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The rapid and precise acquisition of forest stand parameters is a key challenge in forest resource assessment. Terrestrial laser scanning (TLS) provides a fast and accurate method, but its accuracy is influenced by factors like tree segmentation parameters. This study focuses on Pinus tabuliformis plantations in the Caijiachuan watershed, Jixian, Shanxi, on the Loess Plateau. Based on field survey data, including tree number, height (H), diameter at breast height (DBH), and biomass, high-precision point cloud data were acquired using TLS. A comparative shortest path (CSP) algorithm was used for individual tree segmentation to investigate the effect of parameter selection on measurement accuracy. The results show that minimum tree height has a significant impact on segmentation accuracy. As the minimum tree height increased from 3.0 to 5.5 m, the recall rate (R) decreased while the precision (P) increased. The highest precision (F-score = 0.9470) and biomass estimation accuracy (0.9066) were obtained with a minimum tree height of 4.5 m, and the best extraction accuracies for H and DBH (0.9677 and 0.9518) were obtained at 5.0 m. Optimizing the minimum tree height parameter improves segmentation accuracy, thereby enhancing the use of TLS for soil and water conservation on the Loess Plateau.

Winter dormancy ensures that trees in temperate zones respond appropriately to environmental variations, thereby enhancing their adaptability and resilience. In the northern hemisphere, the dormancy of conifers is induced by short-day and cold temperature. Previous studies have revealed that TFL2 is a key regulator involved in conifers’ bud set and growth cessation during the dormancy-induced phase. Based on the annual expression profile analysis of PtTFL2 in Chinese pine ( Pinus tabuliformis Carr.), we identified key time nodes for dormancy initiation in autumn. To provide insight of the diurnal transcriptome dynamic in needles and roots during dormancy introduction, RNA-seq was performed at 12 consecutive time points in 24 h under natural environment in P. tabuliformis . Interestingly, we found that both needles and roots have rhythmic oscillatory genes, even though the roots could not receive light signals directly. We applied weighted gene co-expression network analysis (WGCNA) to integrate differentially expressed genes between needles and roots at different time points into highly correlated gene modules. Although the two modules are subject to different transcriptional controls during dormancy, both contain 35 identical transcriptional regulators. Some transcriptional factors with functional similarities and synergistic effects were found to play a role in the regulatory pathway, which provided some data support for mining gene functions and analyzing related regulatory pathways. Our results provide new insights into the molecular regulatory mechanisms involved in pine dormancy.

Global climate change can affect the sensitivity of tree radial growth to climate factors, but the specific responses of tree radial growth to microclimate along the altitudinal gradient in the long term are still unclear. In this study, the tree-ring width chronologies of Carr. in Shanxi Province of China were studied at three altitude gradients (1200-1300 m (low altitude), 1300-1400 m (medium altitude) and 1400-1500 m (high altitude)) during 1958-2017. The results showed that (1) the climate background could be divided into two periods based on the Mann-Kendall test analysis: 1958-1996 was a stable period (mean annual temperature (MAT)=10.25°C, mean annual precipitation (MAP)=614.39 mm), and 1997-2017 was a rapid change period (MAT=10.91°C, MAP=564.70 mm), indicating a warming and drying trend in the study region. (2) The radial growth of at different altitudes showed inconsistent variation patterns. The tree radial growth at low and medium altitudes (CV=27.01% for low altitude and CV=24.69% for medium altitude) showed larger variation amplitudes during the rapid change period than that in the stable period (CV=12.40% for low altitude and CV=18.42% for medium altitude). In contrast to the increasing trend, the tree radial growth rates at the high altitude showed a decreasing trend across years. (3) In the stable period, the radial growth of at the low altitude showed a significantly negative response to temperature and a positive response to precipitation in May and June. The tree radial growth at the medium altitude was positively related to precipitation in June and minimum temperature in February. The tree growth at the high altitude was mainly positively correlated with the temperature in May and August. In the rapid change period, the radial growth of at the low altitude was affected by more meteorological factors than that in the stable period. Medium-altitude trees were positively influenced by precipitation in June and minimum temperature in January, whereas high-altitude trees responded positively to wind speed in February. (4) Along altitudinal gradients, tree radial growth was more related to temperature than precipitation in the stable period. The tree radial growth at the high altitude during the rapid change period was only affected by wind speed in February, whereas the tree radial growth at low and medium altitudes was mainly affected by temperature to a similar extent during the two periods. The study indicated that tree growth-climate response models could help deeply understand the impact of climate change on tree growth adaptation and would be beneficial for developing sustainable management policies for forest ecosystems in the transition zone from warm-temperate to subtropical climates.

Ecological stoichiometry is an important index that reflects the element cycle and ecosystem stability. In this study, two sites (sunny and shady slopes) and five forest ages (young stage, half-mature stage, near-mature stage, mature stage, and over-mature stage) in a Pinus tabuliformis plantation were chosen to illustrate the effects of forest ages and site conditions on the biomass and stoichiometric characteristics of leaves and soils in the temperate mountainous area of China. Except for young stage, the biomass of the leaves of P. tabuliformis on sunny slopes were higher than those on shady slopes in other forest ages, the average carbon content of the leaves in sunny slopes was higher than that in shady slope, while the average total nitrogen contents and average total phosphorus contents of the leaves showed the opposite of this. The biomass of leaves increased on sunny slopes, and increased first and then decreased in shady slopes with increasing forest ages. The contents of soil total carbon (STC) and soil total nitrogen (STN) decreased with increasing soil depth, while the soil total phosphorus (STP) and soil available phosphorus (SAP) contents displayed the opposite. In addition to SAP, the average content of STC, STN, and STP in shady slopes was higher than that in sunny slopes, and the ratio was the opposite. Except for STC: STN on shady slopes, the other ratios showed a downward trend with an increase in soil depth. Excluding the topsoil, the change trend of STC : STP and STN : STP in shady slopes and sunny slopes was consistent with forest ages. The results showed that forest ages and site conditions had significant effects on leaf biomass. The biomass of the leaves is mainly limited by nitrogen. These results have important significance in improving the refinement of local forestry management of Pinus tabuliformis plantations in the temperate mountainous area of China.

【Objective】Soil water infiltration is critical for moisture retention, vegetation growth and long-term ecosystem stability, particularly in ecologically fragile areas like the Loess Plateau. Pinus tabuliformis is a key species used in regional reforestation and plays a vital role in soil hydrological processes. This paper investigates soil water infiltration in P. tabuliformis plantations with different stand densities in the Ziwuling region of the Loess Plateau.【Method】Field experiments were conducted in August 2023 at the Lianjiabian Forest Farm, Heshui County, Gansu Province. Five stand densities, 2 222, 3 200, 4 802, 6 250 and 7 503 plants/hm2, were selected. Soil water infiltration in each stand was measured using the double-ring infiltrometer method. Five models were evaluated for their ability to simulate water infiltration: the General Infiltration Model, the Jiang Dingsheng Model, the Horton Model, the Philip Model, and the Kostiakov Model.【Result】① With increasing stand density, the initial infiltration rate, steady infiltration rate, average infiltration rate and cumulative infiltration showed unimodal trends, all peaking at stand density of 4 802 plants/hm2; their corresponding average values were 18.27 mm/min, 11.31 mm/min, 13.57 mm/min, and 143.45 cm, respectively. ② Cumulative infiltration under different stand density ranked (from high to low) in the order of 4 802＞6 250＞7 503＞3 200＞2 222 plants/hm2. ③ Overall, soil infiltration capacity, based on all indicators, ranked with stand density in the order of 4 802＞6 250＞3 200＞7 503＞ 2 222 plants/hm2. ④ The R2 value of the general infiltration model, the Jiang Dingsheng model, the Horton model, the Philip model and the Kostiakov model was 0.985, 0.966, 0.951, 0.867 and 0.760, respectively.【Conclusion】Among all stand densities of Pinus tabuliformis plantations, the density 4 802 plants/hm2 had the highest water infiltration capacity, showing superior water conservation potential. The general infiltration model proved to be the most suitable for simulating soil water infiltration processes in this region.

Background Functional genomic studies using genetics approaches of conifers are hampered by the complex and enormous genome, long vegetative growth period, and exertion in genetic transformation. Thus, the research carried out on gene function in Pinus tabuliformis is typically performed by heterologous expression based on the model plant Arabidopsis. However, due to the evolutionary and vast diversification from non-flowering (gymnosperms) to flowering (angiosperms) plants, several key differences may alter the underlying genetic concerns and the analysis of variants. Therefore, it is essential to develop an efficient genetic transformation and gene function identification protocol for P . tabuliformis . Results In the present study we established a highly efficient transgene Agrobacterium -mediated transient expression system for P . tabuliformis . Using a β-glucuronidase gene (GUS) as a reporter gene expression, the highest transformation efficiency (70.1%) was obtained by co-cultivation with Agrobacterium strain GV3101 at an optical density at 600 nm of 0.8, with 150 μM acetosyringone for 30 min followed by 3 days in the dark at 23 ± 1 °C. This protocol would be applied to other conifers; GUS staining was observed 24 h post-infection. Conclusions We report a simple, fast, and resilient system for transient Agrobacterium -mediated transformation high-level expression of target genes in P . tabuliformis , which will also improve transformation efficiency in other conifer species.

The geographical variation and domestication of tree species are an important part of the theory of forest introduction, and the tracing of the germplasm is the theoretical basis for the establishment of high‐quality plantations. Chinese pine (Pinus tabuliformis Carr.) is an important native timber tree species widely distributed in northern China, but it is unclear exactly where germplasm of the main Chinese pine plantation populations originated. Here, using two mtDNA markers, we analyzed 796 individuals representing 35 populations (matR marker), and 873 individuals representing 38 populations (nad5‐1 marker) of the major natural and artificial populations in northern China, respectively (Shanxi, Hebei and Liaoning provinces). The results confirmed that the core position of natural SX* populations (“*” means natural population) in the Chinese pine populations of northern China, the genetic diversity of HB and LN plantations was higher than that of natural SX* populations, and there was a large difference in genetic background within the groups of SX* and LN, HB showed the opposite. More importantly, we completed the “point by point” tracing of the HB and LN plantings. The results indicated that almost all HB populations originated from SX* (GDS*, ZTS*, GCS*, and THS*), which resulted in homogeneity of the genetic background of HB populations. Most of germplasm of the LN plantations originated from LN* (ZJS* and WF*), and the other part originated from GDS* (SX*), resulting in the large differences in the genetic background within the LN group. Our results provided a reliable theoretical basis for the scientific allocation, management, and utilization of Chinese pine populations in northern China, and for promoting the high‐quality establishment of Chinese pine plantations. Based on two mtDNA markers, accurately tracing the germplasm source of Chinese pine plantations in north China. Analyzed the genetic diversity and genetic structure of plantation and natural populations. Confirmed the core position of SX* natural populations.

Examining the land-atmosphere interaction in vegetation rehabilitation areas is important for better understanding of land surface processes affected by human activities. In this study, energy flux observations were used to investigate surface energy partitioning and evapotranspiration (ET) in a Pinus tabuliformis plantation in Northeast China in 2020 and 2021. The sensible heat flux (H) was the dominant component of R n , and the ratio of H to the latent heat flux was higher than 1 at all growth stages. The two most important factors influencing the midday evaporative fraction and daily ET were the normalized difference vegetation index (NDVI) and soil water content at 10 cm depth (SWC 10 ). Cumulative precipitation (P) minus ET was 62.83 and 239.90 mm in 2020 (annual P of 435.2 mm) and 2021 (annual P of 632.8 mm), respectively. The midday Priestley–Taylor coefficient (α), surface conductance (g s ), and decoupling coefficient increased gradually from the onset of the mid-growing stage and decreased from the later growing stage. Midday α and g s increased with NDVI and SWC 10 increasing until the NDVI (0.5) and SWC 10 (0.17 mm 3 mm −3 ) thresholds were reached, respectively. Midday α and g s were significantly influenced by vapor pressure deficit below 3 kPa, and the threshold value of midday g s was approximately 12 mm s −1 . In conclusion, this Pinus tabuliformis plantation regulated surface energy partitioning properly, and left a part of P for surface runoff and groundwater recharge in the semiarid region of Northeast China.

The selection of suitable tree species and the reasonable allocation of planting areas are important measures for improving soil quality. To evaluate the soil quality (SQ) and its driving factors of Pinus tabuliformis forests in loess hilly areas where forestry ecological projects, such as returning farmland to forest (grass), have been implemented, this study selected P. tabuliformis forests with different restoration years (1a, 6a, 11a, 18a, and 22a) in Wuqi County and used grassland before afforestation (PRG) and abandoned grassland (AG) with 22 years as controls. In this study, soil physicochemical indices, soil fauna indices, and herbaceous plant indices obtained via principal component analysis were used to establish a soil quality evaluation model via the fuzzy comprehensive evaluation method to comprehensively evaluate SQ. Structural equation modeling (SEM) was used to identify the key factors affecting the SQ of P. tabuliformis forests. The goal was to create a model that could effectively evaluate the SQ while considering all relevant factors. The findings of the study showed that: (1) by performing a principal component analysis on the 27 indicator factors, the first six principal components had eigenvalues > 1, and the cumulative contribution rate was 90.028%, effectively encompassing the information of the original variables. (2) The highest soil quality index (SQI) was 0.592 (p < 0.05) in the restored 6a P. tabuliformis forest, whereas the lowest SQI was 0.323 in the restored 1a P. tabuliformis forest. As the number of years of restoration increased, the SQ of the P. tabuliformis plantation forest progressively approached that of the long-term abandoned grassland, with only a 1.8% difference after 22 years of restoration. The SQI of the P. tabuliformis woodland in restored 6a was 83% higher than that of 1a, and following 6a of restoration, the SQI showed a decreasing trend with increasing restoration years. Nevertheless, the SQI increased by >52% compared with the early stage of restoration (1a) and by 31% compared with the grassland before afforestation (PRG). (3) SEM revealed that the SQ of P. tabuliformis forest land was mainly driven by soil physical and herbaceous plant indicators, and soil fauna indicators and restoration years had a negative effect on the evolution of SQ in P. tabuliformis forests. The driving factors of P. tabuliformis forests of different restoration years were different, and with the increase in restoration years, the effects of soil fauna and herbaceous plant indicators on the SQ of P. tabuliformis plantation forests showed an overall upward trend.

Background Seasonal flowering time is an ecologically and economically important trait in temperate trees. Previous studies have shown that temperature in many tree species plays a pivotal role in regulating flowering time. However, genetic control of flowering time is not synchronised in different individual trees under comparable temperature conditions, the underlying molecular mechanism is mainly to be investigated. Results In the present study, we analysed the transcript abundance in male cones and needles from six early pollen-shedding trees (EPs) and six neighbouring late pollen-shedding trees (LPs) in Pinus tabuliformis at three consecutive time points in early spring. We found that the EPs and LPs had distinct preferred transcriptional modules in their male cones and, interestingly, the expression pattern was also consistently maintained in needles even during the winter dormancy period. Additionally, the preferred pattern in EPs was also adopted by other fast-growing tissues, such as elongating new shoots. Enhancement of nucleic acid synthesis and stress resistance pathways under cold conditions can facilitate rapid growth and maintain higher transcriptional activity. Conclusions During the cold winter and early spring seasons, the EPs were more sensitive to relatively warmer temperatures and showed higher transcriptomic activity than the LPs, indicating that EPs required less heat accumulation for pollen shedding than LPs. These results provided a transcriptomic-wide understanding of the temporal regulation of pollen shedding in pines.