[MUSIC] One of the most noticeable changes in the landscape as you track up a mountain is the increasing prevalence of coniferous trees, such as white spruce and white bark pine. Conifers are a type of plant that reproduces from seeds in cones, and can be easily recognized by their needle like leaves. These needles allow coniferous trees to thrive in cold and dry conditions at high elevations. The compactness and small surface area of needles compared to broader leaves, help's reduce evaporative water loss. The needles also have a waxy coating called a cuticle, that helps retain moisture and provides protection from ultraviolet radiation. Plants need to retain water in mountain environments because thin soils have a poor capacity to retain moisture. However, many conifers also have extensive root systems, that increases their capacity to obtain water and nutrients from the soil. Needles are the sites where photosynthesis takes place. Photosynthesis, is the process by which plants use light energy to convert carbon dioxide and water into sugar and oxygen. These sugars are, in turn, converted into biomolecules that form plant biomass, the leaves, stems, roots, and reproductive structures. Conifers can photosynthesize at relatively high rates, even at low temperatures, compensating for the smaller surface area of needles, this makes them very well suited to cold environments. Conifers are also evergreens, meaning that they retain their leaves throughout the year. As a result, evergreens are able to photosynthesize longer into the fall after deciduous trees have already lost their leaves. And then start again earlier in the spring, as soon as temperatures rise above freezing. This allows evergreens to take full advantage of the short growing season at high elevations. The small surface area of needles also means that evergreens do not accumulate snow that might otherwise weigh down and damage the trees. The cone shape of evergreens and the flexibility of their branches allows them to shed snow as it accumulates. The wood of conifers is also adapted for cold conditions at high elevation. The tissue that forms wood in the trunks on the trees contains vessels that transport water and nutrients upwards from the roots. During winter, water freezes in the vessels and gas bubbles can form, similar to the gas bubbles that form in ice cubes. These gas bubbles can be problematic for trees because they block the transport of water. To deal with this issue, conifers have narrower transport vessels called tracheids that decreases the likelihood that gas bubbles will develop. So while most conifer species share a number of similar morphological and physiological adaptations to mountain environments. Each individual species has also evolved some very specific adaptations to these sometimes extreme conditions. For example, let's consider white bark pine and limber pine growing at the highest tree line elevations in the Rocky Mountains. Their canopies provide shade for winter snow and can prolong the timing of snow melt. Thereby regulating downstream flows. Individual trees do not reach full cone production until they are 60 to 100 years old. And even some 1,000 year old trees have been known to reproduce. For whitebark pine, fire has the star key played integral role in providing suitable regeneration habitat. Whitebark pine is more resistant to low-severity ground fires than other competing species, such as subalpine fir and Engelmann spruce. The open areas produced by these fires attract seed-dispersing species, such as Clark's nutcrackers. This active movement of whitebark pine seeds into burned areas gives them a competitive advantage over other species with wind-dispersed seeds in the mountains. Robert Sissons, is the Vegetation and Restoration Ecologist in Waterton Lakes National Park. Let's join Robert for a closer look at the ecology of whitebark pine and limber pine trees, and the conservation efforts that he leads in the Rocky Mountain National Parks. Here we are in Waterton Lakes National Park. And I'm joined by Robert Sissions, the Restoration and Vegetation Ecologist in the park. And we're surrounded by this alpine forest and two very special species in these alpine forests are whitebark pine and limber pine and what's so special about them? >> Well they're just unique species and in where they live. First whitebark pine is in the upper alpine region, which is very harsh, windy, dry area. Limber pines in the same area, but does migrate down into the montane region as well. And the whitebark pine is really considered a keystone species. It primarily regulates snow melt in its region where it's in thick canopies, it's a bigger bushier tree in that area and prevents the sunlight from melting the snow over, it delays that melt into the summertime. >> Right. So they're a really important part of the hydrological cycle, the trees, [CROSSTALK]. >> Absolutely, in their own way, yeah. >> Yeah, that was great [CROSSTALK] Now these trees are pretty old. >> Yeah. >> And some of them are really adapted, to these cold and windy conditions- >> Correct. >> But also to fire. I can see a burn behind us. >> Yes, actually. Yeah. >> And that's sort of typical of this environment and necessary for their regeneration. >> Correct, because the seedlings of whitebark pine can't stand a shaded environment- >> Okay. >> To grow up in. They need that open stand. How their seeds disperse >> Is quite a unique factor. Whitebark pine in particular, their cones don't open on their own. They don't open through fire, like we would think with some other species of pine. They require the nutcracker to come in and pry open that cone, and take that seed, and cache that seed in those openings created by fire, or avalanche, or other disturbances. >> So, the other thing about white bark pine is it's a species at risk in Alberta. >> Yes. >> What are some of the threats for these populations? >> Yeah, primarily there's three or four main threats. So, number one is the change in the fire regime over time and in this system, or our past fire management practices as to every fire, we must put it out, must put it out. So we're changing our practices on that, we're introducing fire back into the landscape. [COUGH] And that will help just in letting fire that natural process, do it's thing on the landscape. >> Right >> Secondarily is climate change. So the whole changing regime of snow-pack and snow-melt and that type of thing is having a long term impact. >> Right. >> A third issue is an introduced pathogen called the whitepine blister rust. So that's a fungus, that infects the tree through its needles into its steam and then the main trunk. >> Right, so we're standing here next to a very healthy looking limber pine in a typical krummholz growth form that you find in the alpine. What are some of the characteristics of limber pine that we should recognize? >> Yeah, first we're just asking ourselves if it's a five-needle pine. We're looking at the needles and we're counting if there's five needles at each of the fascicle and once we have that, you're looking at the pollen cones. When we see that this tree has pollen cones and the same time it has first year growth, female cones where the seeds are going to be produced. >> Right. >> So these are growing this year, they'll take a year >> Before they grow into a bigger cone at this size. And this is now the stage where we want to start protecting it from predators. If you're interested in protecting the seed. And then we come back in September, October, and collect that seed. And limber pine, as I mentioned before, this cone will open up on its own, and the seeds will just fall open. So when we cage it we have to protect the catches. >> How many seeds would that cone produce? >> Typically maybe about 40 to 60 seeds in cone. Great. So Robert, the restoration and conservation efforts that Parks Canada is involved in are really important for whitebark pine and you spent an awful lot of your effort to make sure that that's successful. >> Yeah, absolutely. And it's a project bigger than just Waterton Park, it involves all the mountain national parks, and partners in the U.S. and B.C. So what we do, is we find a stand of white bark pine or limber pine. And usually our stands have a high infection rate of the blister rust. >> Mm-hm. >> The introduced pathogen, and we look in that stand and we find that one or two individuals in there that seem to have. No rust infection at all or a very minor infection. So it's just showing a natural resistance to that rust. So when we target those trees we call them plus trees, and we monitor those trees over time. We protect those trees over time, and we collect seeds from those plus trees. And the seeds we collect. We send out to Glacier National Park in Montana, has a great partner with us as well. And they grow out those seeds into seedlings and then we take those seedlings and plant them back into the burn site that we showed before. >> Right. >> And, >> we also take some portion of those seeds and we send them out to partners of the U.S. Forest Service in Idaho, Oregon and B.C. Forest Service. They each have trials set up to understand if those trees actually have a genetic reason resistance to that. And that takes a good five or seven years to figure out. >> How long would those seedlings take to grow to mature trees? >> The mature cone bearing it takes at least 60 years, probably 80 years before the first cones are produced and then at least about 100 years before they produce cones on a regular basis. Now on each burn site we plant about a thousand trees, in order to have some, at least a portion of them survive over that 60 or 80 year period. >> Great. Well our grandkids are going to come back and look at these forests in the future. >> Yes, absolutely. >> Thanks so much for telling me about that. >> Okay, you're welcome. >> Thank you. A few high elevation conifer species, like larch or tamarack. Are not evergreens and shed their needles in the fall. This strategy may seem counter intuitive when compared to other conifer species but it's proven highly successful in mountain ecosystems. Larches develop softer, more fragile needles that are a less costly investment than the hearty needles of evergreens. They flower very early in the spring, and photosynthesize more efficiently than evergreens. Larches have a broad canopy relative to the cone-shaped evergreens, which allows them to capture more solar radiation. They also are highly efficient at extracting nutrients from their needles back into their wood tissue before dropping needles in the fall. By efficiently extracting nutrients, larches have adapted to withstand the nutrient poor soils that are characteristic of mountain environments. One additional benefit of this life history strategy that you can enjoy each year, is when large forests turn into stunning yellow and gold in September, just before the arrival of the first snowfall.
