1 Introduction

Eucalyptus, a genus comprising over 700 species, is one of the most significant and widely planted forest trees globally. Native to Australia, Eucalyptus species have been introduced to various parts of the world, including Europe, Africa, Asia, and the Americas, due to their rapid growth, adaptability to diverse environmental conditions, and economic value. Eucalyptus plantations cover more than 22 million hectares worldwide, representing approximately 13.4% of global forest plantations (Hoogar et al., 2019; Hua et al., 2022). These trees are crucial for the timber, pulp, and paper industries, providing a sustainable source of raw materials (Tomé et al., 2021; Hua et al., 2022). Additionally, Eucalyptus species are used in agroforestry, ecological restoration, and as a source of essential oils and medicinal compounds (Santos et al., 2019; Kaur et al., 2021).

The cultivation of Eucalyptus outside its native range began in the 19th century, driven by the need for fast-growing trees to meet the increasing demand for wood and other forest products. Eucalyptus was first introduced to Europe, particularly the Iberian Peninsula, where it has become a dominant species in forestry (Tomé et al., 2021). The tree's ability to thrive in various soil and climatic conditions has facilitated its spread to other continents, including Africa, where it plays a significant role in social forestry and agroforestry programs (Bayle, 2019; Hoogar et al., 2019). In Brazil, Eucalyptus plantations are integral to the forestry sector, contributing to both economic development and ecological restoration efforts (Amazonas et al., 2018; Elli et al., 2020a). Despite its benefits, the expansion of Eucalyptus has also raised environmental concerns, such as water consumption, soil nutrient depletion, and impacts on local biodiversity (Bayle, 2019; Hoogar et al., 2019).

This study provides a comprehensive analysis of the role of Eucalyptus in global forestry. It summarizes the importance of Eucalyptus plantations worldwide by examining their economic, ecological, and social impacts, as well as their contributions to the forestry industry and environmental conservation; second, analyzes the opportunities and challenges associated with Eucalyptus cultivation, assessing both the benefits and drawbacks, including impacts on water resources, soil health, biodiversity, and their potential for climate change adaptation and mitigation; and provides policy and management recommendations based on the findings, offering guidelines for sustainable Eucalyptus plantation management that address both positive and negative aspects, including strategies for minimizing environmental impacts while maximizing economic and social benefits. By synthesizing current research and delivering a balanced perspective, this study aims to inform policymakers, forest managers, and researchers on best practices for utilizing Eucalyptus in global forestry.

2 Biology and Ecology of Eucalyptus

2.1 Description of the Eucalyptus genus, species diversity, and key characteristics

The Eucalyptus genus, belonging to the Myrtaceae family, is a hyper-diverse group of long-lived trees comprising more than 700 species. These species are predominantly native to Australia, where they dominate much of the woody vegetation (Alwadani et al., 2019; Santos et al., 2019). Eucalyptus species are known for their rapid growth, resilience, and ability to thrive in a variety of environmental conditions, which has led to their widespread cultivation globally, particularly in regions such as the Iberian Peninsula and California (Tomé et al., 2021; Yost et al., 2021). Key characteristics of Eucalyptus include their distinctive aromatic leaves, high oil content, and specialized metabolites such as formylated phloroglucinol compounds (FPCs), which play a crucial role in their defense mechanisms against herbivory and other biotic stresses (Santos et al., 2019).

2.2 Ecological roles and adaptations of Eucalyptus in native and non-native habitats

Eucalyptus species serve as foundation trees in their native Australian habitats, providing essential habitat and modulating ecosystem services (Murray et al., 2019; Bird et al., 2021). They exhibit high genetic diversity and adaptive potential, which allows them to thrive in diverse environmental conditions. This adaptability is evident in their ability to establish and naturalize in non-native regions such as California, where they have been planted for over 150 years and have become an integral part of the local ecosystem (Yost et al., 2021). The ecological success of Eucalyptus in both native and non-native habitats can be attributed to their specialized metabolites, such as FPCs, which enhance their ability to cope with abiotic and biotic stresses (Figure 1) (Santos et al., 2019). Additionally, Eucalyptus species have evolved complex mechanisms to manage reactive oxygen species (ROS), further contributing to their resilience and adaptability (Li et al., 2020).

Figure 1 Localization of FPCs in Eucalyptus camphora flower bud (A) and E. globulus stem (B) (Adopted from Santos et al., 2019) Image caption: A longitudinal section of a flower bud and transverse section of a stem were prepared for matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI). Corresponding ion maps of different FPCs are shown: yellow; m/z 493.2351; [M+K]+, green m/z511.2449; [M+K]+, pink m/z525.2249; [M+K]+, and a combination of all selected ions overlaid. FPCs are associated to the embedded glands, adjacent to the epidermis of the flower bud, to the embedded glands beneath the nectary, and to the stamens. For the stems, FPCs are localized to embedded glands within the cortex. All images are root mean square (RMS) normalized, with internal scaling of 50% for the ions m/z 493.2351 and 511.2449, and 25% for m/z 525.2249. Scale bar = 500 μM. C, cortex; P, pith; V, vascular tissue (Adopted from Santos et al., 2019)

Santos et al. (2019) utilizes MALDI-MSI to investigate the spatial distribution of formylated phloroglucinol compounds (FPCs) in Eucalyptus tissues, offering insights into their localized functions. The study confirms that FPCs are consistently associated with embedded glands in various tissues, highlighting their potential role in plant defense mechanisms. By mapping FPCs in both E. camphora flower buds and E. globulus stems, the research demonstrates a clear tissue-specific accumulation of these compounds, particularly in regions related to reproductive and vascular structures. This detailed localization underscores the ecological significance of FPCs in protecting critical plant tissues from environmental stresses, contributing to the broader understanding of secondary metabolite functions in Eucalyptus.

2.3 Overview of Eucalyptus growth patterns, reproductive strategies, and lifespan

Eucalyptus species are known for their fast growth rates and significant biomass production, making them valuable for both ecological restoration and commercial forestry (Amazonas et al., 2018; Bird et al., 2021). Their growth patterns are influenced by genetic factors, as evidenced by genome-wide association studies (GWAS) that have identified genes associated with growth traits such as tree height (Müller et al., 2018). Eucalyptus trees exhibit a range of reproductive strategies, including both sexual and asexual reproduction. Their ability to resprout after disturbances such as fire is a notable adaptation that contributes to their persistence and dominance in various landscapes (Tomé et al., 2021). The lifespan of Eucalyptus trees can vary widely among species, with some living for several decades to over a century, depending on environmental conditions and management practices (Alwadani et al., 2019; Santos et al., 2019).

In summary, the Eucalyptus genus is characterized by its high species diversity, ecological adaptability, and significant economic and ecological roles in both native and non-native habitats. Their growth patterns, reproductive strategies, and lifespan are influenced by a combination of genetic and environmental factors, making them a versatile and resilient group of trees.

3 Economic Importance of Eucalyptus

3.1 Role of Eucalyptus in the timber, pulp, and paper industries

Eucalyptus species play a significant role in the timber, pulp, and paper industries globally. Eucalyptus is a primary source of raw material for the pulp and paper industries, particularly in developed countries. The timber extracted from Eucalyptus plantations is used for solid wood products and engineered wood products (EWPs) such as particleboard, fibreboard, and plywood, due to its higher rigidity compared to most softwood species (Hua et al., 2022). In the Iberian Peninsula, Eucalyptus globulus is extensively harvested for the pulp industry, contributing significantly to the local economy (Tomé et al., 2021). Additionally, in Uruguay, Eucalyptus globulus plantations are primarily harvested for the pulp industry, with rotation lengths impacting wood production and economic returns (Resquin et al., 2022).

3.2 Economic benefits of Eucalyptus plantations in different regions

Eucalyptus plantations provide substantial economic benefits across various regions. In Vietnam, Eucalyptus plantations have been shown to generate the highest net present value (NPV) among other species, significantly contributing to rural livelihoods and development (Cuong et al., 2020). In India, Eucalyptus plantations are raised on diverse lands, including degraded and waterlogged areas, providing socioeconomic and industrial services such as timber, pulp, and essential oils (Kaur et al., 2021). In Europe, particularly in the Iberian Peninsula, Eucalyptus plantations are a major source of income for non-industrial owners, despite the environmental challenges associated with their expansion (Tomé et al., 2021). Furthermore, in Italy, there is a growing market for Eucalyptus firewood, with consumer willingness to pay influenced by factors such as energetic density and environmental concerns, indicating potential economic opportunities (Palmieri et al., 2020).

3.3 Comparison of Eucalyptus with other major forestry species in terms of yield and profitability

When compared to other major forestry species, Eucalyptus often demonstrates superior yield and profitability. In Vietnam, Eucalyptus plantations have shown the highest NPV, although Acacia mangium generated the greatest internal rate of return (IRR) (Cuong et al., 2020). In Uruguay, Eucalyptus globulus plantations, when managed with optimal rotation lengths, produce high volumes of wood and cellulose per hectare, although profitability may decrease with longer rotations (Resquin et al., 2022). Eucalyptus is also noted for its fast growth and high biomass production, making it a preferred species for meeting the increasing demand for wood products (Kaur et al., 2021). Additionally, mixed plantations of Eucalyptus and native species in Brazil have shown that Eucalyptus can yield nearly 75% of the basal area produced by monocultures, indicating its competitive advantage in mixed forestry systems (Amazonas et al., 2018).

In summary, Eucalyptus stands out in the forestry sector due to its significant contributions to the timber, pulp, and paper industries, its economic benefits across various regions, and its competitive yield and profitability compared to other forestry species. These attributes underscore the importance of Eucalyptus in global forestry and its potential for sustainable economic development.

4 Environmental Impact of Eucalyptus Plantations

4.1 Effects on soil health, water resources, and local ecosystems

Eucalyptus plantations have a significant impact on soil health, water resources, and local ecosystems. Studies have shown that Eucalyptus species can influence soil respiration rates, which are crucial for carbon cycling and soil fertility. For instance, non-native Eucalyptus species have been found to limit microbial decomposition and reduce soil respiration due to extreme soil moisture and temperature conditions, which can negatively affect soil health (Ontong et al., 2023). Additionally, Eucalyptus plantations tend to decrease soil fertility compared to native vegetation, as observed in various ecosystems (Castro-Díez et al., 2021).

Water resource management is another critical area affected by Eucalyptus plantations. These trees have been shown to increase evapotranspiration rates, leading to reduced streamflow and water availability in the surrounding areas. This effect is particularly pronounced in regions where Eucalyptus is planted in place of native grasslands, resulting in higher canopy interception and transpiration rates (Ferreto et al., 2020). Moreover, a meta-analysis comparing Eucalyptus and Pinus species found that Eucalyptus plantations generally have higher water use efficiency, which can exacerbate water scarcity issues in certain climates (White et al., 2022).

4.2 Controversies surrounding Eucalyptus as an invasive species in non-native regions

The introduction of Eucalyptus species outside their native range has sparked considerable debate due to their potential to become invasive and disrupt local ecosystems. Eucalyptus plantations are known to reduce local biodiversity, groundwater levels, and increase soil degradation and erosion (Meneses et al., 2022). These plantations can also alter the microbial communities in the soil, which can have cascading effects on nutrient cycling and soil health. For example, mixed Eucalyptus plantations with N2-fixing trees have been shown to enhance carbon and nitrogen cycling, but pure Eucalyptus plantations can lead to nutrient imbalances and soil degradation (Pereira et al., 2019).

Despite these concerns, some studies suggest that Eucalyptus does not always inhibit the growth of native species. For instance, research on the allelopathic effects of Eucalyptus globulus found that it does not significantly affect the germination of Polylepis subtusalbida, a keystone species in the Bolivian Andes, indicating that Eucalyptus removal projects for habitat restoration may not need to be as extensive as previously thought (Meneses et al., 2022).

4.3 The role of Eucalyptus in carbon sequestration and climate change mitigation

Eucalyptus plantations play a dual role in carbon sequestration and climate change mitigation. These fast-growing trees are often used in reforestation and afforestation projects to quickly rehabilitate degraded lands and sequester atmospheric carbon. Studies have shown that Eucalyptus plantations can store significant amounts of carbon in both biomass and soil. For example, mixed-species plantations of Eucalyptus and Castanopsis hystrix have been found to enhance carbon sequestration more effectively than mono-specific plantations, due to complementary ecological niches that maximize resource use and stand productivity (Wang et al., 2022).

Furthermore, Eucalyptus-based silvopastoral systems (SPS) in the Brazilian Cerrado have demonstrated the potential to store substantial amounts of soil organic carbon (SOC), although the effectiveness can vary depending on the specific land-use system and tree-planting configuration (Pinheiro et al., 2021). However, the long-term sustainability of these plantations under traditional silviculture regimes remains a concern, as continuous monoculture planting can lead to soil degradation and reduced carbon sequestration potential (Cheng et al., 2023).

In summary, while Eucalyptus plantations offer significant benefits for carbon sequestration and climate change mitigation, their environmental impacts on soil health, water resources, and local ecosystems must be carefully managed to ensure sustainable outcomes.

5 Eucalyptus in Agroforestry Systems

5.1 Integration of Eucalyptus into Agroforestry Practices

Integrating Eucalyptus into agroforestry systems involves combining Eucalyptus trees with agricultural crops or livestock on the same land. This practice aims to enhance resource utilization, improve soil health, and increase overall productivity. Eucalyptus, known for its fast growth and high biomass production, is a popular choice in agroforestry systems, particularly in regions like India and Brazil. For instance, in Tamil Nadu, India, Eucalyptus clones were intercropped with various crops such as pearl millet, sorghum, maize, sesame, small onions, green gram, and red gram, demonstrating the feasibility of such integrations (Ramesh et al., 2023). Similarly, in the Brazilian Amazon, Eucalyptus was integrated with pasture and crops, showing promising results in terms of pasture productivity and animal performance (Domiciano et al., 2020).

5.2 Benefits and challenges of using Eucalyptus in mixed-cropping systems

The integration of Eucalyptus in mixed-cropping systems offers several benefits, including improved soil properties, enhanced biodiversity, and increased carbon sequestration. Eucalyptus-based agroforestry systems have been shown to improve soil fertility and structure, reduce erosion, and enhance water retention (Fahad et al., 2022; Chavan et al., 2023). Additionally, these systems can provide economic benefits through diversified income sources from both timber and agricultural products (Chavan et al., 2023; Ramesh et al., 2023).

However, there are challenges associated with Eucalyptus in agroforestry. One significant issue is the allelopathic effect of Eucalyptus, which can inhibit the growth of certain crops due to the release of chemical compounds from its leaves and roots (Castle et al., 2021; Ramesh et al., 2023). Competition for light, water, and nutrients between Eucalyptus trees and crops can also pose challenges, potentially reducing crop yields (Nadir et al., 2018; Castle et al., 2021). Effective management practices, such as appropriate spacing and selection of compatible crop species, are crucial to mitigate these challenges and optimize the benefits of Eucalyptus agroforestry systems (Nadir et al., 2018; Dupraz et al., 2019).

5.3 Case examples of successful Eucalyptus agroforestry projects

Several successful Eucalyptus agroforestry projects highlight the potential of this practice. In Tamil Nadu, India, a study demonstrated that intercropping Eucalyptus with crops like red gram and small onions resulted in high gross and net incomes, as well as improved soil nutrient levels (Ramesh et al., 2023). Another example from the Indo-Gangetic Plains of India showed that Eucalyptus-based agroforestry systems significantly contributed to carbon sequestration, with Eucalyptus plantations sequestering up to 237.2 Mg C ha⁻¹ (Figure 2) (Chavan et al., 2023).

Figure 2 Total carbon stock (Mg ha−1) of Dhaincha–barley crop rotation in eucalyptus-based agroforestry system (3 m × 3 m) over a rotation of 8 years (Adopted from Chavan et al., 2023)

Chavan et al. (2023) presents a detailed breakdown of the total carbon stock in a eucalyptus-based agroforestry system with Dhaincha-barley crop rotation over eight years. The carbon sequestration contributions are divided among different components of the system, including the tree bole (116.92 Mg C ha⁻¹), branches (12.3 Mg C ha⁻¹), leaves (5.07 Mg C ha⁻¹), roots (32 Mg C ha⁻¹), and soil organic matter (SOM: 45.97 Mg C ha⁻¹). The total system carbon stock is 237 Mg C ha⁻¹. The study highlights the potential of integrating eucalyptus in agroforestry to enhance carbon sequestration compared to sole cropping, showing that eucalyptus increases total carbon stock by 2.8 times. This research underscores the significance of agroforestry in climate change mitigation efforts.

In the Brazilian Amazon, integrating Eucalyptus with pasture and crops in a crop-livestock-forestry system led to increased herbage accumulation and improved beef cattle productivity, showcasing the synergy between different components of the system (Domiciano et al., 2020). These case studies underscore the potential of Eucalyptus agroforestry systems to enhance productivity, improve environmental sustainability, and provide economic benefits to farmers.

By carefully managing the integration of Eucalyptus into agroforestry systems, it is possible to harness the benefits while addressing the associated challenges, thereby promoting sustainable and productive land-use practices.

6 Genetic Improvement and Breeding Programs

6.1 Advances in Eucalyptus breeding for disease resistance, growth rate, and wood quality

Recent advancements in Eucalyptus breeding have focused on enhancing disease resistance, growth rate, and wood quality through various genetic and genomic approaches. Genomic selection (GS) has shown promise in reducing breeding cycle times and increasing genetic gains. For instance, a study on Eucalyptus grandis demonstrated that GS could achieve genetic gains in wood density and fiber length significantly faster than traditional breeding methods, with efficiencies ranging from 1.20 to 1.62 times higher (Mphahlele et al., 2020). Similarly, in Eucalyptus benthamii, genomic selection models have improved the accuracy of trait predictions, particularly for wood density and growth traits, by capturing both additive and non-additive genetic variances (Paludeto et al., 2021).

Moreover, breeding programs have also targeted disease resistance. For example, genomic breeding strategies in Eucalyptus grandis have been developed to enhance tolerance to pests like the Leptocybe gall wasp and fungal diseases such as Botryosphaeria and Teratosphaeria, achieving expected genetic gains of 10% for Lepto tolerance and 12.4% for diameter growth (Mphahlele et al., 2021). These advancements highlight the potential of genomic tools in accelerating the breeding process and improving key traits in Eucalyptus species.

6.2 Role of biotechnology in enhancing Eucalyptus traits

Biotechnology has played a crucial role in enhancing Eucalyptus traits, particularly through genetic engineering and genome editing techniques. The use of CRISPR/Cas9 technology has enabled precise genetic modifications, facilitating the improvement of germplasm resources. For instance, a study on Eucalyptus urophylla × Eucalyptus grandis demonstrated the successful application of CRISPR/Cas9 for genetic transformation, which can significantly enhance plantation productivity and wood quality (Wang et al., 2021). This method allows for the efficient selection of positive transformed progenies, thereby streamlining the breeding process.

Additionally, genome-wide association studies (GWAS) and genomic prediction models have been employed to identify and select for desirable traits. Joint-GWAS approaches, which combine data from multiple breeding populations, have been particularly effective in detecting significant genetic associations for growth traits, explaining up to 20% of the phenotypic variance (Müller et al., 2018). These biotechnological advancements provide powerful tools for the precise and efficient improvement of Eucalyptus traits.

6.3 Challenges and future directions in Eucalyptus breeding

Despite the significant progress in Eucalyptus breeding, several challenges remain. One major challenge is the integration of genomic selection into operational breeding programs. Adjustments in breeding strategies and infrastructure are necessary to fully realize the potential genetic gains from GS (Mphahlele et al., 2020). Additionally, the complexity of genetic interactions, such as genotype by environment (GxE) interactions, poses a challenge for breeding programs. For example, studies on Eucalyptus dunnii have shown that while selection across multiple environments is feasible, certain environments require further investigation to understand the drivers of GxE interactions (Bird et al., 2021).

Future directions in Eucalyptus breeding should focus on addressing these challenges by developing more robust and adaptable breeding strategies. This includes leveraging advanced biotechnological tools, such as CRISPR/Cas9 and GWAS, to enhance the precision and efficiency of breeding programs. Furthermore, expanding the genetic base by incorporating diverse Eucalyptus species and hybrids can provide additional genetic resources for improving disease resistance, growth rate, and wood quality (Lima et al., 2019; Ibarra et al., 2023). By addressing these challenges and exploring new avenues, Eucalyptus breeding programs can continue to make significant strides in enhancing the productivity and sustainability of global forestry.

7 Case Study: Eucalyptus Plantations in Brazil

7.1 History and development of Eucalyptus plantations in Brazil

Eucalyptus plantations have a long history in Brazil, dating back to the early 20th century when the species was first introduced for its fast growth and adaptability to various climatic conditions. Over the decades, Eucalyptus has become a cornerstone of the Brazilian forestry sector, representing 73% of the total planted forests in the country (Silva et al., 2020). The development of these plantations has been driven by the high demand for wood products, leading to intensive management practices that have significantly increased wood production per unit of land (McMahon et al., 2019). The Brazilian roundwood industry, heavily reliant on Eucalyptus, is now one of the most productive in the world (Silva et al., 2020).

7.2 Economic and environmental impact of Eucalyptus in Brazilian forestry

Economically, Eucalyptus plantations are vital to Brazil's forestry sector, contributing significantly to the country's wood production and export revenues. The plantations have been shown to maintain wood production over multiple harvest cycles, with management intensification playing a crucial role in sustaining productivity (McMahon and Jackson, 2019). However, the environmental impact of these plantations is multifaceted. On one hand, Eucalyptus plantations have been associated with high water use, which can negatively impact water availability for other users (Ferraz et al., 2019). Studies have shown that evapotranspiration in these plantations often exceeds 80% of precipitation, leading to reduced streamflow and potential conflicts over water resources (Ferraz et al., 2019). On the other hand, Eucalyptus plantations can also contribute positively to soil nutrient stocks, with research indicating that soil nutrients are not significantly depleted over time and may even increase in some cases (McMahon et al., 2019).

7.3 Lessons learned and future prospects for Eucalyptus in Brazil

Several lessons have been learned from the extensive cultivation of Eucalyptus in Brazil. One key insight is the importance of adapting plantation management to local environmental conditions to mitigate negative impacts and enhance productivity. For instance, the use of drought-tolerant genotypes and improved soil management practices can help reduce growth gaps caused by water deficits, which are a major limiting factor in many regions (Elli et al., 2019). Additionally, mixed plantations of Eucalyptus and native species have shown promise as a strategy for balancing wood production with ecological restoration, providing a potential model for sustainable forestry in the tropics (Amazonas et al., 2018).

Looking to the future, the prospects for Eucalyptus in Brazil will likely depend on the ability to address environmental concerns while continuing to meet economic demands. Climate change poses a significant challenge, with projections indicating site-specific impacts on Eucalyptus productivity across Brazil (Elli et al., 2020a). Therefore, ongoing research and adaptive management strategies will be essential to ensure the sustainability of Eucalyptus plantations in the face of changing climatic conditions (Elli et al., 2020b). Moreover, the potential for Eucalyptus plantations to serve as hybrid ecosystems that support biodiversity conservation highlights the need for integrated management approaches that consider both production and ecological values (Tavares et al., 2019).

8 Conservation and Biodiversity Concerns

8.1 Impact of eucalyptus plantations on native biodiversity

Eucalyptus plantations have been shown to impact native biodiversity in various ways. Studies indicate that while Eucalyptus monocultures can negatively affect native species, mixed plantations of Eucalyptus and native trees can mitigate some of these impacts. For instance, mixed plantations in the Atlantic Forest region of Brazil demonstrated that Eucalyptus trees in high diversity mixtures grew larger and yielded nearly 75% of the basal area produced by Eucalyptus monocultures, even though they accounted for only 50% of seedlings in the mixtures. However, Eucalyptus negatively affected the growth of native species proportionate to their growth rate (Amazonas et al., 2018). Additionally, Eucalyptus plantations in the Brazilian Atlantic Forest were found to harbor a less diverse assemblage of fruit-feeding butterflies compared to native forest fragments, indicating that these plantations cannot substitute forests for a vast majority of butterfly species (Vasconcelos et al., 2019). Furthermore, Eucalyptus plantations were classified as hybrid ecosystems, sharing species with both historical forests and pastures, but were distinct enough not to be classified as either, highlighting their potential conservation value as complementary habitats (Tavares et al., 2019).

8.2 Strategies for mitigating biodiversity loss in eucalyptus-dominated landscapes

To mitigate biodiversity loss in Eucalyptus-dominated landscapes, several strategies have been proposed. One effective approach is the intercropping of Eucalyptus with native tree species. Research in southern China showed that intercropping plantations with not less than 30% native trees were more favorable for the long-term survival and growth of both planted Eucalyptus and native trees, and provided better conditions for the natural immigration of other native trees, leading to a healthier plant community (Wang et al., 2023). Additionally, maintaining or restoring native forest areas within or around Eucalyptus plantations can enhance biodiversity. For example, dung beetle community composition in Eucalyptus plantations was largely explained by the surrounding native forest cover, suggesting that integrated management could improve biodiversity without reducing timber production (Beiroz et al., 2019). Moreover, studies have shown that Eucalyptus plantations do not inhibit the germination of certain native species, such as Polylepis subtusalbida, indicating that restoration projects aiming to remove Eucalyptus can succeed without the resource-consuming removal of leaf litter (Meneses et al., 2022).

8.3 Role of eucalyptus in conservation programs and habitat restoration

Eucalyptus plantations can play a role in conservation programs and habitat restoration, particularly when integrated with native species. Mixed plantations of Eucalyptus and native trees have been shown to be a viable silvicultural solution for offsetting the costs of forest landscape restoration in the tropics, combining biodiversity recovery with wood production (Amazonas et al., 2021). Additionally, Eucalyptus plantations can contribute to the conservation of certain species in fragmented landscapes. For instance, small forest fragments within Eucalyptus plantations were found to harbor a significant portion of regional butterfly diversity, reinforcing the importance of preserving these fragments and increasing landscape connectivity for conservation purposes (Vasconcelos et al., 2019). Furthermore, afforestation with native species mixtures has been shown to restore vegetation and most aspects of soil biodiversity more effectively than Eucalyptus monocultures, suggesting that native species mixtures have greater potential to reach similar levels of biodiversity as natural forests (Wu et al., 2021).

In summary, while Eucalyptus plantations can negatively impact native biodiversity, strategies such as intercropping with native species and maintaining native forest areas can mitigate these effects. Eucalyptus can also play a role in conservation and habitat restoration when integrated with native species, contributing to biodiversity recovery and ecosystem health.

9 Policy and Management Recommendations

9.1 Global policies and regulations governing Eucalyptus cultivation

Eucalyptus species, originally native to Australia, have been widely planted across various continents due to their fast growth and economic benefits. However, their cultivation is subject to diverse policies and regulations aimed at balancing economic gains with environmental sustainability. In Europe, particularly in the Iberian Peninsula, Eucalyptus globulus is extensively planted, contributing significantly to the pulp and paper industries. The expansion of Eucalyptus plantations in Europe is governed by policies that aim to mitigate negative environmental impacts while promoting economic benefits (Tomé et al., 2021). In Brazil, climate change projections and their impact on Eucalyptus productivity are considered in policy-making to ensure sustainable forestry practices under changing climatic conditions (Elli et al., 2020a). In China, policies focus on managing the spatial distribution and productivity of Eucalyptus plantations to address concerns about soil fertility and sustainability (Zhang and Wang, 2021).

9.2 Best management practices for sustainable Eucalyptus forestry

Sustainable management of Eucalyptus plantations involves practices that enhance productivity while minimizing environmental impacts. In the Iberian Peninsula, forest management practices at both stand and landscape levels are recommended to reduce negative impacts such as biodiversity loss and soil degradation (Tomé et al., 2021). In China, it is suggested that proper crop rotation and improved management measures can mitigate the high soil fertility consumption associated with Eucalyptus plantations, allowing for the reuse of abandoned plantations (Zhang and Wang, 2021). Additionally, mixed plantations of Eucalyptus and native tree species in the tropics have shown promise in balancing production with ecological restoration. These mixed plantations can yield substantial wood production while supporting biodiversity and ecosystem services (Amazonas et al., 2018).

9.3 The role of international cooperation in addressing the challenges of Eucalyptus forestry

International cooperation is crucial in addressing the challenges associated with Eucalyptus forestry, such as climate change impacts, soil fertility issues, and biodiversity conservation. Collaborative research and policy-making can facilitate the exchange of knowledge and best practices across regions. For instance, the use of global circulation models and Eucalyptus simulation models in Brazil provides valuable information for regional and national policy decision-making, which can be shared with other countries facing similar challenges (Elli et al., 2020a). Furthermore, international efforts in promoting mixed-species plantations can enhance the sustainability of Eucalyptus forestry by integrating production with ecological restoration, as demonstrated in the Atlantic Forest region of Brazil (Amazonas et al., 2018). Such cooperation can lead to the development of global guidelines and standards for sustainable Eucalyptus cultivation, benefiting both the environment and the forestry industry.

By implementing these policy and management recommendations, the global forestry sector can harness the economic benefits of Eucalyptus plantations while ensuring their sustainability and minimizing environmental impacts.

10 Concluding Remarks

Eucalyptus species have demonstrated significant versatility and adaptability in various global forestry contexts. Mixed plantations of Eucalyptus and native species have shown promising results, with Eucalyptus trees achieving substantial growth and yield even when intercropped with a high diversity of native species. However, the impact of climate change on Eucalyptus productivity is site-specific, with potential increases in productivity in some regions and reductions in others, highlighting the need for region-specific adaptation strategies. Eucalyptus plantations have also been found to influence ecosystem services variably, enhancing some services like climate regulation while potentially reducing others such as soil fertility and water availability. Despite controversies regarding their ecological impact, Eucalyptus species remain a valuable resource for timber, pulp, essential oils, and other products, contributing significantly to socioeconomic and industrial sectors.

The future of Eucalyptus in global forestry appears promising but complex. The species' ability to thrive in diverse environments and its economic benefits make it a valuable asset. However, the ecological implications of widespread Eucalyptus plantations necessitate careful management. Climate change poses both opportunities and challenges, with potential productivity gains in some regions and losses in others. The role of Eucalyptus in carbon sequestration is significant, particularly in integrated livestock-forestry systems, which can offset emissions from other agricultural activities. Additionally, the potential therapeutic uses of Eucalyptus essential oils add another dimension to its value . However, the environmental impacts, such as water consumption and soil nutrient depletion, must be addressed to ensure sustainable use.

To ensure the sustainable use of Eucalyptus in global forestry, further research is needed in several key areas. First, more studies are required to understand the long-term ecological impacts of Eucalyptus plantations, particularly concerning soil health and water resources. Research should also focus on breeding and genetic improvement to enhance traits that improve resilience to climate variability and change. Additionally, the development of integrated management practices that balance productivity with ecological sustainability is crucial. Policymakers should consider the context-specific impacts of Eucalyptus and promote practices that mitigate negative effects while enhancing positive outcomes. Finally, there is a need for comprehensive monitoring and evaluation frameworks to assess the effectiveness of different management strategies and inform adaptive management practices.

Acknowledgments

EcoEvo Publisher appreciates the valuable feedback from the reviewers.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

References

Alwadani K., Janes J., and Andrew R., 2019, Chloroplast genome analysis of box-ironbark Eucalyptus, Molecular Phylogenetics and Evolution, 136: 76-86.

https://doi.org/10.1016/j.ympev.2019.04.001

Amazonas N., Forrester D., Silva C., Almeida D., Oliveira R., Rodrigues R., and Brancalion P., 2021, Light- and nutrient-related relationships in mixed plantations of Eucalyptus and a high diversity of native tree species, New Forests, 52(5): 807-828.

https://doi.org/10.1007/s11056-020-09826-x

Amazonas N., Forrester D., Silva C., Almeida D., Rodrigues R., and Brancalion P., 2018, High diversity mixed plantations of Eucalyptus and native trees: An interface between production and restoration for the tropics, Forest Ecology and Management, 417: 247-256.

https://doi.org/10.1016/J.FORECO.2018.03.015

Bayle G., 2019, Ecological and social impacts of Eucalyptus tree plantation on the environment, Journal of Biodiversity Conservation and Bioresource Management, 5(1): 93-104.

https://doi.org/10.3329/JBCBM.V5I1.42189

Beiroz W., Barlow J., Slade E., Borges C., Louzada J., and Sayer E., 2019, Biodiversity in tropical plantations is influenced by surrounding native vegetation but not yield: A case study with dung beetles in Amazonia, Forest Ecology and Management, 444: 107-114.

https://doi.org/10.1016/J.FORECO.2019.04.036

Bird M., Hardner C., Dieters M., Heberling M., Montouto C., Arnold R., Ruiz F., Schapovaloff J., and Gore P., 2021, Global genotype by environment trends in growth traits for Eucalyptus dunnii, New Forests, 53: 101-123.

https://doi.org/10.1007/s11056-021-09846-1

Castle S., Miller D., Ordonez P., Baylis K., and Hughes K., 2021, The impacts of agroforestry interventions on agricultural productivity, ecosystem services, and human well-being in low- and middle-income countries: A systematic review, Campbell Systematic Reviews, 17(2): e1167.

https://doi.org/10.1002/CL2.1167

Castro-Díez P., Alonso Á., Saldaña-López A., and Granda E., 2021, Effects of widespread non-native trees on regulating ecosystem services, The Science of the Total Environment, 778: 146141.

https://doi.org/10.1016/j.scitotenv.2021.146141

Chavan S., Dhillon R., Sirohi C., Uthappa A., Jinger D., Jatav H., Chichaghare A., Kakade V., Paramesh V., Kumari S., Yadav D., Minkina T., and Rajput V., 2023, Carbon sequestration potential of commercial agroforestry systems in Indo-Gangetic Plains of India: Poplar and Eucalyptus-based agroforestry systems, Forests, 14(3): 559.

https://doi.org/10.3390/f14030559

Cheng Y., Du A., Wang Z., Zhu W., Ren S., Xu Y., and Ren S., 2023, Soil enzyme activity differs among native species and continuously planted Eucalyptus plantations, Forests, 14(11): 2210.

https://doi.org/10.3390/f14112210

Cuong T., Chinh T., Zhang Y., and Xie Y., 2020, Economic performance of forest plantations in Vietnam: Eucalyptus, Acacia mangium, and Manglietia conifera, Forests, 11(3): 284.

https://doi.org/10.3390/f11030284

Domiciano L., Pedreira B., Silva N., Mombach M., Chizzotti F., Batista E., Carvalho P., Cabral L., Pereira D., and Nascimento H., 2020, Agroforestry systems: An alternative to intensify forage-based livestock in the Brazilian Amazon, Agroforestry Systems, 94: 1839-1849.

https://doi.org/10.1007/s10457-020-00499-1

Dupraz C., Wolz K., Lecomte I., Talbot G., Vincent G., Mulia R., Bussière F., Ozier-Lafontaine H., Andrianarisoa S., Jackson N., Lawson G., Donès N., Sinoquet H., Lusiana B., Harja D., Domenicano S., Reyes F., Gosme M., and Noordwijk M., 2019, Hi-sAFe: A 3D agroforestry model for integrating dynamic tree–crop interactions, Sustainability, 11(8): 2293.

https://doi.org/10.3390/SU11082293

Elli E., Sentelhas P., and Bender F., 2020a, Impacts and uncertainties of climate change projections on Eucalyptus plantations productivity across Brazil, Forest Ecology and Management, 474: 118365.

https://doi.org/10.1016/j.foreco.2020.118365

Elli E., Sentelhas P., Freitas C., Carneiro R., and Alvares C., 2019, Assessing the growth gaps of Eucalyptus plantations in Brazil – magnitudes, causes and possible mitigation strategies, Forest Ecology and Management, 451: 117464.

https://doi.org/10.1016/j.foreco.2019.117464

Elli E., Sentelhas P., Huth N., Carneiro R., and Alvares C., 2020b, Gauging the effects of climate variability on Eucalyptus plantations productivity across Brazil: A process-based modelling approach, Ecological Indicators, 114: 106325.

https://doi.org/10.1016/j.ecolind.2020.106325

Fahad S., Chavan S., Chichaghare A., Uthappa A., Kumar M., Kakade V., Pradhan A., Jinger D., Rawale G., Yadav D., Kumar P., Farooq T., Ali B., Sawant A., Saud S., Chen S., and Poczai P., 2022, Agroforestry systems for soil health improvement and maintenance, Sustainability, 14(22): 14877.

https://doi.org/10.3390/su142214877

Ferraz S., Rodrigues C., Garcia L., Alvares C., and Lima W., 2019, Effects of Eucalyptus plantations on streamflow in Brazil: Moving beyond the water use debate, Forest Ecology and Management, 453: 117571.

https://doi.org/10.1016/j.foreco.2019.117571

Ferreto D., Reichert J., Cavalcante R., and Srinivasan R., 2020, Water budget fluxes in catchments under grassland and Eucalyptus plantations of different ages, Canadian Journal of Forest Research, 51(4): 513-523.

https://doi.org/10.1139/cjfr-2020-0156

Hoogar R., Malakannavar S., and Sujatha H., 2019, Impact of Eucalyptus plantations on ground water and soil ecosystem in dry regions, Journal of Pharmacognosy and Phytochemistry, 8: 2929-2933.

Hua L., Chen L., Antov P., Krišťák Ľ., and Tahir P., 2022, Engineering wood products from Eucalyptus spp., Advances in Materials Science and Engineering, 2022(1): 8000780.

https://doi.org/10.1155/2022/8000780

Ibarra L., Hodge G., and Acosta J., 2023, Quantitative genetics of a hybrid population of Eucalyptus nitens × Eucalyptus globulus: Estimation of genetic parameters and implications for breeding strategies, Forests, 14(2): 381.

https://doi.org/10.3390/f14020381

Kaur A., Forestry S., and Monga R., 2021, Eucalyptus trees plantation: A review on suitability and their beneficial role, International Journal of Bio-resource and Stress Management, 12(1): 16-25.

https://doi.org/10.23910/1.2021.2174

Li Q., Clemente H., He Y., Fu Y., and Dunand C., 2020, Global evolutionary analysis of 11 gene families part of reactive oxygen species (ROS) gene network in four Eucalyptus species, Antioxidants, 9(3): 257.

https://doi.org/10.3390/antiox9030257

Lima B., Cappa E., Silva-Junior O., Garcia C., Mansfield S., and Grattapaglia D., 2019, Quantitative genetic parameters for growth and wood properties in Eucalyptus “urograndis” hybrid using near-infrared phenotyping and genome-wide SNP-based relationships, PLoS ONE, 14(6): e0218747.

https://doi.org/10.1371/journal.pone.0218747

McMahon D., and Jackson R., 2019, Management intensification maintains wood production over multiple harvests in tropical Eucalyptus plantations, Ecological Applications, 29(4): e01879.

https://doi.org/10.1002/eap.1879

McMahon D., Vergütz L., Valadares S., Silva I., and Jackson R., 2019, Soil nutrient stocks are maintained over multiple rotations in Brazilian Eucalyptus plantations, Forest Ecology and Management, 448: 364-375.

https://doi.org/10.1016/J.FORECO.2019.06.027

Meneses L., Martínez Y., Antonelli A., and Gareca E., 2022, Good news for habitat restoration projects: Eucalyptus does not inhibit the germination of Polylepis, Restoration Ecology, 30(8): e13651.

https://doi.org/10.1111/rec.13651

Mphahlele M., Isik F., Hodge G., and Myburg A., 2021, Genomic breeding for diameter growth and tolerance to Leptocybe gall wasp and Botryosphaeria/Teratosphaeria fungal disease complex in Eucalyptus grandis, Frontiers in Plant Science, 12: 638969.

https://doi.org/10.3389/fpls.2021.638969

Mphahlele M., Isik F., Mostert-O’Neill M., Reynolds S., Hodge G., and Myburg A., 2020, Expected benefits of genomic selection for growth and wood quality traits in Eucalyptus grandis, Tree Genetics & Genomes, 16(4): 49.

https://doi.org/10.1007/s11295-020-01443-1

Müller B., Filho J., Lima B., Garcia C., Missiaggia A., Aguiar A., Takahashi E., Kirst M., Gezan S., Silva-Junior O., Neves L., and Grattapaglia D., 2018, Independent and joint-GWAS for growth traits in Eucalyptus by assembling genome-wide data for 3373 individuals across four breeding populations, The New Phytologist, 221(2): 818-833.

https://doi.org/10.1111/nph.15449

Murray K., Janes J., Jones A., Bothwell H., Andrew R., and Borevitz J., 2019, Landscape drivers of genomic diversity and divergence in woodland Eucalyptus, Molecular Ecology, 28: 5232-5247.

https://doi.org/10.1111/mec.15287

Nadir S., Ng'etich W., and Kebeney S., 2018, Performance of crops under Eucalyptus tree-crop mixtures and its potential for adoption in agroforestry systems, Australian Journal of Crop Science, 12(8): 1231-1240.

https://doi.org/10.21475/AJCS.18.12.08.PNE939

Ontong N., Poolsiri R., Diloksumpun S., Staporn D., and Jenke M., 2023, Effects of tree functional traits on soil respiration in tropical forest plantations, Forests, 14(4): 715.

https://doi.org/10.3390/f14040715

Palmieri N., Suardi A., and Pari L., 2020, Italian consumers’ willingness to pay for Eucalyptus firewood, Sustainability, 12(7): 2629.

https://doi.org/10.3390/su12072629

Paludeto J., Grattapaglia D., Estopa R., and Tambarussi E., 2021, Genomic relationship–based genetic parameters and prospects of genomic selection for growth and wood quality traits in Eucalyptus benthamii, Tree Genetics & Genomes, 17(4): 38.

https://doi.org/10.1007/s11295-021-01516-9

Pereira A., Durrer A., Gumiere T., Gonçalves J., Robin A., Bouillet J., Wang J., Verma J., Singh B., and Cardoso E., 2019, Mixed Eucalyptus plantations induce changes in microbial communities and increase biological functions in the soil and litter layers, Forest Ecology and Management, 433: 332-342.

https://doi.org/10.1016/J.FORECO.2018.11.018

Pinheiro F., Nair P., Nair V., Tonucci R., and Venturin R., 2021, Soil carbon stock and stability under Eucalyptus-based silvopasture and other land-use systems in the Cerrado biodiversity hotspot, Journal of Environmental Management, 299: 113676.

https://doi.org/10.1016/j.jenvman.2021.113676

Ramesh K., Deshmukh H., Sivakumar K., Guleria V., Umedsinh R., Krishnakumar N., Thangamalar A., Suganya K., Kiruba M., Selvan T., Balasubramanian P., Ushamalini C., Thiyagarajan G., Vincent S., Rajeswari P., Bavish S., Riaz A., and Senthil K., 2023, Influence of Eucalyptus agroforestry on crop yields, soil properties, and system economics in southern regions of India, Sustainability, 15(4): 3797.

https://doi.org/10.3390/su15043797

Resquin F., Farina I., Rachid-Casnati C., Rava A., Doldán J., Hirigoyen A., Inderkum F., Alen S., Olmos V., and Carrasco-Letelier L., 2022, Impact of rotation length of Eucalyptus globulus Labill. on wood production, kraft pulping, and forest value, iForest - Biogeosciences and Forestry, 15(5): 433.

https://doi.org/10.3832/ifor4040-015

Santos B., Zibrandtsen J., Gunbilig D., Sørensen M., Cozzi F., Boughton B., Heskes A., and Neilson E., 2019, Quantification and localization of formylated phloroglucinol compounds (FPCs) in Eucalyptus species, Frontiers in Plant Science, 10: 186.

https://doi.org/10.3389/fpls.2019.00186

Silva V., Nogueira T., Abreu-Junior C., He Z., Buzetti S., Laclau J., Filho M., Grilli E., Murgia I., and Capra G., 2020, Influences of edaphoclimatic conditions on deep rooting and soil water availability in Brazilian Eucalyptus plantations, Forest Ecology and Management, 455: 117673.

https://doi.org/10.1016/j.foreco.2019.117673

Tavares A., Beiroz W., Fialho Á., Frazão F., Macedo R., Louzada J., and Audino L., 2019, Eucalyptus plantations as hybrid ecosystems: Implications for species conservation in the Brazilian Atlantic Forest, Forest Ecology and Management, 433: 131-139.

https://doi.org/10.1016/J.FORECO.2018.10.063

Tomé M., Almeida M., Barreiro S., Branco M., Deus E., Pinto G., Silva J., Soares P., and Rodríguez-Soalleiro R., 2021, Opportunities and challenges of Eucalyptus plantations in Europe: The Iberian Peninsula experience, European Journal of Forest Research, 140: 489-510.

https://doi.org/10.1007/s10342-021-01358-z

Vasconcelos R., Cambui E., Mariano‐Neto E., Rocha P., and Cardoso M., 2019, The role of Eucalyptus planted forests for fruit-feeding butterflies' conservation in fragmented areas of the Brazilian Atlantic Forest, Forest Ecology and Management, 432: 115-120.

https://doi.org/10.1016/J.FORECO.2018.09.017

Wang L., Zhou X., Wen Y., and Sun D., 2022, Non-additive effects of mixing Eucalyptus and Castanopsis hystrix trees on carbon stocks under an eco-silviculture regime in southern China, Forests, 13(5): 733.

https://doi.org/10.3390/f13050733

Wang Y., Lin Y., Zhang L., Liu S., Wang J., Tian Y., Campbell D., Lin R., Ren H., and Lu H., 2023, Long-term effects of intercropping on multi-trophic structure and bio-thermodynamic health of mixed Eucalyptus-native tree plantations, Journal of Applied Ecology, 61(1): 103-119.

https://doi.org/10.1111/1365-2664.14558

Wang Z., Li L., and Ouyang L., 2021, Efficient genetic transformation method for Eucalyptus genome editing, PLoS ONE, 16(5): e0252011.

https://doi.org/10.1371/journal.pone.0252011

White D., Ren S., Mendham D., Balocchi-Contreras F., Silberstein R., Meason D., Iroumé A., and Arellano P., 2022, Is the reputation of Eucalyptus plantations for using more water than Pinus plantations justified?, Hydrology and Earth System Sciences, 26(20): 5357-5371.

https://doi.org/10.5194/hess-26-5357-2022

Wu W., Kuang L., Li Y., He L., Mou Z., Wang F., Zhang J., Wang J., Li Z., Lambers H., Sardans J., Peñuelas J., Geisen S., and Liu Z., 2021, Faster recovery of soil biodiversity in native species mixture than in Eucalyptus monoculture after 60 years afforestation in tropical degraded coastal terraces, Global Change Biology, 27: 5329-5340.

https://doi.org/10.1111/gcb.15774

Yost J., Wise S., Love N., Steane D., Jones R., Ritter M., and Potts B., 2021, Origins, diversity and naturalization of Eucalyptus globulus (Myrtaceae) in California, Forests, 12(8): 1129.

https://doi.org/10.3390/f12081129

Zhang Y., and Wang X., 2021, Geographical spatial distribution and productivity dynamic change of Eucalyptus plantations in China, Scientific Reports, 11(1): 19764.

https://doi.org/10.1038/s41598-021-97089-7