Forest bathing is receiving increased attention due to its health benefits for humans. However, knowledge is scarce about the adjunctive therapeutic effects of forest bathing in different seasons on geriatric hypertension. The aim of the current study was to evaluate the antihypertensive effects of forest bathing in a Cinnamomum camphora (C. camphora) forest environment in four seasons. One group of participants with geriatric hypertension was sent to a C. camphora forest to experience a 3 day trip, while, as a control, another group was sent to the urban center. The participants’ blood pressure, blood routine, and blood biochemistry were assessed. The profile of the mood states (POMS) of the participants was assessed before and after the experiment. The air quality, atmospheric environment, and content of volatile organic compounds (VOCs) at the two experimental sites were monitored during the experiment. This experiment was repeated across four seasons. The advantages of the urban forest groups over the control groups were mainly represented by reductions in diastolic blood pressure (DBP), systolic blood pressure (SBP), and heart rate (HR), as well as increased oxygen saturation (SpO₂). The antihypertensive effects of forest bathing in the C. camphora forest environment changed with the seasons. Compared with the baseline level, SBP and DBP declined after forest bathing across the whole year, except during winter, whereas SpO₂ increased. The effect of forest bathing on lowering blood pressure was particularly pronounced during summer and autumn. The antihypertensive effects of forest bathing in the four seasons were highly consistent with the seasonal dynamics of VOCs and negative air ions (NAIs), which implies that the effect of forest bathing may be attributed to alterations of the atmospheric environment. The antihypertensive effects of C. camphora forest were confirmed in our study, and the results can provide a reference for scheduling bathing trips.

Phosphorus (P) is a key nutrient in forest ecosystems in subtropical regions. However, the effects of the long-term application of organic amendments on P availability are poorly understood. Here, we compared the soil P fractions and associated soil properties in southern Chinese Lei bamboo plantations using both an intensive management system (IMS) and a traditional management system (TMS). The results show that the IMS significantly (p < 0.05) increased the soil total organic carbon (C), soil ammonium N (NH₄-N), total P, and available potassium content; microbial biomass C and P content; P activation coefficient, and soil C:P ratios, while significantly (p < 0.05) decreasing pH and microbial C:P. The labile-P-to-total-phosphorus-content ratio increased significantly in the IMS (46%) compared with that in the TMS (32%). The selected soil properties (except nitrate [NO₃-N]) were significantly related to soil P fractions (except for concentrated HCl-extracted organic P). The IMS had a higher C:P ratio and labile P content than the TMS, suggesting that the IMS could promote soil P transformation and availability. Overall, the IMS increased soil P availability and supply capacity, and the changes in P forms could be a risk factor for P loss.

Soil nutrient and fertility assessments provide a direct measure for evaluating forest management effects. In this study, we examined soil nutrient content in Chinese fir (Cunninghamia lanceolata) plantations under four reconstruction patterns: pure plantation, introduced broadleaf, introduced needleleaf, and introduced mixed broadleaf-needleleaf. The soil fertility index (SFI) evaluation model was constructed based on partial least squares path modeling (PLS-PM), revealing the influence of stand characteristics on SFI in early stand reconstruction. The results showed that, compared to pure plantations, total nutrient content increased in the introduced needleleaf pattern by 13.94% to 21.15% and available nutrient content by 18.21% to 26.91%. In contrast, both introduced broadleaf and mixed broadleaf-needleleaf exhibited a declining trend. Significant differences were observed among the reconstruction patterns (p < 0.05). In the SFI evaluation model, soil chemistry total nutrient (SCT) and soil chemistry available nutrient (SCA) made significant contributions. The weights of SCT and SCA in SFI were 0.52 and 0.48, respectively. The SFI of four patterns ranged from 0.43 to 0.58, indicating relatively low soil fertility. Compared to pure plantations, introduced trees did not enhance soil fertility in early stand reconstruction. The SFI of the introduced needleleaf was significantly higher than that of the other two reconstruction patterns (p < 0.05). Stand construction (including diameter at breast height, tree density, and tree biomass) explained 14.69% of SFI variation, with a contribution of 31.72% in the surface soil layer (0~20 cm). Tree biomass significantly influenced SFI variation, accounting for over 40% of the total stand factors. Retained tree biomass had a substantially greater effect than introduced tree biomass, contributing twice as much to SFI variation. PLS-PM could effectively reflect the soil nutrient status and accurately estimate the weight of soil fertility. In early stand reconstruction, retained tree biomass might be the major influence on soil fertility variation. We suggest determining reasonable thinning intensity to retain enough Chinese fir and promote the growth of introduced trees. This study introduces a novel approach to soil fertility assessment and provides theoretical support for formulating effective forest management strategies in the early reconstruction of Chinese fir plantations.