20 Tree Planting

Why “New Trees”?

Trees are important to our environment. They could clean the air and regulate climate by storage carbon, capture rainwater and reduce the risk of natural disasters like floods and landslides, maintain the biodiversity, influence human health, and provide job opportunities.

However, trees are being taken from the planet through human activities. Here’s some deforestation facts from Earth. Org: the farming industry cleared estimated 81,081 square miles of forest for cattle and livestocks in order to keep the supply of beef. The palm oil industry produce chocolate, biscuits and household products result that “forest land equivalent to 300 football fields is being cleared every hour”^[1]. Data shows we loss around 10 million hectares of forest every year and deforestation contributes about 4.8 billion tonnes of carbon dioxide a year^[2]. Similar situation is faced by PNW forest. Defenders of wildlife suggests that not long ago, the region’s economy was dominated by timber, pulp and paper production and from the mid-1960s to the 1990s, industrial timber giants logged on both public and private forests in order to produce raw materials that could support the needs. “Switchback roads zig-zagging up the mountainsides built to access logging areas scarred the landscape, with soil and sediment eroding down the hillsides to foul rivers and streams (Gubosh^[3]).”

Why not “Planting”?

Planting trees seems to be useful solution to problems caused by tree logging: recover the logging place with some new trees. However, the thing may be much more complicated. When the trees are being logging, we not only take trees, but also take one of important part in forest ecosystem. However, when we planting trees we only give back the tree itself.

Planting Location

Location is one of the major factor that should be considered when planting new trees. Improper location will cause unintended negative effects. When consider planting location, natural conditions and social conditions should be considered.

Natural conditions

Natural conditions include climate conditions (weather, temperature, water), soil conditions and biological factors that directly decided whether trees could grow.

For natural grow forests, trees go through strictly natural selection within the conditions therefore they are naturally adapt to the surroundings environment while whether the planting trees could survive is a hard problem to solve. For example, Kodikara and the research team analyzed the planting program of Sri Lanka. In 2004, Sri Lanka spent about $13 million to plant mangrove trees in the lagoons and estuaries after the Indian Ocean tsunami. However, restoration project sites had survival levels ranging from 0 to 78 percent, with only three sites having survival levels above 50 percent. “Survival rates showed significant correlations with a range of soil parameters except soil pH. Disturbance and stress caused by cattle trampling, browsing, algal accumulation, and insect attacks, factors that may themselves relate to choosing sites with inappropriate topography and hydrology, were common to most sites ^[4]“. This inappropriate soil conditions for mangroves was caused by incorrect topography. As a result, the program did not achieve its intended environmental function.

Natural conditions of planting location not only influence tree survival, but also conflict with the natural resources demand of humans. Water supply is a great example of this conflicting between ecosystem and humans. Over a 10- to 15- year period, Grainfor-Green tree-planting program in China had successfully increased the forests cover by 32% and reducing soil erosion by 45% in southwestern. But in such a water limited area, the decrease of the ratio of river runoff to annual precipitation caused by the increase of evapotranspiration means the population will suffer water shortages if the water supply keep falling^[5]. 

Social conditions

Social conditions refer to the conditions that related to human, consider the political function or economy use of the land.

New planting trees may take up some residential area or vegetable fields that cause social inequality problems. When people plan to planting new trees, the location that are originally forest will be the best choice. However, the reason why the place is originally forest but later not is usually by human use like residential construction or agricultural production. Therefore, plant new trees on those place should cut down the original function and cause social inequality. For instance, in Cronon’s Trouble with Wilderness he talked about the ironies that Indians were forced to move out of their home land which people view as wilderness^[6].

Further more, although the taking up areas become forest, the program still couldn’t even fully cover the deforestation area. Similar area-taking-up situation happened in Grainfor-Green tree-planting program in China. In southwestern China, major forest protection and reforestation policies came into effect between 2000–2015 that region’s gross tree cover grew by 32%. However, when we look closer to the situation, the native forests even suffered a net loss of 6.6% because of the vegetarian land needs. When one vegetable field became artificial trees, another native forest was taken up into agriculture use. Therefore, the deforestation problem wasn’t solved, but was converted into another problem: plantation replaces old-growth forest^[7].

Tree Species

Tree species varies a lot. The greatest difference between natural species and artificial forests is that artificial forests will definitely choose the specie that grow the fastest. An example of problem caused by tree planting species is the fire in Similipal Tiger Reserve (STR) and other forests in Odisha in 2021. Eucalyptus trees planted may be among the reasons the reserve continues to be on fire 15 days after the first reported incident^[8].  In this case, the improper choice of tree species caused negative effects on climate.

Also, almost all the planting program choose only one specie of tree and the result forest are particularly  monocultures (including the example in southeastern China and Yellow river program) that lack biodiversity. Click to learn more about why biodiversity matters and the impacts of environment on biodiversity.

Tree Age

When we compare the natural grow forest with the new planting forest, tree age is an obvious difference: natural forests spend hundreds or even thousands of years to expand into a what we called forest, but planting tree just became organized programs decades ago. So what’s the difference between an old forest and a young forest?

Carbon storage is one of the main function of forests. OSU expert Beverly Law explained about how tree age related to the carbon storage in a Youtube video^[9] (you can watch the video below) called “The Surprising Truth behind Planting Trees and Climate Change.” according to her team’s research paper “Old-Growth Forests as Global Carbon Sinks” (2008) published on Nature^[10]. The research measured the amount of carbon storage of forests of different age. Surprisingly, they found that old forests do better job than young forests as carbon sink and young artificial forest even emit more carbon than it absorb due to respiration process. Therefore, planting trees may not reach our expected result of carbon neutral.

Program Problem: Lack Maintaining

Instead of the difference in trees, there are unintended problems that exist within the planting programs that could cause negative effects on forest functions.

For the same tree planting program in Sri Lanka, Kodikara and the research team also investigate the relationship between the survival rate and the post-care. They counted the survival rate of trees with and without post-maintenance respectively and found that the survival rate of mangrove trees was positively correlated with post-maintenance^[11]. Therefore, they conclude that post-care is also one of the reasons that cause the program to fail its goal. Planting tree is a common strategy of environmental protection that everyone should support. However, the reality of tree planting is much more complicated. This chapter will begin by discussing reasons for planting new trees and the benefits of new trees, then move to the unintended negative effects and caused factors. Finally, there are some suggestions based on what talked.

List of Negative Influences^[12]

• Reduced water supply
• Destruction of native grasslands and spread of invasive tree species
• Increase social inequality
• Displacement of farmland
• Increased deforestation

What to do?

Instead of tree planting

Pay more attention on old native forest protection instead of planting new trees. Old trees act excellent on climate adjusting, carbon storage and water storage. The spent on native forest protection worth better than new trees planting.

If tree planting

Make the goal clear. Instead of plant how many trees, set the goal based on planting reasons like how many trees could survive, how many water will being storage. A more functional goal could give people more space to think of the relationship between the trees and environment instead of simply planting trees and therefore consider deeper on the planting choices like locations, species and planting strategies.

Maintaining trees over the long term. Program does not finish after planting. Maintaining trees are one of the most decisive factor of whether the planting program will be success. Let every planted tree play its maximum function.