Non-karst Forests Research Articles

Lithology and elevated temperature impact phoD-harboring bacteria on soil available P enhancing in subtropical forests

Plants are generally limited by soil phosphorus (P) deficiency in forest ecosystems. Soil available P is influenced by lithology, temperature, and soil microbes. However, the interactive effects of these factors on soil P availability in subtropical forests remain unclear. To assess their impacts, we measured soil inorganic and available P fractions and the diversity, composition, and co-occurrence network of phoD-harboring bacteria in two contrasting forest soils (lithosols in karst forests and ferralsols in non-karst forests) in the subtropical regions of southwestern China across six temperature gradients. The present results showed that the complexities in composition and network and the diversity indices of phoD-harboring bacteria were higher in the karst forest soils than those in the non-karst forest soils, with marked differences in composition. In both types of forest soils, the complexities of composition and networks and the diversity indices were higher in the high-temperature regions (mean annual temperature (MAT) > 16 °C) compared to the low-temperature regions (MAT <16 °C). Soil total inorganic and available P contents were lower in the karst forest soils compared to the non-karst forest soils. Soil total available P contents were lower in the high temperature regions than those in the low temperature regions in both forest soils, whereas soil total inorganic P contents were contrary. Variance partitioning analysis showed that soil inorganic and available P fractions were predominantly explained by lithology and its interaction with soil microbes and climate. The present findings demonstrate that soil P availability in subtropical forests of southwestern China is influenced by lithology and temperature, which regulate the diversity, composition, and network connectivity of phoD-harboring bacteria. Furthermore, this study highlights the significance of controlling the composition of phoD-harboring bacteria for mitigating plant P deficiency in karst ecosystems.

The phoD-Harboring Microorganism Communities and Networks in Karst and Non-Karst Forests in Southwest China

Phosphorous (P) limitation is common not only in tropical rainforest and savanna ecosystems, but also in karst forest ecosystems. Soil phoD-harboring microorganisms are essential in soil P cycles, but very little information is available about them in karst ecosystems. A total of 36 soil samples were collected from two types of forest ecosystems (karst and non-karst) over two seasons (rainy and dry), and the diversity and community structure of soil phoD-harboring microorganisms were measured. The contents of available P (AP), soil total P (TP), microbial biomass P (MBP) and the activity of alkaline phosphatase (ALP) in karst forest soils were higher than those in non-karst forest soils, whereas the contents of CaCl2-P, citrate-P, enzyme-P and the activity of acid phosphatase (ACP) were the opposite. Soil AP content was significantly higher in the rainy season than in the dry season, whereas ALP activity was the opposite. The community structure of phoD-harboring microorganisms was more influenced by forest-type than season. The network connectivity was higher in non-karst forests than in karst forests. Two dominant orders, Burkholderiales and Rhizobiales, were the keystone taxa in these networks in two forests, and their relative abundances were higher in non-karst forests than in karst forests. The microorganic diversity indices (e.g., Shannon–Wiener, Evenness, Richness, and Chao1) were substantially higher in karst than in non-karst forests. These indices were positively correlated with the contents of SOC and TN in the two forests; meanwhile, richness and evenness indices were positively correlated with citrate-P, HCl-P, and TP in non-karst forests. Structural equation modelling results showed that the relative abundance of phoD-harboring microorganisms was mainly influenced by pH and AP, with direct affection of soil AP, pH, and ALP activity, and indirect affection of ALP activity through affecting AP. These findings highlight that the P cycle is mainly regulated by the diversity of phoD-harboring microorganisms in karst forest ecosystems, whereas it is mainly regulated by dominant taxa in non-karst forest ecosystems. In future, regulating the interaction networks and keystone taxa of phoD-harboring microorganisms may be critical to alleviating P limitations in karst forest ecosystems.

Effects of rock lithology and soil nutrients on nitrogen and phosphorus mobility in trees in non-karst and karst forests of southwest China

The primary productivity of terrestrial plants is widely limited by nitrogen (N) and phosphorus (P), and the mobility of N and P in plants is the key to predicting plant growth and development. Non-karst and karst forests soil have different nutrient supply capacities due to the difference in soil parent material, but the effect mechanism of the two soil nutrient conditions on the N and P mobility process of trees remains unclear. In this study, forests dominated by three typical tree species, Eucalyptus maideni, Pinus yunnanensis, and Quercus franchetii were selected as the research objects in non-karst and karst areas of southwest China to investigate the effects of soil nutrient conditions on plants’ N and P foraging, transportation and resorption. The results showed that the rock lithology had significant effects on the soil nutrients, plants’ N and P foraging, transportation, and resorption. The soil total N and P concentrations, soil organic carbon concentration, and pH were higher in karst forests than those in the non-karst forests, but the green leaves N and P concentrations exhibited opposite characteristics. The root foraging potential for N and P in non-karst forests was significantly higher than that in karst forests. The N resorption efficiency of trees in karst forests was higher than that in non-karst forests, but the P resorption efficiency was lower than that in non-karst forests. The trade-offs of foraging, transportation and resorption of trees were adjusted according to changes in nutrient conditions, but the trade-offs of the three processes were not continuous in non-karst and karst forests. Compared with non-karst forests, the decreased degree of root nutrient foraging potential in karst forests was greater than the transportation factor and resorption efficiency. The slow-growing Quercus franchetii among the three typical forests showed better adaptability to foraging, transportation, and resorption of N and P in karst areas. The results revealed the response of different forests’ N and P mobility patterns of trees to different nutrient conditions in non-karst and karst areas, which was helpful to improve the prediction and mechanistic understanding of nutrient cycling in local forest ecosystems.

Lower Sensitivity of Soil Carbon and Nitrogen to Regional Temperature Change in Karst Forests Than in Non-Karst Forests

Lithology has such an important effect on the sustainability of soil carbon (C) pools. Forests are an important part of terrestrial C sinks; yet, it is unclear whether their soil carbon sensitivity to temperature changes is regulated by lithology, especially in karst ecosystems, which are widely distributed globally. Along a climate gradient in the subtropical region of southwest China, we compared the contents of soil organic C (SOC) and total N (TN) in karst and non-karst forests. The data were analyzed and processed using ANOVA, regression analysis, and random forest. The results showed that the karst forests had significantly higher SOC and TN contents but lower ratio of SOC to TN (C:N) than non-karst forests, mainly because of the higher soil calcium (Ca) content and microbial biomass. With rising mean annual temperature (MAT), SOC and TN contents in non-karst forests significantly decreased, whereas in karst forests they were not correlated with MAT; while, the opposite was true for C:N. In karst forests, soil Ca constrain warming induced decomposition of SOC and TN by forming stable complexes with SOM through exchangeable Ca, and by promoting aggregate stability through the role of calcium carbonate. The correlation between δ13C and the logarithm of SOC concentration also supported that conclusion. In karst forests compared to non-karst forests, soil C pools are larger and less sensitive to regional temperature change. Nevertheless, climate warming may still accelerate soil C loss in karst forests by increasing microbial C limitation. Thus, soil C sequestration potential and loss risk coexist in karst areas. The ratio of SOC to TN (C:N) is regulated through appropriate management measures in the process of karst vegetation restoration, thus promoting long-term stable sequestration of soil carbon pools.

Habitat heterogeneity in karst environments influences the proportion and distribution of random framework

• Karst forests comprises soil and rock habitats. • A linear relationship between the proportions of frameworks and tree size. • Random framework accounts for approximately 58% of trees. • Habitat heterogeneity and lifeform markedly alter the proportion of random framework. In the absence of exogenous disturbance, natural forests usually display stable and orderly distribution patterns. Recent studies have demonstrated that the random framework (RF), based on the locations of four neighboring trees, remains stable in non-karst forests. However, it is not clear whether tree size, lifeform (tree vs shrub), and habitat heterogeneity affect the proportion and distribution of RF. We established a 200 × 110 m fixed plot in an old-growth karst forest in southwest China. Trees were divided into 20 different-sized groups based on minimum measured diameters (MMDs) of 1–20 cm, and the proportion and distribution of various frameworks (clumped, random, and regular) of the quadrat and trees and shrubs growing on rock and soil were analyzed using the uniform angle index ( W ). The results indicated that: (1) the proportion of RF was stable at the stand level, and accounted for approximately 58% of trees in all MMD classes; (2) With increasing MMD, the proportions of trees and trees + shrubs growing on soil also increased, while the univariate distribution of W maintained an ideal normal distribution. The distribution patterns shifted from aggregated to random, and then to regular. On rock, the proportion of the RF decreased with increasing MMD; clumped distribution patterns were seen, and the mean value of W was discrete; (3) The proportion of RF decreased with increasing MMD for shrubs growing on soil, but increased for shrubs growing on rock. Shrubs were predominantly clumped; (4) A linear relationship between the relative proportions of frameworks and tree size was observed. Our results suggest that the proportion of RF in karst forests is scarcely affected by tree size, whereas markedly altered by habitat heterogeneity and lifeform. The tradeoff between clumped and regular frameworks alters distribution patterns, and habitat heterogeneity promotes aggregation.

Comparison of bacterial and fungal diversity and network connectivity in karst and non-karst forests in southwest China

Microbial communities contribute to sustaining the function of terrestrial ecosystems and are influenced by soil type and climate gradients. The effects of karst and non-karst soils on bacterial and fungal profiles for seven climate gradients were assessed to better understand bacterial and fungal diversity and community composition in response to soil type with changes in soil physicochemical properties under different temperatures and precipitations. Bacterial and fungal abundance, diversity, and community composition differed between karst and non-karst forests. Bacterial and fungal richness, Shannon index, and bacterial abundance in karst forests were higher than non-karst forests, but the fungal abundance was lower. Mean annual temperature was negatively correlated with bacterial diversity in the karst forest and fungal abundance in karst and non-karst forests. The community composition of bacteria and fungi differed among these two soil types. The karst forest had greater connectivity among bacterial and fungal communities than non-karst forests. The bacterial members of Acidobacteria, Proteobacteria, Actinobacteria, and fungal groups of Ascomycota and Basidiomycota were mainly connected with other taxa in the network, implying that taxa were associated with highly functional potential. The relative abundance of Actinobacteria and Ascomycota was higher in karst than in non-karst forests. Proteobacteria and Basidiomycota showed the opposite results. A random forest and multiple regression tree analyses revealed that soil properties, specifically pH, calcium, and total nitrogen, were the main factors influencing the variation in bacterial and fungal profiles between karst and non-karst forests. This study provides novel evidence that the abundant microbial taxa were kinless hubs in co-occurrence patterns. Controlling complex networks of species interactions may contribute to improving soil nutrient processes rather than microbial diversity, enhancing our understanding of developing sustainable recovery strategies in fragile ecosystems.

Diazotroph and arbuscular mycorrhizal fungal diversity and community composition responses to karst and non-karst soils

Diazotrophs and arbuscular mycorrhizal fungi (AMF) are important functional microbes that provide and transport nutrients to plants. Diazotroph and AMF diversity and community composition were investigated in karst mature forests (MFs) and non-karst forests, as well as in croplands (CRs) as a reference. Diazotroph diversity and community composition significantly shifted in MFs between karst and non-karst soils, with a higher diazotroph richness and Shannon index in karst MFs than in non-karst soils. Similar levels of AMF diversity and community composition were observed between karst and non-karst CRs and MFs. According to the co-occurrence network analysis results, the pairs of correlation links within the diazotroph and AMF groups were higher in karst MFs than in non-karst MFs, whereas this interaction was lower in karst CRs than in non-karst CRs. The diazotroph genera Bradyrhizobium and Anabaena and the AMF genera Glomus and Rhizophagus were mostly correlated with other species in both karst and non-karst soils. Diazotrophs and AMF communities were mainly affected available nutrients (e.g., nitrogen and phosphorus) and environmental factors (e.g., temperature and precipitation), respectively. Soil calcium content was an important factor that affected the distributions of diazotrophs and AMF between karst and non-karst soils. Overall, our study suggested that the increased interactions between diazotrophs and AMF in karst forests, as compared with those in non-karst soil, led to the stability of the diazotrophs and AMF co-occurrence patterns for maintaining nutrients that are effectively absorbed and utilized. Thus, strengthening the cooperative relationships between diazotrophs and AMF are important and necessary in calcareous soils during natural vegetation restoration.

Increase in leaf organic acids to enhance adaptability of dominant plant species in karst habitats.

Estimation of leaf nutrient composition of dominant plant species from contrasting habitats (i.e., karst and nonkarst forests) provides an opportunity to understand how plants are adapted to karst habitats from the perspective of leaf traits. Here, we measured leaf traits—specific leaf area (SLA), concentrations of total carbon ([TC]), nitrogen ([TN]), phosphorus ([TP]), calcium ([Ca]), magnesium ([Mg]), manganese ([Mn]), minerals ([Min]), soluble sugars, soluble phenolics, lipids, and organic acids ([OA])—and calculated water‐use efficiency (WUE), construction costs (CC), and N/P ratios, and searched for correlations between these traits of 18 abundant plant species in karst and nonkarst forests in southwestern China. Variation in leaf traits within and across the abundant species was both divergent and convergent. Leaf [TC], [Ca], [Min], [OA], and CC were habitat‐dependent, while the others were not habitat‐ but species‐specific. The correlations among [TN], [TP], SLA, [TC], CC, [Min], WUE, [OA], and CC were habitat‐independent, and inherently associated with plant growth and carbon allocation; those between [CC] and [Lip], between [Ca] and [Mg], and between [Mg] and [WUE] were habitat‐dependent. Habitat significantly affected leaf [Ca] and thus indirectly affected leaf [OA], [Min], and CC. Our results indicate that plants may regulate leaf [Ca] to moderate levels via adjusting leaf [OA] under both high and low soil Ca availability, and offer new insights into the abundance of common plant species in contrasting habitats.

Environmental filtering and dispersal limitation jointly shaped the taxonomic and phylogenetic beta diversity of natural forests in southern China.

AimThe mechanisms underlying the maintenance of biodiversity remain to be elucidated. Taxonomic diversity alone remains an unresolved issue, especially in terms of the mechanisms of species co‐existence. We hypothesized that phylogenetic information could help to elucidate the mechanism of community assembly and the services and functions of ecosystems. The aim of this study was to explore the mechanisms driving floral diversity in subtropical forests and evaluate the relative effects of these mechanisms on diversity variation, by combining taxonomic and phylogenetic information.LocationWe examined 35 1‐ha tree stem‐mapped plots across eight national nature reserves in Guangxi Zhuang Autonomous Region, China.TaxonTrees.MethodsWe quantified the taxonomic and phylogenetic β‐diversity between each pair of plots using the (abundance‐based) Rao's quadratic entropy and the (incidence‐based) Sørensen dissimilarity indices. Using a null model approach, we compared the observed β‐diversity with the expected diversity at random and calculated the standard effect size of the observed β‐diversity deviation. Furthermore, we used distance‐based redundancy analysis (dbRDA) to partition the variations in taxonomic and phylogenetic observed β‐diversity and β‐deviation into four parts to assess the environmental and spatial effects.ResultsThe taxonomic β‐deviation was related to and higher than the phylogenetic β‐deviation (r = .74). This indicated that the species turnover between pairwise plots was mainly the turnover of closely related species. Higher taxonomic and phylogenetic β‐deviation were mainly concentrated in the pairwise karst and nonkarst forest plots, indicating that the species in karst forests and nonkarst forests were predominantly from distantly related clades. A large proportions of the variation in taxonomic and phylogenetic β‐deviation were explained by the joint effect of environmental and spatial variables, while the contribution of environmental variables was greater than that of spatial variables, probably owing to the influence of the sampling scale dependence, integrality of sampling size and species pool, and the unique climatic and geomorphic characteristics.Main conclusionsOur study highlights the importance of phylogeny in biodiversity research. The incorporation of taxonomic and phylogenetic information provides a perspective to explore potential underlying mechanisms that have shaped species assemblages and phylogenetic patterns in biodiversity hotspots.

Litterfall biomass and nutrient cycling in karst and nearby non-karst forests in tropical China: A 10-year comparison

Litterfall helps maintaining primary production and nutrient cycling in forest ecosystems. However, few studies have investigated long-term characteristics of litterfall in tropical karst and non-karst forests co-occurring in the same region. A 10-year comparative study was conducted to estimate the biomass, litter accumulation, turnover rate, nutrient return and nutrient use efficiency associated with litterfall in a karst forest (KF) and a nearby non-karst forest (NKF) in northern tropical China. Significant spatial-temporal variation was observed in monthly and annual litterfall biomass in the two forests. Annual mean litterfall biomass in KF (9.75 Mg ha−1 year−1) was obviously lower than that in NKF (10.49 Mg ha−1 year−1). The litterfall biomass in NKF was significantly correlated with maximum air temperature, wind speed and total solar radiation, whereas that in KF was significantly correlated with relative humidity, wind speed and low temperature. Average stand litter in KF (2.92 Mg ha−1 year−1) was significantly higher than that in NKF (2.38 Mg ha−1 year−1). Stand litter mostly occurred during the cool and dry season, which coincided with litterfall input and exhibited bimodal pattern. Turnover rate was 1.3 time higher in NKF than in KF, suggesting that litter decomposed slowly in karst habitats. Distinct temporal dynamic and significant differences were observed in chemical composition of litterfall between KF and NKF. Total amounts of C, P, K and total nutrients returned to the topsoil in KF were significantly lower than those in NKF. The KF exhibited relatively high P and K use efficiency because of their low availability in karst soils. Compared with the non-karst habitat, the tropical karst habitats are more likely to develop a plant community with certain nutrient concentrations of litterfall and with a nutrient cycling mechanism that is well-adapted to harsh and heterogeneous condition.

CO2 Transfer Characteristics of Calcareous Humid Subtropical Forest Soils and Associated Contributions to Carbon Source and Sink in Guilin, Southwest China

In karst landscapes, soil CO2 is a key factor in weathering processes and carbon cycling, where its distribution and migration characteristics directly affect fluxes in carbon source–sink dynamics. We measured the CO2 emission and dissolution rates of carbonate tablets in calcareous soil developed from limestone and red soil developed from clastic rock, in karst and non-karst subtropical forests, in Guilin, southwest China between 2015 and 2018, to analyze their CO2 transfer characteristics and source–sink effects. The results showed similar average soil respiration rates between calcareous soil and red soil, with an average CO2 emission flux of 1305 and 1167 t C km−2 a−1, respectively. Carbonate tablet dissolution rates were bidirectional with increasing depth and were greater in red soil than calcareous soil, averaging 13.88 ± 5.42 and 7.20 ± 2.11 mg cm−2 a−1, respectively. CO2 concentration was bidirectional with increasing soil depth, reaching a maximum at the base of the soil–atmosphere interface (50–60 cm), and the bidirectional gradient was more distinctive in red soil. Change in the carbon isotope value of soil CO2 was also bidirectional in calcareous soils, for which the overall average was 0.87‰ heavier in calcareous than red soil. The carbon sink in calcareous soil in karst regions was estimated to be 11.97 times that of red soil in non-karst regions, whereas its role as a carbon source is just 1.12 times that of red soil, thus indicating the key role of karst soil in the reduction of atmospheric CO2.

The contrasting leaf functional traits between a karst forest and a nearby non-karst forest in south-west China.

Karst and non-karst forests occur in the same region in south-west China, but the soil water and mineral nutrients availability are different between the forests. Our hypothesis was that the leaves of karst trees would be better adapted to dry, nutrient-poor conditions than those of trees in a nearby non-karst forest. We compared the gas exchange, anatomical characteristics and mineral nutrient concentrations in leaves from 21 tree species in a tropical karst forest and 19 species in a nearby non-karst forest in south-west China. We found that the leaves of karst trees had higher P concentrations, photosynthetic capacity and water use efficiency, and greater adaxial and abaxial epidermis thickness than leaves of non-karst forest trees. Evergreen and deciduous trees differed more significantly in leaf functional traits in the karst forest than in the non-karst forest. The leaf palisade:spongy mesophyll thickness ratio was positively correlated with stomatal conductance and negatively correlated with photosynthetic water use efficiency in the karst forest but not in the non-karst forest. Our findings indicate that karst forest trees are more conservative in water use, whereas soil P deficiency could be a major limiting factor for the growth of non-karst forest trees.

贵州高原型喀斯特次生林C、N、P生态化学计量特征与储量

PDF HTML阅读 XML下载 导出引用 引用提醒 贵州高原型喀斯特次生林C、N、P生态化学计量特征与储量 DOI: 10.5846/stxb201805311207 作者: 作者单位: 浙江师范大学,中国科学院地球化学研究所,浙江师范大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2018YFC0507203，2016YFC0502101，2016YFC0502304）；国家自然科学基金面上项目（31870462） Ecosystem C: N: P stoichiometry and storages of a secondary plateau-surface karst forest in Guizhou Province, southwestern China Author: Affiliation: Zhejiang Normal University,Institute of Geochemistry, Chinese Academy of Sciences,Zhejiang Normal University Fund Project: National Basic Research Program of China (2018YFC0507203, 2016YFC0502101, 2016YFC0502304) and National Science Foundation of China (31870462) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取贵州高原型喀斯特次生常绿落叶阔叶混交林为对象，对其生态系统各组分碳（C）、氮（N）、磷（P）生态化学计量特征进行了研究，并全面估算了其生态系统C、N、P储量。结果表明，N、P含量在各树种和各器官（干、皮、枝、叶）之间表现出较大的变异，而C含量在各树种和各器官之间变异较小。C/N和C/P表现为叶片最高，树干（乔木）/枝干（灌木）最低，N/P在各器官间差异不显著（P > 0.05）。凋落物和木质残体的N/P显著（P < 0.01）高于植物活体。土壤C、N、P含量均随土壤深度的增加而降低，最表层（0-10 cm）土壤的C、N、P含量及N/P显著（P < 0.05）高于深层土壤；C/N和C/P在各土层间差异不显著（P > 0.05）。高原型喀斯特次生常绿落叶阔叶混交林的生态系统C、N、P储量分别为172.42 Mg/hm2、5.24 Mg/hm2和1.19 Mg/hm2。大部分森林C（54.69%）、N（84.46%）、P（97.26%）存储于土壤中。与非喀斯特森林相比，喀斯特森林植物叶片N、P含量低，土壤C含量高，生态系统C、N、P储量低。 Abstract:Carbon (C), nitrogen (N) and phosphorus (P) stoichiometry characteristics and storages of all components in a secondary plateau-surface karst evergreen and deciduous broad-leaved mixed forest in central Guizhou Province, southwestern China, are analyzed and estimated. Results show N and P concentrations vary greatly among species and organs. C/N and C/P are highest in leaf and lowest in stem. N/P shows no significant (P > 0.05) differences among organs. Litter and woody debris present significantly (P < 0.01) higher N/P than live vegetation. Soil C, N and P concentrations decrease with increasing soil depth. Soil C, N and P concentrations and N/P in the first top layer (0-10 cm) are significantly (P < 0.05) higher than those in deeper soils. C/N and C/P show no significant (P > 0.05) differences among soil layers. C, N and P storages of the entire forest are 172.42, 5.24 and 1.19 Mg/hm2, respectively. Most C (54.69%), N (84.46%) and P (97.26%) are stored in soils. Compared with nonkarst forests, the karst forest presents lower leaf C and N concentrations, higher soil C concentration and lower C, N and P storages. 参考文献 相似文献 引证文献

Comparative study of the stoichiometric characteristics of karst and non-karst forests in Guizhou, China

Carbon (C), nitrogen (N), and phosphorous (P) levels and their stoichiometry in plant components (leaves, branch trunks, roots) of trees in a karst forest and non-karst forest are compared. The results show that the C contents, C:N and C:P ratios of dominant species in the karst forest were lower than those in the non-karst forest, but the N and P and the N:P ratio were higher; C:N:P ratios in plant organs of trees in the karst forest were in the order of trunks > roots > branches > leaves. However, C:N:P ratio in the non-karst forest trees were trunks > branches > roots > leaves. Moreover, ratio of C:N:P in trunks was highest and lowest in leaves in both forests. In non-karst forest trees, N:P was in the order of leaves > roots > branches > trunks. There were no significant differences in the ratio of N:P in different plant components of trees in the karst forest. However, in karst and non-karst forest trees, the ratio of N:P in leaves was highest; positive correlations between N and P contents, and N and N:P ratios were observed in both karst and non-karst forests (p < 0.001). Negative correlations between P and N:P ratios (p < 0.05) were observed in karst forest trees, while positive correlations were observed in non-karst forest trees.

High Mortality and Low Net Change in Live Woody Biomass of Karst Evergreen and Deciduous Broad-Leaved Mixed Forest in Southwestern China

Repeated observation based on large permanent monitoring plots is a key method for directly understanding forest regeneration dynamics. Karst forests grow slowly in adverse habitats and possess a special regeneration mode. However, no data can support these properties because no repeated observations have been performed. The mortality, recruitment, and net change in live woody biomass (NPPlw) of a karst evergreen and deciduous broad-leaved mixed forest in Central Guizhou Province, Southwestern China, were studied on the basis of a short-term continuous monitoring (3 years) of a 2 ha plot. The species richness of individuals with a diameter at breast height (DBH) ≥ 1 cm decreased from 66 to 58 during the study period. Eight species disappeared, and no new species appeared. The individual number declined from 16,821 to 15,003 because most species indicated more deaths than recruitments. Trees presented the lowest mortality rate, and shrubs presented the highest recruitment rate among the species. Individual death number decreased with the increase in DBH classes. The estimated aboveground NPPlw was 8.41 t ha−1 year−1. The survivors, recruitments, and deaths contributed 10.88, 0.11, and −2.58 t ha−1 year−1, respectively. Trees (8.37 t ha−1 year−1), rather than shrubs (0.04 t ha−1 year−1) and lianas (−0.004 t ha−1 year−1), were the major contributors. The karst forest presented higher mortality and lower NPPlw than nonkarst forests in subtropical China and in the world.

广西地区喀斯特与非喀斯特山地森林树木物种多样性及系统发育结构比较

PDF HTML阅读 XML下载 导出引用 引用提醒 广西地区喀斯特与非喀斯特山地森林树木物种多样性及系统发育结构比较 DOI: 10.5846/stxb201808021643 作者: 作者单位: 广西大学林学院,广西大学林学院,广西大学林学院,广西大学林学院,广西大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划子课题（2016YFC0502101-04）；广西重点研发计划项目（桂科AB16380254）；广西"八桂学者"人才项目（2016A32） Comparison of the species diversity and phylogenetic structure of tree communities in karst and non-karst mountains in Guangxi Author: Affiliation: College of Forestry, Guangxi University,,,,College of Forestry, Guangxi University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以广西地区植被调查集资料总共365个群落样方（样方面积在300-1000 m2，50%左右为400 m2）为基础，将样方分为海拔≤1000 m喀斯特和非喀斯特森林以及海拔 > 1000 m的非喀斯特森林三类生境，探讨这3种生境森林物种丰富度和群落系统发育结构差异及其与年均温的关系。结果表明，海拔≤1000 m非喀斯特森林含有4种以上的科比海拔 > 1000 m非喀斯特森林多24科，比喀斯特森林多18科，其中樟科、壳斗科、山茶科、杜鹃花科等都是两种非喀斯特森林生境的重要组成科；大戟科为喀斯特森林含有种数最多的科，其中出现在非喀斯特森林的山茶科和杜鹃花科等没有在喀斯特森林出现。森林物种多样性及系统发育指数与年均温不相关或相关不强；海拔≤1000 m的喀斯特与非喀斯特森林的Gleason物种多样性指数没有显著差异，而海拔 > 1000 m的非喀斯特森林的Gleason指数比另外两种生境显著高。海拔≤1000 m非喀斯特森林系统发育多样性PD指数比中山地带的非喀斯特生境的森林高。喀斯特森林和海拔 > 1000 m非喀斯特的绝大部分样地以及海拔≤1000 m的非喀斯特大部分样地都表现出系统发育结构聚集，推测生境过滤在广西地区喀斯特和非喀斯特森林群落构建中发挥着主要作用。但是喀斯特和海拔 > 1000 m的非喀斯特两种生境森林群落发生系统发育发散的比例都比海拔≤1000 m的非喀斯特森林低，揭示生境过滤在这两个生境更为明显。 Abstract:We compiled data of 365 tree community plots from the literature, which were sampled across Guangxi and varied in plot area from 400 to 1000 m2(with 50% of plots 400 m2), and characterized the species diversity and community phylogenetic diversity (PD) and structure, and their relationship with the mean annual temperature (MAT) of the sampling location in three types of forest habitats:non-karst with an elevation of ≤ 1000 m, non-karst with an elevation of > 1000 m, and karst with an elevation of ≤ 1000 m. We found that in comparison of the number of the families with more than 4 species in the forests, the non-karst forests with an elevation of ≤ 1000 m contained 24 more families than non-karst forests with an elevation of < 1000 m, and 18 more families than karst forests. Lauraceae, Fagaceae, Theaceae, and Ericaceae are important and common families of non-karst forests at both low and high elevations. Euphorbiaceae was the family that contains the largest number of species in karst forests. Theaceae and Ericaceae that appeared in the non-karst forests were absent in karst forests. The species diversity and phylogenetic structure index of the tree communities in the three habitats were not significantly associated with the MAT. Gleason's diversity indices of karst and non-karst forests with an elevation of ≤ 1000 m were not significantly different, but significantly lower that of non-karst forests with an elevation of > 1000 m. The PD of the non-karst forests with elevations ≤ 1000 m was higher than that of the non-karst forests with elevations of either > 1000 m, indicating the former is favourable for hosting the more distant-related species. The phylogenetic net relatedness index (NRI) and the nearest taxon index (NTI) revealed that most of the forest plots in the three habitats showed phylogenetic clustering, and a small proportion of plots displayed phylogenetic overdispersion or randomness. These suggest that habitat filtration plays a major role in the community assembly of karst and non-karst forests in Guangxi. The proportions of plots with phylogenetic overdispersion in the karst forests and non-karst forests with an elevation of > 1000 m were lower that in the non-karst forests with an elevation of ≤ 1000 m, revealing that environmental filtration was stronger in these two habitats. 参考文献 相似文献 引证文献

Tree species effects on asymbiotic N2 fixation in subtropical karst and non-karst forests

Asymbiotic dinitrogen (N2) fixation (ANF) plays an important role in determining forest nitrogen (N) availability. Yet, the controls on ANF variation within or between forests remain poorly understood. In the present study, ANF in bulk leaf litter (or litter ANF hereafter) and soil (or soil ANF hereafter) within the crown radius of the dominant tree species was investigated in a karst forest over limestone and a nearby non-karst forest over clasolite, southwest China. Lithology exerted significant (P < 0.05) influences on ANF in litter but not in soil. ANF in litter was 4.9 times higher in the karst forest than in the non-karst forest. Tree species had significant effects on litter ANF in the karst and non-karst forests with the rates varying 23-fold and 71-fold, respectively. Significant effect of tree species on soil ANF was only encountered in the non-karst forest. The strongest explanatory variables were substrate and forest specific, but generally included litter moisture, total nitrogen, total phosphorus, calcium and soil organic carbon. The findings suggest that tree species and lithology may provide new mechanisms explaining the great variation of ANF within and between forests, respectively.

Soil Gross Nitrogen Transformations in Typical Karst and Nonkarst Forests, Southwest China

AbstractSoil gross nitrogen (N) transformations are crucial for assessing forest N status. Although there is evidence suggesting that the N cycle is open in the karst forest, southwest China, process‐based investigation of gross soil N transformations is limited. In the current study, gross soil N transformations were investigated using 15N isotope dilution and 15N tracer techniques in a typical karst forest with calcareous soil (Calcareous lithosols) in comparison with an adjacent nonkarst forest with red soil (Haplic acrisol).The gross rates of N mineralization, nitrification, dissimilatory nitrate reduction to ammonium (DNRA), and nitrate immobilization were significantly greater in the karst forest. Ammonium immobilization was comparable to gross N mineralization, so that ammonium could be efficiently conserved in the nonkarst forest. Meanwhile, the produced nitrate was mostly retained via DNRA and nitrate immobilization. This resulted in a negligible net nitrate production in the nonkarst forest. In contrast, ammonium immobilization rate only accounted for half of gross N mineralization rate in the karst forest. The nitrate retention capacity is relatively low, with 41.6 ± 4.2% of the produced nitrate being retained via DNRA and nitrate immobilization. Due to relatively low nitrate retention capacity, nitrate was accumulated in the karst forest soil. Our results indicate that the nonkarst forest with red soil holds a very conservative N cycle, but the N cycle in the karst forest is leaky.

Biomass of karst evergreen and deciduous broad-leaved mixed forest in central Guizhou province, southwestern China: a comprehensive inventory of a 2 ha plot

The biomass of a secondary evergreen and deciduous broad-leaved mixed forest was comprehensively inventoried in a permanent 2 ha plot in southwestern China. Biomass models, sub-sampling, soil pit method, and published data were utilized to determine the biomass of all components. Results showed that the total biomass of the forest was 158.1 Mg ha; the total biomass included the major aboveground (137.7 Mg ha) and belowground (20.3 Mg ha) biomass components of vascular plants as well as the minor biomass components of bryophytes (0.078 Mg ha) and lichens (0.043 Mg ha). The necromass was 17.6 Mg ha and included woody debris (9.0 Mg ha) and litter (8.6 Mg ha). The spatial pattern of the aboveground biomass was determined by the spatial distribution of dominant trees with large diameter, tall height, and dense wood. The belowground biomass differed in terms of root diameter and decreased with increasing soil depth. The belowground biomass in each soil pit in local habitats was not related to the spatial distribution of woody plants and soil pit depth. The karst forest presented lower biomass compared than the nonkarst forests in the subtropical zone. Biomass carbon in the karst terrains would increase substantially if degraded karst vegetation could be successfully restored to the forest. Comprehensive site-based biomass inventory of karst vegetation will contribute not only to provide data for benchmarking global and regional vegetation and carbon models but also for regional carbon inventory and vegetation restoration.−1−1−1−1−1−1−1−1

A Comparison of Tree Species Diversity in Two Subtropical Forests, Guangxi, Southwest China

Natural karst forests can support very high level of biodiversity, but difference of species diversity between the natural karst forests and non-karst forests is still less concerned. To analyze the difference of species diversity of the natural karst forests and non-karst forests in subtropics, we made a census of all woody species with diameter at breast height (dbh)≥1 cm in a 1-ha plot in Mulun subtropical karst forests and a 1-ha plot in Maoershan subtropical non-karst forests, Guangxi of south-western China. Species richness in Mulun plot (120 species) was higher than that in Maoershan plot (116 species). Mulun plot contained more families and genera, more stems and a larger proportion of rare species (species of individuals less than or equal to 1 ha -1 ). At smaller scale ( 5000 m 2 ). Total basal area in Mulun plot (18.47 m 2 ) was smaller than that in Maoershan plot (30.74 m 2 ). Size structure distribution of all woody species in the two plots showed insignificant difference. The ten most dominant species, families and genera were quite different in the two plots. In Mulun plot, the most important species and family were Sinosideroxylon wightianum and Sapindaceae, while in Maoershan plot, Castanopsis carlesii and Fagaceae were the most important species and family. All these results suggest that middle subtropical natural karst forest in Mulun supports diverse species with high spatial variability, and their species composition are quite different with non-karst forests. This study implies that special attention is needed on selecting suitable species in karst forest restoration and vegetation management strategies.