The AP2/ERF gene family involves numerous plant processes, including growth, development, metabolism, and various plant stress responses. However, several studies have been conducted on the AP2/ERF gene family in yellow horn, a new type of oil woody crop and an essential oil crop in China. According to sequence alignment and phylogenetic analyses, one hundred and forty-five AP2/ERF genes were detected from the yellow horn genome. They were divided into four relatively conserved subfamilies, including 21 AP2 genes, 119 ERBP genes, 4 RAV genes, and 1 Soloist gene. Gene analysis of XsAP2/ERF TFs showed 87 XsAP2/ERF TFs lacked introns. There were 75 pairs of collinearity relationships between X. sorbifolium and Arabidopsis, indicating a close similarity. In addition, the expression patterns of XsAP2/ERF TFs under cold treatments confirmed that the XsAP2/ERF TFs play essential roles in abiotic stress response. The expression of eight XsAP2/ERF transcription factors was verified in different tissues and under various stress treatments using RT-qPCR. This study establishes a starting point for further research to explore the potential mechanisms of identifying candidate AP2/ERF TFs that could respond to the abiotic stress of yellow horn.

Carbon:nitrogen:phosphorus (C:N:P) stoichiometry plays a critical role in nutrient cycling, biodiversity, and ecosystem functionality. However, our understanding of the responses of C:N:P stoichiometry to elevation and forest management remains elusive. Here we sampled 18 Larix principis-rupprechtii sites along altitudinal gradients (1700-2300 m) on Guandishan Mountain in the Loess Plateau, China. We determined the leaf, litter, and soil C N P contents and C:N:P stoichiometric ratios, as well as nutrient resorption efficiency (NuRE), and diameter at breast height (DBH) increments in both planted and natural stands, and then tested the impacts of elevation and stand origin on these parameters’ management. We found different C:N:P stoichiometry between natural and planted forests. The results revealed that: soil C, N, and N:P ratios, litter C:P and N:P ratios, leaf C:N and N:P ratios increased significantly; however, soil C:N ratios, litter P, leaf N and P, nitrogen resorption efficiency (NRE), and DBH increments decreased significantly with elevation in the planted forests. Soil C,N and N:P ratios, litter C, as well as C:N and C:P ratios increased significantly with elevation in natural forests. The soil N, P and N:P ratios, litter C:P and N:P ratios, leaf C, C:P and N:P ratios, nitrogen resorption efficiency (NRE), phosphorus resorption efficiency (PRE), and DBH increments were, on average, higher in the planted, rather than natural forests. Our results indicated that there was an enhancing P-limitation in both the planted and natural forests, and the plantations were more restricted by P. Moreover, compared to natural forests, plantations converged toward a higher conservative N- and P-use strategy by enhancing resorption efficiencies of internal nutrient cycling and a higher annual growth rate.

An accurate estimate of the site index is essential for informing decision-making in forestry. In this study, we developed site index (SI) models using stem analysis data to estimate the site index and the dominant height growth for Larix gmelinii var. principis-rupprechtii in northern China. The data included 5122 height–age pairs from 75 dominant trees in 29 temporary sample plots (TSPs). Nine commonly used growth functions were parameterized using the modeling method, which accounts for heterogeneous variance and autocorrelation in the time-series data and introduces sample plot-level random effects in the model. The results show that the Duplat and Tran-Ha I model with random effects described the largest proportion of the dominant height variation. This model accurately evaluated the site quality and predicted the dominant tree height growth in natural Larix forests in the Guandi Mountain region. As an important supplement in improving methods for site quality evaluation, the model may serve as a fundamental tool in the scientific management of larch forests. The research results can inform an accurate evaluation of the site quality and predict the growth of the dominant height in a larch forest in the Guandi Mountain forest area as well as provide a theoretical basis for forest site quality evaluation at similar sites.

Aims: Investigations into the nutrient content and changes in the stoichiometry and nutrient resorption strategies of different original forests during their development are of great significance toward the establishment of healthy, high-quality forest ecosystems. Methods: 24 sample plots with age gradients were established in natural Larix principis-rupprechtii forests and plantations, from which mature and senescent leaves, new branches, fine roots, and soil were collected for analysis. The carbon (C), nitrogen (N), and phosphorus (P) contents were determined, and the stoichiometric ratios and resorption efficiencies were calculated. Results and Conclusions: The soil organic carbon and total nitrogen of the forests accumulated with advancing age, while the total phosphorus decreased due to higher consumption. Plantation trees tended to store scarce nutrients within inactive plant structures to prevent nutrient loss, whereas natural forest trees maintained a stable nutrient concentration within their active organs. Plantation and natural forest trees adopted highly conservative N and P utilization strategies through improved resorption efficiencies. However, natural forest change was weaker than in plantations. The mature leaves, litter, branches, and fine roots of natural forestswere more susceptible to soil P concentrations, whereas those of their plantation counterparts were more affected by soil N. Nutrient concentrations within the active organs of plantation trees were more strongly dependent on soil than natural forests. We considered that natural forests likely possessed a more extensive range of strategies to deal with the variable compositions and concentrations of soil nutrients, which might strengthen their resilience against the effects of aging.