New methodology combines forestry and forest restoration – 01/08/2024 – Environment

The topic of forest restoration has gained prominence in recent years, both in the private sector and in the financial market, as well as in academia and among governments — mainly in the case of Brazil, which has made a commitment, since the Paris Agreement in 2015, to recover forests native 12 million hectares, that is, practically the equivalent of the territory of North Korea.

However, the initiatives still depend on the expensive process of planting trees and suffer from a lack of data on the growth of species and the total areas recovered.

Research published in the scientific journal Perspectives in Ecology and Conservation contributes to the advancement of the sector. It shows that the application of silvicultural methods in large-scale forest restoration projects can increase productivity and profitability, enabling supply to the timber industry and reducing pressure on natural biomes, such as the Amazon.

The scientists concluded that to achieve high productivity, restoration value chains must incorporate specific criteria involving a combination of native species; tree growth models that allow for the creation of management and harvesting plans with shorter deadlines; as well as combining the development of research and innovation with silvicultural treatments.

Led by forestry engineer Pedro Medrado Krainovic, the study created a model that projects the growth time of tree species native to the Atlantic Forest until they reach the “maturity” necessary to serve the timber industry.

Normally, growth rates for commercialization are defined according to the time it takes for the tree to reach 35 centimeters in diameter.

With the new method, the researchers achieved a 25% reduction in harvest time and a 38% increase in the basal area of ​​the trees. This represented an average anticipation of the ideal cut-off age of 13 years.

“We identify patterns of productivity versus time, which provides an indication of when a given species can be managed to obtain wood for the market. This helps to make large-scale forest restoration viable, improving its attractiveness for landowners and meeting global pro-climate agreements”, says Krainovic, who developed the work during his post-doctorate at the Tropical Forestry Laboratory (Lastrop) at the Luiz de Queiroz College of Agriculture, linked to the University of São Paulo.

“Based on our data, we projected a scenario in which silvicultural knowledge would be improved, providing a more attractive restoration for multiple interested parties”, says the researcher.

The project was conducted within the scope of the Biota-Fapesp Program. It also received support through four other projects, including the theme “Understanding restored forests for the benefit of people and nature – NewFor” and scholarships awarded to researchers Danilo Roberti de Almeida, Catherine Torres de Almeida and Angélica Faria de Resende, co-authors of the article.

The work was supervised by researchers Ricardo Ribeiro Rodrigues, from the Laboratory of Ecology and Forest Restoration, and Pedro Brancalion, linked to Lastrop and the Biota Síntese project.

Context

Even though it was chosen by the UN (United Nations) in 2022 as one of the ten global references in restoration, the Atlantic forest is the Brazilian biome that has lost the most forest area to date. Of the approximately 140 million hectares in Brazil, 24% of forest cover remains. Of this total, only 12% correspond to well-preserved forests (around 16.3 million hectares), according to data from the SOS Mata Atlântica Foundation.

However, efforts to contain deforestation have achieved positive results — a 42% drop between January and May 2023 compared to 2022 (from 12,166 hectares devastated to 7,088 hectares) —, in addition to the restoration actions having had an effect. In 2021, the UN established the Decade of Ecosystem Restoration until 2030, a call for the protection and revitalization of ecosystems around the world, for the benefit of people and nature.

“Restoration needs to have more data that provide favorable horizons for land use. For a public policy, it is necessary to have more information to support decision-making. And this article serves in several ways, including a list of species that can offer subsidies for the landowner. It opens a door to the enrichment of forest restoration with an economic purpose, more attractive and achieving multiple objectives, such as returning ecosystem services to certain areas”, explains Krainovic.

The results of the study should feed into the Refloresta-SP program, coordinated by the State Secretariat for the Environment, Infrastructure and Logistics, which has, among its objectives, ecological restoration, the recovery of degraded areas and the implementation of multifunctional forests and systems agroforestry.

Krainovic lived for 12 years in the Amazon and worked not only on projects to recover degraded areas using tree species with economic potential, but also on production chains of non-timber forest products that supply the cosmetics industry, such as seeds, essential oils and butter.

“A difference in my career is that I didn’t just stay in academia. I know what companies are like, the interface with traditional people in these production chains and the academic area”, he adds.

Step by step

The study analyzed a chronosequence of 13 unmanaged forest restoration areas distributed across the state of São Paulo, which were at different stages — between 6 and 96 years of planting. These regions have a diverse mix of native species —between 30 and 100—, which contributes to the promotion of ecosystem services with characteristics similar to those of spontaneous forests.

The scientists chose ten commercial native tree species, with different wood densities and historically exploited by the market. They are: guatambu (Balfourodendron riedelianum); jequitibá-rosa (Cariniana legalis); pink cedar (Cedrela fissilis); arariba (Centrolobium tomentosum); guarantã (Esenbeckia leiocarpa); Jatobá (Hymenaea courbaril); yellow acacia (Peltophorum dubium); purple IPE (Handroanthus impetiginosus); mastic (Astronium graveolens) and pau-vermelho or cabreúva (Myroxylon peruiferum).

Currently, most of these species are protected by law and cannot be legally sold because they are endemic to the Atlantic Forest and Cerrado and are threatened with extinction. However, some, such as Jatobá and Ipê-roxo, are still exploited in the Amazon.

Growth models were developed for each of them, based on data collected in the plantations. The GOL method (acronym for Growth-Oriented Logging) was applied to the growth curves to determine technical management criteria, including an optimized scenario focused on wood production.

After initial tests, the researchers modeled the growth in diameter and basal area of ​​each selected species along the chronosequence. Productivity scenarios were constructed using the 30% highest diameter values ​​found for each species by location and age, the “optimized scenario”, which represents the application of silvicultural treatments, providing greater productivity.

The species were classified using the time needed to reach 35 centimeters in diameter for harvesting into three bands: fast growing (less than 50 years), intermediate (50-70 years) and slow (greater than 70 years). When applying the GOL approach, they were grouped into rapid growth rate (less than 25 years); intermediate (25-50 years old); slow (50-75 years) and super slow (75-100 years).

The optimized scenario had the harvest time reduced by 25%, representing an average anticipation of the ideal harvest age of 13 years.

The exceptions were jequitibá-rosa and Jatobá, which had an extended ideal harvest period, but the basal area increased by more than 50%. On the other hand, pink cedar had a 36.6% reduction in the basal harvest area (646.6 cm2/tree), but an anticipation of 47 years in harvest time (51% faster than the GOL).

In total, nine of the ten species reached a diameter of 35 cm before the age of 60 — the exception was the guarantã, with a high wood density.

The study Potential native timber production in tropical forest restoration plantations can be found at: www.perspectecolconserv.com/en-potential-native-timber-production-in-avance-S2530064423000640.