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Partial harvesting has been proposed as a key aspect to implementing ecosystem management in the Canadian boreal forest. We report on a replicated experiment located in boreal mixedwoods of Northwestern Quebec. In the winter of 2000–2001, two partial harvesting treatments, one using a dispersed pattern, and a second, which created a (400 m2) gap pattern, were applied to a 90-year-old aspen-dominated mixed stand. The design also included a clear cut and a control. Over the course of the following eight years, live tree, coarse woody debris, regeneration and ground beetles were inventoried at variable intervals. Our results indicate that all harvesting treatments created conditions favorable to balsam fir (Abies balsamea) sapling growth and trembling aspen (Populus tremuloides) sapling recruitment. However, balsam fir and trembling aspen regeneration and ground beetles response to gap cuts were closer to patterns observed in clear cuts than in dispersed harvesting. The underlying reasons for these differing patterns can be linked to factors associated with the contrasting light regimes created by the two partial harvesting treatments. The study confirms that partially harvesting is an ecologically sound approach in boreal mixedwoods and could contribute to maintaining the distribution of stand ages at the landscape level.

Extensive forest restoration is a key strategy to meet nature-based sustainable development goals and provide multiple social and environmental benefits 1 . Yet achieving forest restoration at scale requires cost-effective methods 2 . Tree planting in degraded landscapes is a popular but costly forest restoration method that often results in less biodiverse forests when compared to natural regeneration techniques under similar conditions 3 . Here we assess the current spatial distribution of pantropical natural forest (from 2000 to 2016) and use this to present a model of the potential for natural regeneration across tropical forested countries and biomes at a spatial resolution of 30 m. We estimate that an area of 215 million hectares—an area greater than the entire country of Mexico—has potential for natural forest regeneration, representing an above-ground carbon sequestration potential of 23.4 Gt C (range, 21.1–25.7 Gt) over 30 years. Five countries (Brazil, Indonesia, China, Mexico and Colombia) account for 52% of this estimated potential, showcasing the need for targeting restoration initiatives that leverage natural regeneration potential. Our results facilitate broader equitable decision-making processes that capitalize on the widespread opportunity for natural regeneration to help achieve national and global environmental agendas. An estimated area of 215 million hectares has the potential for natural forest regeneration across tropical forested countries and biomes, representing an above-ground carbon sequestration potential of 23.4 Gt C.

The potential of agroforestry systems (AFS) for atmospheric carbon sequestration in degraded tropical lands is of key interest for climate change and rural development policies. This study evaluated aboveground and soil (0–20 cm) carbon stocks of AFS, secondary forests (SF), conserved and logged mature forests, on 88 sites in the eastern Brazilian Amazon. Tree carbon stock was higher in young (< 10 years) and advanced (> 30 years) AFS (10.2 ± 2.0 and 47.2 ± 8.1 Mg ha−1, respectively) when compared to the same age SF (5.8 ± 2.5 and 26.5 ± 19.5 Mg ha−1). However, aboveground and total carbon stocks were statistically similar within the same age categories of AFS and SF, because shrub pool were higher in SF. Conserved mature forests had the highest carbon stocks (190.2 ± 11.0 Mg ha−1), and carbon stocks in logged mature forests (119.4 ± 5.1 Mg ha−1) were similar to the advanced stages of AFS (108.6 ± 7.5 Mg ha−1). Litter and soil organic carbon (SOC) did not differ significantly between land-use systems nor along succession. At 30 years, aboveground carbon recovery was 46% (± 16) in AFS and 35% (± 21) in SF. Vegetation structural diversity (measured by DBH and height variation) was a good predictor of aboveground carbon stocks. Our results show the potential of AFS for carbon recovery, especially in the tree pool at late stages of development. Structurally more complex AFS provide an alternative to recover degraded lands and to develop synergies between climate change mitigation, adaptation, and goods production in Amazon.

Multi-year studies comparing changes in litterfall biomass and nutrient inputs in sites under different restoration practices are lacking. We evaluated litterfall dynamics and nutrient inputs at 5 yr and after a decade of recovery in four treatments (natural regeneration—no planting, plantation—entire area planted, tree islands—planting in patches, and reference forest) at multiple sites in an agricultural landscape in southern Costa Rica. We inter-planted two native species (Terminalia amazonia and Vochysia guatemalensis) and two naturalized N-fixing species (Inga edulis and Erythrina poeppigiana) in plantation and island treatments. Although litterfall N was higher in plantations in the first sampling period, litter production and overall inputs of C, N, Ca, Mg, P, Cu, Mn, and Fe did not differ between island, plantation, or reference forest after a decade; however, all were greater than in natural regeneration. Potassium inputs were lower in the natural regeneration, intermediate in island and plantation, and greater in reference forest. The percentage of litterfall comprised by the N-fixing planted species declined by nearly two-thirds in both plantations and islands between sampling periods, while the percentage of V. guatemalensis more than doubled, and the percentage from naturally regenerated species increased from 27 to 47 percent in islands. Island and plantation treatments were equally effective at restoring litterfall and nutrient inputs to levels similar to the reference system. The nutrient input changed substantially over the 7-yr interval between measurements, reflecting shifts in vegetation composition and demonstrating how rapidly nutrient cycling dynamics can change in recovering forests.

Land degradation and rural poverty are widespread in the Eastern Brazilian Amazon. Slash-and-burn agriculture is the main source of livelihood in small farms but also a driver of degradation. In this context, Agroforestry Systems (AFS) are an alternative for climate change mitigation and land restoration, allying food security and ecosystem services reestablishment. We evaluated the increment of carbon stock (aboveground biomass, necromass, and soil) and standing litter nutrients in AFS and compared with natural succession. Treatments were established in 30 × 30 m plots with six repetitions (randomized block design) on a very degraded soil at UEMA School farm, in Eastern Amazon. In AFS, the 17 planted tree species of local interest (for fruit, timber, N-fixing) were associated with agricultural species and fertilized according to local standards. Carbon stock was measured in 2012 before the experiment setup (baseline) and in 2018. Aboveground carbon increment (Mg ha−1) was higher in AFS (26.79 ± 23.41) than in natural succession (1.13 ± 1.5), because of tree and shrub cover as a result of planting efforts. We found very high variability in plant development and carbon sequestration between plots. Soil organic carbon did not present increment between 2012 and 2018, and no differences between treatments were found in 2018. Species choice plays a keyhole for carbon sequestration and nutrient cycling reestablishment. Areas under natural succession presented very low resilience, evidencing the need for active restoration. Diverse agroforestry systems are an efficient strategy to restore forest cover on degraded soils of Amazon allying ecosystem services reestablishment and production.

In degraded tropical pastures, active restoration strategies have the potential to facilitate forest regrowth at rates that are faster than natural recovery, enhancing litterfall, and nutrient inputs to the forest floor. We evaluated litterfall and nutrient dynamics under four treatments: plantation (entire area planted), tree islands (planting in six patches of three sizes), control (same age natural regeneration), and young secondary forest (7-9-yr-old natural regeneration). Treatments were established in plots of 50 × 50 m at six replicate sites in southern Costa Rica and the annual litterfall production was measured 5 yr after treatment establishment. Planted species included two native timber-producing hardwoods (Terminalia amazonia and Vochysia guatemalensis) interplanted with two N-fixing species (Inga edulis and Erythrina poeppigiana). Litter production was highest in secondary forests (7.3 Mg/ha/yr) and plantations (6.3), intermediate in islands (3.5), and lowest in controls (1.4). Secondary forests had higher input of all nutrients except N when compared with the plantation plots. Inga contributed 70 percent of leaffall in the plantations, demonstrating the influence that one species can have on litter quantity and quality. Although tree islands had lower litterfall rates, they were similar to plantations in inputs of Mg, K, P, Zn, and Mn. Tree islands increased litter production and nutrient inputs more quickly than natural regeneration. In addition to being less resource intensive than conventional plantations, this planting design promotes a more rapid increase in litter diversity and more spatial heterogeneity, which can accelerate the rate of nutrient cycling and facilitate forest recovery. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.

Table 3 has been published incorrectly in the original publication of the article. The correct version of Table 3 is provided with this Correction.

 Amazon deforestation damages nature, people, and their closer biocultural relationship, eroding fundamental elements for its reproduction. The recognition and use of traditional knowledge to plan and implement restoration efforts are essential to its success. This study identified forest tree species of biocultural value for indigenous communities, quilombolas, and settled farmers in Maranhão state, eastern Brazilian Amazon. Semi-structured interviews, informal conversations, Free Lists, and guided walks were carried out in three different landscapes to identify species with ecological importance and/or use-value according to local communities’ perceptions. Eight categories of species use were defined (food, woody, medicinal, income, cultural, hunting, honey, and energy); and the Smith Salience Index (S) was utilized to identify species with higher importance. A total of 58 native trees (S > 0.1) were listed as biocultural species, five of which were cited for ecological importance only, without a use-value associated. The highest number of species with cultural salience (S > 0.1) was reported in the indigenous group (47), followed by settlers (11) and quilombolas (9). Among the indigenous, we identified a higher number of uses for the same species, and a remarkable spiritual relationship with plants from their cosmological vision. The reproduction of biocultural values in societies needs to receive more attention in the restoration science and praxis. The identification of species of biocultural value can serve as an important ally for the assertive design of conservation and restoration initiatives.

Tropical forests provide essential environmental services to human well-being. In the world, Brazil has the largest continuous area of these forests. However, in the state of Maranhão, in the eastern Amazon, only 24% of the original forest cover remains. We integrated and analyzed active fires, burned area, land use and land cover, rainfall, and surface temperature datasets to understand forest fragmentation and forest fire dynamics from a remote sensing approach. We found that forest cover in the Maranhão Amazon region had a net reduction of 31,302 km2 between 1985 and 2017, with 63% of losses occurring in forest core areas. Forest edges extent was reduced by 38%, while the size of isolated forest patches increased by 239%. Forest fires impacted, on average, around 1031 ± 695 km2 year−1 of forest edges between 2003 and 2017, the equivalent of 60% of the total burned forest in this period. Our results demonstrated that forest fragmentation is an important factor controlling temporal and spatial variability of forest fires in the eastern Amazon region. Thus, both directly and indirectly, forest fragmentation can compromise biodiversity and carbon stocks in this Amazon region.