yellowstone national park founded in 1872 it's considered to be the first national park in the world there's really important lessons from yellowstone the great lessons as the first national park this is the place that saved some of the great mammals but this vast carefully managed ecosystem can't protect itself from forces the outside global forces of environmental change that are happening so quickly that their impact is being felt here by both plants and animals sean carroll is visiting yellowstone with liz hadley who has been studying the biodiversity of yellowstone for 30 years they are here to trace the threads that connect the plants and animals living in this park their first stop is a grove of white bark pine trees this is what a healthy tree looks like this bark you know first of all you can see this is kind of what's given it white bark its name this is what a healthy tree should look like so the stand that we're in is is really in good shape this particular tree has had a hungry visitor so these are bear claw marks well what's it doing here why is it approaching this tree well it's because white bark pine produced very high nutrient seeds the bears will come here right before they go into hibernation and this is when they really pack on a lot of fat in order to overwinter the nutrients from those seeds is directly correlated with over winter survival of bears but grizzly bears cannot reach most of the pine cones because they're too high up on the trees so they rely on a smaller animal for their snack red squirrels easily get up to the pine cones to eat the seeds storing the excess in ground burrows or middens further down the path they find evidence that a hungry grizzly bear dug up one of the hiding places all around us are mittens from squirrels and this is what the bears go after and indeed here is a pile of bear scat and in the scat are seeds from white bark pine so this is most all seed 100 seeds from white bark pine yeah and found what he was looking for he dug up the midden and there they are these three organisms the tree the squirrel the bear represent a healthy food web but a tiny creature is threatening the survival of all three organisms okay sean this tree it's been hit by the mountain pine beetle what happens with these what you see the evidence are these little holes what happens when you see this kind of response on the part of the tree is that the beetles want this tree is dead how old do you think this tree is this tree probably 700 years or so 700 years how long does it take the beetles once they attack to kill a tree like so once they attack this is a big attack it's a day or two a day or two a day or two after 700 years after 700 years the beetle has always existed in yellowstone it's not a foreign species what has changed is where and for how long it survives the warming climate in in this high elevation region as allowing beetles to move into these what were previously high elevation cold regions and now their high elevation it still gets cold but it's not cold enough to kill the beetle so they're surviving longer and killing whitebark pines so the warmer yellowstones create an opportunity for the beetles but to the detriment of the whitebark pine absolutely the changing climate is also affecting life lower down the mountain there's a pond right here this is a pond that sometimes holds water earlier in the year you can see it's drying out it's almost dry now look over here look at the dust over there where the bison are moving around that pond no longer stores water at all you can see that's dry ponds are less permanent there are fewer ponds that retain water and there are more ponds that never get water at all and why is that so it's we've been getting less rainfall and temperatures have gotten warmer even just over the last couple of decades what effects do the drying ponds have on the wildlife so the big effect that we've noticed is on the amphibians so we've monitored amphibians for the last 20 years and what we see is that there are fewer ponds that have amphibians so there are fewer populations of amphibians there's been a decline in the species diversity within the ponds that have amphibians to begin with and there are fewer populations for each species in in the area they visit a pond where aquatic life used to be teeming okay sean so this is perfect amphibian habitat you see the cover around the margins of the pond you see you know cover for birds and for salamanders and frogs but i don't hear the frogs no you used to hear the frogs i don't hear the frogs either so there's a really incredible parallel between what's going on with the amphibians and what's going on with the white bark pine like the white bark pine forests high in the mountains habitats for amphibians here in the valleys are being degraded by climate change yellowstone shows us that it's possible to protect animals even those that have been pushed virtually to the brink of extinction we don't want lions and bears and tigers to go the way of the dinosaur be gone forever just something that we'd see in the museum and have no idea what they looked like what they lived like yellowstone is a special place it's a success story in many ways but it's not immune to global threats climate change invasive species population growth all of these can chip away at the diversity here our work is not done you