The ruined landscapes of the Mediterranean littoral are a consequence of millennia of human impact and include abandoned agricultural lands, deforested areas, and degraded coastal areas. One of the drivers is the historical pattern of land use, which has resulted in the clearing of vegetation, soil erosion, and overgrazing. These have caused significant damage to natural ecosystems and landscapes leading to soil degradation, loss of biodiversity, and the destruction of habitats. The UN Sustainable Development Goal 15 Life on Land recommends a substantial increase in afforestation (SDG 15.2). Whilst this goal is certainly necessary in places, it should be implemented with caution. The general perception that certain ecosystems, such as forests, are inherently more valuable than grasslands and shrublands contributes to afforestation drives prioritising quick and visible results. This, however, increases the possibility of misguided afforestation, particularly in areas that never supported forests under the present climatic conditions. We argue that in areas that have not supported forest ecosystems, targeted reinforcement of existing populations and recreation of historical ones is preferable to wholesale ecosystem modification disguised as afforestation. We present a possible strategy for targeted reinforcement in areas that never supported forests and that would still achieve the goals of SDGs 15.5 and 15.8.
The objective of this study was to advance sustainable forestry development through the creation of mechanical equipment, taking into account forestry operational methods. A suspended automatic feeding and retracting excavation device for tree pits was engineered, and its interaction with soil was investigated by integrating the Discrete Element Method (DEM) with Multi-Flexible Body Dynamics (MFBD). Based on simulation results, the research explored the impact mechanisms of the machine on soil transportation, working load, and fatigue lifespan of the spiral blades for different terrains and operating conditions. The coupling simulation method demonstrated the potential for designing and testing forestry equipment in specific operating environments, reducing time and resource consumption for field testing. Terrain significantly influenced soil disturbance variability, while the effect of operating direction was minor. Operational parameters should consider soil and water conservation, favoring the formation of fish-scale pits. Field tests in forested areas validate the practicality of the apparatus, providing valuable insights for the operation and equipment design of earth augers in hilly regions.
Check dams and afforestation are widely used to control debris flows; however, the combined effects of mitigation changes caused by sedimentation behind the check dams as well as the growth of vegetation are unclear. This paper reports long-term measurements of the erosion base level behind check dams along the Shengou gully, which is an active debris flow gully with 19 shallow soil landslides along its banks. The loose sediment on the shallow soil landslides, which is affected by afforestation, is the main source of material and energy for debris flows in this gully. The change in the mechanical properties of the loose sediment on the shallow soil landslides was determined. Based on the mechanical properties of the shallow soil landslides and the erosion base level behind the check dams, the volume and potential energy of the shallow soil landslide sediment were calculated. A model of the vegetation coverage, shallow soil landslide energy, and debris flow volume was established and applied to the Shengou gully. The results show that the model can evaluate the different benefits of check dams and afforestation on debris flow mitigation given the sedimentation behind the check dams and the vegetation growth.
Purpose of ReviewInternational ambitions for massive afforestation and restoration are high. To make these investments sustainable and resilient under future climate change, science is calling for a shift from planting monocultures to mixed forests. But what is the scientific basis for promoting diverse plantations, and what is the feasibility of their establishment and management? As the largest global network of tree diversity experiments, TreeDivNet is uniquely positioned to answer these pressing questions. Building on 428 peer-reviewed TreeDivNet studies, combined with the results of a questionnaire completed by managers of 32 TreeDivNet sites, we aimed to answer the following questions: (i) How and where have TreeDivNet experiments enabled the relationship between tree diversity and tree performance (including productivity, survival, and pathogen damage) to be studied, and what has been learned? (ii) What are the remaining key knowledge gaps in our understanding of the relationship between tree diversity and tree performance? and (iii) What practical insights can be gained from the TreeDivNet experiments for operational, real-world forest plantations?Recent FindingsWe developed a conceptual framework that identifies the variety of pathways through which target tree performance is related to local neighbourhood diversity and mapped the research efforts for each of those pathways. Experimental research on forest mixtures has focused primarily on direct tree diversity effects on productivity, with generally positive effects of species and functional diversity on productivity. Fewer studies focused on indirect effects mediated via biotic growing conditions (e.g. soil microbes and herbivores) and resource availability and uptake. Most studies examining light uptake found positive effects of species diversity. For pests and diseases, the evidence points mostly towards lower levels of infection for target trees when growing in mixed plantations. Tree diversity effects on the abiotic growing conditions (e.g. microclimate, soil properties) and resource-use efficiency have been less well studied to date. The majority of tree diversity experiments are situated in temperate forests, while (sub)tropical forests, and boreal forests in particular, remain underrepresented.SummaryTreeDivNet provides evidence in favour of mixing tree species to increase tree productivity while identifying a variety of different processes that drive these diversity effects. The design, scale, age, and management of TreeDivNet experiments reflect their focus on fundamental research questions pertaining to tree diversity-ecosystem function relationships and this scientific focus complicates translation of findings into direct practical management guidelines. Future research could focus on (i) filling the knowledge gaps related to underlying processes of tree diversity effects to better design plantation schemes, (ii) identifying optimal species mixtures, and (iii) developing practical approaches to make experimental mixed plantings more management oriented.
The 2011 off the Pacific coast of Tohoku Earthquake occurred, and coastal forests were severely damaged by a huge tsunami. Since the disaster, coastal forest restoration projects have been underway by the Forestry Agency and local governments. Detailed time-series monitoring of the regeneration process of coastal forests is important in order to proceed with regeneration appropriately. The Normalized Difference Vegetation Index (NDVI), which uses near-infrared and visible red images obtained from optical satellite observations, has been widely used to survey trees and vegetation. However, it has been reported that NDVI tends to be saturated depending on the observation period and vegetation type. In addition, there is a tendency for index values to be overestimated on the soil surface. In particular, in the case of coastal forest regeneration, the influence of the soil surface is even greater because the complex mixture of soil surface and afforestation is assessed from observation images. To date, many improvement vegetation indices have been proposed to reduce soil surface effects and more appropriately evaluate vegetation activity. However, the applicability of improvement indexes using higher-resolution satellite images for evaluating the regeneration of tsunami-affected coastal forests has not yet been sufficiently investigated.