Tropical Reforestation

Tree Meditation
Trees are somehow a focus for my life.  Ayurveda teaches that I should be like a tree: no-harm, no killing, no lying, no stealing, no sexual misconduct, no intoxicants.  Simple clean food offered freely, with fresh air and rain.  And a place to stand and grow - upward and downward.

Earth molds water.  Water nourishes trees.  Trees touch the earth and feel the air.  Trees stand apart from all philosophy, and yet are subject to our philosophy, our economy.  Strange that in my job I plan the cutting of hundreds of trees from computer documents and databases. Somehow I am both, I have my roots in the reality of trees and mud, but my arms in the ethereal computer worlds of planning and economy, laws.

Can I do something to balance the world, something electronic for the trees?

Forest Reforestation
There are problems with many reforestation efforts. Monocultures that don't help local people, protests around the world against REDD+.  In Japan, people are waking up to the problem.  (Link)  The problem of monoculture or few species planted in US cities has led to invasive insect pests wiping out large areas, for example in Worcester, MA.  The International Society of Arboriculture says the goal should be to follow the 20% rule (max 20% of any genus/species).

Example solutions: Health in Harmony listen to people. They give people healthcare, pay them to plant and monitor forest.  Other groups like Eden also pay people to plant.  Trees for the Future tries to create sustainable agroforestry.  Search engine ecosia donates money to these and other organizations.

But I have concerns about cost effectiveness and the ability to scale.  TFTF has only helped a few thousand farmers in the 30 years they've been around.  But CharityNavigator rates these groups highly; they have good governance, but they may not be as effective.

Policy action to improve REDD+ payments could make a huge difference, but the scale is too big for me to think about, and maybe for anyone. There will always be problems with a system that big.  The Effective Altruism community's assessment of Coalition of Rainforest Nations (CoRN) tries in vain to wrap their analysis around policy.  Policy is just too amorphous to apply straightforward risk and return.

WRI's Global Forest Tracker (10 year report on deforestation) will be important to measure and monitor leakage.  Mondabay also has good rainforest statistics page.

WRI supports restoration with venture capital as a way to scale, it is unclear how this makes money. they speak in corporate-ease, another example of how the real work is in board rooms or on the ground? Its hard to tell.

Ecosia has nice on-the-ground videos showing the work they support.

Conclusion
I need to research more, learn more.  Restoration is a passion project for me, but to be professional it may need to be something like WRI or EDF. But i'm not a corporate person, being in the field is what inspires me.  Maybe, like a tree, I can grow from the earth and reach into board rooms?

REDD+

[A note on REDD+]

During the negotiations for the Kyoto Protocol the inclusion of tropical forest management was debated but eventually dropped due to anticipated methodological difficulties in establishing – in particular – additionality and leakage (detrimental effects outside of the project area attributable to project activities). Eventually, the national forest monitoring system was introduced, with elements of measurement, reporting and verification (MRV).

Reference levels are a key component for any national REDD+ program and critical in at least two aspects. First, they serve as a baseline for measuring the success of REDD+ programs in reducing greenhouse gas emissions from forests. Second, they are available for examination by the international community to assess the reported emission reductions or enhanced removals. In that sense it establishes the confidence of the international community in the national REDD+ program. The results measured against these baselines may be eligible for results-based payments.]

The Theory and the Reality of Shelterbelt Afforestation Projects

The Theory of Shelterbelts

The Reality

Introduction:  dust bowl, us efforts

Following the dust bowl years in the U.S. the government planted 220 million trees in a strip 100 miles wide, stretching 18,600 miles from Canada to the Brazos river.  1935-1942  Today, the growth and vigor of many trees has declined due to close spacing, age, and invasion of undesirable short-lived trees.  Wikipedia.

There are currently two major afforestation programs, one in China, and one in the Sahel.

Great Green Wall in China. 

This project aims to afforest 90 million hectares and eventually contain 100 billion trees in a 4500km belt.

A recent paper by Tan (2014) found decreased dust transport due to the plantings so far.  But independent Chinese media reported in 2013 that dust storms were increasing:  For centuries in northern China, annual sandstorms, called the Yellow Dragon, have been ripping through the city.  Wind erosion is obvious and most pronounced in spring, when sandstorms are common and the vegetation is still absent or dormant after severe winter temperatures. Sandstorms have increased in the last few years, calling into question whether the Great Green Wall is working.

Liu Tuo, head of the desertification control office in the state forestry administration, is of the opinion that there are huge gaps in the country's efforts to reclaim the land that has become desert. At present there are around 1.73 million sq kilometers that have become desert in China, of which 530,000 km2 are treatable. But at the present rate of treating 1,717 km2 per year, it would take 300 years to reclaim the land that has become desert.  

Background
In early times, Korqin was not a semi-desert, but savannah-type woodland, in transition between dense forest and the steppe zone. The rolling sand-sheet was deposited during the last glacial period (12000 years BP). During 10,000 years of vegetation growth, thick dark topsoil developed. Since historical times, the region has gone through several cycles of man-induced desertification and subsequent recovery, when human pressure lessened. Fertile dark topsoil vanished and extensive dune fields gradually build up.  Overgrazing (by cattle, goats, sheep, camels, horses), clearing of land for agriculture and over-cutting of trees and shrubs in this vulnerable ecosystem have resulted in an increasingly severe land degradation and desertification.

Other Approaches?

There are many who do not believe the Green Wall is an appropriate solution to China’s desertification problems. Gao Yuchuan, the Forest Bureau head of Jingbian County, Shanxi, stated that “planting for 10 years is not as good as enclosure for one year,” referring to the alternative non-invasive restoration technique that fences off (encloses) a degraded area for two years to allow the land to restore itself.  Soil fertility, already critically low, has shown a sharp decline as all organic residues from crops are removed for fuel and fodder during wintertime. Willow and poplar stands are pollarded in autumn, before leaf fall, for the same purpose. The continuous removal of potential nutrients to the soil is not balanced by the relatively small amounts of manure and inorganic fertiliser applied to crops.

Problems

 Jiang Gaoming, an ecologist from the Chinese Academy of Sciences and proponent of enclosure, says that “planting trees in arid and semi-arid land violates [ecological] principles”.The worry is that the fragile land cannot support such massive, forced growth. Tree growth in Korqin is largely dependent on the presence of a high groundwater table, fed by percolation and inflow from the western and southern mountainous areas. The long-term trend of a decreasing depth of the groundwater table is due to an increasing demand for water to irrigate crops and for human and industrial needs. If the trees succeed in taking root, they could soak up large amounts of groundwater, which would be extremely problematic for arid regions like northern China.  For example, in Minqin, an area in north-western China, studies showed that groundwater levels have dropped by 12–19 metres since the advent of the project.

Progress So Far

As of 2009 China’s planted forest covered more than 500,000 square kilometers (increasing tree cover from 12% to 18%) – the largest artificial forest in the world.However, of the 53,000 hectares planted that year, a quarter died. In 2008 winter storms destroyed 10% of the new forest stock, causing the World Bank to advise China to focus more on quality rather than quantity in its stock species.  FAO report

But the program’s widespread tree planting campaigns typically allot only one or two species of tree to an area. Professor Jiang wrote in a 2009 Epoch Times article, “In Ningxia, for example, 70 percent of the trees planted were poplar and willow. In 2000, one billion poplar trees were lost to a disease (Anoplophora), wiping out 20 years of planting efforts.”  FAO report followup

More criticisms:  Wikipedia.

Great Green Wall in Africa - the Sahel

The Great Green Wall initiative is much more nuanced than simply planting a belt of trees across the continent: “Behind the name or the brand ‘Great Green Wall,’ different people see different things. Some people saw just a stripe of trees from east to west, but that has never been our vision,” he says. “In Niger, Mali, and Burkina Faso . . . natural regeneration managed by farmers has yielded great results. We want to replicate and scale up these achievements across the region. It’s very possible to restore trees to a landscape and to restore agroforestry practices without planting any trees. This is also a sustainable way of regenerating agroforestry and parkland.”

But it should be noted that the Great Green Wall is not designed to prevent the Sahara Desert from expanding. “We are not fighting the desert,” he says. “In the majority of the areas we are working in these 11 countries, the desert is not advancing. The [Sahara] Desert is a very stable ecosystem. Of course, there are some areas on the margins—for instance in Senegal, Mauritania, and Nigeria—where there are some sand movements. But from a geographic perspective, over time the desert has been relatively stable in this area.” (Source)

But some authors advocate  "a shift from planting trees in the GGW to utilizing shrubs (e.g., Leptospermum scoparium, Boscia senegalensis, Grewia flava, Euclea undulata or Diospyros lycioides), which would have multiple benefits, including having a faster growth rate and proving the basis for silvo-pastoral livelihoods based on bee-keeping and honey production.” (Connors and Ford, 2014 Sustainability)

To Burn or Decay? What is the best management practice to deal with excess biomass?

 Conventional forest restoration in Western pine ecosystems involves reduction of biomass through thinning, which is sometimes followed by prescribed burning to further reduce fuels.  Burning slash piles sterilizes soil patches and doesn't decrease overall site litter, so broad-scale prescribed burns have traditionally been the best management practice to reduce fuel loads.

Passing over the discussion of what was historically "natural," is fire the best tool for increasing site productivity?

Apparently not.  Duff burning kills fungi, small roots, and (obviously) removes duff. “EMF mortality and complete duff reduction after fire have been implicated with poor tree survival and slow stand recovery in forest ecosystems world-wide.”  (Smith, McKay, Brenner, mcIver, Spatafora.  2005: Early impacts of forest restoration treatments on the ectomycorrhizal fungal community and fine root biomass in a mixed conifer forest.  (PDF)

As Stametz and others have pointed out, burning is not the best use of available resources: fire volatilizes stored nutrients such as nitrogen and organic carbon (N and SOC).  Fire can also form hydrophobic soil crusts, kill flora and fauna, decrease soil microbiota (important for decomposition), destroy tree roots, mycelial networks, and sometimes mature trees.  In contrast, decomposing organic material could increase site productivity.


Permaculture forest restoration?
Restoration projects proceed with multiple goals, either explicit or implicit.  One such goal has been the return of historical fire to degraded forests.  According to a large body of research, at least some pine forests historically experienced short return-interval, low-intensity fire.  However, using this to justify current prescribed fire approaches assumes that we can --and should-- attempt to replicate historical ecosystems.  I believe it is a fallacy to assume that ecosystems, like species, must be maintained in the face of changing environmental conditions; paleoecology clearly shows that species migrated independently throughout prehistory, indicating that the ecosystems we see today are only contingent associations of species; there may be better arrangements of species and better ways of managing ecosystems than relying on historical norms.

That being said, there are even better reasons to question prescribed fire in forest restoration.  If we abandon the idea of mimicking natural disturbances we are free to innovate more productive restoration methods.  For example, Permaculture-inspired ideas of maximizing species diversity and ecosystem services could inspire a new type of forest restoration.  I envisage a restoration program designed to optimize current site conditions rather than recreate history...

What Controls Decomposition Rate in Conifer Forests?

Source: Litter decomposition, climate, and litter quality. Link.

Nutrients:  Mn and N

Manganese and Nitrogen control forest decomposition, but in an unexpected way. Mn is an essential component of ligninolytic enzymes important for degrading litter in the later stages of decomposition.  But high available N can limit decomposition. The most efficient degraders of lignin and humic acids are wood-rotting or litter-decomposing white-rot fungi (Hintikka 1970; Hatakka 2001).  For several of the lignin-degrading white-rot fungi, high concentrations of low-molecular weight N compounds suppress the synthesis of the lignin-degrading enzymes (Keyser et al. 1978; Eriksson et al. 1990; Carreiro et al. 2000). 

Further, N has repeatedly been reported to react with remains of degrading lignin to form recalcitrant condensation products. Such products form chemically (Vahtras 1982; Stevenson 1982) rather than biologically.  Spaccini (1999) suggested that such bonds create a hydrophobic surface thereby resisting decomposition. The higher the concentrations of lignin and N in a litter material the more likely it seems that such covalent bonds will be formed. Using 106 sets of foliar litter comprising 21 tree species (both coniferous and deciduous) representing a wide range in chemical composition, Berg (2000) found a highly significant negative relationship between limit values and initial N concentrations in litter.

Many examples exist in which addition of N to a N-deficient system slows down decomposition, especially where organic matter with high lignin content is present (Verhoef and Brussaard, 1990; Carreiro et al., 2000). Nitrogen and other fertilizers may negatively influence specific groups of organisms, particularly microbes.  Any shift in microbial composition can have a negative effect on other soil fauna.  As a result, decomposition and mineralization may decrease. Additionally, plants can compete successfully with decomposers for nutrients.  (Neher 2003.)

What about pH?

In a review of 58 studies, Wardle (1998) found that temporal variability in soil carbon (C) was related most closely to soil N content in forests and soil pH in arable and grassland ecosystems. (Neher 2003.)

But a study by Parn et al adding ash to a pine forest to increase soil pH did not observe increased decomposition.  A large meta-review noted that 22-85% of treatment trials have failed to affect decomposition: “This analysis shows that Ca additions are not universally beneficial and provides insight into when Ca additions to forest soils are likely to be most effective." (Evaluating the effects of liming and wood-ash treatment on forest ecosystems through systematic meta-analysis. Carolyn Reid, Shaun A. Watmough)

Decomposition Rate and Ecosystem Integrity

Neher 2003 "Effects of disturbance and ecosystem on decomposition." is a great review of this topic.  (PDF)  They conclude that "decomposition of organic matter is a useful indicator of soil condition because it is measured easily and serves as integrator of the collective activities of organisms within the soil food web."  For example, slowing rates of decomposition serve as an early warning sign of pathology in forest ecosystems (Bormann and Likens 1979),  A difference in decomposition rate between similar sites implies either a change in the decomposer community or quality of the biotic and abiotic resources at a site. 

This WSU website has a great review of pine forest decomposition.

What stand density is optimal in Ponderosa pine forest restoration?

 In my humble opinion, there is really only one chart needed to answer the question of what density is best for Ponderosa pine trees:

Source: The role of stand density on growth efficiency, leaf area index, and resin flow in southwestern ponderosa pine forests.  McDowell, Adams, Bailey, and Kolb.  (link)

 The lower the basal area, the more trees grow.  Growth is especially important in drought-stressed trees because lower growth can weaken tree defenses.  The lowest treatment in this study reduced trees to 7 m2 ha-1, and trees in this treatment had the highest leaf area per tree, indicating that they were healthiest at the time of the study.

Leaf area of understory plants was also highest at the lowest stand densities:

Source: ibid.

However, in the interest of full disclosure, this chart also shows (in panel B) that total forest resource utilization, measured by total leaf area, is highest at medium tree densities.

Herbaceous Vegetation in Southwestern Pine Forests

Herbaceous forage in southwestern pine forests can be few and far between.  Especially in unnaturally-overgrown thickets, there is simply not enough light and too much acidic leaf needle litter to grow robust grasses and forbs.  The high carbon content and resistant nature of conifer bark and needles means that few nutrients are available to growing plants.  

Even when forest thinning restores natural stand densities, the recalcitrant accumulated biomass often seems to limit production.  There is simply too much carbon and it is clogging up microbial turnover of nutrients.  Sure, you'll find plenty of aboveground mushrooms and mycelial hypahe at work in the soil, but I have to wonder if there isn't a more productive alternate-stable state.

What is the limiting resource?  I've theorized that light may still be limiting when forests aren't thinned enough to create light gaps in the canopy.  But it also seems that the overabundance of carbon may be soaking up nitrogen.  In these nutrient-poor systems we typically find 'tolerator' species like sedges, that can eke out a frugal living in acidic conditions.

What about blueberries?  In some parts of the world, conifers and blueberries go together like apples and pie, but in many of the southwestern mountain ranges we have no native Vaccinium.  I'm still not sure why, except that they seem to prefer colder (moister?) climes than New Mexico can provide....

There are two species of Vaccinium in the southwest, with Vaccinium myrtillus much more common.  However, south of Santa Fe even this species only occurs at scattered locations in mixed conifer and subalpine forests.  These high-elevation forests are being rapidly lost to stand-replacing forest fires.  Even with current climate change, it is unlikely that extensive tracts of cooler forests will be able to regrow.

What about legumes?  Fabaceae are often able to supply their own nitrogen requirements and eventually supplement total ecosystem N.  But I'm surprised by how rarely I find good legumes in the forest.  Thermopsis is surprisingly rare, as are Lotus and I almost never find clovers growing in conifer needle duff.  

Robinia neomexicana seems to be one legume shrub that has found its way into a diversity of habitats, growing almost like a weedy in mountainous areas throughout the southwest.  

Seeding mixtures in forests typically use annual grasses, but I wonder if there isn't a Fabaceae that could dramatically enhance production to increase ground-cover, forage, pollinator, and wildlife habitat?  Should standard thin-and-chip treatments be supplemented with seeding efforts?

What about increasing disturbance to disrupt pine duff accumulation?  These thick, undecomposed layers and inhibit germination of many forbs...

Disturbance is good for productivity

Making a "moder" pine forest a little more like a "mull" prarie....

Timber Harvest Effect on Soil

The overall effect is a small loss in total soil carbon; both total carbon content and concentration decrease in the "forest floor," but not in the surface or deep mineral soils. 

Black dots are total carbon; white dots are carbon concentration.

The decrease in total forest floor carbon is greater in hardwood forests, although there is some evidence that it takes longer to rebound in conifer forests because of their lower litter production.

Citation:
Nave LE, Vance ED, Swanston CW, Curtis PS. Harvest impacts on soil carbon storage in temperate forests. Forest Ecology and Management. 2010;259(5):857–866.

Agroforestry: the "Evergreen Revolution"

Dr. Dennis Garrity spoke today at SENR about how agroforestry is transforming entire landscapes in Africa. Dr. Garrity detailed a number of ways farmers are growing more crops by cultivating trees in their field. The details differ, but usually involve a leguminous tree that can provide both fertilizer for the field and fodder for livestock. One such tree, Acacia (Faidherbia), has the amazing added benefit of loosing its leaves during the wet season when farmers grow crops. This is basically the perfect tree, providing timed inputs of fertilizer, light, and forage at just the times the crops, farmer, and livestock need them.

According to Dr. Garrity, Faidherbia does not grow in the wild and is dependent on human cultivation. But until 10 years ago, no one knew how to propagate the tree: farmers tended them when they found them, but attempts to plant seeds or take cuttings had failed. Once researchers from the World Agroforestry Centre developed a cheap and easy way to propagate Faidherbia, its use has been rapidly adopted, especially in the Sahel region of Africa, where millions of hectares have been transformed.

Many of the questions from the audience focussed on possible problems and objections to this agronomic technique. What if pests wiped out the tree, or used the tree as refuges? If it was so good, why hadn't farmers adopted it before? What would happen when commercial farms replaced small holders? Some of these questions had initially occurred to me as well, but after reflection, the question I was most interested to ask would have focussed on what this example of agroforestry innovation could teach us to look for in the future. How can we learn from this example to look for other species in other parts of the world that might become essential components of new agricultural systems that can increase diversity, resilience, and production for the 21st century?

The real insight of this talk is that productivity is not set in stone: humans can and should manage their environments to improve them over and above what is "natural".

This presentation has in-depth information on the spread of agroforestry in Niger.

This is a great agroforestry organization: http://www.plant-trees.org/about.htm