Agroforestry integrates woody perennials with arable crops, livestock, or fodder in the same piece of land, promoting the more efficient utilization of resources as compared to monocropping via the structural and functional diversification of components. This integration of trees provides various soil-related ecological services such as fertility enhancements and improvements in soil physical, biological, and chemical properties, along with food, wood, and fodder. By providing a particular habitat, refugia for epigenic organisms, microclimate heterogeneity, buffering action, soil moisture, and humidity, agroforestry can enhance biodiversity more than monocropping. Various studies confirmed the internal restoration potential of agroforestry. Agroforestry reduces runoff, intercepts rainfall, and binds soil particles together, helping in erosion control. This trade-off between various non-cash ecological services and crop production is not a serious constraint in the integration of trees on the farmland and also provides other important co-benefits for practitioners. Tree-based systems increase livelihoods, yields, and resilience in agriculture, thereby ensuring nutrition and food security. Agroforestry can be a cost-effective and climate-smart farming practice, which will help to cope with the climate-related extremities of dryland areas cultivated by smallholders through diversifying food, improving and protecting soil, and reducing wind erosion. This review highlighted the role of agroforestry in soil improvements, microclimate amelioration, and improvements in productivity through agroforestry, particularly in semi-arid and degraded areas under careful consideration of management practices.

Worldwide, forests are increasingly exposed to extreme droughts causing tree mortality. Because of the complex nature of the mechanisms involved, various traits have been linked to tree drought responses with contrasting results. This may be due to species-specific strategies in regulating water potential, a process that unfolds in two distinct phases: a first phase until stomatal closure, and a second phase until reaching lethal xylem hydraulic thresholds. We conducted dry-down experiments with five broadleaved temperate tree species differing in their degree of isohydry to estimate the time to stomatal closure (t_sc) and subsequent time to critical hydraulic failure (t_crit). We measured various traits linked to tree drought responses, such as the water potentials at turgor loss point (P_tlp), stomatal closure (P_gs90), and 12%, 50% and 88% loss of xylem hydraulic conductance (P₁₂, P₅₀, P₈₈), hydraulic capacitance (C), minimum leaf conductance (g_min), hydroscape area (HSA) and hydraulic safety margins (HSM). We found that P_gs90 followed previously recorded patterns of isohydry and was associated with HSA. Species ranked from more to less isohydric in the sequence Acer pseudoplatanus < Betula pendula < Tilia cordata < Sorbus aucuparia < Fagus sylvatica. Their degree of isohydry was associated with leaf safety (P_tlp and g_min), drought avoidance (C) and t_sc, but decoupled from xylem safety (HSM and P₈₈) and t_crit. Regardless of their stomatal stringency, species with wider HSM and lower P₈₈ reached critical hydraulic failure later. We conclude that the duration of the first phase is determined by stomatal regulation, while the duration of the second phase is associated with xylem safety. Isohydry is thus linked to water use rather than to drought survival strategies, confirming the proposed use of HSA as a complement to HSM for describing plant drought responses before and after stomatal closure.

The evolution of the internal water transport system was a prerequisite for high plant productivity. In times of climate change, understanding the dependency of juvenile growth on xylem hydraulic physiology is therefore of high importance. Here, we explored various wood anatomical, hydraulic, and leaf morphological traits related to hydraulic safety and efficiency in three temperate broadleaved tree species (Acer pseudoplatanus, Betula pendula, and Sorbus aucuparia). We took advantage of a severe natural heat wave that resulted in different climatic growing conditions for even-aged plants from the same seed source growing inside a greenhouse and outside. Inside the greenhouse, the daily maximum vapour pressure deficit was on average 36% higher than outside during the growing seasons. Because of the higher atmospheric moisture stress, the biomass production differed up to 5.6-fold between both groups. Except for one species, a high productivity was associated with a high hydraulic efficiency caused by large xylem vessels and a large, supported leaf area. Although no safety-efficiency trade-off was observed, productivity was significantly related to P₅₀ in two of the tree species but without revealing any clear pattern. A considerable plasticity in given traits was observed between both groups, with safety-related traits being more static while efficiency-related traits revealed a higher intra-specific plasticity. This was associated with other wood anatomical and leaf morphological adjustments. We confirm that a high hydraulic efficiency seems to be a prerequisite for a high biomass production, while our controversial results on the growth–xylem safety relationship confirm that safety-efficiency traits are decoupled and that their relationship with juvenile growth and water regime is species-specific.

Temperate forests face increasing tree mortality from extreme droughts, highlighting the need to understand the mechanisms behind tree drought responses. While complex, these responses can be simplified into two distinct phases: a first phase that lasts until stomatal closure (t_sc) and a second that extends until reaching lethal xylem hydraulic thresholds (t_crit). We conducted dry-down experiments on 8 temperate broad-leaved and 8 conifer species to estimate t_sc and t_crit. We also measured various hydraulic traits, including water potentials at turgor loss point (P_tlp), stomatal closure (P_gs90), and 12%, 50%, and 88% loss of xylem hydraulic conductivity (P₁₂, P₅₀, P₈₈), hydraulic capacitance, and minimum leaf and bark conductance (g_min, g_bark). We then tested these traits in a dynamic model to predict t_crit based on functional traits. Our results indicate that t_sc dominates the desiccation process and is closely associated to xylem vulnerability to embolism, while t_crit is influenced by water storage and residual conductance traits. Despite differences between conifers and broad-leaved species, our updated multi-trait model accurately predicted t_crit. We show that while drought-response coordination is too complex to be captured by a single-trait approach, it can be effectively described using a concise set of traits, an approach that may inform forest management under climate change.