Several Strategies for Tree Growths Under Different Abiotic Stresses

1. Introduction

Forests, often referred to as the “lungs of the Earth”, provide essential resources such as energy and food while also playing a critical role in carbon sequestration and maintaining biodiversity [1]. However, escalating pressures from climate change, drought, invasive species, and various biotic and abiotic stresses are progressively undermining the health and resilience of forest ecosystems [2]. To develop effective strategies for mitigating the adverse impacts of environmental stresses on forest ecosystems, a comprehensive understanding of the genetic, developmental, and molecular mechanisms driving trees to adapt to these challenges is imperative. This Special Issue on “Strategies for Tree Improvement under Stress Conditions—2nd Edition” presents seven research papers that highlight the recent advances in understanding the physiological and molecular mechanisms wherein how woody plants adapt to stress.

2. Drought

This collection of research papers investigates the physiological and molecular responses of certain tree species to drought stress. In arid regions, the efficient utilization of soil water is crucial for maintaining a balance between forest vegetation restoration and soil water availability [3]. Ma et al. focused on the use of an in situ rainwater harvesting and infiltration system (IRCIS) in degraded black locust forests on the Loess Plateau [4].

The system substantially enhanced soil moisture content and improved water transport efficiency in black locust, making it a vital strategy for strengthening drought resistance of the degraded black locust forests on the Loess Plateau [4]. Ma et al. also emphasized the fundamental role of black locust height in influencing conduit diameter and revealed that black locust exhibited significantly superior xylem structure and hydraulic traits during the growth phase compared with the senescence phase [5]. Thus, careful consideration must be given to the plant’s distinct growth stages and its adaptability to diverse environmental conditions when breeding tree varieties.

3. Nutrients, pH, and Temperature

Nutrient limitations, acidity, and temperature stress significantly affect the physiological and ecological processes of forest trees, leading to varying degrees of adverse impacts on forest productivity [6,7]. Cheng et al. found that the cultivation at pH 5.5 or 6.5 partially mitigated nitrogen (N) limitation in Cunninghamia lanceolata and Schima superba [8]. C. lanceolata was more susceptible to N limitation, while S. superba was susceptible to N and phosphorus (P) limitations [8]. Li et al. reported the relationship between the aquaporin (AQP) gene family in Catalpa bungei and cold stress, identifying that the genes CbPIP2;5, CbPIP1;2, CbTIP4;1, and CbNIP2;1 may play key essential roles in enhancing the cold tolerance of C. bungei [9]. These findings provide a theoretical basis for improving C. bungei seedling quality, breeding for enhanced cold resistance, and expanding its distribution range [9].

4. Other Strategies for Tree Improvement

Dou et al. found that the peroxidase gene family is associated with root growth and stress resistance in Platycladus orientalis [10]. Five key genes were identified, namely F01.PB13906, F01.PB12754, F01.PB6924, F01.PB23047, and F01.PB2408, providing valuable insights and guidance for root development research [10]. Zhang et al. also found that transcripts of CsYUC2.1, CsYUC11.4, CsYUC8, CsYUC11.8, CsYUC11.9, CsYUC11.4, and YUC10 were remarkably linked to the development of roots, stems, leaves, and flowers in Camellia sinensis [11]. Additionally, the cold-induced expression of CsYUC2.2, CsYUC11.8, and CsYUC11.9 was observed, while the expression of nine genes was induced by drought stress and the expression of eight genes was induced by NaCl stress [11]. These findings hold potential implications for improving the development and stress tolerance of C. sinensis [11]. Dou et al. indicated that the AP2/ERF gene family in Morus notabilis was involved in abiotic stresses, including low temperature, contributing to the growth and development of roots, male flowers, leaves, bark, and winter buds [12]. These findings establish a foundation for investigating the role of the AP2/ERF gene family in the growth, development, and stress response of M. notabilis and provide valuable genetic resources for the breeding of stress-tolerant varieties [12].

5. Conclusions and Prospects

These studies collectively explore the physiological and molecular responses of forest trees to abiotic stresses and their practical implications. Understanding the genetic, physiological, and molecular mechanisms of trees in response to abiotic stresses enables well-directed breeding of stress-resistant plants.

We believe this Special Issue provides valuable findings to advance understanding of tree responses to abiotic stresses and their improvement strategies. The tree species investigated in these studies display critical physiological and molecular genetic traits that are vital for sustaining forest health and ensuring ecosystem stability. However, further research is needed to expand our knowledge of how forest trees respond to other biotic stresses (such as pest and species competition) and abiotic stresses (including climate change and air pollution). Furthermore, it is essential to validate the practical impacts and socio-economic benefits of these findings under diverse environmental conditions. In-depth studies of physiological and molecular mechanisms will provide critical insights for the well-directed application of tree species, fostering sustainable forest development in the future.