The Effects of Logging on Neotropical Forests
In the Brazilian Amazon alone from the year 1999 – 2002, approximately 12,000 square miles of forest underwent some form of logging (Kircher, 2011). Continuing this trend, approximately 20% of the tropical forest biome was selectively logged between the years 2000 and 2005 (Edwards et al., 2014). Logging is a main contributor to tropical deforestation, the cutting of forest and its replacement by another type of ecosystem (Kircher, 2011). Tropical deforestation is really driven by three main proximate causes; agricultural expansion, wood extraction, and infrastructure extension (Geist and Lambin 2001). Logging is component of each one of these practices.
The connection between wood extraction and logging is obvious and has many uses both domestically and industrially. Additionally, when pressure is on cultivators to expand their operations, the method of expansion is that of logging, in order to clear more land for cultivation or ranching. Similarly, area for infrastructure is gained in the same fashion and access roads for areas must be made by clearing trees. In this way, deforestation by logging is very prevalent in the tropics, an area where human presence is increasing and there is an ever-present need for more viable space for human occupation.
Logging is one of the main anthropogenic threats facing tropical rainforests, occurring at a rapid rate over a vast area. Previous studies have shown that logging decreases the density of dominant tree species, creates gaps in the canopy so additional light enters the forest, increases mortality of dominant tree species, favors the regeneration of pioneer species, and decreases tree species richness (Toyama et al., 2015). Most industrial logging is selective, as opposed to clear cut, meaning only specific tree species or trees of a specific height and girth are harvested. (Brodie et al., 2015). Although selective logging results in less damage than total deforestation, the damage to the canopy can leave tropical forests more at risk for drought or fire. In addition, high-damage levels from selective logging may alter ecological processes such as regeneration and succession (Asner et al., 2006).
Tropical organisms are sensitive to climatic variation, resulting in an increased vulnerability to habitat loss and fragmentation such as occurs with logging. In addition, many forest species are dependent on interactions with other species across different trophic levels. The complexity and specialization of these interactions mean that if one partner is lost, the other will be negatively impacted as well. Logging may also negatively impact ecosystem services such as carbon storage, temperature regulation, and watershed services (Edwards et al., 2014). In the temperate zones of North America and Europe, sustainable logging is practiced, in which harvested trees are replaced and ecosystems are replaced. In the tropics however, sustainable logging is not so simple (Kircher, 2011).
HISTORY OF LOGGING
Deforestation in the Amazon has been strongly linked to the economic status of countries and the fate of large landholders. Fearnside (2005) explains that individuals or companies that own a large amount of land are very sensitive to economic changes. Depending on economic factors such as interest rates, government subsidies on agriculture, and the rate and inflation of land prices, landholders will either been incentivized or discouraged from expanding their land. In the 1970’s and 1980’s, there were many tax incentives in Brazil to own more land and so these tax incentives led to high rates of deforestation and have continued to influence deforestation even today, although they have not been as frequently used since 1984. From 1978-1988, Brazilian Amazonian deforestation rates remained constant at 20.4 x 103 km2/ year. An economic recession in the early 1990s caused a drop in deforestation rates (11.1 x 103 km2/ year) and the following economic boom in 1995 raised deforestation rates to 29.1 x 103 km2/ year (Figure 1). Economic status and government subsidies highly influence the amount of land that is beneficial to own, which has had a large historical impact on deforestation rates in the tropics (Fernside 2015).
As to date, there have not been many studies examining how phylogenetic diversity is affected by human disturbances. This was recently changed, when one study published in 2015 examined the effect of logging on community phylogenetic structure in 32 different forests of Cambodia, which has a high rate of illegal logging. The results of this study showed that not only has logging increased over the years, but logging is associated with a decrease in the phylogenetic diversity of tree species (Toyama et al., 2015).
As with many sustainability issues, the history of the practice indicates a lack of concern for future generations’ ability to continue to use the resource. Management of the resource has been only concerned about the largest yield for the current year without forethought of how it will impact the future years’ yields and the government perpetuates this ideal with its regulations. For example, the Peruvian Ministry of Agriculture, the institution in charge of managing forests, frequently gave out permits for agriculture use in areas with the potential for long-term timber harvest (Torres, 2003). Additionally, the focus of the militarized Peruvian government in the 1970s was expansion of agricultural lands, (Barrantes and Trivelli, 1996) so timber companies were logging to extend agricultural lands as opposed to setting up land for permanent timber harvesting.
As well as a lack of proper regulation, there is also a history of minimal to no enforcement in the rainforests of Peru. A study by Smith et al. (2005) conducted a survey of the logging areas in Peru. They then classified the different areas as small-scale extractors, companies with multiple contracts, and companies with large contracts. Of these three division, they found that 62% of the small-scale extractors, 39% of companies with multiple contracts, and 14% of companies with large contracts had never been visited by enforcement agencies. They also found that even when violations were identified, no penalties were imposed.
CURRENT STATUS OF LOGGING
Tropical forests are currently being logged at a rate 2-3 times faster than the natural rate at which they could recover from. In order to combat tropical deforestation and reach a compromise with the logging industries, an international community, comprised mainly of countries belonging to the United Nations, has tried to promote industrial-scale Sustainable Forest Management (SFM). The goal of SFM is to balance the needs of the logging industries with the regeneration of tropical forests by offering incentives to participating governments. To do this, SFM provides guidelines for the number of trees to be harvested from one area, the size of a tree that can be cut down, and the length of time a section of forest should be given in order to regenerate. SFM is endorsed by the UN General Assembly, and is an activity under Reducing Emissions from Deforestation and Forest Degradation, which receives an estimated $28 billion – $31 billion annually. The regeneration processes that take place after forest loss are vital for promoting the growth of tree species in the same region. Unfortunately, current SFM protocols do not give tropical forests enough time for this regeneration. Several studies have shown that by SFM protocols, logging rotation cycles are half as short as they should be, the minimum diameters for felling are too small to preserve a big enough population of reproductive adults, harvest intensities are too high, and seed-tree retention rates are too low (Zimmerman et al., 2012).
Selective logging is thought to be a more sustainable method of logging. In this method, only certain species, ages, or numbers of trees are logged during one yield. In this way, some percentage of the natural composition and richness still remains and the forest can remain relatively undisturbed as compared to a clear-cut style harvest. A recent study by Asner et al. (2006) found that selective logging actually had a negative impact on Brazilian forests. They found that selective logging adds 60-123% more forest-area damage than was reported for deforestation alone during a three year time period. The authors hypothesize this is the result of selective logging done by high-damage operations. Additionally, the authors found that selective logging increases the gross annual anthropogenic flux of carbon by up to 25% when compared to deforestation alone. This is again most likely due to the high-damage operations that facilitate the majority of selective-logging in the Brazilian Amazon. This study illustrates that, unfortunately, a sustainable method of logging that has been proven successful in other regions has not been successful in South America, and in fact has an increased negative impact on rainforests and the larger global community.
The past two decades have seen an effort in policy reform on logging within Peruvian forests, with twenty-five million hectares being set aside and designated for permanent timber management. Additionally, the government introduced open competition to timber extraction which is based on bids for annual extraction fees with a minimum bid of 0.4 US$/hectare. This encourages the timber industry to increase their value of production per area rather than buying more areas to log. Additionally, every five years the logging practices of the industry will be evaluated for compliance with an approved Forest Management Plan and an Annual Operation Plan overseen by the Peruvian government (Smith et al., 2005).
As of 2003 however, the Peruvian government has had issues getting timber companies to comply with the new policies and submit the new required documentation. It is also difficult for logging companies with few resources to shift their practices and comply with the new regulations. It was also an option for companies to opt out of the new regulations which many large companies have done because they do not want to be subject to more stringent supervision by the government. Moreover, some of these companies also run illegal logging arrangements on the side. Finally, because companies do not pay the annual timber extraction fees, enforcement agencies cannot function as efficiently, since they are partly funded by timber taxes. Unfortunately, despite the good theoretical intentions of the new regulations, it is believed that illegal logging that increased significantly since the policy reform (Smith et al., 2005).
LOCAL AND GLOBAL ACTIONS TO COMBAT LOGGING
In Costa Rica, efforts have been made to preserve forests by placing them under the protection of protected areas or parks. Researchers were able to show that this conservation method does reduce deforestation compared to what it would have had the forest remained unprotected. One study used matching and regression methods to control for the differences in land characteristics with different policy arrangements throughout Costa Rica. The researchers then compared deforestation rates between these different groups. The results revealed that due to the creation of protected areas, as well as strict enforcement, Costa Rica is currently 25% covered in National Parks and deforestation steadily decreased from 1963 – 1996 (Robalino et al., 2015). For this type of conservation to work in larger countries, such as Brazil or Peru, lots of funding would be required to first set aside land for the parks and then reinforce protection of these areas.
Figure 3. Protected areas and parks in Costa Rica (Robalino et al., 2015).
Protected areas have begun to become more popular as a possibility for protecting forests from deforestation methods such as logging, and a recent 2016 study examined the effectiveness of protected areas (PAs) in the forests of Chile. A Chilean law in 1984 created a national public system of PAs, with the goal of forming a united conservation system to preserve Chilean natural resources. Currently, 18.7% of Chilean territory is sequestered in PAs. Most of this land is not ideal for agriculture and has soil with high erodibility, making it less desirable to be farmed. Because of this, Arriagada et al. (2016) determined that PAs only avoid deforestation when compared to private lands, as opposed to public lands (Arriagada et al., 2016).
One not-so-novel idea that still holds great merit is that of recycling. According to the University of Southern Indiana, each ton of paper that is recycled can save 17 trees. Americans use approximately 680 lbs of paper per person, per year. This means that if each American recycles all the paper he or she uses, about 6 trees would be saved per person, per year. Multiply those 6 trees by the approximately 319 million Americans living in the U.S. and that is over a trillion trees saved in a single year. This is a way to make a difference individually and on a small scale. In order to be effective, more awareness needs to be raised about the benefits of recycling and the consequences of deforestation. It is much harder to throw away paper products with the knowledge that one is contributing to the destruction of kinkajou or jaguar habitats.
With enough funding, a larger scale idea would be to offer subsidies to loggers to become park rangers. In this way, individuals could still make a living in an area they are familiar with but would be preventing deforestation as opposed to accelerating deforestation. Workers could be trained to plant trees and reinforce protection laws, grooming the rainforest back to its prime and eventually creating an economically viable park. The profit generated by the park could then be used to extend the subsidy program to other forests, with the idea of creating a large-scale park system similar to that of Costa Rica. Similarly to recycling, awareness is key to promoting understanding of the consequences of continuing to harvest the land without allowing for regeneration. More of the rainforest needs to be preserved if it is to continue to remain a beneficial ecosystem in the tropics.
Arriagada RA, Echeverria CM, Moya DE. Creating Protected Areas on Public Lands: Is ThereRoom for Additional Conservation? Webb E, ed. PLoS ONE. 2016;11(2):e0148094.doi:10.1371/journal.pone.0148094.
Asner GP, Broadbent EN, Oliveira PJC, Keller M, Knapp DE, Silva JNM. Condition and fate of logged forests in the Brazilian Amazon. Proceedings of the National Academy ofSciences. 2006;103(34):12947–12950.
Barrantes, R., Trivelli, C. Forests and Wood; Economic Analysis of the Peruvian Case. Consortium of Economic Research, Lima, Peru. 1996.
Brodie, J. F., Giordano, A. J., Zipkin, E. F., Bernard, H., Mohd-Azlan, J. and Ambu, L. (2015), Correlation and persistence of hunting and logging impacts on tropical rainforest mammals. Conservation Biology, 29: 110–121. doi:10.1111/cobi.12389
Edwards DP, Tobias JA, Sheil D, Meijaard E, Laurance WF. Maintaining ecosystem function and services in logged tropical forests. Trends in Ecology & Evolution. 2014;29(9):511–520.
Fearnside, P.M. 2005. Deforestation in Brazilian Amazonia: History, rates and consequences. Conservation Biology 19(3): 680-688.
Geist, Helmut J., and Eric F. Lambin. What drives tropical deforestation: a meta-analysis of proximate and underlying causes of deforestation based on subnational case study evidence. Louvain-la-Neuve: CIACO, 2001. Print.
Kricher, J. C. (2011). Tropical ecology. Princeton, NJ: Princeton University Press.
Robalino J, Sandoval C, Barton DN, Chacon A, Pfaff A. Evaluating Interactions of Forest Conservation Policies on Avoided Deforestation. Bauch CT, ed. PLoS ONE. 2015;10(4):e0124910. doi:10.1371/journal.pone.0124910.
Smith, J., Colan, V., Sobogal, C., Snook, L. (2005). Why Policy Reform Fails to Improve Logging Practices: The Role of Governance and Norms in Peru. Forest Policy and Economics, 8(4), 458-469.
Torres, M. The Tables of Dialogue and Concertacion Forestall (MDCF) and its Role in Forest Management and Institutionality. Pro Naturaleza. 2003
Toyama H, Kajisa T, Tagane S, et al. Effects of logging and recruitment on community phylogenetic structure in 32 permanent forest plots of Kampong Thom, Cambodia. Philosophical Transactions of the Royal Society B: Biological Sciences. 2015;370(1662):20140008. doi:10.1098/rstb.2014.0008.
Zimmerman, Barbara L., Kormos Cyril F.; Prospects for Sustainable Logging in Tropical Forests. BioScience 2012; 62 (5): 479-487. doi: 10.1525/bio.2012.62.5.9
Services, U. W. (n.d.). Paper Recycling Facts. Retrieved March 18, 2017, from https://www.usi.edu/recycle/paper-recycling-facts/