Carbon of Chaillu forests based on a phytosociological analysis in Republic of Congo,more than meets the eye?

The objectives were to quantify aboveground, belowground and dead wood carbon pools near Mayoko in the Chaillu massif of Republic of Congo and explore relationships between carbon storage and plant diversity of all growth forms. A total of 190 plots (25 m by 25 m) were sampled (5072 stems, 211 species) and data analysed using recommended central-African forest allometric equations. Mean stem diameter at breast height was 33.6 cm, mean basal area 47.7 m² ha⁻¹ and mean density of individuals 407 ha⁻¹. Mean aboveground carbon (AGC) ranged from 13.93–412.66 Mg C ha⁻¹, belowground carbon from 2.86–96.97 Mg C ha⁻¹ and dead wood from 0.00–7.59 Mg C ha⁻¹. The maximum AGC value recorded in a plot was 916 Mg C ha⁻¹. The analysis performed using phytosociological association as basis rather than broad vegetation type is unique. AGC values for undisturbed terra firme forest sites featured among the highest recorded for African tropical forests. Considering only tree diversity, a weak, yet significant, relationship existed between AGC and species richness, Shannon-Wiener index of diversity and Fisher's alpha. However, if diversity of all plant growth forms is considered, no relationship between carbon and plant diversity existed.     

Altitudinal changes in carbon storage of temperate forests on Mt Changbai, Northeast China

A number of studies have investigated regional and continental scale patterns of carbon (C) stocks in forest ecosystems; however, the altitudinal changes in C storage in different components (vegetation, detritus, and soil) of forest ecosystems remain poorly understood. In this study, we measured C stocks of vegetation, detritus, and soil of 22 forest plots along an altitudinal gradient of 700–2,000 m to quantify altitudinal changes in carbon storage of major forest ecosystems (Pinus koraiensis and broadleaf mixed forest, 700–1,100 m; Picea and Abies forest, 1,100–1,800 m; and Betula ermanii forest, 1,800–2,000 m) on Mt Changbai, Northeast China. Total ecosystem C density (carbon stock per hectare) averaged 237 t C ha⁻¹ (ranging from 112 to 338 t C ha⁻¹) across all the forest stands, of which 153 t C ha⁻¹ (52–245 t C ha⁻¹) was stored in vegetation biomass, 14 t C ha⁻¹ (2.2–48 t C ha⁻¹) in forest detritus (including standing dead trees, fallen trees, and floor material), and 70 t C ha⁻¹ (35–113 t C ha⁻¹) in soil organic matter (1-m depth). Among all the forest types, the lowest vegetation and total C density but the highest soil organic carbon (SOC) density occurred in Betula ermanii forest, whereas the highest detritus C density was observed in Picea and Abies forest. The C density of the three ecosystem components showed distinct altitudinal patterns: with increasing altitude, vegetation C density decreased significantly, detritus C density first increased and then decreased, and SOC density exhibited increasing but insignificant trends. The allocation of total ecosystem C to each component exhibited similar but more significant trends along the altitudinal gradient. Our results suggest that carbon storage and partitioning among different components in temperate forests on Mt Changbai vary greatly with forest type and altitude.     

The effect of altitude,patch size and disturbance on species richness and density of lianas in montane forest patches

The species richness and density of lianas (woody vines) in tropical forests is determined by various abiotic and biotic factors. Factors such as altitude, forest patch size and the degree of forest disturbance are known to exert strong influences on liana species richness and density. We investigated how liana species richness and density were concurrently influenced by altitude (1700–2360 m), forest patch size, forest patch location (edge or interior) and disturbance intensity in the tropical montane evergreen forests, of the Nilgiri and Palni hills, Western Ghats, southern India. All woody lianas (≥1 cm dbh) were enumerated in plots of 30 × 30 m in small, medium and large forest patches, which were located along an altitudinal gradient ranging from 1700 to 2360 m. A total of 1980 individual lianas were recorded, belonging to 45 species, 32 genera and 21 families, from a total sampling area of 13.86 ha (across 154 plots). Liana species richness and density decreased significantly with increasing altitude and increased with increasing forest patch size. Within forest patches, the proportion of forest edge or interior habitat influenced liana distribution and succession especially when compared across the patch size categories. Liana species richness and density also varied along the altitudinal gradient when examined using eco-physiological guilds (i.e. shade tolerance, dispersal mode and climbing mechanism). The species richness and density of lianas within these ecological guilds responded negatively to increasing altitude and positively to increasing patch size and additionally displayed differing sensitivities to forest disturbance. Importantly, the degree of forest disturbance significantly altered the relationship between liana species richness and density to increasing altitude and patches size, and as such is likely the primary influence on liana response to montane forest succession. Our findings suggest that managing forest disturbance in the examined montane forests would assist in conserving local liana diversity across the examined altitudinal range.     

川西卧龙岷江冷杉林土壤有机碳组分与氮素关系随海拔梯度的变化特征

土壤碳氮沿海拔梯度变化及其耦合关系是山地生态系统碳氮循环研究的重要内容。为分析不同土层土壤有机碳,土壤全氮及有机碳活性组分在海拔梯度上的分布规律及相互之间的耦合关系,选取亚高山物种岷江冷杉(Abies faxoniana)原始林为研究对象,以卧龙邓生野牛沟岷江冷杉原始林2920—3700 m的样地调查数据为基础,分析不同土层土壤碳氮及活性组分沿海拔的变化规律,总结土壤有机碳稳定性沿海拔主要规律,从土壤有机碳活性组分和碳氮关系的角度揭示其对土壤有机碳沿海拔变化的影响。结果表明:1)腐殖质层土壤有机碳(SOC)随海拔升高逐渐增加,与温度显著负相关,轻组有机碳(LFOC)及颗粒态有机碳(POC)随海拔上升均表现先增加后降低的趋势,土壤全氮(TN)随海拔变化不显著,但林线处LOFC、POC和TN均显著增加;0—10 cm土壤有机碳及全氮则表现为双峰特征,峰值分别在3089 m和3260 m处,与年均温度无显著关系。2)LFOC及POC在腐殖质层和0—10 cm土层中所占比例较大,是表征土壤有机碳含量沿海拔变化规律的主要活性组分,腐殖质层LFOC/SOC和POC/SOC随海拔上升逐渐增高,0—10 cm层则逐渐降低,暗示腐殖质层有机碳稳定性沿海拔逐渐降低,0—10 cm有机碳稳定性逐渐升高。3)SOC与TN显著正相关,SOC是影响TN的主要因子,但腐殖质层TN与有机碳活性组分无显著相关关系。4)土壤C/N和微生物量C/N在3177 m大于25:1,是引起土壤有机碳含量显著降低的主要因素。     

Savanna fires and their impact on net ecosystem productivity in North Australia

Savannas comprise a large area of the global land surface and are subject to frequent disturbance through fire. The role of fire as one of the primary natural carbon cycling mechanisms is a key issue in considering global change feedbacks. The savannas of Northern Australia burn regularly and we aimed to determine their annual net ecosystem productivity (NEP) and the impact of fire on productivity. We established a long‐term eddy covariance flux tower at Howard Springs, Australia and present here 5 years of data from 2001 to 2005. Fire has direct impacts through emissions but also has indirect effects through the loss of productivity due to reduced functional leaf area index and the carbon costs of rebuilding the canopy. The impact of fire on the canopy latent energy exchange was evident for 40 days while the canopy was rebuilt; however, the carbon balance took approximately 70 days to recover. The annual fire free NEP at Howard Springs was estimated at −4.3 t C ha⁻¹ yr⁻¹ with a range of −3.5 to −5.1 t C ha⁻¹ yr⁻¹ across years. We calculated the average annual indirect fire effect as +0.7 t C ha⁻¹ yr⁻¹ using a neural network model approach and estimated average emissions of fine and coarse fuels as +1.6 t C ha⁻¹ yr^‐1. This allowed us to calculate a net biome production of −2.0 t C ha⁻¹ yr^‐1. We then partitioned this remaining sink and suggest that most of this can be accounted for by woody increment (1.2 t C ha⁻¹ yr^‐1) and shrub encroachment (0.5 t C ha⁻¹ yr^‐1). Given the consistent sink at this site, even under an almost annual fire regime, there may be management options to increase carbon sequestration by reducing fire frequency.     

苦竹叶片碳氮磷化学计量特征的海拔梯度效应

为揭示海拔梯度对苦竹林立竹叶片碳(C)、氮(N)、磷(P)化学计量特征的影响,该文以3个海拔梯度[低海拔,(200±10) m;中海拔,(400±10) m;高海拔,(800±10) m]苦竹林为研究对象,测定1至3年生立竹叶片C、N、P含量,分析其化学计量特征和异速增长关系。结果表明:(1)立竹年龄对苦竹叶片C、N、P含量及其化学计量特征影响明显,随立竹年龄的增大,苦竹叶片C、N、P含量和N∶P总体上均呈降低趋势,而C∶N、C∶P总体上呈升高趋势。(2)海拔对苦竹叶片C、N、P含量及其化学计量特征有重要影响,随海拔梯度升高,不同年龄立竹叶片C含量呈先升高后下降变化趋势,N、P含量总体上呈降低趋势,而C∶N、C∶P和N∶P均呈升高趋势。(3)不同海拔梯度苦竹林立竹叶片C、N、P含量和C∶N、C∶P差异显著,中、高海拔苦竹林立竹叶片N∶P无显著差异,均显著高于低海拔苦竹林;不同海拔梯度苦竹林立竹叶片C、N、P间呈显著的正异速增长关系,随海拔梯度的升高,C-N、C-P异速增长指数显著升高,而N-P异速增长指数显著下降。综上结果表明,高海拔苦竹林虽然N、P利用效率提高,但立竹叶片C含量较低,P限制性作用增强;中海拔苦竹林不但具有较高的N、P利用效率,而且立竹叶片C含量高,说明中海拔是苦竹林丰产培育的适宜海拔。     

The distribution of ground spiders (Araneae, Gnaphosidae) along the altitudinal gradient of Crete, Greece: species richness, activity and altitudinal range

Aim To study the altitudinal variation of ground spiders (Araneae, Gnaphosidae) of Crete, Greece, as far as species composition, species richness, activity and range of distribution are concerned. Location Altitudinal zones (0–2400 m) along the three main mountain massifs of the island of Crete. Methods Thirty‐three sampling sites were located from 0 to 2400 m a.s.l. on Crete, and sampled using pitfall traps. Material from the high‐activity period of Gnaphosidae (mid‐spring to mid‐autumn) was analysed. Sampling sites were divided into five altitudinal zones of 500 m each. Statistical analysis involved univariate statistics (anova ) and multivariate statistics, such as multidimensional scaling (MDS) and cluster analysis (UPGMA) using binomial data of species presence or absence. Results Species richness declines with altitude and follows a hump‐shaped pattern. The activity pattern of the family, as a whole, is not correlated with altitude and is highly species‐specific. In the highest zone, both species richness and activity decline dramatically. The altitudinal range of species distribution increases with altitude. On the Cretan summits live highly tolerant lowland species and isolated residents of the high mountains of Crete. Two different patterns of community structure are recorded. Main conclusions Communities of Gnaphosidae on Crete present two distinct structures following the altitudinal gradient, these being separated by a transitional zone between 1600 and 2000 m. This study supports previous results which show a hump‐shaped decline in species richness of Gnaphosidae along altitudinal gradients, leading to a peak at 400–700 m, where an optimum of environmental factors exists. This makes this zone the meeting point of the often opportunistic lowland species with the older and most permanent residents of the island. Rapoport's rule on the positive correlation of the altitudinal range of species distributions with altitude is also supported. The high activity recorded for the species that persist on the high mountains of Crete is indicative of a tolerant arachnofauna, and is considered to result from relaxation of competitive interactions with other species. This is related to a reduction in species numbers, shortening of the activity period on high mountains and the unique presence of high mountain species that thrive only there. As shown in our study, strategies to cope with altitude are species‐specific. Therefore, there cannot exist one single model to describe how animals react to the change in altitude, even under the same environmental conditions.     

鼎湖山森林土壤活性碳及惰性碳沿海拔梯度的变化

对鼎湖山3个不同海拔高度下的沟谷雨林(LA)、低地常绿阔叶林(MA)和山地常绿阔叶林(UA)的土壤活性碳库和惰性碳库进行了研究。结果表明:(1)土壤总碳库仅在30—45 cm土层中存在显著差异且碳库大小随着海拔的增加而增加。(2)土壤微生物生物量碳(MBC)碳库在0—15 cm是LA和MA显著大于UA,在30—45 cm是MA和UA显著高于LA,在45—60 cm土层中MA最大。水溶性碳(WSOC)和颗粒碳(POC)碳库均不随海拔高度而改变。WSOC碳库占总碳库的百分比仅在30—45cm土层中存在差异且大小顺序为:LAUAMA,POC碳库占总碳库的百分比仅在土层15—30 cm上存在显著差异且MA比值最大。易氧化性碳(ROC)碳库及占总碳库百分比都是在表层土壤(0—15 cm)中产生显著变化,且UA极显著地大于LA和MA。(3)惰性碳(RC)碳库仅在深层土壤中存在显著差异且MA中RC碳库最大,UA次之,LA最小。RC碳库占总碳库比值仅在表层土壤0—15 cm存在显著差异且UA最大。表层土壤中ROC碳库和RC碳库占总碳库百分比的增加是导致中高海拔森林土壤总碳库最大的主要原因。(4)不同海拔高度上森林土壤理化性质与土壤碳库组成存在显著相关,土壤理化性质的改变是引起不同海拔高度森林土壤碳库组成变化的重要原因。     

Shifts in chemical and microbiological properties belowground of invader Ageratina adenophora along an altitudinal gradient

入侵植物紫茎泽兰根围土壤化学及微生物属性海拔变化格局 热带地区山地生态系统是外来植物入侵的重要区域,是研究外来植物扩散机制的“天然实验室”。本研究试图探明入侵植物紫茎泽兰(Ageratina adenophora)根围土壤化学(pH及土壤养分)和微生物(酶活性和细菌群落)特性沿海拔梯度的变化规律。本研究以哀牢山(1400–2400 m)不同海拔梯度分布的紫茎泽兰为研究对象,采集根围土,测定土壤有机碳及养分含量,以及植物根系碳和氮含量。分析与土壤有机碳、氮及磷循环的酶活性,通过计算土壤酶化学计量参数,探究微生物生长代谢利用碳、氮及磷的规律。借助高通量测序技术对16S rDNA的V4区测序,分析细菌群落结构。研究结果显示,海拔显著影响紫茎泽兰根系氮及及其根围土壤有机碳含量,且这些测量指标在海拔2000 m  出现拐点。处在低海拔,入侵植物快速生长耗竭土壤中相对缺乏的磷,磷素是限制微生物生长的重要养分元素;而在高海拔,微生物需要投入更多的能量降解有机质获取碳,导致微生物生长的碳限制。细菌群落β多样性及pH  是决定不同海拔酶化学计量参数差异的重要因子;变形菌门和酸杆菌门是决定微生物养分利用状况的主要细菌门类。这些结果阐明了不同海拔梯度上紫茎泽兰根围土壤微生物的养分利用规律,有助于认识入侵植物沿海拔扩散机制。     

尖峰岭热带天然林不同土层细菌群落多样性和组成的海拔变异规律

土壤微生物群落结构沿海拔梯度的变异是微生物生物地理学分异和群落空间分布的重要内容,然而,热带森林土壤微生物多样性及其群落特征的海拔模式尚不明确。研究海南省尖峰岭自然保护区0—20cm和20—40cm土壤细菌多样性和群落组成沿海拔梯度(400—1410m)的变化及其与环境因子的关系。结果表明：在0—20cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高(峰顶降低)而增加,20—40cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高呈先升高后降低趋势;整体上,变形菌门、放线菌门、酸杆菌门、拟杆菌门、厚壁菌门在0—20cm中占优势,丰度总和占该层细菌总量的88.17%;变形菌门、放线菌门、酸杆菌门、厚壁菌门、绿弯菌门在20—40cm中占优势,丰度总和占该层细菌总量的90.82%;随海拔增加,0—20cm细菌多样性线性减少,20—40cm细菌多样性变化不显著;沿海拔梯度,0—20cm细菌群落组成可分为低(409—1018m),中(1018—1357m)和高(1410m)三个海拔聚集群落,20—40cm细菌群落组成随海拔无显著性变化;两土层细菌多样性与土壤pH显著正相关,土壤细菌群落组成在0...     

Carbon dynamics in successional and afforested spruce stands in Thuringia and the Alps

Changes in the carbon stocks of stem biomass, organic layers and the upper 50 cm of the mineral soil during succession and afforestation of spruce (Picea abies) on former grassland were examined along six chronosequences in Thuringia and the Alps. Three chronosequences were established on calcareous and three on acidic bedrocks. Stand elevation and mean annual precipitation of the chronosequences were different. Maximum stand age was 93 years on acid and 112 years on calcareous bedrocks. Stem biomass increased with stand age and reached values of 250–400 t C ha^?1 in the oldest successional stands. On acidic bedrocks, the organic layers accumulated linearly during forest succession at a rate of 0.34 t C ha^?1 yr^?1. On calcareous bedrocks, a maximum carbon stock in the humus layers was reached at an age of 60 years. Total carbon stocks in stem biomass, organic layers and the mineral soil increased during forest development from 75 t C ha^?1 in the meadows to 350 t C ha^?1 in the oldest successional forest stands (2.75 t C ha^?1 yr^?1). Carbon sequestration occurred in stem biomass and in the organic layers (0.34 t C ha^?1 yr^?1on acid bedrock), while mineral soil carbon stocks declined. Mineral soil carbon stocks were larger in areas with higher precipitation. During forest succession, mineral soil carbon stocks of the upper 50 cm decreased until they reached approximately 80% of the meadow level and increased slightly thereafter. Carbon dynamics in soil layers were examined by a process model. Results showed that sustained input of meadow fine roots is the factor, which most likely reduces carbon losses in the upper 10 cm. Carbon losses in 10–20 cm depth were lower on acidic than on calcareous bedrocks. In this depth, continuous dissolved organic carbon inputs and low soil respiration rates could promote carbon sequestration following initial carbon loss. At least 80 years are necessary to regain former stock levels in the mineral soil. Despite the comparatively larger amount of carbon stored in the regrowing vegetation, afforestation projects under the Kyoto protocol should also aim at the preservation or increase of carbon in the mineral soil regarding its greater stability of compared with stocks in biomass and humus layers. If grassland afforestation is planned, suitable management options and a sufficient rotation length should be chosen to achieve these objectives. Maintenance of grass cover reduces the initial loss.     

Environmental indicators for estimating the potential soil respiration rate in alpine zone

Soil respiration is the main form of carbon flux from soil to atmosphere in the global carbon cycle. The effect of temperature on soil respiration rate is important in evaluating the potential feedback of soil organic carbon to global warming. We incubated soils from the alpine meadow zone and upper rocky zone along an altitudinal gradient (4400–5500 m a.s.l.) on the Tibetan Plateau under various temperature and soil moisture conditions. We evaluated the potential effects of temperature and soil moisture on soil respiration and its variation across altitudes. Soil respiration rates increased as the temperature increased. At 60% of soil water content, they averaged 0.21–5.33 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.11–0.50 μmol g soil⁻¹ day⁻¹ in the rocky zone over the experimental temperature range. Soil respiration rates in the rocky zone did not increase between 25 and 35 °C, probably because of heat stress. Rates of decomposition of organic matter were high in the rocky zone, where the CN ratio was smaller than in the middle altitudes. Soil respiration rates also increased with increasing soil water content from 10% to 80% at 15 °C, averaging 0.04–2.00 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.03–0.35 μmol g soil⁻¹ day⁻¹ in the rocky zone. Maximum respiration rates were obtained in the middle part of the alpine slope in any case of experimental temperature and soil moisture. The change patterns in soil respiration rate along altitude showed similar change pattern in soil carbon content. Although the altitude is a variable including various environmental factors, it might be used as a surrogate parameter of soil carbon content in alpine zone. Results suggest that temperature, soil moisture and altitude are used as appropriate environmental indicators for estimating the spatial distribution of potential soil respiration in alpine zone.     

Effects of cropland reclamation on soil organic carbon in China's black soil region over the past 35 years

The long-term use of cropland and cropland reclamation from natural ecosystems led to soil degradation. This study investigated the effect of the long-term use of cropland and cropland reclamation from natural ecosystems on soil organic carbon (SOC) content and density over the past 35 years. Altogether, 2140 topsoil samples (0–20 cm) were collected across Northeast China. Landsat images were acquired from 1985 to 2020 through Google Earth Engine, and the reflectance of each soil sample was extracted from the Landsat image that its time was consistent with sampling. The hybrid model that included two individual SOC prediction models for two clustering regions was built for accurate estimation after k-means clustering. The probability hybrid model, a combination between the hybrid model and classification probabilities of pixels, was introduced to enhance the accuracy of SOC mapping. Cropland reclamation results were extracted from the land cover time-series dataset at a 5-year interval. Our study indicated that: (1) Long-term use of cropland led to a 3.07 g kg⁻¹ and 6.71 Mg C ha⁻¹ decrease in SOC content and density, respectively, and the decrease of SOC stock was 0.32 Pg over the past 35 years; (2) nearly 64% of cropland had a negative change in terms of SOC content from 1985 to 2020; (3) cropland reclamation track changed from high to low SOC content, and almost no cropland was reclaimed on the “Black soils” after 2005; (4) cropland reclamation from wetlands resulted in the highest decrease, and reclamation period of years 31–35 decreased when SOC density and SOC stock were 16.05 Mg C ha⁻¹ and 0.005 Pg, respectively, while reclamation period of years 26–30 from forest witnessed SOC density and stock decreases of 8.33 Mg C ha⁻¹ and 0.01 Pg, respectively. Our research results provide a reference for SOC change in the black soil region of Northeast China and can attract more attention to the area of the protection of “Black soils” and natural ecosystems.     

Changes in tropical forest vegetation along an altitudinal gradient in the Udzungwa Mountains National Park, Tanzania

This study describes changes in woody vegetation in the Mwanihana forest, Udzungwa Mountains National Park, Tanzania, over an altitude range of 470–1700 m. Two methods, fixed‐ and variable‐area plots, are compared to elucidate altitudinal variation in tropical forest structure, diversity and community composition. Six 25 m × 100 m fixed area plots recorded a total of 2143 woody stems of ≥3 cm d.b.h. from 204 species. The 78 variable‐area plots recorded the nearest twenty trees of ≥20 cm d.b.h. to an objectively chosen point, giving a total of 1560 stems in 9.1 ha from 156 species. A linear trend of increasing stem density with altitude was seen for variable‐area plots. Species diversity is highest at high elevations. There was no clear zonation of elevational vegetation types. Restricted range taxa occur at all altitudes sampled. The study also revealed some methodological considerations. Bias in sample size and plot area can be tested by employing two sampling methods. Of the two methods used, fixed area plots are preferred as variable area plots are impractical in tangled understorey. Plot size must be controlled for in order to make reliable observations of diversity. Sampling along a continuous or near‐continuous altitudinal gradient with sufficient replication is also important.     

Plant species and growth form richness along altitudinal gradients in the southwest Ethiopian highlands

Questions: Do growth forms and vascular plant richness follow similar patterns along an altitudinal gradient? What are the driving mechanisms that structure richness patterns at the landscape scale? Location: Southwest Ethiopian highlands. Methods: Floristic and environmental data were collected from 74 plots, each covering 400 m². The plots were distributed along altitudinal gradients. Boosted regression trees were used to derive the patterns of richness distribution along altitudinal gradients. Results: Total vascular plant richness did not show any strong response to altitude. Contrasting patterns of richness were observed for several growth forms. Woody, graminoid and climber species richness showed a unimodal structure. However, each of these morphological groups had a peak of richness at different altitudes: graminoid species attained maximum importance at a lower elevations, followed by climbers and finally woody species at higher elevations. Fern species richness increased monotonically towards higher altitudes, but herbaceous richness had a dented structure at mid‐altitudes. Soil sand fraction, silt, slope and organic matter were found to contribute a considerable amount of the predicted variance of richness for total vascular plants and growth forms. Main Conclusions: Hump‐shaped species richness patterns were observed for several growth forms. A mid‐altitudinal richness peak was the result of a combination of climate‐related water–energy dynamics, species–area relationships and local environmental factors, which have direct effects on plant physiological performance. However, altitude represents the composite gradient of several environmental variables that were interrelated. Thus, considering multiple gradients would provide a better picture of richness and the potential mechanisms responsible for the distribution of biodiversity in high‐mountain regions of the tropics.     

Importance of mangrove plantations for climate change mitigation in Bangladesh

Mangroves have been identified as blue carbon ecosystems that are natural carbon sinks. In Bangladesh, the establishment of mangrove plantations for coastal protection has occurred since the 1960s, but the plantations may also be a sustainable pathway to enhance carbon sequestration, which can help Bangladesh meet its greenhouse gas (GHG) emission reduction targets, contributing to climate change mitigation. As a part of its Nationally Determined Contribution (NDC) under the Paris Agreement 2016, Bangladesh is committed to limiting the GHG emissions through the expansion of mangrove plantations, but the level of carbon removal that could be achieved through the establishment of plantations has not yet been estimated. The mean ecosystem carbon stock of 5–42 years aged (average age: 25.5 years) mangrove plantations was 190.1 (±30.3) Mg C ha⁻¹, with ecosystem carbon stocks varying regionally. The biomass carbon stock was 60.3 (±5.6) Mg C ha⁻¹ and the soil carbon stock was 129.8 (±24.8) Mg C ha⁻¹ in the top 1 m of which 43.9 Mg C ha⁻¹ was added to the soil after plantation establishment. Plantations at age 5 to 42 years achieved 52% of the mean ecosystem carbon stock calculated for the reference site (Sundarbans natural mangroves). Since 1966, the 28,000 ha of established plantations to the east of the Sundarbans have accumulated approximately 76,607 Mg C year⁻¹ sequestration in biomass and 37,542 Mg C year⁻¹ sequestration in soils, totaling 114,149 Mg C year⁻¹. Continuation of the current plantation success rate would sequester an additional 664,850 Mg C by 2030, which is 4.4% of Bangladesh's 2030 GHG reduction target from all sectors described in its NDC, however, plantations for climate change mitigation would be most effective 20 years after establishment. Higher levels of investment in mangrove plantations and higher plantation establishment success could contribute up to 2,098,093 Mg C to blue carbon sequestration and climate change mitigation in Bangladesh by 2030.     

Trees outside forest (TOFs) aids in mitigating global climatic change through carbon sequestration: Example from academic institutional landscapes

TOF including urban and other plantations like road side, homestead gardens, residential areas or in various institutional or academic landscapes make positive contribution to living conditions of different towns and cities. The present work reports the amount of biomass and its contribution to carbon stock of different woody perrennials in the campus of Uttar Banga Krishi Viswavidyalaya, West Bengal, India. The study was carried out by enumerating the entire study area for volume estimation and further calculation was done through validated methodologies. A total of 1816 numbers of individuals with dbh ≥ 10 cm of 95 woody perennials species belonging to 79 genera and 38 families were enlisted. Out of 95 species, the contribution was dominated by 52 forestry tree species followed by road side plantation (21) and fruit crops (14). A total of 812.211 Mg ha⁻¹ of biomass was recorded from the woody tree species with 79.40% contribution from above ground biomass (AGB) and 20.60% (BGB) below ground biomass. In the AGB forestry tree species showed dominance in terms of contribution (322.95 Mg ha⁻¹) followed by plantation crops (169.695 Mg ha⁻¹), road side plantation (107.069 Mg ha⁻¹) and least by fruit crops (45.190 Mg ha⁻¹). The overall carbon stock found was 403.176 Mg Cha⁻¹ with highest contribution from forestry tree species (200.53 Mg Cha⁻¹) followed by plantation crops (106.720 Mg C ha⁻¹) and least by fruit crops (28.470 Mg Cha⁻¹). The study recommends plantaion of more and more woody species across the academic landscapes especially with threatened category flora for conservation and carbon sequestration for mitigating global climate change. TOFs will have to play an important role for sustaining future generations due to shrinking of other forest landuse systems.     

长白山亚高山针叶林沼泽湿地碳源/汇沿水分环境梯度变化规律

高纬度和高海拔区为气候变化敏感区,该区域湿地碳循环与气候反馈关系倍受关注。为探究在全球变暖背景下高海拔区沼泽湿地碳源/汇功能是否发生了转化,以长白山高海拔区沿水分环境梯度分布的5种沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX、落叶松苔草沼泽-LT)为对象,采用静态箱-气相色谱法和相对生长方程法,同步测定各沼泽类型全年尺度上的土壤异养呼吸碳排放量(CO₂和CH₄)、植被年净固碳量及相关环境因子(温度、水位和土壤有机碳等),并依据生态系统净碳收支平衡,量化各沼泽类型的碳源/汇作用,揭示其沿水分环境梯度变化规律及形成机制。结果表明：(1)5种沼泽类型土壤CO₂年均通量((97.68±8.64)—(291.01±18.31)mg m^-2 h^-1)沿水分环境梯度呈阶梯式递增规律性(环境梯度上部生境地段的落叶松苔草沼泽和落叶松藓类沼泽最高,中部生境地段的落叶松泥炭藓沼泽和灌丛沼泽居中,草丛沼泽最低);(2)CH₄年均通量((-0....     

Altitudinal gradients of grassland carbon and nitrogen isotope composition are recorded in the hair of grazers

Aim The hair of grazers provides an isotopic record of environmental and nutritional signals. Here, we assess the effect of altitude on the carbon and nitrogen isotope composition of the hair of ruminant grazers and its relation to grassland vegetation, to evaluate the use of hair isotope data for ecosystem reconstruction, animal nutritional ecology and biogeochemical studies in montane environments. Location European Alps. Methods We sampled grassland vegetation (pure C₃) and the hair of ruminants along an altitudinal gradient (400–2500 m), and analysed their isotope composition (δ¹³C and δ¹⁵N). Results were compared with published effects of altitude on ¹³C in C₃ plants at the species level and on ¹⁵N at the community level. The study was complemented with a comparison of diet and hair isotope composition in ruminants held in confinement. Results δ¹³C of hair increased (c. 1.1‰ km⁻¹) and δ¹⁵N decreased (c. 1.1‰ km⁻¹) with altitude. The same changes occurred in local grassland vegetation, and in regional to global grassland data sets. Offsets between hair and vegetation ¹³C or ¹⁵N (‘diet–hair shift’) were independent of altitude. Sheep (Ovis aries) and cattle (Bos taurus) exhibited a ¹³C shift near +3‰, but that of goats (Capra hircus) was larger (+4.2‰) in alpine environments and in confinement. The diet–hair shift for ¹⁵N was more variable (+2.1 to +3.6‰). Main conclusions Grazer hair provides a faithful spatially and temporally integrated record of grassland isotope composition, useful for ecosystem and environment reconstruction. The effect of altitude on hair ¹⁵N is important for studies of trophic relationships: an altitude shift of 2000 m produced the same effect in hair ¹⁵N as would a shift from an animal tissue‐based to a plant‐based diet. The similarity of altitude effects on δ¹³C of individual plant species, vegetation and hair indicates that the effect of altitude on species‐level ‘intrinsic water use efficiency’ scales up linearly to the community and landscape level.     

秦岭小陇山保护区维管植物丰富度和种域海拔梯度格局及其对Rapoport法则验证

物种丰富度和种域的海拔梯度格局及其形成机制一直是生物地理学和生物多样性研究的重点.海拔Rapoport法则认为,物种丰富度随海拔升高而逐渐降低,种域逐渐变宽.本文分析了秦岭小陇山国家级自然保护区维管植物物种丰富度及其种域宽度的海拔梯度格局;采用4种常用方法,验证不同类群、不同生长型和不同阶元的物种丰富度与其分布中点间的关系,并检验其是否支持海拔Rapoport法则.结果表明: 除窄域种外,秦岭小陇山维管植物物种丰富度随海拔升高呈先升后降的单峰分布格局;狭域种主要分布在低海拔和高海拔段,低海拔段的丰富度高于高海拔段;物种海拔分布宽度与海拔关系因不同类群和验证方法而异,随分类阶元的增大更容易支持Rapoport法则,这可能与不同分类阶元所占据的生态位不同有关;被子植物的平均种域呈单峰分布格局,蕨类植物和裸子植物的种域海拔梯度格局无明显规律;藤本植物平均种域随海拔升高而变宽,灌木能适应不同的环境条件,因此,灌木分布对海拔梯度的变化不敏感.Pagel验证方法最容易支持Rapoport法则,Stevens方法次之,中点法受中域效应的影响物种平均种域分布呈单峰分布格局而不支持Rapoport法则,逐种法受散点图分布格局的影响线性模型拟合结果解释力很低.