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Caryota obtusa of Arecaceae is a fascinating palm tree native to southwestern China, India, Myanmar, Thailand, Laos and Vietnam. It is an economically important and threatened species and appears as a canopy dominant in some karst areas in Yunnan. We aim to clarify the forest structure, species diversity, population status and regeneration dynamics of C. obtusa in the karst forest ecosystem of Yunnan, China. We established 56 vegetation plots dominated by C. obtusa in 10 counties of southern Yunnan. Based on the plot data, we analyzed the community stratification, floristic composition and C. obtusa 's population structure. We used questionnaires to interview local people and recorded the human activity history in C. obtusa -dominated forests. Caryota obtusa palm forests were distributed on limestone mountain slopes and gullies. There were seven forest community types. The stratification of each community included arborous layer, shrub layer and understory. The communities had rich species composition. For all the plots as a whole of each community type, Shannon–Wiener diversity index of either woody or herbaceous species ranged from 2.1 to 3.8. The diameter at breast height (DBH)-class frequency distribution of C. obtusa was a multimodal type. The regeneration was sporadic and dependent on intermediate natural disturbances. In the current population structure, a number of C. obtusa trees with small DBHs consisted mainly of the forest communities with no or a slight degree of human disturbances. Intensive human activities terribly hindered recruitment of C. obtuse , followed by the medium intensity of human activities. [ABSTRACT FROM AUTHOR]

Background: Schima genus of Theaceae is confined to subtropics and tropics of South, East and Southeast Asia. Thirteen species of Schima are distributed in subtropical China. Many of them appear as dominant canopy species in the subtropical forests. To date, Schima species richness distribution patterns of China have remained unknown. Meanwhile, there has been a longtime debate as to whether forests dominated by Schima species are early or late successional forests. We aim to clarify Schima species richness patterns and these species' roles in the forest succession and regeneration dynamics of the subtropical ecosystem in Yunnan Province, China. Method: We mapped Schima species richness distribution patterns in China. Based on 71 vegetation plots, we analyzed forest characteristics, population structure, and regeneration dynamics of Schima species in Yunnan. Results: Yunnan was found to harbor the greatest richness and the highest rarity-weighted richness of Schima species in the subtropical regions of China. We classified five primary and six secondary forest types containing Schima species as one of dominants. Yunnan had the high floristic diversity and varying stand structure of forests containing Schima species. The Schima species studied generally had a sporadic regeneration type and a long life-span. Four species (Schima argentea, Schima villosa, Schima sinensis, Schima sericans) were shade-intolerant. But three species (Schima noronhae, Schima khasiana and Schima wallichii) were considered as bi-modal type species having shade-intolerant and shade-tolerant traits. Schima noronhae was seen to be a top dominant in late successional forests, while S. wallichii was found as a top-dominant in early or middle or late successional forests. S. khasiana, Schima villosa, Schima sinensis usually appeared as a top dominant in early or middle successional secondary forests, though they also presented as a second dominant in late-successional forests. Schima argentea and Schima sericans dominated only in the early or middle/seral successional forests. Schima species' regeneration establishment depended mainly on forest canopy gap formation through moderate human and natural disturbances. Conclusions: Yunnan has high species richness and rarity-weighted richness of Schima. Both moderate human and natural disturbances have provided regeneration niches for Schima species. Some of the Schima species studied as a second dominant (rare as the top-dominant) present in the late-successional forests. Some of them are more often as the top-dominant in early or middle successional forests, where as time goes by the dominance of Schima species would be replaced by their associated dominant taxa such as Castanopsis species. [ABSTRACT FROM AUTHOR]

• Rare species exhibited higher functional richness and functional evenness; • Functional divergence has the greatest impact on ecosystem multifunctionality; • Rare species contribute more to ecosystem multifunctionality from a functional view. Global environmental change and increased human activities have led to rare species being given vulnerable status, as well as species losses and extinctions in recent years. However, most of the species in the community are rare species and they usually harbor unique functional traits that disproportionately contribute to community functional diversity. Numerous studies have also shown that functional diversity is a better predictor of ecosystem functioning than species diversity. Consequently, the evaluation of functional diversity of rare species and their contribution to ecosystem function is essential for the conservation of rare species. In this study, differences in functional diversity between rare and common plant species were analyzed based on functional diversity indices and species richness metrics in 30 1-ha plots comprising monsoonal evergreen broad-leaved forest in Pu'er City in the Yunnan Province of China. The roles of functional diversity of rare and common species in affecting ecosystem functions were also evaluated, in addition to the extent that either species group contributes to ecosystem functions or multifunctionality. The results indicated that functional diversity metrics including functional evenness and functional richness of rare species were higher than for common species in this subtropical forest. In addition, the functional diversity indices of rare species contributed greater to most ecosystem functions compared to those of common species. Moreover, the functional divergence of both rare and common species exerted obvious effects on ecosystem multifunctionality, although rare species exerted greater overall contributions. Rare species in the forest community of this study exhibited higher functional diversity and played a more important role in ecosystem multifunctionality via their diverse functional traits. Based on these results, it is necessary to focus greater conservation efforts on rare plants in a community. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and biomass is an essential element of the natural ecosystem functioning. Our research aims at assessing the effects of species richness on the aboveground biomass and the ecological driver of this relationship in a primary Pinus kesiya forest. We sampled 112 plots of the primary P. kesiya forests in Yunnan Province. The general linear model and the structural equation model were used to estimate relative effects of multivariate factors among aboveground biomass, species richness and the other explanatory variables, including climate moisture index, soil nutrient regime and stand age. We found a positive linear regression relationship between the species richness and aboveground biomass using ordinary least squares regressions. The species richness and soil nutrient regime had no direct significant effect on aboveground biomass. However, the climate moisture index and stand age had direct effects on aboveground biomass. The climate moisture index could be a better link to mediate the relationship between species richness and aboveground biomass. The species richness affected aboveground biomass which was mediated by the climate moisture index. Stand age had direct and indirect effects on aboveground biomass through the climate moisture index. Our results revealed that climate moisture index had a positive feedback in the relationship between species richness and aboveground biomass, which played an important role in a link between biodiversity maintenance and ecosystem functioning. Meanwhile, climate moisture index not only affected positively on aboveground biomass, but also indirectly through species richness. The information would be helpful in understanding the biodiversity-aboveground biomass relationship of a primary P. kesiya forest and for forest management. [ABSTRACT FROM AUTHOR]

• Tree growth is highly dependent on local climate rather than on large-scale climate change. • Climate drivers for tree growth are redistributed under climate warming. • The sensitivity of tree growth to climate under favorable conditions is more stable than in harsh ones. The relative influence of energy and water availability on tree growth at specific sites under warming conditions remains insufficiently understood on the Yunnan Plateau, which obstructs the rational selection and development of forest management measures in the context of climate change. In this study, a dendroecological investigation was conducted in four sites on the Yunnan Plateau to evaluate growth trends and climate responses of Pinus yunnanensis under warming and drought stress across cold-dry (CD), warm-humid (WH), warm (WR), and hot-dry (HD) zones. The effects of energy and water availability on the radial growth of P. yunnanensis varied in different sites and showed site-specific characteristics. The radial growth of P. yunnanensis in the CD zone benefited from rising temperatures, especially in the pre-growing season and core growing season. However the radial growth of P. yunnanensis in the WH zone was restricted by excess water in the core growing season. The radial growth of P. yunnanensis in the WR and HD zones became increasingly limited by temperature and drought stress, and the growth switched from responding to energy stress to moisture stress. The sensitivity of P. yunnanensis to climate factors in the warm-humid zone and humid seasons was relatively stable; in contrast, this species was vulnerable to warming and drought stress under harsh growth conditions and showed considerable instability. Intense warming in the future may cause a significant variation of tree growth response to climate. It would trigger a noticeable redistribution effect of energy and water availability on forest growth, which motivates assessments of climate-growth relationships, not only at large spatial scales, but also in specific sites. This research provides a basis for the adoption of effective forest management measures for specific sites according to their response characteristics associated with the distribution of climate drivers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Converting primary forest to agricultural production decreased fungal, bacterial, and total microbial residue C. • Soil fungal abundance increased microbial residue C accumulation. • Soil bacterial abundance declined fungal and total microbial residue C accumulation. • Soil fertility improved fungal, bacterial, and total microbial residue C accumulation. Soil microbes mediate soil organic carbon (SOC) storage by affecting microbial residue carbon (C) in terrestrial ecosystems, a main source of SOC. However, how microbial residue C accumulation changes during the conversion of subtropical primary forest to plantations and the role of soil microbial community structure in regulating these changes remain unclear. Here, effects of conversion from forest on microbial residue C accumulation in three plantations, including tea (Camellia sinensis var. assamica), walnut (Juglans regia), and macadamia (Macadamia integrifolia). We assessed amino sugars content and the relative importance of soil microbial community structure, soil fertility, and aboveground biomass in four forest types in southwest Yunnan province, China. Our results show that total microbial residue C accounted for 27.8 % of SOC on average across all forest types, and fungal residue C contributed more to SOC than bacterial residue C across different forest types. Conversion from primary forest decreased fungal, bacterial, and total microbial residue C content in all plantation types except tea. Microbial residue C contents was significantly lower in the macadamia plantation than in the primary forest and the tea plantation. Fungal and total microbial residue C content increased with increasing soil microbial community composition, soil fungal abundance, and soil fertility. Soil fertility regulated fungal, bacterial, and total microbial residue C accumulation, which was major determinant of microbial residue C via its influence on soil fungal and bacterial abundance. Overall, we found that soil fungal abundance contributed more to microbial residue C accumulation than change in soil microbial community composition. We also found that soil bacterial abundance was negatively correlated with fungal and microbial residue C, while soil fungal abundance was positively related to microbial residue C accumulation. Ascomycota was most important phylum regulating microbial residue C. These findings suggest that soil fungal and bacterial abundance and soil fertility are the principal regulators of microbial residue C accumulation during the conversion from primary forest to different plantations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Macadamia-based agroforestry systems influence microbial necromass C and its contribution to SOC. • Soil fungal β diversity controlled and significant negative effect over microbial necromass C and its contribution to SOC. • Woody aboveground biomass indirectly affected microbial necromass C via soil fungal β diversity. Agroforestry management practices governed soil organic carbon (SOC) and microbial community structure in terrestrial ecosystems, yet the effect of these practices on microbial necromass carbon (C) remain poorly understood in a subtropical region. Here, we compared the differences in fungal, bacterial, and microbial necromass C (indicated by amino sugars) and their contributions to SOC among different forest types including macadamia monoculture plantation (MMP) and macadamia-based agroforestry systems intercropping with dasheen (MDAS), konjac (MKAS), and maize (MMAS) in the Lincang city, southwest Yunnan province, China, and assessed the impact of aboveground biomass, soil fertility, and soil microbial community structure on microbial necromass C and its contribution to SOC. Compared with monoculture plantation, macadamia-based agroforestry decreased SOC, and changed significantly soil microbial α diversity, β diversity, and microbial necromass C and its contribution to SOC (P < 0.01). Microbial necromass C and its contribution to SOC were no significant difference between MMP and MMAS. MDAS and MKAS had lower microbial necromass C than MMP (35.11 % and 63.62 %, respectively). SOC increased with increasing soil fungal and microbial necromass C among the agroforestry systems. Soil fertility was the most important factor affecting fungal (41.45 %), bacterial (33.84 %), and microbial necromass C (40.63 %). Importantly, soil fertility and fungal β diversity directly negatively affected soil fungal and microbial necromass C and their contributions to SOC. Furthermore, woody aboveground biomass affected microbial necromass C directly or indirectly via soil fungal β diversity. Overall, our findings suggest that soil fungal β diversity drove microbial necromass C accumulation and its contribution to SOC in a macadamia-based agroforestry systems, which reveal that sowing crop may be key considerations in mitigating climate change. [ABSTRACT FROM AUTHOR]

Identifying and protecting refugia is a priority for conservation management under projected anthropogenic climate change. We have two main objectives: the first is to explore the spatial (East Asia) and temporal (Last Glacial Maximum to year 2070) distribution patterns of dominant Castanopsis species of evergreen broad-leaved forests, also the relation with their niche breadths; the second is to identify long-term stable refugia for preserving these species and provide a framework of conservation strategies. We find that there is an extraordinary richness with 32 dominant Castanopsis species, and they form both a geographically and climatically almost unbroken connection from ca. 5°N to 38°N, having thus ecological significance. During the Mid-Holocene and, particularly, the Last Glacial Maximum, the predicted suitable areas of the species as a whole were larger than those in the present. By 2070, potentially suitable areas with high richness of dominant Castanopsis species will be reduced by 94.5 % on average. No correlation between species niche breadths and distribution ranges is found, which could be due to regional climate stability. Mountains of southwestern and southern Yunnan in China are identified as climatically long-term stable refugia for 7–9 Castanopsis species. We recommend that these refugia have the highest priority of conservation to prevent their extinction. Our suggested urgent measures include improving the effectiveness of currently protected Castanopsis species and expanding the network of protected areas to cover a larger fraction of the refugia, as well as ensuring Castanopsis species natural regeneration potential in fragmented and natural secondary forest areas. [ABSTRACT FROM AUTHOR]