monumental challenges for over a century. >> i think about the people that saw this for the very first time. >> it is one of the most beloved places on earth. >> it's one of the most iconic spots on the planet. >> to the soaring granite walls of the lower valley. this is a landscape that defies enspripgs. >> now that we've seen it we are off struck with this. >> but from the moment tourists began to come to yoe semitea and fire was literally shoved over cliffs for a light show better suited for a theme park. >> as the fire burns low. >> reporter: the passing years have brought fires, rock slides, flooding, protests, crowds and traffic. >> people have been telling us for years that they want that changed. >> reporter: after 125 years this is a park at a cross roads. so tonight we'll show you how a new generation of park leaders are finding new ways to preserve this land improve your experience as a visitor and shape the park's future. >> again , we've made some mistakes but we're really trying to get it right for the next 100 years. >> reporter: the biggest challenge for facing is all of us. the millions of people who cruise through this park every year. crowd control in yoe semitea has always been a work in progress. >> we have spectacular falls. but the worst of the worst is traffic, crowding, all of those kinds of things. >> reporter: and managing those crowds have has been a challenge for decades. >> for people to spend 45 minutes to an hour and a half or bitting the park trying to find parking. >> the park starting rolling out free shuttle buses. >> exactly for the time of the shuttle buses it was much worse. >> reporter: the long-term goal here is a change of culture. getting people out of their cars and onto bikes or this growing system of board walks built to protect the valley meadows. >> not only is it going to lessen the impact on the park but it's going to provide a better experience for people. we want people to come here and find that connection to the park. >> reporter: the other challenge is parking. >> people could come and camp in owe semitea and find out almost any place they wanted and set up a tent. >> reporter: and if you want to spend a few nights on the john muir trail you'll need a wilderness permit. but this is a kind of congestion by design ensuring that the park isn't overused. . >> getting us back to managing the park and managing it as a natural system. . >> reporter: which brings us to wild life. when the number of bear incidents exploded the park shifted the responsibility to visitors handing out citations to those who don't secure their food. >> our bear incidents have gone from almost 2000 incidents to about 60. >> reporter: so crowd controlling in owe semitea is an endless balancing act. >> we don't claim to be perfect but we claim to be learning. learning from a lot of experiences. >> reporter: of course owe semitea's story doesn't begin with tourists and vacationers. the mooe walk lived here for generations and there's evidence of habitation in owe semitea up to 5,000 even 6,000 years ago and beyond. the gold rush changed everything. sight seers started to arrive and then the man who would show owe semitea to the world. >> john muir was originally from sot land. he was a botanist. -- scotland. he was a botanist. he was passionate about understanding it. he was known for his tenacity and exploring. but the owe semitea that muir explored is changing dramatically. as wilson walker shows us it's melting right before our very eyes. >> we have this walk that is a great intersection of natural landscape and human history. . >> reporter: once a year naturalist pete divine leads a small group of people. >> the group came down this valley and the people went up this valley to the high peaks to understand the source. >> up this valley forged by ice to an understanding of what shapes the land we now call owe semitea. >> we walk literally in the very footsteps of john muir, gay land clark, all these great names that came before us and in particular the paths of the glaciers. but the remains of those glaciers are tucked away in the highest points of the park and making your way across this vast must ray of rocks and bolders. but eventually you reach the ice. >> it does take work. this is not something most visitors at owe semitea will get close to. >> if you live in san francisco it's also the very start of your drinking water and it was on these very peaks where john muir drove stakes into this ice and 46 days he shattered conventional wisdom and reimagined the historical landscape. >> it was actually a living glacier flowing down the mountain. >> reporter: those pictures tell a dramatic story. >> the glacier is 5% or 10% the volume that it was when john muir was here. >> reporter: a dramatic example of a changing climate. >> the glaciers themselves don't say that people are doing this but it does tell us the climate is changing. >> reporter: changing so quickly that all of this could be gone within a generation. >> it's going to be sad when this is gone. >> reporter: ice that coded the land's history for us. at least for a little while there's ice you can still put your hands on. . >> here's a treasure from another time still persisting at the top of the mountain. >> reporter: from vanishing ice in owe semitea attic to the drought floor. the landscape is always changing. just like our understanding of how best to manage this land and as julia good rich shows us tackling that challenge is playing with fire. >> the last fire we had in this burn area was 1990. some of this has never burned. >> reporter: it took four years of planning and absolutely perfect conditions. but crews just burned more than 100 acres of the owe semitea valley floor. >> we accomplished a lot when you look at the landscape compared to the other side of the trail here. >> reporter: we sent 150 years trying to prevent any and all fires. >> since we've put the fire out for so long the fuel loading's grown. >> reporter: and fire is very much part of this land's history. >> there's strong evidence that the native americans were managing this landscape before we got here through the use of fire. >> reporter: and once we started putting fires out problems piled up like stacks of kindling. >> look at all this stacked we burned off. >> reporter: there's more fuel, more trees and less diversity. >> way too many mix confer pines in relation to the oak trees. >> reporter: more people. >> all these things come together to make it very, very challenging to put back on the ground. >> reporter: and it's not just a problem in the often crowded valley. think back to this summer's fire near toeg ga pass. >> it's more likely to run into a community than it was 50 years ago. >> reporter: so owe semitea bem one of the first national parks to actually embrace fire and hopefully with more controlled burns like this one we can prevent a truly catastrophic fire in the heart of owe semitea. >> we really don't have any other tool in your tool box to affect landscape scale change than fire and fire management. >> so what does the park's future hold? 10, 20, 50 years from now? we'll give you a look at the long-ranged plans including work underway to some of the most famous trees on earth. 4 million people could leave a lot of litter. how a military style mobilize sdaegs manages to pick it all up. and for daredevils around the world why these granite walls are still some of the best climbing areas,, for many americans there's a hidden chapter to yosemite vast history. the story has to do with the park's first rangers. len ramirez turns the page to the buffalo soldiers. . this is our story and every part of it needs to be told. [ flute playing ] . >> reporter: over 100 years ago more than 400 african soldiers. . >> here in yosemite secoya between 1891. so there were people who were instrumental to yosemite's history. >> reporter: he explains how these men grew up facing discrimination. >> for many of these african american soldiers becoming a soldier was a safe haven. >> these native people encountered these african american men and in close combat they saw that the hair on their head was just like the matted cushion between the horns of the buffalo. >> during the philippine insushgs. >> they lived here on the main post. the first time black soldiers had ever been placed permit innocently. >> in this rare film buffalo soldiers on horse back. at the same time the resign to yosemite where they built the first roads and trails and protected the park from illegal grazing, poaching, and timber theft. johnson tells their story. >> if you a colored man. >> by reenacting the history through the eyes of buffalo soldier sergeant who brought me back in time. >> most of those folks are not accustomed to seeing a colored man in a uniform where he's representing the united states army. >> reporter: the ranger can be found sharing his stories with visitors at the park. but there's a missing piece. >> over 100 years ago the sons and grandsons of slaves were among those entrusted to protect yosemite. yet today only about 1% of the park's visitors are african american. >> reporter: teri bradford of oakland noticed. >> when i looked around i see no one else. >> this entire place. >> reporter: he now plans to keep their history alive by telling others and coming back. >> i feel much more comfortable after hearing what you had to say. >> reporter: as for the buffalo soldiers the national cemetery is the final resting place for hundreds. you'll find their spirits in the rivers, the meadows, the secoyas and the majestic grant it walls. >> reporter: these days yosemite is better known for a different kind of pioneer. because for rock climbers there's really no place on earth quite like this. the weather, the easy access, and the spectacular granite walls. from john muir who in 1869 climbed cathedral peak. the first to free climb the don wall of el captain in 2015. and pushing our limits. >> they are the daredevils. . >> getting pretty rowdy. >> the thrill seekers. >> look at this. >> the true rock stars. >> they think every climber in their heart wants to spend some time in yosemite valleys. >> reporter: once in the park, the sky's the limit. >> everything's just huge. >> reporter: some defy gravity with the tips of their fingers and toes. back when yosemite became a national park 125 years ago these big walls were considered impossible to climb. but now with new equipment and a lot of skill, places like mount watkins half dome and el captain can be done in a single day. above the valley perched on a ledge i met the president of the climbing association. >> this is the mecca of big wall climbing. >> it is for me and many other people. >> reporter: he's pioneered hundreds of routes many at yosemite. yaeger showed me the ropes on how to repel down a steep rock face. my route about 60 feet up on swan slab. in good hands more than 100 climbing accidents happen a year. most of the injured stagger into the park's medical clinic. but a quarter will require the help of yosemite's elite rescue squad. >> we have argue burglary the best search and es cue team in all national parks. >> reporter: goe tea says climbers play a critical role as park stewarts by managing, protecting and defending. and thanks to climbing stewarts. the once endangered falcon has made a remarkable recovery. >> did you hear that? >> here on the west face of the leaning tower on they juany ledge. a pare can falcon lands next to mark kuden. >> this particular pea taun is the most famous pe tan in the world. in the first ever assent of the nose route. >> i'm on a facility where people can come learn about the history of climbing. >> as for stacy brown rock climbing with her new husband in yosemite she wants to see yosemite on permanent display forever. >> yosemite's a good reminder that we do need to preserve what we have. >> reporter: preserving what we have is no small task. so up next the man is in charge of the big picture. when it comes to managing yosemite for generations to come and how you can become part of the park by becoming a volunteer. even,,,,,,,,,,,,,, ,, with so much traffic here you're bound to end up with some litter and by some we literally mean tons of it. >> i don't understand littering even in the city but especially in a beautiful place like this. i don't get it, but people do it. >> reporter: whether they intend to or not the millions of people visiting yosemite leave a lot of litter. and every september for one week hundreds of volunteers pick it all up. the idea was born among the park's rock climbing. . >> well the climbing community sees a lot more litter than the community does. >> reporter: the facelift now covers the entire park. >> the roads, river beside, campgrounds, hiking trails. >> reporter: and it's all done with military precision. organizers keep close track of where the troops are dispatched. then every pound of trash that comes in is weighed. >> eight pounds. >> reporter: horded and tallied up. >> that's where we're at now. still coming in. >> reporter: and just to make sure there are enough boots on the ground they bring in the kids. >> a granola bar. >> reporter: then there are the larger hauls. >> 34 pounds. >> hopefully it was the rope that their life was depending on at the time and we're not sure how the car seat exited the car. >> reporter: that's not great news for the environmentment but it's good fuzz for being able to pick up trash like this down by the water. >> we come so much throughout the year it's only fair to give back. >> reporter: over the course of the week the numbers become staggering. >> so that was 14,000 pounds of garbage that was collected last year. >> reporter: but even more impressive all the time and effort the volunteers put in to make sure the park is clean for your next visit. >> yeah they're spending part of their vacation to pick up other people's trash. >> reporter: people have been coming to yosemite for generations and there has always been a man at the top making sure this place stays as pristine as we all want it to. jakela gooern has his snapshot of his plan of the future. >> there's basket dome behind. >> reporter: he's been coming here for decades. >> we camped here as kids. so this place was apart of me and i always dreamed of coming to yosemite as the superintendent. my job is to make sure and your job is to make sure that this place is in excellent shape for future generations. >> reporter: is spearheading nearly a dozen of what he refers to as centennial signature projects. everything from adding new camp sites to upgrading the historic owe juany hotel. even wild life is getting a helping hand or hoof. >> they've been gone for 100 years. >> reporter: but the biggest project could very well be these giant beauties. hundreds of secoyas. . >> we did a lot of things wrong. we paved up to the base of trees and now we realize because better science we can do a much better job in ensuring the long-term history. . >> yosemite at any one time can only handle so much people. you come here in wintertime when these cathedral walls are loaded with white and snow. please come. >> reporter: from a guy who knows just how important this place is and will always be. >> i'm going to be gone so we need that next generation to step up make sure they support it and protect it. >> this park is going to face changes of its own and a lot of challenges in the future. >> whether it's the values that shape how we use this land. >> for us in oolts of ways going forward is going back. . >> with a science that guides how we protect it. >> we would be naive if we said the science we're looking at today is the last word in that book. >> reporter: it's always changing just like the land itself. but our best hope for preserving yosemite is our collective wonder at this incredible special place. to learn how you can volunteer use the link on our website cbs newschannel9.com nwe'll see you next time. what's considered a time's up for a homeless tent city in another part of san francisco. the crackdown by city hall to get what's considered a public nuisance cleared out. good evening, i'm elizabeth cook. >> i'm brian hackney. the homeless crisis in san francisco can be seen all over the city. encampments are growing as police shuffled people around. the public outcry is greater than ever before and they're looking to city hall for answers. joe vazquez is at the one of the locations where the tent city was ordered out by 5:00 this afternoon. >> as a matter of fact, this is the second tent city ordered to vacate. the second deadline. like you said, 5:00, just half