Changes in subsurface ecological processes in the context of global change have become one of the hot issues of concern in the field of ecology. Mycorrhiza are symbiotic relationships between plant roots and mycorrhizal fungi, widely distributed in terrestrial ecosystems. As two major types of mycorrhizal fungi related to trees, arbuscular mycorrhizal fungi and ectomycorrhizal fungi exhibit significant differences in morphology and function. Root exudates, as an important medium for exchange of matter, energy, and information between plants and soil, play a crucial role in soil carbon dynamics. The root exudates of tree species associated with different mycorrhizal types can actively respond to environmental changes by continuously adjusting their quantity and chemical composition, and influence the belowground carbon dynamics and cycling processes of forest ecosystems. Currently, the composition and function of root exudates from different types of mycorrhizal fungi, as well as the variation and impact on plant and soil, remain unclear. Therefore, the article combines current frontier dynamics in the field both domestically and internationally, and summarizes the root exudate characteristics, influencing mechanisms, and rhizosphere effects of tree species associated with different mycorrhizal types. This review is expected to provide references for further research on the response and adaptation mechanism of root systems and exudates to global changes. In addition, it also proposes directions for future research on root exudates among different types of mycorrhizal fungi that require further investigation: (1) strengthening systematic research on root exudates among different types of mycorrhizal fungi; (2) studying the influence mechanism of mycorrhizal type on root exudates in combination with other environmental factors; (3) using more precise technological means to comprehensively understand the changes in root exudate characteristics among different types of mycorrhizal fungi; (4) deeply revealing the influencing mechanism of root exudates among different types of mycorrhizal fungi from the perspective of plant physiology and metabolism; (5) conducting long-term dynamic monitoring and simulation experiments on different types of mycorrhizal fungi to predict their impact on soil ecological processes.

Aims Alpine shrublands are crucial for global carbon cycle due to their substantial soil carbon storage and sensitivity to global changes. Twig and leaf litter play a crucial role in terrestrial ecosystem carbon and nutrient cycling; however, comparative studies on their production and decomposition remain limited. This knowledge gap hinders accurate assessments of their contributions to soil carbon and nutrient cycling. Methods This study investigated the annual production, decomposition rates, and carbon and nitrogen retention of twig and leaf litter in an alpine shrubland ecosystem on the eastern margin of the Qinghai–Tibetan Plateau of China over a four-year period. Important findings Results found that: (1) Leaf litter production (138.94 g·m?2·a?1) was 4.41 times higher than twig litter production (31.48 g·m?2·a?1). Thus, leaf litter had a higher annual carbon and nitrogen inputs than twig litter. (2) Decomposition rate of twig litter (K = 0.356 a-1) was significantly slower than that of leaf litter (K = 0.522 a-1). The proportion of recalcitrant fraction of twig litter during decomposition was 4.86 times higher than that of leaf litter (0.287 vs. 0.059, respectively). (3) Nitrogen release patterns differed between twig and leaf litter: leaf litter exhibited a net nitrogen release, while twig litter followed a pattern of “enrichment—stabilization—release”. (4) After four years of decomposition, the estimated annual carbon retention of twig and leaf litter was similar (3.85 g?m-2?a-1 for twig litter and 3.72 g?m-2?a-1 for leaf litter). However, leaf litter retained significantly more nitrogen than twig litter (0.11 g?m-2?a-1 vs. 0.06 g?m-2?a-1). This study highlights the complementary roles of twig litter in promoting carbon accumulation in alpine shrubland due to its slower decomposition. In contrast, leaf litter plays a more crucial role in alleviating soil nitrogen limitation due to its faster nitrogen release and higher nitrogen return. Our results provide valuable foundation for accurately assessing the contributions of twig and leaf litter to soil carbon and nitrogen cycling.

Aims Plant sexual systems is an important reproductive role that affects plant mating, genetics, evolution, and species distribution. They are classified into three categories based on the floral organ's pistil and stamen arrangement: hermaphroditism, dioecy, and monoecy. Methods This article takes forest communities in Daiyun Mountain (elevation 900-1600 m) as the research object, analyzing changes in the quantitative characteristics of woody plant sexual systems and investigating their correlation with environmental factors via Mantel correlation analysis. Important findings The study area encompassed 85 woody plant species, with 49 hermaphroditic (57.6%), 26 dioecious (30.6%), and 10 monoecious (11.8%) species. Altitudinal increase led to a significant rise in the number of hermaphroditic and dioecious individuals, with no significant change in their species ratio, while monoecious individuals' number and species ratio significantly declined. The Shannon Wiener index and Pielou evenness index for sexual systems generally decreased with altitude, whereas the Simpson dominance index remained stable. Effective phosphorus and soil temperature were identified as the primary drivers of altitudinal changes in sexual systems characteristics. In conclusion, the quantitative characteristics of the sexual systems of woody plants on the altitudinal gradient of Daiyun Mountain showed significant differences, and the altitudinal distribution of the sexual systems was highly sensitive to environmental changes, indicating that plants adapt to environmental changes by regulating the composition of their reproductive systems, thereby ensuring the continuous survival and reproduction of their populations.

Aims Revealing the regional variation of functional traits and adaptation strategies of eurybiont is of great significance for predicting the adaptation potential of plants under climate change. Methods Here, Setaria viridis was studied with 18 water-carbon related functional traits of stem and leaf organs measured and 9 study sites were selected along the precipitation gradient from southeast to northwest China. The methods of trait network and principal component analysis were used to quantify the regional differentiation of traits, and to clarify their habitat adaptation strategies. Important findings The results showed that: (1) In humid regions, Setaria viridis exhibited the largest vessel diameter and specific leaf mass; in the semiarid/humid region, Setaria viridis exhibited the highest maximum net photosynthetic rate per unit leaf area, anatomical maximum stomatal conductance and stomatal area fraction; in arid regions, Setaria viridis exhibited the highest thickness-to-span ratio of vessel and maximum net photosynthetic rate per unit leaf mass. These various reflected the Setaria viridis’ adaptation strategies in different regions. (2) With the decrease of precipitation, the correlation between traits decreased, the connectivity of the network decreased, and the complexity increased. The proportion of positive correlation between traits of the network reached the maximum in the semiarid/humid regions, showing the best cooperative relationship between plant traits, which may be related to the balanced allocation of water and light resources in this region. (3) The results of the trait network of 9 sites indicating that the adaptation of Setaria viridis along the precipitation gradient was mainly regulated by stomatal traits. This study has great significance for predicting the potential mechanisms of plant’/vegetation’ adaptation under the background of climate change.

Aims The Shenzhen Bay Mangrove Nature Reserve is the only national nature reserve in China located within an urban area. Studying the potential biodiversity of urban mangrove wetlands, which are significantly impacted by human disturbance, can provide a pathway for the sustainable management of mangrove ecosystems. Methods This study conducted an ecological survey of different areas (core/non-core) in the Shenzhen Bay Mangrove National Nature Reserve. Species co-occurrence and distribution probability was assessed using the hy-pergeometric method, and the vegetation characteristics of the area were analyzed based on the survey data. Important findings (1) A total of nine mangrove species were distributed in the Shenzhen Bay Mangrove Nature Reserve, with Kandelia obovata being the dominant species. In the core area, K. obovata had the highest importance value (IV) (mean = 96.4%), while its importance value in the non-core area was significantly lower (p < 0.05), where Sonneratia apetala and S. caseolaris appeared. (2) In the Shenzhen Bay mangrove ecosystem, S. caseolaris and S. apetala exhibited a strong coexistence tendency, with a z-score value of 2.82. Meanwhile, S. apetala and K. obovata displayed competitive exclusion, with a z-score value of -2.41. Z-score values reflect non-random species co-occurrence patterns. (3) A significant positive correlation was found between the existing species diversity and the community integrity index in the Shenzhen Bay mangroves. The higher the community integrity, the higher the existing species diversity. Some non-core area plots are at risk of S. apetala spreading, and ecosystem management and protection should be strengthened. The distribution probability of K. obovata in the core area (0.51 ± 0.09) is significantly higher than that in the non-core area (0.41 ± 0.15). However, in certain plots of the core area, such as the plots in the mid-tide zones of transects 8, community completeness is relatively low. It is recommended to appro-priately replant native mangroves to enhance species diversity.

Aims Nitrogen (N) addition significantly affected the aboveground net primary productivity (ANPP) and belowground net primary productivity (BNPP) of grassland ecosystems. However, the different responses of plant ANPP and BNPP to N addition and their saturation response thresholds at different levels of N addition are not clear. Methods Therefore, eight N addition levels (0, 1, 2, 4, 8, 16, 24, 32 g N m-2 year-1) were set up in the Leymus secalinus grassland in northern Shanxi Province, and the changes of plant ANPP, BNPP and total net primary productivity (NPP) were monitored for five years from 2017 to 2021. The temporal stability, N saturation threshold and N response efficiency of plant productivity were also calculated. Important findings The results showed that: (1) ANPP and NPP were increased nonlinearly with the increase of N addition level. The saturation response thresholds of ANPP and NPP across five years (2017-2021) were 25.7 g N m-2year-1 and 21.3 g N m-2year-1, respectively. (2) ANPP and BNPP had different sensitivities to N addition, and the sensitivity of ANPP was higher than that of BNPP. The change in NPP was mainly caused by changes in ANPP, suggesting that plant productivity distribution to the ground increased as the level of N addition increased. (3) NREANPP showed an exponential downward trend with the increase of N addition levels, while the NREBNPP and NRENPP showed a linear downward trend with the increase of N addition level. (4) Structural equation model analysis showed that soil NO3--N and pH regulated the effects of N addition and years on plant ANPP and BNPP. There was different regulatory mechanisms of ANPP and BNPP under low N and high N addition treatments. Both ANPP and BNPP were directly affected by N addition under low N addition treatments, while the soil inorganic N indirectly regulated the response of ANPP and BNPP to N addition under high N addition treatments. This study showed that plant productivity in grassland ecosystem responded nonlinearly with N addition level, which provided data support for improving the ecosystem service function of Leymus secalinus grassland in northern Shanxi Province under the background of N deposition.

Aims Ants play important roles in material cycling and energy flow in subtropical forests. However, there remains a knowledge gap regarding how different canopy tree species regulate ant community structure by altering seasonal patterns of understory microclimate, soil surface environment, and litter properties. Methods From July 2023 to March 2024, ant community structure composition, taxonomic and functional group differences, diversity characteristics, as well as their seasonal dynamic changes were investigated in a common garden of Fujian Sanming Forest Ecosystem National Observation and Research Station. Six representative canopy tree species were selected to check the relationships between trees and ant community in the mid-subtropical evergreen broad-leaf forests. Important findings During the investigation, a total of 30 389 ants were collected, belonging to 19 genera and 30 species with the dominant species of Pheidole nodus and Crematogaster rogenhoferi. we found higher ant diversity in summer and fall but lower diversity in winter and spring. The tree species significantly influenced ant abundance, with the following order: Liquidambar formosana > Castanopsis carlesii > Sapindus saponaria > Cunninghamia lanceolata > Michelia macclurei > Pinus massoniana. Moreover, sampling season and its interaction with tree species also significantly affected the structure of ant functional groups. Among others, the abundance of Generalized Myrmicinae under Cunninghamia lanceolata in summer was significantly higher than them under other tree species, whereas Climate Specialists showed relatively higher abundance under Castanopsis carlesii in spring but lower abundance under Pinus massoniana. Canonical correspondence analysis revealed that soil temperature, soil organic matter content, aboveground biomass, and litter production could explain more than 50% of the variation in ant community structure. The results not only elucidated the relationships between tree species and ant community in mid-subtropical forests, but also provided primary data for knowledge on other similar soil fauna.