This was an international agreement made in 2014 to “halve deforestation and restore 150 million hectares of forests by 2020”. At the 5 year mark, this plan is “not on track”.
The New York Declaration on Forests
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Tag Archives: trees
treehouses
There’s a treehouse hotel you can stay at in Ohio. It’s a pretty cool idea. You could pretend to be an Ewok. I wonder what the maximum density would be for a sustainable treehouse-based civilization. You could use gondolas to get around, minimizing the transportation footprint. You would still need electricity and water infrastructure, hospitals, etc. You would need food, but maybe you could rely heavily on tree nuts and fruit to provide a lot of it. And obviously, you couldn’t cut down too many trees to build the treehouses or you wouldn’t have enough trees left to build them in.
forestry robot
Here’s a robot that can help forestry scientists collect data in the field.
Mikhailov is a 16-year-old student atITMO University, the renowned science and technology institution in St. Petersburg, Russia. As a member of the school’s Youth Robotics Lab, he was perfectly positioned to bring his idea to life. With a full team working on the the project, the robot won the gold medal at last year’s World Robot Olympiad; it can record tree locations within a forest, identify their species, measure the widths of their trunks, and even identify if a tree is healthy or not.
Its name is Forester, and most of its job is to explore forests and hit trees with its mallet. It’s a robotic adaptation of a technique that human tree experts often use, called “sounding,” to help their appraisal of a tree’s health.
urban (redevelopment) and trees
Redevelopment of private property in urban areas is generally a good thing for the regional economy, as is renewal of public infrastructure. It can be good for people and the environment too, if there are well-thought-out and well-implemented policies in place to make sure that is the case. But when those policies are not in place, or when enlightened and well-intentioned policies founder on the rocks of change-resistant and dysfunctional institutions that are supposed to implement them, I think the default is that this is not the case. Case in point: Seattle is experiencing a redevelopment boom, and has set goals to increase its tree canopy, but the development boom has resulted in a loss of tree canopy. The city is considering measures to try to reverse that trend. I would like to see my city (Philadelphia), which is also experiencing a development boom and (anecdotally, at least, from what I see with my own eyes) also losing trees, take similar measures. But after seeing a number of enlightened and well-intentioned local policies founder on the rocks of poor implementation, my confidence in the city’s political and bureaucratic leadership at the moment is not particularly high.
the latest on trees and ecosystem services
I don’t have to be sold on trees and ecosystem services at this point. Planting a ton of trees in cities, and maintaining them well, should be a priority given what we know at this point. I wish we were doing that and ready to move on to talk about adding other layers of vegetation in cities, and designing networks and corridors to connect urban green infrastructure to neighborhood and regional parks and larger reserves outside the city. We are not there, at least in my city, which is generally viewed as somewhat progressive. Anyway, here are some new papers and resources I have come across while perusing the various Elsevier journals:
Urban Heat Islands in Relation to Green Land Use in European Cities
The effects of trees on air pollutant levels in peri-urban near-road environments
trees and public health
A new report from the Nature Conservancy makes the case for the value of urban trees to human health. They go through a number of economic valuation studies that are out there, and the literature on health benefits: air quality, heat stress, mental and physical health, climate change. Then they make a case that urban tree canopy in the U.S. is actually declining and that it is severely under-funded in most cities.
Also, on the tree front, here is a recent paper on the rate at which wood inside urban trees decays. I think one important concept with urban trees is to think of them as infrastructure that has to be maintained and replaced at some rate. They just don’t live as long as forest trees, because they are in stressful environments, performing functions for us, and getting worn out. And the cost of maintaining and replacing them is actually low, and their benefits high, compared to other types of infrastructure. But even though the engineering, planning and architecture professions have been talking a lot about green infrastructure for at least a decade, most of us still aren’t taking it seriously as infrastructure, and the construction industry, bureaucrats and politicians are not taking it seriously, if they have even absorbed the concepts at all. I think this is a case where wealthy private foundations or individuals could make an enormous difference if they wanted to, because the institutions to plant and maintain trees typically exist, but are just severely underfunded. So all I have to do is become a wealthy private individual and I will take care of this. Okay, a solution exists and I’ll get right on that.
The overlooked carbon loss due to decayed wood in urban trees
Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm2) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R2 = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17-0.75 m3, equivalent to 5% to 25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69 to 110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.
100 million dead trees in California
USDA says more than 100 million trees have died in California as a result of drought.
The majority of the 102 million dead trees are located in ten counties in the southern and central Sierra Nevada region. The Forest Service also identified increasing mortality in the northern part of the state, including Siskiyou, Modoc, Plumas and Lassen counties. Five consecutive years of severe drought in California, a dramatic rise in bark beetle infestation and warmer temperatures are leading to these historic levels of tree die-off. As a result, in October 2015 California Governor Jerry Brown declared a state of emergency on the unprecedented tree die-off and formed a Tree Mortality Task Force to help mobilize additional resources for the safe removal of dead and dying trees.
This year, California had a record setting wildfire season, with the Blue Cut fire alone scorching over 30,000 acres and triggering the evacuation of 80,000 people. In the southeastern United States wildfires have burned more than 120,000 acres this fall. The southeast region of the Forest Service is operating at the highest preparedness level, PL 5, reflecting the high level of physical resources and funding devoted to the region. Extreme drought conditions persist, and many areas have not seen rain for as many as 95 days.
Longer, hotter fire seasons where extreme fire behavior has become the new norm, as well as increased development in forested areas, is dramatically driving up the cost of fighting fires and squeezing funding for the very efforts that would protect watersheds and restore forests to make them more resilient to fire. Last year fire management alone consumed 56 percent of the Forest Service’s budget and is anticipated to rise to 67 percent in by 2025.
street tree survey using Google Street View
An automated analysis program can produce street tree data using Google Street View.
Google Street View shows promise for virtual street tree surveys
Geospatial technologies are increasingly relevant to urban forestry, but their use may be limited by cost and technical expertise. Technologies like Google Street View™ are appealing because they are free and easy to use. We used Street View to conduct a virtual survey of street trees in three municipalities, and compared our results to existing field data from the same locations. The virtual survey analyst recorded the locations of street trees, identified trees to the species level, and estimated diameter at breast height. Over 93% of the 597 trees documented in the field survey were also observed in the virtual survey. Tree identification in the virtual survey agreed with the field data for 90% of trees at the genus level and 66% of trees at the species level. Identification was less reliable for small trees, rare taxa, and for trees with multiple species in the same genus. In general, tree diameter was underestimated in the virtual survey, but estimates improved as the analyst became more experienced. This study is the first to report on manual interpretation of street tree characteristics using Street View. Our results suggest that virtual surveys in Street View may be suitable for generating some types of street tree data or updating existing data sets more efficiently than field surveys.
tree type and heat mitigation
Here is an article on how the specific type of street tree affects the urban heat island locally, focusing on plant area index.
The way a street tree is able to modify the local microclimate on pedestrian walkways may vary according to tree species according to key canopy and leaf characteristics, such as leaf angle, leaf size, canopy architecture or simply canopy density. Three similar north-south orientated streets, with three different tree species possessing different canopy and leaf characteristics were studied in summer 2014. Microclimatic parameters were measured on pedestrian walkways below and away from tree canopies between 06:00 and 20:00 on three cloudless days. Physiological Equivalent Temperature (PET) was estimated to indicate pedestrian thermal comfort. Microclimate conditions were measured below and away from trees at solar noon for a wide range of trees with different Plant Area Index (PAI) as determined using full-frame photography. In streets with Ulmus procera and Platanus x acerifolia trees, the microclimatic benefits were significantly greater than the street with Eucalyptus scoparia trees, however no significant differences in the estimated PET. Microclimate benefit increased with increasing PAI for all three tree species, however no significant difference in under-canopy microclimate amongst tree species when the PAI was similar. It appears that differences in PAI are paramount in determining the microclimatic and PET benefits. Obviously, certain tree species have a limit of the PAI they can achieve, and that should be considered when selecting or comparing tree species for shading and cooling benefits. This study assists urban planners and landscape professionals in selecting street tree species for cooling benefits based on the expected or managed tree canopy area.
I’d heard of Leaf Area Index before I read this abstract, but not Plant Area Index. A search for Plant Area Index on Google brings up a Wikipedia definition of Leaf Area Index as the top hit.
Leaf area index (LAI) is a dimensionless quantity that characterizes plant canopies. It is defined as the one-sided green leaf area per unit ground surface area (LAI = leaf area / ground area, m2 / m2) in broadleaf canopies.
The best explanation of the difference I could find on the internet is here:
Leaf (or needles in the case of conifers) should be seen here as a generic term for designing the above ground aeral extent of vegetation. if no distinction is made between leaves (needles) and the other elements, the proper term to use is PAI: Plant Area Index rather than LAI.
So I guess the plant area index accounts for the trunk, branches, stems, etc.
value of trees
There have been a lot of studies on the value of urban trees. Well, here’s another. This one is notable for giving a canopy target at which value is maximized (30% at the property level, 38% at the county level).
The implicit value of tree cover in the U.S.: A meta-analysis of hedonic property value studies
Trees in residential neighborhoods and communities provide benefits for homeowners that are capitalized into residential property values. In this paper, we collected data from hedonic property value studies and merged these data with ancillary spatial data describing forest and socio-economic characteristics surrounding each study area to conduct a meta-analysis of the impact of tree canopy cover on the value of residential properties. The meta-analysis suggests that property-level tree cover of about 30% and county-level tree cover of about 38% maximize the implicit price of tree cover in property values. Currently, tree cover in the original study areas was about 14%, on average, around or near study properties. The empirical results, therefore suggest under investment of tree cover on private property from the perspective of individual property owners and from a societal perspective. The findings also have implications for community forest programs regarding planting trees and protection of mature trees to address potential changes in tree abundance, species diversity and stand age due to development and climate change.