Roody

There was a park behind my old house. There were lots of trees (mostly ash) growing there, and the ground beneath them was dry and grass covered. then they had to cut down dozens of trees because of Emerald Ash Borer. After that, the ground was often waterlogged and covered with puddles. The park was located in old swampland. The trees had "sucked up" standing groundwater. With the trees gone, the water just stayed on the surface until it eventually evaporated. So sometimes, at least in poorly drained areas, trees can actually reduce water amounts, and sometimes this is desirable and some times it is not..

I think that the lesson to be learned is that trees (or anything else) are not a "one size fits everybody" answer for the environment. Sometimes they're a good thing and sometimes they're bad. The best bet is usually to preserve or recreate the "natural" conditions whenver possible. Eucalyptus trees are native to parts of Australia, and they are probably a good fit for their original habitats. But they might not be a good fit in California or even in other regions of Australia.

Organisms evolve together to form unique systems in given geographical niches. At this time, I don't think humans understand enough to try to improve on nature when it comes to creating habitats.

Bike lanes, IMO, are similar. Often they're a good fit for built environments, but sometimes they are not. Each site must be individually assessed, rather than trying a "one size fits everybody" solution.

eja_ bottecchia

You have to stop listening to toe two reactionary imbeciles, John and Ken, at KFI. You will be much happier.

tandempower

It could also be that the tree root systems loosen the soil so water can seep further underground, plus the roots, trunks, and branches contain water and protect it from evaporation so water is somewhat more protected inside a tree than as a standing pond, although the water is also converted to oxygen during photosynthesis.

Generally, natural conditions evolve to keep the land in a life-nurturing condition. If they didn't, everything would die of draught. You should read the wiki entry on eucalyptus, though, because it sounds like these trees have evolved in Australia as dryers of land prone to fire. I'm not sure what evolutionary function this would have, except that the trees seem to be successful at penetrating down through the ground to seek deeper water sources. Maybe this has the function of breaking up rocky ground and making it more suitable for microbe and plant infiltration, idk.

I think we should try to understand how nature works and how it is undermined in order to protect natural ecosystems, restore them in areas where they've been destroyed, and make them more sustainable where they've become less sustainable.

True, but there are plenty of obstructionists who make it a point to thwart progress in pedestrian/bike infrastructure reform. Such interests abuse this logic of local autonomy to prevent or bamboozle reforms instead of facilitating them.

Trevtassie

I know you don't want to plant eucalypts next to bike paths either, not unless you like random speed humps that grow all the time, the roots will travel many metres to get to a leaking water main or drain... plus there are a couple of species that randomly drop branches with no warning, even in windless conditions. Clunk, 100kg of tree dropping out of the sky onto the path. Then there is the bark and leaves, which are generally shed in the summer, not winter, to encourage fire, bloody slippery on a corner. Most species need fire to regenerate, the seeds like the ash bed, which answers your question about how they reproduce Tandempower, they germinate after a fire when there is less competition and lots of nutrients from all the burned bark, leaves and branches they've dropped.
Getting back to bike paths, you should see what the transport minister in NSW, the biggest state in Australia is up too: Cycling laws: NSW to become 'laughing stock of the world' over push for bike riders to carry ID - ABC News (Australian Broadcasting Corporation) Same guy ripped up a long length of bike lane that cost millions to build.

Roody

That fits in with what I was saying. At this time, I said, I don't think our knowledge about biosystems comes close to an ability to create new systems that work as well as the systems that have evolved naturally over the course of thousands or millions of years. But we are making progress. For example, I doubt if the importation of eucalyptus trees from Australia into drought-prone California would have been allowed today, as it was 100 years ago when these trees became endemic.

And producing inappropriate bike lanes (or any inappropriate infrastructure) is just playing into the hands of these obstructionists, as well as making daily life miserable for LCF folks and bicyclists in general.

Designing systems for bikes and pedestrians is still an infant science. A lot of progress is being made, and there are many challenging opportunities ahead.

cruiserhead

I admire the idealism but don't get too caught up in the politics along the way. It's always going to be messy.
LA simply has to push forward, with visionary leadership, to get bike and alternative transportation up to something that isn't an embarassment to a world famous city.

It's slowly getting there and people are always going to fight ANY public works. People deeply fear change, especially in LA. The Metrorail proved that, and also proved how utterly wrong they were about those fears.

Machka 

Yes, and a good place for you to start would be to take some classes on biology. Since you seem to like trees, try to find a class on that particular subject. Who knows, it could lead into a whole new line of work for you.

cooker

Perhaps you could get a job as a career counselor

tandempower

You don't have to take classes to study something, engage in discussion about it, etc. If that was the case, we'd all be completely specialized and would avoid thinking about or discussing anything and everything outside the fields in which we hold official degrees.

I have told you before that shifting discussions from content to these kinds of issues regarding posters is ad hom derailment of discussion. I admit that the discussion of trees and reforestation sidetracked the discussion of bike lanes in L.A. a bit, but it is relevant because someone implied that burning less fuel is the only environmental benefit of transportation cycling.

You don't have to take classes in biology to recognize the simple logic of how deforestation causes heat and dryness. The basic concepts of photosynthesis are taught even in elementary school, and the relationship between direct sun-exposure and heating is self-evident.

Most importantly, I think you are being intentionally rude when you tell me to go take biology classes. Once I post this, you'll insist that you are really just suggesting it as a friendly gesture, but it's much more likely that you're irritated by the intellectual depth of posts and so you're subtly suggesting that the place for biology discussions is in a biology class.

Roody

Or at least take a class in it.

Machka 

+1

Which is why trees are often cleared away from bicycle paths and busier roads.

Even when they drop somewhat smaller branches, it can be quite startling!

McBTC

I thought something was odd here... Now I get it. Of course, trees should have rights. I hope they get more effective representation.

Smallwheels

Impacts of invading alien plant species on water flows at stand and catchment scales

Mobile 155

I hate to see LA fighting bike lanes even if I tend to be a VC cyclist except when the lanes are there. I find Long Beach and many of the beach cities like Redondo a joy to ride in. In parts of Long Beach the whole left lane has painted Sharrows indicating that bicycles in the lane have the lane.

As as for the other subject under debate we might want to be careful about planting new growth trees in places that need water recharging. They tend to be take far more grand water used for recharging than the old growth did. Look at page 5 of this study. https://www.northlandnemo.org/images/...by%20Trees.pdf

There are no simple answers to much of anything.

tandempower

Roads, bike paths, and sidewalks are better shaded. The pavement soaks up sun and gets hot. Especially for cyclists and pedestrians exposed to direct sunlight otherwise, shade is a major part of making outdoor life more comfortable. Arborists should be able to identify trees and branches that are prone to falling and deal with those. Eucalyptus seems particularly volatile in this regard from what I've read in wiki but the question is what other trees are good to plant in dry areas like those of California and L.A.


That article says that groundwater increases when trees are removed, but that is probably because the moisture balance underground is thrown off once the tree is gone so that moisture seeps down into aquifers. The long term effect, though, is that the ground loses its water-holding capacity.


I don't know how much good it does to plant isolated trees here and there, but if you look at a forested area, the combined shading and moisture retention builds up levels of humidity from the canopy down that are less susceptible to evaporation and wind than a bare field. Trees transpire, as do grasses and other plants, but in a forest, the trees absorb and block the wind so that the moisture doesn't blow away, and so the canopy and area below it stays moister. Yes, tree roots tap water from deeper under ground, but this also allows rainfall to seep down deeper as well. In a grassy field, the rain might not penetrate as deep into the ground and the grass will suck it up and transpire it without providing any wind-blockade to prevent the humidity from blowing away.


I don't know exactly what the solution is to reforesting highly deforested areas like L.A. and other cities, but I do think it makes sense that tree and plant cover needs to be robust in an area to maintain a living reservoir for water that gradually seeps down into the ground to replenish ground water. If all you have is pavement, buildings, and dry sunny open fields, any rain that does fall is going to either evaporate quickly or flush down through the ground so quickly that it will just flow through out to the sea. A healthy aquifer is one that is gradually fed by a thick spongy layer of organic material below the surface, including roots and composting biomass.

Machka 

Maybe in your part of the world ... not in my part of the world.

This is my point when I suggest to do more study. What works for one area doesn't necessarily work for another area. One size does not fit all.

Oh, and arborists (and pretty much anyone who has encountered a eucalyptus tree) have identified that eucalyptus trees are prone to falling and dropping branches, and so they are often cleared away from roads and paths, as much as possible. They are so plentiful, in many areas, there's only so much you can do.

tandempower

I read up on Eucalyptus but what I want to know is what other draught-pioneering species of trees could take their place?

And are you saying that "in your part of the world," direct sunlight isn't uncomfortable and damaging? Is it so cold there you don't notice the heat of the sun? If so, I can appreciate why you would want sunlight to warm you up while outdoors, but I have been wondering lately whether all the land-clearing in northern regions is contributing to the climate warming and ice melting. After all, if moisture isn't building up in these northern areas and getting pre-cooled by forests before the long nights of winter hit, won't that mean less ice and snowfall?

I'm not saying it might not be nice to have some sunny paths and sidewalks for people to warm up during spring and fall before the leaves have fallen off the trees. I just think we should be careful about dismissing the effect northern deforestation has on climate warming just because those regions are cold in terms of human comfort.

Machka 

Do you have any idea what you're talking about?

There are millions or billions of native eucalyptus trees in various varieties of here ... and you want to replace them???

Machka 

This is a photo of Hobart which I took on one of my walks. In the foreground there are various trees, but if you look on the hills and on Mt Wellington in the background, you see how it looks kind of fuzzy and dark green? Those are all eucalyptus trees.





Looking the other direction, there's the Tasman Bridge. See the hills in the distance? Notice how they too look kind of fuzzy and dark green. All eucalyptus trees ...




When roads and paths and other things are built around here, the trees are cleared back so the road or path can be put in, and hopefully cleared back far enough so that when the trees drop heavy branches, they don't cause too much damage. But, of course, there's not enough money in the budgets to clear the trees back from all roads because that would be a huge job.

And there are, of course, parts of Australia without so many eucalyptus trees. Australia is a big place and has a wide variety of terrain, vegetation, climates, etc. etc.

tandempower

Thanks for posting this article. I had a negative reaction at first to some of the assumptions but after reading the whole thing, it does make sense in many ways. Definitely the problem of young trees using more water is a problem, but faster growth is also how they absorb more CO2. I think they mention mixing old and new growth in forests for this reason, which is most important, imo, because larger canopies shade more ground and drop more leaves to prevent evaporation and retain moisture.

It also mentions the high evaporation of grass fields, but I think the benefit of deeper roots was overlooked insofar as pulling water up from deeper underground allows shallower ground moisture to filter down instead of staying near the surface. In simple terms, I view the root systems as a moisture regulator and redistributor since roots in wetter areas will soak up moisture, which drives growth of other roots through dryer areas in search of water. So as the roots spread into dry areas, they carve a path for water to seep down into those areas while also bringing moisture with them because the tree as a whole consists of moist wood. So as the roots grow into dryer areas, worms, microbes etc. also move into those areas to work the soil and make it richer and moister. Living organisms contain water so tree root systems are the infrastructure those organisms use to spread, which spreads water more broadly throughout the ground.

tandempower

Thanks for posting the pics. I wasn't talking about replacing all eucalyptus trees. I was responding specifically to what you said about clearing them away from roads and paths so the limbs don't fall on people. My point was that it's better to have trees shading roads and paths, so I wondered if there were other tree species that would work well along those roads and paths besides eucalyptus. My impression from reading wiki about the eucalyptus is that it is a dry-climate tree so I wouldn't assume that other trees can grow well where eucalyptus grows. From your pictures, however, the land doesn't look too dry.

Australia is practically a continent. It is a stereotype that people tend to assume greater homogeneity of places than is the reality. This is part of the problem with naming places at all, i.e. the assumption that a place with a single name/identity must also be relatively homogeneous. What works better is to describe the specific conditions of the land or the ecology in question instead of naming places. That way, you avoid assumption based on incomplete or skewed knowledge.

Machka 

Eucalyptus trees grow in various conditions. They aren't specifically a dry climate tree. This article might help:
Eucalypts | australia.gov.auThe article goes on to explain that they are very adaptable.


[HR][/HR]
Shading over roads and paths isn't necessary. It might be nice to have in a city park, and I know that many playground here in Australia will put up shade sails to protect the children from the sun. But it is not a requirement on bicycle paths and roads. In fact, from my experience, road shade is not all that common.

For example, a fairly "typical" Alberta road ... trees, yes, but cleared back for good sight lines and road maintenance. I could post heaps of photos of the unshaded roads I've cycled.





It is less expensive to simply clear the native eucalyptus trees away from the busier roads here (or the pine trees in Alberta) than to try to introduce some non-native species. Australia has had experience introducing non-native species, and putting forth a proposal that we should line our roads with something other than the existing millions of eucalyptus trees is going to have the environmental officers of the various councils sitting up and taking notice. Especially if the only reason for it is shade. It would also be quite an expensive thing to do, and councils simply don't have that kind of budget.


[HR][/HR]
Anyway, this is a road through the eucalyptus trees. Of course, there is a variety of vegetation in the photo. Next to the road is bracken fern and possibly wattle. I'm not up on all my Australian vegetation ... Rowan is much better at that than I am ... and it is kind of hard to see in the photo because I took it while cycling. But all or most of the taller trees are eucalyptus. Along this road, "they" have opted to clear the trees back to accommodate the telephone poles and for better sight lines and road maintenance. You won't get shade there in the middle of the day, but as the sun drops closer to the horizon, you will.

And the hill in the distance is covered in eucalyptus trees.

This was taken on an overnight tour we did at the end of November this year (Nov 28/29) ... if you click the photo, there are lots more of that tour.






Australia is a continent.
The Australian continent | australia.gov.au

Walter S

+1. I hate to see as much clear cutting as I do. It makes new development less expensive but is harmful to the environment in the long term.

I overheard some some tourists here in Atlanta once say "how can they deal with all the trees around here!". I didn't know where they were from. But I can't imagine. I love living where there are lots of plush green shady areas. Sitting in the sun and baking is not my cup of tea. I hate big wide roads where the trees are cut way back and a bicycle ride happens with the sun constantly beating down.

cooker

Those shade sails aren't anything like tarps, are they?

I agree it's not feasible to have shade trees overhanging highways and major commercial streets, and if you are going on a long recreation ride, you might wear sports clothes and expect to sweat, but it certainly is a benefit to me that much of my commute is on shaded streets. I can bike in my office clothes, or on hot days in my office shirt and shorts and change into long pants when I get to work, and it is a huge time saver and convenience that almost every day of the year I can coast into work without sweating too much and without needing to shower or completely change clothes. So in terms of urban bike lanes, shade has a lot of appeal.

here are a couple of examples of my route (both are on recommended commuting routes as per the city cycling committee):

https://www.google.ca/maps/@43.65977...!7i3328!8i1664
https://www.google.ca/maps/@43.71123...7i13312!8i6656

tandempower

Earlier posts referred to them as being detrimental to ground water. This led me to assume that forests of these trees would dry up the ground and so they would have to be very draught resistant or die out. I had pictured them more in the dry interior of Australia and I didn't realize they were as prevalent in the greener areas also.

Walter S and Cooker explain the appeal of shade for cycling. It's even more important for walking because you don't have that extra breeze you generate by moving at 15mph to cool you down. Would you say that being outdoors biking or walking in direct sunlight there is less comfortable than shade? What are average daytime temperatures there like?

Latitude makes a difference. In sub-tropical areas the sun gets pretty direct around summer and shade makes a big difference. In winter, the sun is lower in the sky and it's not as bad. I have been far north (not far south, but it's the same thing, isn't it?) and the indirectness of the sun makes it less damaging in summer.

Still, I've come to question whether all the deforested areas, roads, etc. in areas closer to the poles aren't contributing to global draught and warming as well. People living in those colder climates must enjoy more direct sun exposure, especially in winter, but ice and snow have to build up in those areas to produce the cold air that blows toward the equator helping cause rain there, where it is sorely needed.

I think the importance of photosynthetic shade is underestimated by most people because we are so busy focussing on the CO2 blanketing aspect of climate warming that we are ignoring the simple cause of heat, which is sunlight getting absorbed and re-emitted as convection currents. If we would start quantifying each parcel of land in terms of how much solar energy it absorbs and re-emits as heat, we could start to get a picture of where global heat is coming from. It is ironic that solar panels are big news right now, but no one seems to have realized yet that the world is already full of solar-powered convection ovens called roads and buildings and each of these can be quantified in terms of how much sunlight they absorb and convert into hot air.

It would surprise me if there's not some native species of tree that could be planted along Australian roads and walking paths to shade them without endangering people with falling limbs, as eucalypts seem to do. If the sun is very indirect there and people feel more comfortable walking/biking in direct sunlight, I'm sure it wouldn't destroy the planet to have unshaded bike/pedestrian paths, but in hotter areas, direct sunlight is a deterrent to walking/biking outdoors - in addition to adding heat to the atmosphere.

I've seen many roads cleared like that. Bike paths are sometimes placed through the trees, off the main road, and can be very shaded. The jacket makes it seem cold when the picture was taken, but November is summer there, isn't it? Is it a cold area and that's the reason you have little interest in shade?

When I was in school, they called that continent Oceania, or something to that effect, and it was supposed to include all the other Asian islands as well. Anyway, I think people get too hung up on place-identity issues. Have a look at this: https://youtu.be/eZNSaePjenU

I think they do it because it draws attention to whatever they build on the site to have the trees gone and it makes it easier to get a picture of the whole finished project from a distance. I don't know why it's cheaper to remove more trees. I would think it would be easier to leave them intact for the most part and build something between them. The challenge is making sure the property is identifiable despite being nestled in a little forest.

Driving is epidemic in the southeast because of the hot sun. People don't realize how comfortable the climate can be with widespread shade.

Lol. "Sail," sounds more nautical.

I don't know why trees couldn't overhang highways and commercial streets. If not, then some other photosynthetic shade solution needs to be found, though I don't think anything would be as cheap as trees, since they have their own trunks and branches to hold them up. I've thought about suspending grids of wire or other trellis-material for vines to grow over roads and shade them that way, but can you imagine how much building material that would take? It's almost as unfathomable as covering every road in solar panels.

Gradually, I think what is going to have to happen is for multilane roads to have treed medians installed, which divide the lanes so it will be like driving on multiple single/double lane roads in the same direction separated by treed medians. It will be like driving through a forest beneath the canopy, and it will be tricky to change lanes, but it will be much better for climate and environment.