Transcript for:
The Importance of Native Plants in Ecosystems

growing a greener world is made possible in part by the 2019 Subaru Crosstrek built in a zero landfill planet so you can roam the earth with a lighter footprint Subaru proud sponsor of growing a greener world I'm Joel amble when I created growing a greener world I had one goal to tell stories of everyday people innovators entrepreneurs forward-thinking leaders who are all in ways both big and small dedicated to organic gardening and farming lightening our footprint conserving vital resources protecting natural habitats making a tangible difference for us all they're real they're passionate they're all around us they're the game changers who are literally growing a greener world and inspiring the rest of us to do the same [Music] growing a greener world it's more than a movement it's our mission [Music] every once in a while we encounter a concept so intuitive that we never really give any thought on how to articulate it a good example is all the wild creatures we enjoy in and around our yards and Gardens they're just there right naturally but stop and think about what would happen if you took away their food sources and the places they live well guess what those animals we take for granted as just being a part of our world suddenly won't be there tomorrow and that's exactly what's happening all across America and beyond part of the problem is urban sprawl and habitat destruction in too many areas of the country there's no place left for wildlife but in the landscapes and Gardens we ourselves create have you ever stopped to consider that all the food for all the animals on this planet starts with energy harnessed by plants so choosing the right kinds of plants in our Gardens is playing a bigger and more important role than ever and sustaining directly or indirectly all the animals with which we see our living spaces but we add to the problem when we replace too many of our native plants plants that have adapted to our surroundings over millions of years with exotic specimens and new varieties sometimes called alien plants that are chosen more for aesthetics and maintenance reasons than for the role they play in the local landscape our love affair with non-native plants that have been purposely introduced into our surroundings threatens that delicate relationship it's taking a significant toll on the animals especially insects that we depend on in our own ecosystems and that has to change when it comes to understanding the critical relationships between native plants and the creatures that depend on them Doug Ptolemy is right at the top he's an award-winning author on the subject and professor at the University of Delaware where he's also chair of the department of entomology and wildlife ecology his passion to better understand all the ways insects interact with and how those interactions determine the diversity of larger animal communities so I went to graduate school in entomology became an entomologist fascinated with insects and and part of my graduate training was to learn about plant insect interactions how plants and insects interact this is a huge field because there are a lot of plants and a lot of insects and how they interact depends on what is happening in the rest of the food web and the major theme from from all of those years of study was that most insects are host plant specialists they adapt to the chemical defenses of particular plants but all of Doug's theoretical academic research was about to really come home literally in a very concrete way but in 2000 my wife and I moved into this property here and Oxford Pennsylvania it was overrun with with non-native plants we decided we would we would restore it to its some some former state of nativeness and in the process of doing that I noticed well our local insects are not eating oriental bittersweet autumn olive and Japanese honeysuckle and Bush honeysuckle and I said well no surprise there they did not co-evolved together as we learned in graduate school now nobody was talking about non-native plants back then the term invasive species didn't exist even though they were here we weren't talking about them the terms invasive alien non-native and native plants are common today but they were rarely mentioned even just a generation ago so perhaps it's no surprise that there's still a bit of confusion and disagreement about what they actually mean some people think well if it's from North America it is native and they'll gather plants from all over North America and put them in their garden but what they really done is create a North American plant zoo a native plant by my definition is one that has evolved within the context of the local food web the food webs can be large but for example if we take blue spruce from the Rocky Mountains and plant it in Delaware it is a long way from the ecosystem within which it evolved and also the creatures that that it evolved with so organisms in Delaware have never seen a blue spruce before and even though the plant is from North America it is not from a Delaware II and ecosystem so I like to think of native plants as plants that are from within local food webs that have an evolutionary history with the the other plants and insects and organisms within that that food web Doug's not the only one working on the subject of bringing nature home thankfully there are other key influencers scattered around the world helping to promote the message of creating healthy living landscapes with a focus on indigenous plants in fact Rick dark wrote the book on it along with contributions from his friend and colleague Doug Ptolemy while these two share a zeal for creating and protecting ecologically balanced landscapes their approaches are quite different Rick's rise to horticultural prominence started with a college botany course his studies led to a 20-year career at Longwood Gardens considered one of America's most important Botanic Gardens when he left he was curator of plants with responsibility for over 11,000 plants in Long Woods collection today Rick heads his Pennsylvania based consulting firm focused on the design and management of living landscapes of diverse projects all around the world but it's back home were Rick along with his wife and Co horticulturalist Melendez or get to enjoy their own living landscape that is as biologically balanced as it is beautiful so often people say it's native if it was here before a certain time in a certain place or before certain other people arrived so they're talking about a plant and a place and a time but it doesn't really say anything about relationships we know that what really matters is not just the plant being in a place for a time but what essential relationships have evolved during its time there so it's a plant it's a place it's a time and it's long involved essential relationships and their own unique styles both Rick and Doug's award-winning books take on the topics of what we can and should do to bring more life to our own home landscapes and why that's so important your book bringing nature home first of all I have to tell you I love that title but I also think that it probably raises the question to people that may hear that and go well you know especially the suburban is going well bringing nature home I already have nature all around me I see it everywhere but they probably really don't do that yeah we have we have eliminated so much nature so fast that most people don't realize how little is left and it's deceiving you drive down the road both sides of the road or wooded you picture that going forever it doesn't it goes about 20 feet and then it's some development so we've we've particularly in the East we have devastated our natural areas to the point where if we're going to have functioning ecosystems if we're going to have biodiversity we need to start sharing the property that we've taken with ever-shrinking natural habitats outside of our control it's now more important than ever to make more room in our own home landscapes for the plants and trees that our native wildlife depend on the population in the u.s. is is growing constantly I just read this morning actually about the u.s. is gonna be the fastest growing developed nation in the world shortly we have 320 million people and if you look around you we really are pretty much everywhere either in our cities our suburbs our exurban habitats which are highly developed or our agriculture only 5% of the u.s. is considered relatively pristine so we have to pay attention to the way we landscape all of those areas so I'm encouraging people to to think about the percentage of native plants that they have in the yards the ones that are really productive and supporting life or and you don't have to count species think about the biomass if you have one huge oak in your yard you are doing a great service to your local ecosystem does that mean you can't have any any non natives no it doesn't mean that you could have a crape myrtle as a folk focal point in your yard with the beautiful blooms but when you look around your neighborhood and 80% of the plants are crape myrtles or Bradford pears or burning bushes and that's pretty much what it is when we measure it about 80% of our woody ornamentals are non-native I often say that gardens are the ultimate balancing act if you look around this garden that we're in it is mostly Eastern regional indigenous plants call them natives if you want but there are many exotics in here while it's one thing to host exotic plants in your landscape a common concern is if those exotic are alien plants become invasive there's genuine concern about the the potential detriments of an overuse of alien ornamentals and/or alien plants of any sort really the most obvious is that you you use a plant that goes beyond the garden and establish itself in a place where it takes up space that would normally been occupied by some other plant with deep connective relationships in that local ecology and that's this business of escape and it's very real 85% of our woody invasive plants are actually escapees from our garden and we continue to go on plant explorations sell them in our nurseries exacerbating the problem by invasive I mean they have now left our Gardens they're penetrating the natural areas throughout the country to the point where a third of the vegetation in our natural areas is non-native so that's one issue another issue is that the plants we put in our local landscapes have become the first trophic level those are the plants that are driving food webs and if those plants are from Asia and Asian plants are poor at driving food webs what are the consequences to other things that need to live and in our neighborhoods now in the past we thought you know humans are here Nature someplace else and we can do what we want without any consequence and in the past that largely worked because there weren't that many humans today though we're pretty much everywhere we're either agriculture or we're we're our shopping malls our suburbs our cities and if we landscape those areas with plants that are not supporting food webs we're supporting them very poorly we're going to seriously impact other other creatures in our ecosystems why does that matter because it is the diversity of life and ecosystems that runs those ecosystems as you increase the number of species and ecosystems ecosystem function goes up if you decrease it ecosystem function goes down why do we need ecosystem function because ecosystems create the ecosystem services that support humans so all this is tied together we can be selfish about it we need to preserve other species right where we live for our own good while the term ecosystem function can sound a bit intimidating think of it in terms of this simple yet important things that allow nature to function as it was intended for an entomologist like Doug it always comes back to the bugs you and I share an admiration for a special author Leo Wilson and he has a quote in your book about bugs he says they're the little things that run the world that is so truth because they are they are crucial to almost every aspect of terrestrial ecosystem function they recycle nutrients they pollinate our plants which then sequester carbon they're essential to to food webs if we were to eliminate insects from from the earth according to EO humans would last about two months so now we can do that experiment and see what happens but I'd rather not I'm with you a much less drastic experiment that Doug tried drives home just how critical it is to the entire ecosystem to have lots of native plants to attract large insect populations I definitely experiment last summer this actually is something you can do at home where I simply counted caterpillars on July 25th and July 26th on a white oak in my yard a black cherry in my yard I moved to my neighbor's yard and counted them on Bradford pears and on burning bush I counted the same amount or measured the same amount of vegetation and only look at the caterpillars at head height on the white oak I found 410 caterpillars from 19 different species on the black cherry I found 256 caterpillars from 12 different species on the Bradford pear I found one caterpillar from one species and on the burning bush I found four caterpillars from one species and they were tiny little leaf miners that are too small for for a bird to eat why were there not more caterpillars on Bradford pear or burning bush because there there are chemical defenses in those plants that our local insects have not adapted to plant in sets in China can eat calorie pair that's what Bradford pear is and and burning bush a species of euonymus because they have been exposed to those chemicals for eons but now that they're over here they've only been over here what a hundred years it's nothing in evolutionary time and our insects have not been able to adapt to those plants our insects can eat the oak and the black cherry because they have been in these ecosystems for actually millions of years and the insects have adapted to them very productive plants now in the past one of the reasons we chose Bradford pear and burning bush and all these other plants was the fact that they were pest free they had nothing eating them it was a criterion we looked for and if we're growing our plants strictly as decorations that becomes an important trait but plants are more than decorations they're they're essential components of our local ecosystems so we now have to think about how a plant looks as well as if thing about how it acts what does it do what is it function as well as what does it what does it look like most people would not object to having a beautiful oak tree in their yard an important point when I did that 410 caterpillar study I then stood back from that oak tree took a picture and there was no damage that you could see you couldn't see one of those caterpillars and unless a homeowner went up and carefully inspected the leaves never would have known there were caterpillars on there so so a plant a tree can can support a lot of life without being defoliated so again if I'm a foraging bird looking for a meal that day I would not be going to burning bush or bread prepare I'd be on that white oak and the black cherry so the plants you put in your yard have a tremendous impact on local food webs and yet we continue to fill our yards and landscapes with plants and trees that have little to do with promoting those vital relationships between them and wildlife so what are the hurdles then because we still tend to gravitate towards those alien ornamentals because we like that beauty and we like the fact that those plants are pest free but that's not really what we need we need to adopt more of a philosophy of embracing the natives now we're gonna do that right we need to educate people that this is necessary that that a typical homeowners property is an important component of the local ecosystem they they they can't opt out of ecosystem function anymore they have to participate and the way to participate is to bring those functional plants back to the landscape once that message is delivered I have found that people are very receptive and they're eager to take part in what is a huge conservation movement kind of important very important so what brings life to a landscape in a way that not only promotes more vibrant wildlife habitats but also satisfies the desires of the people living there while plants will always be at the heart of any gardener landscape Rick spends a lot of time studying this very topic he suggests that rather than beginning with a set of objects we start with a set of goals to ensure the landscapes we live in are beautifully layered biologically diverse and broadly functional and the key to that is a focus on building layers with a simple logical process it begins with simply looking around your landscaping taking inventory look at your landscape do you have a canopy what does the ground layer look like is it mulch or is it a richly organic accumulation in which all kinds of things live do you have an understory do you have a shrub layer we are so often taught to approach gardens in terms of what plants you have not what layers do you have that we take an object-oriented approach to the landscape instead of a relationship oriented approach and getting back to layers means you will be thinking about relationships it's important to bring layers back into the garden because there's so many things that depend upon special the special nature of different layers they are layer specialists there are animals and plants that really only live in the ground layer there are others that really live in the mid story there are others that are only canopy dwellers if you don't have these different things you just simply cut out the opportunity for a lot of these these things to live leave it to Rick's colleague Doug and his insatiable quest for understanding ecosystem function to identify a key missing link in the modern landscape when Doug was starting to look at relationships and where they exist and he was looking at how many relationships were disappearing from a lot of our common ground you go out and what you thought was the wild or nature and in fact the layers were gone and there was not that much living there and so he's thinking where can we would we find a new place for that to happen and if you look at the extent of the suburbs and you just said okay if each person who has their suburban plot if they think of themselves as living in a little bit of this new nature they can reprise the layers they can bring that richness back and it really can be a new definition of nature so really the suburbs and our collective gardens become the new nature so as you design or modify your landscape to be a part of the new nature think in terms of how you're building it in layers working from the top down the tallest layer is always the canopy while you don't often notice them from their show eNOS and flower the autumn color of deciduous canopy trees is unsurpassed moreover it's their sheer mass of wood in volume that provides sustenance hunting and resting perches and nesting cavities for an abundance of birds mammals insects and other invertebrates beneath the canopy resides a multitude of smaller trees referred to as the understory tree layer while this layer offers so many choices in size shape color flower and form the aesthetic value to us is vast as are the benefits to a lot of wildlife understory trees offer ideal density height food sources through flower fruit and seeds and branching structure for shelter and nesting these features and more make understory trees the only good option for many species where canopy trees are too high heading back down closer to earth the shrub layer occupies space beneath the understory trees while offering many of the same benefits height density and food sources make these critical plants for attracting a diverse range of insects and other wildlife in addition it's perhaps the most versatile layer for design functionality in the landscape the herbaceous layer is the lowest of the above ground layers it also has the greatest botanical diversity of all above ground layers simply because there are more species of these than of all woody plants and a more diverse layer offers more shelter and cover for wildlife an important added benefit is an overlapping sequence of blooms through the seasons leading to a succession of ripening fruits and seeds a staple food source for countless creatures finally we have the ground layer for most residential landscapes the ground layer of choices mowed turf while it serves a purpose in the landscape it's function and ecological biodiversity is slim in fact motor offers little to the cover shelter and sustenance necessary to sustain wildlife and lastly no yard or garden is too small to play a role in the bigger picture many people are concerned that the piece of property they own is actually too small to make a difference say only on the third of an acre and I can do what I whatever I do and it's not going to help biodiversity you know it's true the bigger the property the the more effective it will be but your your third of an acre is connected to your neighbors and that's all the sudden two-thirds of an acre which is connected to another neighbor and even if you are a little island you're important in a number of respects many of these organisms move around a lot butterflies for example our friend the monarch is migrating all the way to Mexico needs stopover points on the way and birds migrate many of our breeding birds breeding Canada and they've got to move through our suburban and city neighborhoods to get to those those spots and they have to stop along the way and eat so if you have a choice between an oak tree or a gingko as the single tree that can fit in your yard the oak will support migrating birds during stopover the gingko will not so your little piece of the world actually can make a big difference even if your neighbors don't participate but talk to them so that they will while it might seem a bit scary to think that a lot of the habitats that our native wildlife depends on for survival is rapidly going away we can take an active role in taking some of that back starting right in our own yards and balconies bringing nature home really does define our gardens as the new nature and if you'd like more information we have helpful links on what you can do on our website under the show notes for this episode the website address it's the same as our show name it's growing a greener world calm thanks for joining us everybody I'm Joel ampel and we'll see you back here next time for more growing a greener world [Applause] [Music] [Music] [Music] now you can continue your garden learning online and courses for me Joel ample in my online gardening academy 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