it. I personally hike with a plastic bag from a grocery store so I can grab garbage I find on the trail. Sure, the other person should’ve done it, but I’d rather clean up after someone else than allow the ecosystem to be damaged.
Only stick to well established trails. This one is HUGE. You know when you see the small trails that have formed because of a bunch of people walking where they’re not supposed to? Don’t take them! Even more so, don’t create new paths. Your photo of a cool spot isn’t worth the damage you could cause, which can take nature years to undo.
Do your research before you go. Make sure you’re familiar with the area and anything that may change your adventure. Maybe they have an area that looks well trodden but they’re currently trying to bring it back to its former, natural state. Maybe there’s a bird nesting in the area during that season so you should be quiet. The list goes on and on. Being prepared will help the ecosystem and also help you have a safer trip.
Don’t tag the specific location on social media. Ya know Horseshoe Bend? It was a previously undiscovered location a few locals knew about. After some tagging on social media, massive groups of people started to visit. Now it is experiencing ecological damage because of the disrespect of the area. It’s easy to find cool stuff and if you have to work for it, you’ll likely treat it better. So make people hunt for the views and share with those you know will be good stewards.
If you want to learn more about LNT, check out this resource. It’s created by Adventure Instead and it's one of my favorites!
Now I want to dive into my speciality: the ecology of all this. The steps above are easy to remember and easy to implement in your adventures. So why are there still so many people blatantly ignoring them? Why do people think it’s okay to walk past a sign that says they’re damaging the environment by what they’re doing? I think many people don’t entirely understand what they’re doing when they violate those rules and signs. To them, they’re just one person and a few steps off the trail isn’t going to damage it that bad. It’s just a quick photo, they’ll only be in this beautiful place once.
The unfortunate reality is that only one person has a lot more effect than they understand and generally leads to a cascading effect. If a spot already looks like it’s been trampled by people, another group is more likely to use that same section. Eventually we get massive sections of dead ground that will take decades to grow back.
All of this is to emphasize the importance of what I’m about to get into. Leave no trace determines whether others get to enjoy those public lands, and whether they get to enjoy them intact. I firmly believe we all have rights to the public lands we enjoy which makes it extremely selfish and inconsiderate to ruin that beauty for the next group visiting. So with that, here we go!
LNT Science #1: Biomass and Number Pyramids
This first concept is nice and simple but super interesting! This is a concept I taught my high school science classes many times. To help us understand ecology, we have these pyramids that represent how many organisms are on each level based on what they eat. We have producers (plants and other organisms that make their own food) and consumers (organisms that have to eat something else to get their food, they can’t make their own). We further split consumers over what exactly they eat. There’s herbivores (only eat plants), omnivores (eats both plants and animals), and carnivores (only eats animals).
These pyramids usually have to look a certain way for an ecosystem to be stable. Think about your own diet. You don’t eat one plant and you’re good for the day. You’re a much larger organism than that plant so it takes more resources to fuel. Plants are always the base of these pyramids. Plants (and some other producers left out for simplicity) are the only organisms that can turn sunlight, water, and air into organic compounds we can eat. If it wasn’t for them, we wouldn’t have a single food source. It’s not like we sit in the sun and get anything out of it except a sun burn. For an ecosystem to be healthy, it has to have way more plants than the level above it. The herbivores (let’s say mice) have to eat multiple plants to survive. Then the next level up, whatever eats the mice needs to eat more than one mouse to live. So without a solid foundation of plants, the upper levels collapse.
I think we have a problem connecting ourselves with plants. They aren’t a cute, fuzzy animal so it doesn’t break our heart to hurt one. But with the complex interactions of ecosystems, damage to plants can create a magnifying affect through a food chain until another organism is left without enough resources to survive.
LNT Science #2: Succession
I’m going to move onto arguably my favorite ecological concept: succession. Succession is the gradual change of an ecosystem following a disturbance. A disturbance can be anything from a single footprint to a widespread forest fire. It shows the pattern of how an ecosystem recovers from damage. Even beyond that, it indicates how often that environment experiences disturbance. Certain species take over an ecosystem when it’s mature and has spent long periods of time without a disturbance. Succession applies a lot to plant life and focuses on the conditions that affect the plant life (soil, nutrients, water, sunlight access, etc.). Though this concept doesn’t impact fauna as much, the basis of an ecosystem is plants (cue our pyramid of numbers from above) so it has a significant impact on everything else.
Now there’s two parts to succession. We have primary and secondary succession. This simply describes the starting point of the ecosystem before it starts changing. Primary succession is an ecosystem that does not have soil when this process begins. Secondary succession is when the soil is still present after the disturbance. Obviously, it’s much easier for the plant life to recover when the soil is there where the process of turning rock and dead organic matter into soil is a huge process.
A common misconception with LNT is that crawling on rocks is fine. This is where primary succession is super important. There’s this hike I love in Idaho that takes you to a peak that is covered in rocks and boulders. You walk up this giant field of rocks to the overlook. If you look off the main path, you’ll notice some dark shapes on the rocks. Lichen is growing all over those rocks and starting the first step of primary succession. When this lichen eventually dies on the rock, it will create organic matter that less hardy organisms can live on. Our friend moss comes into play. When there’s enough dead lichen to create some nutrients, moss can start to grow. Moss is better at trying to break down the rock. What really move this process is when enough moss and lichen die that it’s enough for small grasses and flowers to grow in. Their roots can penetrate into the rocks and create areas water can seep in which causes rocks to break apart. Our next contender is shrubbery and bushes. The more soil that develops from the break down of rock and the more organic matter that dies, the more fertile soil there is to support larger process. This process continues for thousands of years until the top of that mountain becomes a lush forest.
Let’s take a step back from this incredible process! You’re hiking this Idaho trail and step off the trail. You step on a section of lichen and it falls off the rock into a crevice. It’s no longer contributing to this extreme process of soil creation. If the lichen isn’t there to start it, then the moss can’t show up, then the grasses, and so on. By stepping on lichen, you stop a process that is already challenging enough.
I also have good news, you’re not destroying all the future ecosystems in the world by walking on rocks. There’s lots of rocks that haven’t started this process. You just need to be aware that those blobs on the rocks are very important organisms. They’re all sorts of colors from black to bright green. They’re pretty easy to spot since they don’t fit in with the rest of the rock. It just takes a small bit of extra effort to avoid them and keep to the rocks that don’t have growth yet.
Succession Bonus Fun Facts (because I love succession too much not to include):
All lakes will eventually go through succession until they are a meadow. When plant life grows on the edges of lakes, it dies and falls to the bottom. This raises the level of sediment at the bottom of the lake. The higher the lake floor, the more likely plants can grow on that level. Fast forward hundreds of years and this process has filled the bottom of the lake with sediment and organic matter (aka soil). We now have a meadow ecosystem! It’s easy to see on small lakes so look around next time you’re on the water.
Forest fires are actually super important for ecosystems! Smokey the Bear is right that you shouldn’t start them but we shouldn’t necessarily rush to put them out. Lower level fires help burn dead matter and puts the nutrients back into the soil. Ironically, part of why forest fires are so bad nowadays is because we put out the small fires for so many years. When massive amounts of debris build up, it serves as fuel to create a very severe fire that causes severe damage. If we let the small fires burn, then it just helps recycle nutrients without significant ecosystem damage. This is why you often see control burns in fire prone areas or why some areas are consistently cleared of debris.
There’s some plants that have evolved to be dependent on disturbance. Their cones/seeds are sealed in with a wax. This wax can only be removed with the heat of fire. These trees have seen so much fire through the years that they have created a system that only grows more trees when other trees have likely been killed by a fire. These plants sound cool and exotic? Well it’s actually not. Multiple species of pine trees (along with many others) go through this process.
LNT Science #3: Erosion
I’m just going to keep on my parade about how essential plant life is to ecosystems. So we’ve already discussed how they’re the base of all food chains/webs and the critical role they play in how an ecosystem changes over time. Now let’s chat about their role with the soil. Erosion has become a much bigger problem since human have started developing land. Erosion is a natural process (cue the Grand Canyon) but it can also be triggered unnecessarily by human activity.
The massive root systems of plants actually holds all the soil together. Soil gets crumbly and spreads when there’s not anything holding it. Think about the last time you ran your fingers through dirt. You have all these small chunks of matter and a gust of wind could blow it away. If plants are growing in it, it’s trapped in place. You can see a lot of human caused erosion on roads that were cut into a mountain. We get rid of all the plant life in the spot we cut and rocks tend to fall from the face (with soil falling with it…but soil doesn’t dent your car). Next time you see a “falling rock” sign on the road, that’s likely why.
So why is increased erosion such a problem? Sure it stinks that we get crumbly cliffs on the road but what else? The main issue is water and nutrient retention in soil. Even if a plant doesn’t absorb the water or nutrient, their roots prevent all of the water from just flashing through the soil into the watershed (which we can’t readily get water from). When water flashes through the water, it takes a lot of nutrients with it. It washes away all the materials the plants need to grow. This process is called leeching. So not only did we remove plant life, we ensured that a lot of plants can’t grow there. It would take a whole lot of succession (different plants coming in through time and bigger species coming in through time) to get that environment back to normal.
LNT Science #3: Biomagnification
If you don’t know who Rachel Carson is, you should look her up. She’s an incredible scientist that saved us from ourselves when she started investigating pesticides in the 1940s. She’s my favorite scientist and will likely become a hero of yours if you love nature (take the time to learn the names of women in science y’all). She wrote the infamous book Silent Spring that raised awareness for how much of a problem DDT was. She’s an incredible writer and I highly recommend all her books.
All of a sudden, people started noticing bald eagle populations crashing. They realized it was because the shells of their eggs were thin and breaking which killed the chicks. The root of the problem was called biomagnification. We talked about how we have to eat more than one thing to have enough energy to work our bodies. If we had DDT on a plant, an herbivore would eat multiple plants and would end up with more DDT inside it than the plant had. When another organism comes along and eats that herbivore, they have the DDT of multiple plants from multiple herbivores. The higher up you go, the worse the problem gets. Bald eagles are at the top of the food chain and got the worst hit of the poison. While it was fine for their bodies, the chemical interacted with the egg shells.
We’re now seeing a very similar concept with microplastics. We know about the big litter but microplastics are much easier for organisms to ingest. Microplastics are just like what they sound: very small pieces of plastic. They easily move from organism to organism until the top predator is filled with plastic. Think about those microbeads in your face wash (spoiler, they’re microplastics). Think about the punch out from a plastic folder, just a tiny thing falling off a container you brought, and so much more. Microplastics are hard to fight because they’re the tiny litter you walk past.
This concept is far reaching. The use of certain herbicides, pesticides, other chemicals, pollution, and anything ending up in organisms’ bodies can cause this. If we lose the top predator, we see crazy food chain changes we never expected. I’m not going to get into complex food chain changes with population change (because we could be here a long while) but here’s a video that starts to explain how losing predators can significantly change an ecosystem. I made my students watch this video every year from BioInteractive and it’s one of my favorites.
I hope you all enjoyed the trip down science lane. I firmly believe that completely understanding how complex nature is helps us become better stewards of the environment. You don’t have to look around my website long before you find my statement on how my business strictly adheres to being a good steward of nature. If you don’t understand my science rants, don’t worry, you’re not alone (my poor partner). Feel free to comment your questions below! I have tons of videos to share and years of college education to pull from.