Reflecting on the past few months of writing this blog, I've got mixed feelings. It has reiterated to me that I'm too last-minute (don't check the dates of my posts). Truthfully, I wish I had picked a different topic as I struggled to engage with some of the content. It wasn't easy to write either. Communicating science to an audience is difficult, especially when you're not quite sure what the demographic is other than who marks the final version. It's public to anyone, so I tried to keep it scientific without being too formal. Hopefully I achieved that, and I like to think my writing skills have grown as a result.
I have learned a lot about the Amazon and am glad to have this knowledge now. There are a lot of issues, but nothing is as straightforward as I initially thought. It's not all doom and gloom, and the sheer amount of research makes me equally concerned and hopeful for the Amazon's future. It suggests that the huge amount of deforestation is causing a lot of issues, but it's also introduced me towards huge conservation efforts going on by organisations like the WWF!
So, that's me done. Remember dear reader(s), save the rainforest!
Friday, 5 January 2018
Let's Get Biogeochemical
In a previous post, I spoke about nine planetary boundaries, and how four of those boundaries have already been transgressed (Rockström et al., 2009). I'll link you again to Johan Rockström's TEDTalk about it here and refresh your memory with Figure 1.
As you can see, Biogeochemical flows are one of the nine boundaries transgressed beyond the zone of uncertainty. Human industry and agriculture have altered natural nitrogen and phosphorous flows, creating more reactive nitrogen than occurs naturally and mobilised significant amounts of phosphorous. Much of this ultimately ends up in terrestrial and aquatic ecosystems, polluting waters but fertilising soils (Stockholm Resilience Centre, accessed 2018). Similar occurrences have happened with increased CO2 output from fossil-fuel emissions. Tropical forests and large bodies of water are expected to take up a lot of this excess atmospheric carbon (Mahli et al., 2000; Sabine et al., 2004), although the terrestrial tropical response is hotly debated (Hickler et al., 2008). Since these are global occurrences, the Amazon has of course been affected too, especially considering the amount of forest converted to agricultural land (Hansen et al., 2013).
Increasing severity of droughts under El Nino and deforestation-induced droughts in the Amazon are likely to affect soil emissions of N2O and CH4 in the Amazon. A study into this by Nepstad et al. (2002) reduced rain throughfall in an area of the Amazon to replicate these drought effects, finding that the resultant reduction in productivity led to an increase in N2O soil emissions and an increase in soil consumption of CH4. Although aboveground productivity was also reduced, indicating a reduction in above ground carbon storage. This suggested that carbon and nitrogen emissions in Amazon forests are sensitive to small changes in rainfall. Ultimately, this means that increased drought under anthropogenic climate change and deforestation could significantly alter carbon and nitrogen cycling in the Amazon. A loss of nitrogen from Amazonian soils is concerning considering the deteriorating soil quality in the Amazon (Martinez and Zinck, 2004).
Interestingly, Nepstad et al. suggested no decrease in leaf litter mineralisation, which is thought to be the main way nitrogen is fixed into soils in tropical forests (Körner, 2009). In contrast, Körner’s study suggested that tropical forests, including the Amazon, are likely to experience an increase in nitrogen fixation stimulated by elevated CO2 (which is set to increase in the future) and an increase in productivity and carbon storage as a result. However, the study also suggested that soil nitrogen is less of a limiting factor in growth than phosphorous is in tropical forests.
Tropical forest soil is typically of poor quality, so the previously mentioned mobilisation of phosphorous and increased nitrogen fixation (despite increased N2O emissions) seems like a good thing. More phosphorous and nitrogen would increase soil quality and mitigate the phosphorous limitation, enabling increased biomass growth and above ground carbon storage, right? Taking carbon out of the atmosphere AND encouraging forest growth – that’s two for one! Well, it’s not that simple...
While this does happen, we’re offsetting it with our physical destruction of the rainforest, by reducing Amazon forest extent and reducing biodiversity, which I’ve talked about in my previous posts. That hinders growth immensely. What’s more is the potential for Phosphorous- and Nitrogen-containing fertiliser used in agriculture to run off into the Amazon River and cause algal blooms that reduce light penetration and cause oxygen-starvation to Amazon River plumes as bacteria consume these algae (Lock et al., 2015; Stockholm Resilience Centre, accessed 2018). The fish can’t breathe! Let’s consider also that my previous post determined that dam building is already reducing fish diversity in the Amazon river basin! Concerning, I know.
The issue of biogeochemical cycling is a little less cut-and-dry than some of the other issues I’ve discussed in the Amazon. There appear to be benefits to the Amazonian terrestrial ecosystems; potential increases in productivity and soil fertility, but definite negatives to our effects on biogeochemical cycling, particularly in Amazonia’s aquatic ecosystems. At least we can be sure in the knowledge that we’re effecting change again. We do a lot of that, unfortunately.
See you next time, for the final, reflective post of the blog!
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| Figure 1: The nine defined planetary boundaries. Biogeochemical flows is currently beyond the zone of uncertainty, indicating that it is at high risk. (Source: Stockholm Resilience Centre, accessed 2018) |
As you can see, Biogeochemical flows are one of the nine boundaries transgressed beyond the zone of uncertainty. Human industry and agriculture have altered natural nitrogen and phosphorous flows, creating more reactive nitrogen than occurs naturally and mobilised significant amounts of phosphorous. Much of this ultimately ends up in terrestrial and aquatic ecosystems, polluting waters but fertilising soils (Stockholm Resilience Centre, accessed 2018). Similar occurrences have happened with increased CO2 output from fossil-fuel emissions. Tropical forests and large bodies of water are expected to take up a lot of this excess atmospheric carbon (Mahli et al., 2000; Sabine et al., 2004), although the terrestrial tropical response is hotly debated (Hickler et al., 2008). Since these are global occurrences, the Amazon has of course been affected too, especially considering the amount of forest converted to agricultural land (Hansen et al., 2013).
Increasing severity of droughts under El Nino and deforestation-induced droughts in the Amazon are likely to affect soil emissions of N2O and CH4 in the Amazon. A study into this by Nepstad et al. (2002) reduced rain throughfall in an area of the Amazon to replicate these drought effects, finding that the resultant reduction in productivity led to an increase in N2O soil emissions and an increase in soil consumption of CH4. Although aboveground productivity was also reduced, indicating a reduction in above ground carbon storage. This suggested that carbon and nitrogen emissions in Amazon forests are sensitive to small changes in rainfall. Ultimately, this means that increased drought under anthropogenic climate change and deforestation could significantly alter carbon and nitrogen cycling in the Amazon. A loss of nitrogen from Amazonian soils is concerning considering the deteriorating soil quality in the Amazon (Martinez and Zinck, 2004).
Interestingly, Nepstad et al. suggested no decrease in leaf litter mineralisation, which is thought to be the main way nitrogen is fixed into soils in tropical forests (Körner, 2009). In contrast, Körner’s study suggested that tropical forests, including the Amazon, are likely to experience an increase in nitrogen fixation stimulated by elevated CO2 (which is set to increase in the future) and an increase in productivity and carbon storage as a result. However, the study also suggested that soil nitrogen is less of a limiting factor in growth than phosphorous is in tropical forests.
Tropical forest soil is typically of poor quality, so the previously mentioned mobilisation of phosphorous and increased nitrogen fixation (despite increased N2O emissions) seems like a good thing. More phosphorous and nitrogen would increase soil quality and mitigate the phosphorous limitation, enabling increased biomass growth and above ground carbon storage, right? Taking carbon out of the atmosphere AND encouraging forest growth – that’s two for one! Well, it’s not that simple...
While this does happen, we’re offsetting it with our physical destruction of the rainforest, by reducing Amazon forest extent and reducing biodiversity, which I’ve talked about in my previous posts. That hinders growth immensely. What’s more is the potential for Phosphorous- and Nitrogen-containing fertiliser used in agriculture to run off into the Amazon River and cause algal blooms that reduce light penetration and cause oxygen-starvation to Amazon River plumes as bacteria consume these algae (Lock et al., 2015; Stockholm Resilience Centre, accessed 2018). The fish can’t breathe! Let’s consider also that my previous post determined that dam building is already reducing fish diversity in the Amazon river basin! Concerning, I know.
The issue of biogeochemical cycling is a little less cut-and-dry than some of the other issues I’ve discussed in the Amazon. There appear to be benefits to the Amazonian terrestrial ecosystems; potential increases in productivity and soil fertility, but definite negatives to our effects on biogeochemical cycling, particularly in Amazonia’s aquatic ecosystems. At least we can be sure in the knowledge that we’re effecting change again. We do a lot of that, unfortunately.
See you next time, for the final, reflective post of the blog!
-
Thursday, 4 January 2018
Can't Mistake My Biodiversity
I thought of a title pun this time! Congrats if you got it. Anyway, leading on from my previous post...
The Amazon Rainforest showcases tremendously high genetic diversity and species richness per unit area (Phillips et al., 1994), one of the highest worldwide. It's a global biodiversity hot-spot and is extremely important to preserve! Although the research into this may not be what you expect. The Amazon is actually classified as a zone of low vulnerability as far as biodiversity conservation efforts go. Despite this, it's also a zone of high irreplaceability due to its sheer amount of biodiversity being so ecologically important (Brooks et al., 2006). It's important to consider this when discussing the Amazon Rainforest, even though it may seem contrary to the narrative I've laid out so far. It's not quite as doom and gloom as it seems, but that doesn't mean there isn't a problem!
A recent study explored the effect of building dams for hydropower in the Amazon, Congo, and Mekong river basins and found a worrying correlation between fish diversity and the location of dams (Winemiller et al., 2016) (Figure 1). These basins contain approximately one-third of the world's freshwater fish species (2320 in the Amazon, 1488 of which are endemic), all of which are at risk of population decline. Figure 1 shows just how impactful dam constructions are on fish diversity, and the density of proposed dams in already-impacted areas is concerning. One bit of hope that Winemiller et al. point to, however, is that actual fish diversity is underestimated since multiple new fish species are discovered annually.
In terrestrial fauna, models suggest that significant land-use change in the central Amazon results in biodiversity loss by causing forest fragmentation (Dale et al., 1994). As forest is cleared for anthropogenic use, parts of the forest become isolated from each other, so the total available habitat area for species becomes smaller, particularly for relatively immobile species incapable of crossing these gaps. Ultimately, with a smaller living space, biodiversity rates decrease. Any guesses at what organisms have little to no gap-crossing ability whatsoever? That's right, plants!
The floral side of Amazonian biodiversity is a bit less clear though. According to Hopkins (2007), our knowledge of floral biodiversity in the Amazon is limited by a lack of data, since very few regions of the rainforest are well-documented. This suggests that what knowledge we have is very biased to these few regions and we have little understanding of how floral diversity is distributed across the Amazon. Hopkins' study actually indicated that four major regions of the Amazon basin are poorly understood and likely contain a significant number of plant species. This is particularly problematic given the fragmented nature of the Amazon under current forestry regimes and their propensity to house endemic species as a result (Dale et al., 1994). It's entirely possible that the biases towards certain regions and forest fragmentation mean that our estimates of total floral biodiversity are under or overestimated. Bloody forest clearing. We're compounding our own problems!
Land use change isn't the only thing likely to affect Amazon biodiversity in the future though. Climate Change is a pesky old thing! Increasing temperatures under climate changes and increased frequency of extreme weather events (that can often lead to fires) are predicted to cause habitat destruction and fragmentation, and subsequent species extinctions (Brodie et al., 2012). Though this is acknowledged to be under circumstances in which such changes result in organisms needing to change their habitat distributions in order to avoid rising temperatures under climate change. Unfortunately, Brodie et al. suggest that these extinctions would be the most severe in low lying tropical rainforest drainages, where organisms try to reach higher elevations where temperatures are cooler. Yep, that includes the Amazon.
Remember the anthropogenic fires I talked about in a previous post? Remember how our forest clearing is increasing the possibility of these? Well, yeah, we're ruining things again. If Amazonian ecosystems are unable to adapt or cope with increased fire frequency, then habitat destruction is going to increase as a result, and put a greater number of species at risk of extinction. Worst case scenario; some models have predicted that this deadly combination of climate change and land use change (I told you everything was interlinked!) will cause large scale drying in the Amazon and large enough increases in fire frequency to reach a tipping point in some parts of the Amazon by 2030, causing a shift to drier, savanna-like ecosystems (Nepstad et al., 2008). Figure 2 depicts exactly where this has been predicted.
The profound negative impacts this would have on indigenous peoples is bad enough (Finner et al., 2008), let alone the decrease in biodiversity this would lead to. Tropical Savannah and dry ecosystems typically exhibit lower rates of biodiversity than tropical rainforests (WWF, 2006). Although Savannah ecosystems are still quite diverse, they do not make suitable habitats for most rainforest species that exist within relatively narrow climate envelopes. One thing to note though, is that this shift is projected by a model. It's not a given, so interpret this with a critical lens.
There's a lot science is unsure of or can't decide on, such as Amazonian floral biodiversity, or just how vulnerable the Amazon actually is. What we are quite confident about, however, is that this biodiversity hot spot isn't doing as well as it could be. A lot of species in the Amazon are at risk currently; we're just not sure how much risk. While significant Amazonian extinction may not occur within our lifetimes, we must be careful not to breach a tipping point in the Amazon to cause mass extinction in the future. We certainly don't want the Amazon to follow the same trend as the global genetic diversity planetary boundary.
And on that depressing note, I'm out. See you next time!
The Amazon Rainforest showcases tremendously high genetic diversity and species richness per unit area (Phillips et al., 1994), one of the highest worldwide. It's a global biodiversity hot-spot and is extremely important to preserve! Although the research into this may not be what you expect. The Amazon is actually classified as a zone of low vulnerability as far as biodiversity conservation efforts go. Despite this, it's also a zone of high irreplaceability due to its sheer amount of biodiversity being so ecologically important (Brooks et al., 2006). It's important to consider this when discussing the Amazon Rainforest, even though it may seem contrary to the narrative I've laid out so far. It's not quite as doom and gloom as it seems, but that doesn't mean there isn't a problem!
A recent study explored the effect of building dams for hydropower in the Amazon, Congo, and Mekong river basins and found a worrying correlation between fish diversity and the location of dams (Winemiller et al., 2016) (Figure 1). These basins contain approximately one-third of the world's freshwater fish species (2320 in the Amazon, 1488 of which are endemic), all of which are at risk of population decline. Figure 1 shows just how impactful dam constructions are on fish diversity, and the density of proposed dams in already-impacted areas is concerning. One bit of hope that Winemiller et al. point to, however, is that actual fish diversity is underestimated since multiple new fish species are discovered annually.
 |
| Figure 1: The distribution of existing and planned dams in the Amazon river basin and the species richness distribution. Areas of high dam density appear to coincide with areas of lower species richness. (Source: Winemiller et al., 2016) |
In terrestrial fauna, models suggest that significant land-use change in the central Amazon results in biodiversity loss by causing forest fragmentation (Dale et al., 1994). As forest is cleared for anthropogenic use, parts of the forest become isolated from each other, so the total available habitat area for species becomes smaller, particularly for relatively immobile species incapable of crossing these gaps. Ultimately, with a smaller living space, biodiversity rates decrease. Any guesses at what organisms have little to no gap-crossing ability whatsoever? That's right, plants!
The floral side of Amazonian biodiversity is a bit less clear though. According to Hopkins (2007), our knowledge of floral biodiversity in the Amazon is limited by a lack of data, since very few regions of the rainforest are well-documented. This suggests that what knowledge we have is very biased to these few regions and we have little understanding of how floral diversity is distributed across the Amazon. Hopkins' study actually indicated that four major regions of the Amazon basin are poorly understood and likely contain a significant number of plant species. This is particularly problematic given the fragmented nature of the Amazon under current forestry regimes and their propensity to house endemic species as a result (Dale et al., 1994). It's entirely possible that the biases towards certain regions and forest fragmentation mean that our estimates of total floral biodiversity are under or overestimated. Bloody forest clearing. We're compounding our own problems!
Land use change isn't the only thing likely to affect Amazon biodiversity in the future though. Climate Change is a pesky old thing! Increasing temperatures under climate changes and increased frequency of extreme weather events (that can often lead to fires) are predicted to cause habitat destruction and fragmentation, and subsequent species extinctions (Brodie et al., 2012). Though this is acknowledged to be under circumstances in which such changes result in organisms needing to change their habitat distributions in order to avoid rising temperatures under climate change. Unfortunately, Brodie et al. suggest that these extinctions would be the most severe in low lying tropical rainforest drainages, where organisms try to reach higher elevations where temperatures are cooler. Yep, that includes the Amazon.
Remember the anthropogenic fires I talked about in a previous post? Remember how our forest clearing is increasing the possibility of these? Well, yeah, we're ruining things again. If Amazonian ecosystems are unable to adapt or cope with increased fire frequency, then habitat destruction is going to increase as a result, and put a greater number of species at risk of extinction. Worst case scenario; some models have predicted that this deadly combination of climate change and land use change (I told you everything was interlinked!) will cause large scale drying in the Amazon and large enough increases in fire frequency to reach a tipping point in some parts of the Amazon by 2030, causing a shift to drier, savanna-like ecosystems (Nepstad et al., 2008). Figure 2 depicts exactly where this has been predicted.
 |
| Figure 2: The extent of predicted dry forest covering the Amazon by 2030 as a result of large scale drying under climate change. (Source: Nepstad et al., 2008) |
The profound negative impacts this would have on indigenous peoples is bad enough (Finner et al., 2008), let alone the decrease in biodiversity this would lead to. Tropical Savannah and dry ecosystems typically exhibit lower rates of biodiversity than tropical rainforests (WWF, 2006). Although Savannah ecosystems are still quite diverse, they do not make suitable habitats for most rainforest species that exist within relatively narrow climate envelopes. One thing to note though, is that this shift is projected by a model. It's not a given, so interpret this with a critical lens.
There's a lot science is unsure of or can't decide on, such as Amazonian floral biodiversity, or just how vulnerable the Amazon actually is. What we are quite confident about, however, is that this biodiversity hot spot isn't doing as well as it could be. A lot of species in the Amazon are at risk currently; we're just not sure how much risk. While significant Amazonian extinction may not occur within our lifetimes, we must be careful not to breach a tipping point in the Amazon to cause mass extinction in the future. We certainly don't want the Amazon to follow the same trend as the global genetic diversity planetary boundary.
And on that depressing note, I'm out. See you next time!
Biodiversity (I can't think of a clever title for this one)
The Importance of Biodiversity and Global Trends
Ever wondered what's happening to all those animals, plants, and creepy crawlies living in the Amazon? Not to be all doom and gloom, but our 'burn everything!' approach to land clearing is kind of screwing them over... just a little bit. I've made no secret of this and have explicitly stated in previous posts that many species native to the Amazon Rainforest are under threat. "But, what's really happening?", I pretended to hear you ask! Well, that's what I'm here to tell you; whether you asked for it or not. Be educated, my reader(s)!
A brief note before we begin; I will be splitting the biodiversity post into two since it would otherwise be too lengthy. This post will cover global biodiversity trends and the importance of biodiversity as a concept. The next post will focus specifically on biodiversity in the Amazon in regards to these ideas.
Ecosystem biodiversity, which is sometimes referred to as genetic diversity, is analogous to the species richness of an ecosystem. That is, the number of different species co-existing and living per unit area (Encyclopaedia Britannica, accessed 2018). Basically, it's just how many different kinds of organisms there are. Although simple, it's an important concept and is important in maintaining ecosystem functioning, which provides goods and services to human society, such as freshwater filtration and raw materials. Yep, biodiversity is economically valuable as well - remember this! High biodiversity rates have been shown to increase ecosystem productivity and nutrient retention rates, make ecosystems less susceptible to invasion by foreign species, and somewhat mitigate the negative impacts of environmental disturbances (Hooper et al., 2005).
Experimental work by Balvanera et al. (2006) spanning 50 years has shown increased biodiversity to have a net positive effect, although this is stronger on the community-level, where populations are smaller, than at the ecosystem level. Balvanera et al.'s study also indicated that biodiversity has a greater positive relationship with ecosystem productivity than ecosystem stability.
Figure 1 from Gamfeldt et al. (2008) below conceptualises this relationship well, where species richness is biodiversity. The black and grey lines show the result of changes in species richness with ecosystem functioning for high and low redundancy ecosystems. In high redundancy ecosystems, there are a number of species capable of filling a specific ecological niche that results in a specific ecosystem function. The high redundancy scenario in this case shows the maximum loss in functioning where the species lost are those most efficient at filling their ecological niche. With high redundancy, you would expect functioning to remain higher than with low redundancy, since multiple species are able to fill the same niche in the former, despite the most efficient species being lost. The general trend, however, is that ecosystem functioning remains higher under higher species richness across both redundancy levels. Ultimately, high levels of biodiversity prevent ecosystems from tipping into unenviable states.
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| Figure 1: The relationship between biodiversity (species richness) and ecosystem functioning is neatly conceptualised, distinguishing between the degree of relationship in high and low redundancy ecosystems. (Source: Gamfeldt et al., 2008) |
Knowing that biodiversity is important, it's been monitored and studied extensively on a global scale. A landmark study by Rockström et al. (2009) defined nine planetary boundaries that humanity can safely operate in. Johan Rockström himself did a TED Talk on the topic, which you can find here, in case you're interested! It is suggested by Rockström et al. that transgressing these boundaries could bring about abrupt and potentially irreversible environmental shifts. Biosphere integrity, aka biodiversity, is one of these, and has already been exceeded on a global scale. Figure 2 illustrates this, where the threshold for biodiversity is shown as extinctions per million species-years (E/MSY). It's not surprising that this planetary boundary has been breached, considering that ongoing patterns of biodiversity loss have contributed to the first anthropogenically-driven major extinction event ever seen on Earth - and only the sixth ever event (Chapin et al., 2000).
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| Figure 2: The nine planetary boundaries as defined by Rockstrom et al. (2009). Four of these, including biodiversity (shown here as genetic diversity), have already transgressed into the 'zones of uncertainty', where there is a high risk of potentially irreversible and abrupt environmental shifts to undesirable states. (Source: Stockholm Resilience Centre, accessed 2018) |
So, it looks like loss of biodiversity is currently, and will continue to be, a major problem and we have a good idea about how this might affect ecosystems globally. We know it's not going to be good. But the studies I've presented so far have alluded to an economic impact as well, since ecosystems provide us with a number of goods and services (Gamfeldt et al., 2008). Anyone know of a tropical forest that's being carelessly exploited for economic gains?
Oh, that's right... The Amazon Rainforest! Of course, the Amazon is not exempt from this issue. Nothing is ever so easy! But I'll be ending this post here and continuing on with the Amazon in the next one, as promised at the start of this post. See you soon, dear reader(s)!
Monday, 4 December 2017
Who let the humans out?
There’s one thing I’ve touched on in previous posts but not
gone into much detail on yet. Why has so much deforestation been occurring
since the 1970s? Well, there’s a number of reasons.
The first is, surprisingly, a natural cause. Natural fires,
not to be confused with anthropogenic fires, occur in forests most commonly as
a result of lightning strikes and long-term droughts. The Amazon is no
exception. In 1998, severe drought brought on by an El Niño episode burned 20,000 square kilometres of forest in the Roraima
and southeastern Pará regions of the Amazon (Nepstad et al., 2001). It seems bad, but this is natural variability in fire
occurrence, and is actually a critical component of the Earth system (Whitlock et al., 2010). Despite Amazon rainforests
being more resilient to fires due to their natural microclimates only
infrequently providing suitable conditions for fire ignition (Uhl and Kauffman, 1990; Baretto et al., 2006), anthropogenic
deforestation has been seen to increase the susceptibility of forests to fire
by providing greater ignition and fuel sources, altering the forest
microclimate to observe longer periods with no rain, and decreasing the albedo
of the land surface (Uhl and Kauffman, 1990; Nepstad et al., 2001; Silvestrini et al., 2011). The key word here: anthropogenic.
Anthropogenically-induced fires in the Amazon are common
enough that Baretto et al. (2006) defined ‘fire
zones’ in the Amazon as zones of a 10km radius around a forest fire, and
determined that 28% of the Brazilian Amazon was under significant anthropogenic
fire pressure. Fire itself is used to clear forested land for a number of uses,
referred to as ‘slash and burn agriculture’, but is just one method amongst
many, including forest clear-cutting and selective logging (Ferretti-Gallon and Busch, 2017).
A comprehensive study by Ferretti-Gallon and Busch (2017), based on 121 deforestation studies from 1996 to 2013,
found that the anthropogenic deforestation I’ve been banging on about occurs
almost exclusively due to the potential economic returns. It’s all about money
(duh!). The Amazon offers a wealth of public ecosystem services, including
biodiversity habitats, storm mitigation, and carbon storage (to name just a
few). But it seems like if the private economic returns of croplands, pasture,
mining, and urban development are greater than these ecosystem services, it’s
goodbye Amazon and hello slash and burn, but most importantly, hello money!
That’s essentially why deforestation levels I talked about in my previous post
are above the optimum – it’s all about the money! Remember The Lorax?
Wednesday, 29 November 2017
Where have all the good trees gone?
Extent of Deforestation in the Amazon
Consider this gif:
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| Figure 1: A gif showing deforestation in the Amazon Rainforest (Source: Giphy, accessed 29/11/2017) |
You might remember it from an earlier blog post. It shows how much of the Amazon Rainforest has been removed since the year 2000, i.e. the extent of deforestation in the Amazon. Without any political borders drawn on, I'm not precisely sure which parts of the Amazon are shown exactly. Thankfully, a number of scientists have conducted research precisely into this because of the potential threat such deforestation poses to ecosystem services provided by the Amazon; threats that subsequent posts will detail.
A very nice table of deforestation in the Brazilian Amazon can be found here, based on estimates from the Brazilian National Institute of Space Research and the United Nations Food and Agricultural Organisation. It includes tree cover loss in Brazil beginning from the 1970s, which is particularly important considering that the Brazilian Amazon makes up 60% of the total rainforest. The amount of forest lost annually increased significantly in the 1970s and 1980s from pre-1970s levels, but has begun to slow since then. Although, there are peaks in 1995 and 2004, at which times annual deforestation rates were unsteady.
Rates of forest loss have slowly been declining since then. But remember, considering that full tree regrowth in the Brazilian Amazon is a process that occurs on the scale of hundreds of years (Houghton et al., 2000), deforestation since the 1970s has been largely cumulative. So even though rates of deforestation have been decreasing in the past decade, the total forest lost has continued to increase. Today, only 81% of the pre-1970 Brazilian Amazon forest cover has been retained, compared to 97.6% retained in the 1970s, relating to a 768,935 square kilometer and 98,400 square kilometer loss respectively since 1970. As you can tell, a staggering amount of the Brazilian Amazon has been lost.
As for elsewhere in the Amazon, it's all very concerning as well. To put this into perspective, a high-resolution study of global forest cover in the 21st century by Hansen et al. (2013) estimated that the rate of loss of forest land cover in the Amazon between 2000 and 2012 was, in the words of The Guardian, in the order of magnitude of 50 football pitches a minute, and with a total loss 10 times greater than the size of the UK. Equally concerning, although not directly related, Hansen et al. estimated that global forest loss was 2.3 million square kilometers in the same time period, with only 0.8 million square kilometers afforested. In comparison, the Amazon only had a third of what was deforested replaced.
In the true spirit of science, a number of figures have been created to represent this beautifully.
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| Figure 2: Tree cover loss across various countries containing parts of the Amazon Rainforest. (Source: Butler, 2017, updated) |
Figure 2 from Butler (2017, updated), based on 2017 data from a group of researchers led by Matt Hansen (yes, the very same as the one referenced above!) at the University of Maryland, shows Amazonian forest loss in hectares per year across various regions between 2001 and 2015. Brazil is far and away the winner, or loser, depending on how you look at it. So much so that it's difficult to see the disparity between other countries. It's a good indication of the sheer amount of forest loss occurring in Brazil.
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| Figure 3: Tree cover loss across various countries containing parts of the Amazon Rainforest, without Brazil. (Source: Butler, 2017, updated) |
Figure 3 depicts forest loss across regions without Brazil. It's easier to see the disparity between other countries here, with Bolivia, Peru, and Colombia seeing the greatest deforestation across the whole period. Encouragingly, deforestation in the Amazon seems to be declining across the most significant regions. Finally, some hope!
The disparity between Brazil and the other countries is clear, but don't be fooled by pretty graphs, dear reader(s)! This doesn't necessarily mean that the rate or proportion of loss in Brazil is greater than other nations. Remember, it's thought that Brazil contains about 60% of the Amazon Rainforest within its borders. It's entirely possible that Brazil's greater total forest loss is due to solely to its greater area, although it's difficult to tell without the data. Regardless, the sheer extent of deforestation occurring in the Amazon is alarming, and is clearly evident.
That's all for this post, folks, but I've got another one in the works, a Deforestation: Part 2, if you will. It should be up very soon so stay tuned!
Wednesday, 22 November 2017
Food for thought. Too much of it.
Just a short post this time for you all. I came across two articles in the Guardian that might be of interest to some of you, and are definitely relevant.
The first article, which you can find here, discusses that humans' meat-based diets and over-consumption of food is leading to a decline in forest extent, which disproportionately affects the Amazon Rainforest. I recommend having a read of the comments section too - a lot of people point to over population as opposed to simply individual over-consumption and meat-based diets. What do you think?
The second article, linked for you wonderful reader(s) here, is particularly alarming. Insect populations have declined beginning around the 1980s, and that trend isn't showing any signs of stopping. Fewer creepy crawlies? Sounds great, right? Not when you think about how ecologically important insects are, and how resilient they've been in the past. As the article suggests, it's a catastrophe!
Enjoy the reading and keep an eye out for my next post on deforestation in the Amazon Rainforest and the ecological impacts occurring as a result. It should be coming out next Friday (don't quote me on that)!
The first article, which you can find here, discusses that humans' meat-based diets and over-consumption of food is leading to a decline in forest extent, which disproportionately affects the Amazon Rainforest. I recommend having a read of the comments section too - a lot of people point to over population as opposed to simply individual over-consumption and meat-based diets. What do you think?
The second article, linked for you wonderful reader(s) here, is particularly alarming. Insect populations have declined beginning around the 1980s, and that trend isn't showing any signs of stopping. Fewer creepy crawlies? Sounds great, right? Not when you think about how ecologically important insects are, and how resilient they've been in the past. As the article suggests, it's a catastrophe!
Enjoy the reading and keep an eye out for my next post on deforestation in the Amazon Rainforest and the ecological impacts occurring as a result. It should be coming out next Friday (don't quote me on that)!
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