Species Importance Values Research Articles

Estructura y composición florística de la selva mediana subperennifolia en Bethania, Campeche, México

We characterized the vegetation structure and the floristic composition of the semi evergreen tropical forest in the locality of Bethania, Campeche, Mexico. We marked ten 10 m x 10 m (1 000 m2) plots, where all individuals with a diameter at breast height (DBH) of ≥ 2 cm were measured. The structural analysis of the vegetation is based on the species importance values (IV). We found 490 woody individuals belonging to 34 species, grouped into 33 genera and 23 families. The Fabaceae was the plant family with more species (7). Terminalia buceras was the species with the highest relative dominance, followed by Metopium brownei , Coccoloba barbadensis and Zygia sp . These four species accounted for almost half (43.5%) of the relative importance value. Our results indicate that the medium semievergreen forest is characterized by floristic elements subtect to flooding. The number of woody individuals is concentrated in three families ( Fabaceae, Ochnaceae and Polygonaceae ). Finally, Bravaisia berlandieriana form a competitive hierarchy in the shrub layer that colonizes clearings of semi evergreen tropical forest of the locality of Bethania.

Biodiversity and Carbon Potentials of a Nigerian Forest Reserve: Insights from the Niger Basin

Forest reserves are expected to host a wide array of biodiversity and provide refuge for rare species that may be threatened in nearby forest landscapes. While this is the guiding protocol for most reserves across the tropics, such as Nigeria, the extent to which they host biodiversity and act as potential stores for carbon are quite uncertain. This study used a four hectare randomly selected forest plots to verify the biodiversity of the reserve, its stand structure and potentials for carbon storage. Species importance value was used to summarize the composition of the landscape. Both the diversity (mean diversity = 0.85) and species richness (eleven species) were low. Biodiversity in the area was quite poor and was mostly composed of Elaeis guineensis and Gmelina arborea, which had relative densities of 74.6% and 11.96%, respectively. Over exploitation and preference for fast-growing exotic species explained the poor stand structure and composition of the landscape, respectively. Very few tree stands were found in the mature structural class, and its capacity to facilitate regeneration and resilience seemed low. Its ability to store carbon in its biomass is equally low; since the forest landscape was much degraded. Maximizing the vast land of the reserve for targeted carbon storage (through mass tree planting) is a potential step that could forestall carbon sequestration across the region, especially because, such vast and available (forest) land cannot be guaranteed in most other forest landscapes.

Impacts of reforestation on woody species composition, species diversity and community structure in dry-hot valley of the Jinsha River, southwestern China

To understand the impacts of reforestation on woody species composition, species diversity and community structure, seven plantation forests in dry-hot valley of the Jinsha River in Southwest China were investigated, with adjacent wastelands, natural shrub grassland and a natural forest as references. Species importance value, species richness, species heterogeneity and Sorenson similarity index between plantations and the natural forest were analyzed. Results indicated that compared to wastelands and natural shrub grassland, reforestation improved species diversity and community structure, and more forest woody species found suitable habitats in plantations. Species diversity in understory of plantations and Sorenson similarity index were significantly negatively correlated with stem density in mature plantations (26-31 years old). Higher species diversity and Sorenson similarity index existed in mature sparse plantations due to lower stem density and more tree species planted initially. In contrast, reference natural forest, with species heterogeneity of 2.28 for shrub layer, showed the highest species diversity. It would take a long time for species composition and diversity to recover through reforestation in a dry-hot valley. Therefore, it was essential to protect remnant natural forests strictly and reforest with suitable management such as lower stem density and increasing genetic diversity of trees planted.

ESTRUCTURA Y COMPOSICIÓN FLORÍSTICA DEL BOSQUE DE LA LLANURA ALUVIAL EN LA AMAZONÍA PERUANA: I . EL BOSQUE ALTO

En la llanura aluvial del Perú, adyacentes al río Ucayali, fueron muestreados tres tipos de bosques, usando 9 parcelas permanentes de 1 ha, identificándose y midiéndose los árboles con tallos mayores a 10 cm DAP. Estas parcelas han sido medidas 4 veces, entre 1993-1997, y proporcionan las bases para los resultados reportados aquí. Tres parcelas fueron establecidas en cada uno de los tres tipos de bosque: restinga alta, restinga baja y tahuampa, caracterizada en parte por una inundación anual de 1, 2 y 4 meses por año, respectivamente. La densidad de los tallos varía desde 446 a 601 por ha y los rangos de área basal entre 20-29 m2 /ha. Un total de 321 especies fueron registradas en las 9 ha de muestra, con 88-141 especies en cada una de las parcelas. La composición de las especies indica similaridad relativamente baja entre los tipos de bosque. Las parcelas con inundaciones más prolongadas son las que contienen más especies, expresadas ambas tanto por unidad de área como por 1 000 tallos. Los bosques de llanura aluvial contienen menor cantidad de especies arbóreas que los bosques de tierra firme no inundables. Valores de importancia de las familias son calculados para cada bosque. En los tres tipos de bosques las Leguminosae, Euphorbiaceae, Anonaceae y Lauraceae son importantes. La familia Moraceae es conspícua en restinga alta y baja. Las Arecaceae y Meliaceae son notables en restinga alta como lo es la Rubiaceae en restinga baja. Lecythidaceae, Sapotaceae y Chrysobalanaceae, exhiben relativamente altos valores en los bosques de tahuampa. Valores de las especies de mayor importancia son obtenidos para Maquira coriacea, Guarea macrophylla, Terminalia oblonga, Spondias mombin, Ceiba pentandra, Hura crepitans, Eschweilera spp., Campsiandra angustifolia, Pouteria spp., Licania micrantha, Parinari excelsa y Calycophyllum spruceanum. Entre las especies de más pequeña estatura alcanzan altos valores: Drypetes amazonica, Leonia glycicarpa, Theobroma cacao y Protium nodulosum.

Effects of elevation and disturbance gradients on forest diversity in the Wulingshan Nature Reserve, North China

Forest diversity and conservation in the Wulingshan National Nature Reserve are ecologically important in North China. Forty-one forest plots of 20 m × 20 m were established along an altitudinal gradient. Data on species composition, environmental variables and disturbance intensity were measured in each plot. The TWINSPAN and CCA methods were used to analyze forest community diversity and the forest–environment relationship, and species diversity indices were used to analyze species diversity in this reserve. The results showed that eight forest formations were identified by TWINSPAN using species importance value data, and most of them were typical secondary natural forests. Each forest formation had its own characteristics of composition, structure, function and environment. Forest diversity was most significantly correlated with elevation and disturbance, and was also related to litter thickness, soil depth and slope. The species diversity showed a “humped” distribution pattern along the altitudinal gradient and a quadratic decreasing pattern along the disturbance gradient. Elevation and disturbance were the most important factors influencing species diversity. The effectiveness of conservation is apparent since the reserve was established.

TWINSPAN과 CCA Ordination에 의한 서해안 곰솔림과 토양환경과의 상관 분석

Vegetation and soil conditions of four sites in west coastal forests in South Korea, were examined to analyze the relationship between Pinus thunbergii forests structure and soil conditions. The P. thunbergii forests were divided into four clusters; 1) P. thunbergii - Prunus sargentii var. sargentii, 2) P. thunbergii - Robinia pseudoacacia, 3) P. thunbergii - P. densiflora and 4) P. thunbergii - Quercus serrata. The soil of each site was poor in chemical characteristics but good enough for land plants to grow because of its low salt concentration. According to the results by CCA Ordination, certain excessive soil nutrition has influenced on vegetation and specific species distribution. Forty eight species were found in the whole sites of coastal forests and some species appeared in every site. They are P. thunbergii, R. pseudoacacia, Rhus chinensis, Idesia polycarpa and Morus alba. For the tree species importance value, P. thunbergii was followed by R. pseudoacacia, Q. serrata, P. densiflora, Celtis sinensis, M. alba, I. polycarpa and Q. mongolica in order.

Caracterización y ordenación de los bosques de pino piñonero (Pinus cembroides subsp. orizabensis) de la Cuenca Oriental (Puebla, Tlaxcala y Veracruz)

Pinus cembroides subsp. orizabensis es el pino piñonero con distribución más al sur en América, la mayoría de sus poblaciones se desarrollan dentro de los límites de la Cuenca Oriental, la única zona árida fría en México, donde se distribuyen en por lo menos cinco localidades aisladas. Los objetivos del presente estudio fueron realizar el inventario florístico y estructural de los bosques de pino piñonero de la Cuenca Oriental, cuyo dosel domina el taxón antes referido. El trabajo de campo consistió en la búsqueda y recolección de ejemplares de plantas vasculares mediante técnicas estándar, para su posterior identificación en laboratorio, y en el muestreo de los bosques para determinar la densidad, cobertura y valor de importancia de las especies. El análisis de agrupamiento permitió estimar la semejanza en la composición de especies entre bosques; mediante el análisis de correspondencia canónica se estimó la relación entre factores ambientales y edáficos, con respecto a la composición y distribución de las especies entre las localidades; y con los valores estructurales se realizó la caracterización fisionómica de los bosques. Los resultados indican que los bosques de pino piñonero se desarrollan en sustratos volcánicos, en suelos con pH neutro a ligeramente básico (7-8), en un intervalo altitudinal de entre 2300 m y 2700 m. Las asociaciones vegetales identificadas fueron: Piñón-Nolina, Piñón-Juniperus y Piñón-Pinus pseudostrobus; los taxones Pinus cembroides subsp. orizabensis y Nolina parviflora fueron constantes en todas las localidades. La composición florística de estos bosques se relacionó principalmente con los factores edáficos Ca y N.

Short-term Dynamics and the Effects of Biotic and Abiotic Factors on Plant Physiognomic Groups in a Hurricane-impacted Lower Montane Tropical Forest

We assessed the short-term effects of biotic (density, plant size) and abiotic factors (light), on the dynamics of physiognomically different plant groups (palms, tree ferns, lianas, and trees) in a hurricane-impacted tropical wet montane forest, John Crow Mountains, Jamaica. All plants ≥2 cm (dbh) found within 45, 25 × 25 m permanent sample plots (2.8125 ha), established according to a randomized block design along an elevation gradient, were tagged and measured (dbh) in 2006 and re-assessed in 2012 after Hurricane Dean (2007). Hemispheric light was measured in 2007 and 2008. Tree and liana size class distributions changed due to high mortality in the smallest size classes and their densities declined; however, palm and tree fern density remained unchanged. The dynamics of trees were only related to tree fern and liana dynamics (e.g., tree mortality was negatively related to liana recruitment etc.). Although pre- and posthurricane light was related to palm density and the density of the other plant groups, respectively, there were no significant changes in light. Tree survivorship increased with increasing dbh while posthurricane light and overall density influenced the growth and survivorship of tree species. Species importance value did not change, suggesting that direct regeneration may be the model of forest recovery following this small-scale disturbance. Over the short term, tree species showed life history trade-offs that aid species coexistence after this moderate/low disturbance event. Our study highlights that hurricanes with low impacts can have differential short- and possibly long-term effects on different plant groups.

喀斯特天然林植物多样性指数和土壤理化指标的相关性

PDF HTML阅读 XML下载 导出引用 引用提醒 喀斯特天然林植物多样性指数和土壤理化指标的相关性 DOI: 10.5846/stxb201403220514 作者: 作者单位: 贵州省林业科学研究院,贵州省林业科学研究院;贵州大学,贵州省林业科学研究院,贵州大学;贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州大学;贵州省林业科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项(201104002);贵州省科技厅项目(黔省专合字TZJF2008-17,2009-2083,2008-73,黔科合字2007-1021,2010-05) Correlation on plant diversity indices and soil physical and chemical indicators of karst natural forest, Southern Guizhou Province, China Author: Affiliation: Guizhou Provincial Academy of Forestry,,,,,,,, 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:植物多样性的土壤生态系统功能是喀斯特生态学研究的热点之一。在贵州省茂兰国家级自然保护区不同功能区(干扰等级)内采用野外样地调查和实验室分析相结合的方法,分析了41个喀斯特森林样地的植物多样性指数和土壤理化指标值的变化规律与相关性。结果表明:(1)依据乔木层物种重要值聚类法划分的5个喀斯特森林类型包括小叶栾树-青冈栎林、香叶树-枫香林、香椿-香叶树林、灯台-小花梾木林和檵木-马尾松林,由核心区、缓冲区、实验区至外缘区,乔木层植物多样性指数、林地岩石裸露率、土壤蓄水量、肥力及养分指标呈降低趋势。(2)因子分析表明不同层片植物多样性和不同土层土壤理化因子的相关趋势性各异。相关显著的因子对数量率呈乔木 > 灌木 > 草本的趋势,乔木植物多样性因子起主导作用。(3)喀斯特森林乔木层植物多样性指数和土壤理化指标的相关性分3种类型。直线型是植物多样性指数和土壤理化指标值相关性中较普遍的一类,相应指标对数量率为39.84%;曲线型是植物多样性指数和土壤理化指标值相关性中机理较复杂的一类,相应指标对数量率为46.10%,其中植物多样性指数有拐点值无生态意义的指标对数量率为11.72%,有拐点值有生态意义且呈先降后升、或先升后降趋势的指标对数量率分别为17.19%;无关型是植物多样性指数和土壤理化指标值相关性不显著,相应指标对数量率为54.69%。(4)喀斯特地区水土资源管理为目标的营林措施中,天然林乔木层植物多样性指数对土壤物理、肥力和养分指标响应的拐点值可成为人工造林中物种数量与株数比例选择的参考依据之一。 Abstract:Soil ecosystem function and plant diversity is receiving much attention in karst ecological studies. Changes and correlation laws in plant diversity indices and soil physical and chemical indicators of 41 karst forest plots were analyzed on different functional areas in the Maolan National Nature Reserve of southern Guizhou Province, China. This research adopted the combination method of wild field plot investigation and laboratory analysis. Results show:(1) The importance values of the arbor species clustering method resulted in five karst forest types:Koelreuteria minor-Cyclobalanopsis glauca forest, Lindera communis-Liquidambar formosana forest, Toona sinensis-Lindera communis forest, Cornus controversa-Cornus parviflora forest and Loropetalum chinense-Pinus massoniana forest. The arbor plant diversity indices, bare rock coverage, soil water storage indicators, soil fertility indicators and nutrient indicators showed a decreasing trend from the core area, to the buffer area, to the experimental area and to the outer area. The Margalef index, Simpson index, Shannon-Wiener index and Pielou index of the arbor and herb layer species showed a significant difference between some forest types. However, the diversity indices differences of the shrub layer were not significant. Significant differences of some indicators between the different forest types confirmed the influence of human disturbance to the karst forest in the natural recovery process. (2) Factor analysis revealed different correlation trends between the plant diversity factors of different layers, and the physical and chemical factors of different soil horizons. The analysis conformed to the general regularity of plant growth in the development of the arbor, shrub and herb layer and the co-evolution between the vegetation and soil system of karst forest in the natural recovery process. The number rate of significant factor-pairs of the soil physical and chemical indicators related to the arbor, shrub and herb plant diversity indices were 36.38%, 27.27% and 18.19%, respectively. The arbor plant diversity factor had the strongest relationship with the soil physical and chemical indicators. (3) The significant correlations between the arbor plant diversity indices and the soil physical and chemical indicators were divided into three types:i) Linear correlation is a general relationship between the plant diversity indices and soil physical and chemical indicators; 39.84% of the indicator-pairs were in this category, where the plant diversity indices increased to raise or lower the soil physical and chemical indicators accordingly. ii) Curve correlation is a complex relationship between the plant diversity indices and soil physical and chemical indicators; 46.10% of indicator-pairs are accounted for in this way. Inflection point values of the plant diversity indices without ecological meaning accounted for 11.72% where the relationship could be explained using straight lines or other models. The ecological inflection points of the plant diversity indices, which periodically impacted on soil physical and chemical indicators between the upwards and downwards trends of the quadratic curves, accounted for 17.19% of the indicator-pairs. The values of these plant diversity indices can be adjusted on the basis of the soil management goal in forest planting. iii) No significant correlation means the plant diversity indices are independent of the soil physical and chemical indicators, and planting measures for plant diversity indices cannot effectively change the soil physical and chemical indicators; 54.69% of indicator-pairs corresponded to this model. The different response modes aid the interpretation of ecosystem function through the plant diversity hypothesis. (4) Inflection points are the top values of the upwards and downwards trends in the quadratic curve response of arbor plant diversity indices to soil physical and chemical indicators. They are in index values of Margalef for 0.71-2.70 and 4.80-9.70, Simpson for 0.57-0.66 and 0.72-0.86, Pielou for 0.50-0.76 and 0.83-0.95 and Shannon-Wiener for 1.35-1.43 and 2.57-3.47, respectively. These values are used for one of the selection references of species and number proportions in artificial forestation. 参考文献 相似文献 引证文献

Importance of succession, harvest, and climate change in determining future composition in U.S. Central Hardwood Forests

Most temperate forests in U.S. are recovering from heavy exploitation and are in intermediate successional stages where partial tree harvest is the primary disturbance. Changes in regional forest composition in response to climate change are often predicted for plant functional types using biophysical process models. These models usually simplify the simulation of succession and harvest and may not consider important species‐specific demographic processes driving forests changes. We determined the relative importance of succession, harvest, and climate change to forest composition changes in a 125‐million ha area of the Central Hardwood Forest Region of U.S. We used a forest landscape modeling approach to project changes in density and basal area of 23 tree species due to succession, harvest, and four climate scenarios from 2000 to 2300. On average, succession, harvest, and climate change explained 78, 17, and 1% of the variation in species importance values (IV) at 2050, respectively, but their contribution changed to 46, 26, and 20% by 2300. Climate change led to substantial increases in the importance of red maple and southern species (e.g., yellow‐poplar) and decreases in northern species (e.g., sugar maple) and most of widely distributed species (e.g., white oak). Harvest interacted with climate change and accelerated changes in some species (e.g., increasing southern red oak and decreasing American beech) while ameliorated the changes for others (e.g., increasing red maple and decreasing white ash). Succession was the primary driver of forest composition change over the next 300 years. The effects of harvest on composition were more important than climate change in the short term but climate change became more important than harvest in the long term. Our results show that it is important to model species‐specific responses when predicting changes in forest composition and structure in response to succession, harvest, and climate change.

Effects of Stand Density on Community Structure and Species Diversity of Camptotheca acuminata Plantation in Baiyun Mountain,Mianzhu District,Sichuan Province

By a field experiment,we studied the effects of different densities( low density and high density) on community structure( species composition and important value,diameter class and height class) and species diversity( The richness index S,Shannon-wienner index H,Simpson index H', and Pielou index Jswof Camptotheca acuminata plantation in Baiyun Mountain,Mianzhu District,Sichuan Province). Diameter class and height class had the same response to different density. Partial peak attribution was demonstrated in stand with big density,and peak attribution was demonstrated in stand with small density. In the tree layer of C.acuminata plantation,each species diversity indexes were low in both high and low density. Underground plants showed different responses to stand density,and there were higher species diversity of the herb layer under shrub layer in high and low density,respectively.

English

Kiang'ombe hilltop forest is overexploited for fuel wood, charcoal, timber and non-wood forest products, thus threatening its biodiversity conservation role. The extent of forest degradation is not yet quantified and this impedes rehabilitation interventions. This study was conducted to evaluate the status of Kiang'ombe forest resources to initiate rehabilitation interventions and to support sustainable forest management. Remote sensing and geographic information systems (GIS) were used to determine trends of spatial and temporal vegetation changes over 25 years. Image analysis revealed high, moderate and low categories of forest degradation over the assessment period. Thirty two nested sample plots were used for vegetation inventory in the three degradation gradient clusters. Additional data was obtained from local informants through focused discussions and field observations. A total of 155 plant species belonging to 58 families were identified. Shannon Weiner diversity index of seedling and sapling were higher in low and moderate than in high degraded areas. Based on species importance values, the candidate trees for rehabilitation of degraded areas were Croton macrostachyus, Acacia hockii, Combretum molle and Faurea saligna whereas Enteropogon macrostachys, Cymbopogon sp., Eragrostis superba and Hyparrhenia rufa were the most suitable grass species for reseeding expansive glades. The recommended rehabilitation techniques are enrichment tree planting in water catchments areas, enhancing natural regeneration through protection and grazing management, gully healing at the hill slopes and establishment of woodlots plantations and boundary planting in the surrounding farmlands. Key words: Hilltop forest, geographic information systems (GIS), vegetation inventory, rehabilitation techniques.

The endemic medicinal plants of Northern Balochistan, Pakistan and their uses in traditional medicine

Ethnopharmacological relevanceThe highlands of Northern Balochistan are the hot spots of medicinal and endemic plant in Pakistan. These plants are still commonly used for medicinal purposes by local people in their daily lives. This study first documented the information about the medicinal uses of endemic species of Balochistan-province Pakistan. Materials and methodsA survey was performed using open ended questionnaires, free listening and personal observations with 152 informants (54% female, 46% male). In addition, the use value (MUV), use report (UR), fidelity level (FL), frequency citation (FC), relative frequency citation (RFC), family importance value (FIV) of species were determined and the informant consensus factor (ICF) was calculated for the medicinal plants included in the study. ResultsA total of 24 endemic plants belonging to 19 genera and 14 families were used by the local inhabitants to treat 12 categories of various diseases. The most common families of endemic plant species as depicted by its number of species (6 species) and FIV (9.9) was Fabaceae as the dominant family. The endemic plant species comprised perennial herbs (30%), annual herbs (25%), shrubs (29%) and under shrubs (16% each), no endemic tree species was reported in the study area. The highest number of species were used in the treatment of gastrointestinal diseases (12 species). The main route of administration is oral injection (62%) while the most frequently used form of external administration of herbal medicine was paste (5.4%) and the most commonly applied methods of preparation are powder (48.2%). Highest use report were calculated for Allium baluchistanicum and Viola makranica, (8 UR each), and least use report were calculated for two species Heliotropium remotiflorum and Tetracme stocksii (1 UR for each). Use values of the recorded plant species have been calculated which showed a highest use value of (0.73) for A. baluchistanicum and (0.56) for Berberis baluchistanica while the lowest UVs were attained for T. stocksii (0.13). Highest RFC value were calculated for Achillea millefolium (0.19) and least RFC were calculated for Blepharis sindica (0.02). The endemic species with 100% fidelity level was calculated for two plant species i.e. Seriphidium quettense and B. baluchistanica. ConclusionsThe Balochistan is rich in endemic and other medicinal plants, still needs more exploration and study. Thus, it is important to document and reconstitute the remainders of the ancient medical practices which exist in Balochistan and other areas of the world, and preserve this knowledge for future generations. The endemic species which are used in traditional medicine in the region lacks phototherapeutic evidence. It is necessary to perform phytochemical or pharmacological studies to explore the potential of plants used for medicinal purposes. Overgrazing, urbanization and unsustainable harvesting of such rare and endemic medicinal plants in this region is facing severe threats of extinction. It is thus recommended that cultivation techniques be formulated, especially for the most important endemic plant medicinal species of the region.

Structure of natural Juniperus excelsa stands in Northwest of Iran

Tavankar F. 2015.Structure of natural Juniperus excelsa stands in Northwest of Iran. Biodiversitas 16: 161-167. Juniperusexcelsa M. Bieb. stands are important forest ecosystems in mountain areas of Iran. In this research the structure of J. excelsa stands wasstudied at altitudes of 1,400 to 1,900 m in northwest of Iran. The results showed that the mean densities of trees and seedling (trees withheight up to 1.3 m) were 99.8 ± 32.0 and 70.5 ± 18.3 stem ha-1, respectively. The juniper trees comprise 52.8% of the total tree density,while the juniper seedlings comprise 19.3% of total seedling density. The mean of basal area in this stand was 3.12 ± 0.3 m2 ha-1 and themean of canopy cover was 42.7 ± 17.9 percent. The mean of trees height was obtained 2.75 ± 1.1 m. The total of 28 woody speciesbelonging to 14 families was recorded from the study area. The juniper trees had the maximum value of species importance value(SIV=87.3). Amygdalus lyciodes and Pistacia atlantica were two tree species that have high SIV values, 34.1 and 27.0, respectively.Thedistribution of trees density in different tree diameters resemble to a reverse J-shaped indicating uneven-aged structure. The resultsindicated juniper seedlings were increased by increasing stand crown cover (P< 0.01). Moreover extreme environmental conditions,grazing and timber harvesting for firewood are two important socioeconomic problems in these forests. These valuable stands needs tourgently conservation strategies.

Responses of plant community composition and biomass production to warming and nitrogen deposition in a temperate meadow ecosystem.

Climate change has profound influences on plant community composition and ecosystem functions. However, its effects on plant community composition and biomass production are not well understood. A four-year field experiment was conducted to examine the effects of warming, nitrogen (N) addition, and their interactions on plant community composition and biomass production in a temperate meadow ecosystem in northeast China. Experimental warming had no significant effect on plant species richness, evenness, and diversity, while N addition highly reduced the species richness and diversity. Warming tended to reduce the importance value of graminoid species but increased the value of forbs, while N addition had the opposite effect. Warming tended to increase the belowground biomass, but had an opposite tendency to decrease the aboveground biomass. The influences of warming on aboveground production were dependent upon precipitation. Experimental warming had little effect on aboveground biomass in the years with higher precipitation, but significantly suppressed aboveground biomass in dry years. Our results suggest that warming had indirect effects on plant production via its effect on the water availability. Nitrogen addition significantly increased above- and below-ground production, suggesting that N is one of the most important limiting factors determining plant productivity in the studied meadow steppe. Significant interactive effects of warming plus N addition on belowground biomass were also detected. Our observations revealed that environmental changes (warming and N deposition) play significant roles in regulating plant community composition and biomass production in temperate meadow steppe ecosystem in northeast China.

Spatial heterogeneity of soil and vegetation characteristics and soil-vegetation relationships along an ecotone in Southern Mu Us Sandy Land, China

This study aims to examine the changes in the spatial heterogeneity of soil properties at different soil layers, the spatial heterogeneity of soil and vegetation characteristics along an ecotone, and soil-vegetation relationships along the ecotone in a critical area of desertification. A study site was established across a Lespedeza potaninii (dominant) community (LPC) and an Artemisia ordosica (dominant) community (AOC), with the ecotone between these two communities. In this study, “along the ecotone” means from LPC, via the ecotone, and then to AOC. Three parallel transects (300-m long) were arranged at 50-m intervals along the site. Along each transect, at 10-m spacings, 1 m × 1-m quadrats were marked for the vegetation survey and soil sampling. Soil samples were analyzed in the laboratory after natural air-drying. Data analyses were conducted with a combination of classical and geostatistical methods. In most cases, species importance values and soil properties changed significantly (P < 0.05) along the ecotone. Most soil and vegetation variables were moderately spatially autocorrelated. Kriging interpolated maps showed patch patterns of soil chemical properties. The C/(Co + C) values of soil properties were larger at 5–10-cm than those at 0–5-cm. Vegetation characteristics were mainly positively correlated with soil organic carbon (SOC), total nitrogen (TN), and electrical conductivity (EC). TN at 0–5-cm (TN1), EC at 0–5-cm (EC1), and available potassium at 5–10-cm (AK2) were selected as the predictors for plant species richness and diversity in the stepwise regression analysis between vegetation characteristics and soil properties. Soil nutrients decreased significantly (P < 0.05) along the ecotone. Soil and vegetation properties had moderate spatial heterogeneity. Soil properties had a stronger spatial heterogeneity at subsurface layers compared to surface layers. TN1, EC1, and AK2 were the predominant factors for the plant community structure along the ecotone in the critical area of desertification.

黄河下游平原不同非农生境中植物多样性研究

The well-being and survival of humanity depends upon the stability and sustainability of services provided by agricultural ecosystems. Natural and semi-natural habitats within agricultural landscapes,as well as the associated plant communities thereof, are of vital importance for preserving biodiversity in agro-ecosystems. Agricultural landscapes interspersed with forest and hedge patches dominate the lower reaches of the Yellow River Plain. In order to understand the characteristics and ecological functions of plant communities in non-agricultural habitats,a total of 54 plots were set up in Fengqiu county of Henan Province,reflecting landscape patterns. Within these plots,the vegetation in natural and seminatural habitats was investigated by using the Braun-Blanquet method. The surveyed habitats were mainly planted forests,hedges,field roads,and ditches. The results of this study are as follows:( 1) A total of 184 species belonging to 51 families and 157 genera( 1 species belonging to ferns) have been encountered in the study area,6 dominant families( Compositae,Gamineae,Leguminosae,Cruciferae,Labiatae,and Solanaceae) account for 48. 9% of all species. The plants are predominantly cosmopolitan( 26 families,148 species) and pantropic( 14 families,23 species) types,accounting for 80.0%( 40 / 50) of the total families and 93.4%( 171 / 183) of the total species. Ditches and field roads are primary habitats of the cosmopolitan types-respectively,88.5% and 86.0% of the plant species have been detected in these two habitats. The genera show complex patterns of geographical distribution type,comprising 13 of the 15 distribution types of Chinese seed plants. The temperate( 53 genera,56 species),cosmopolitan( 32 genera,48 species) and pantropic( 30 genera,34 species) are the dominant distribution types( 73.7% of all genera and 75.4% of all species). Overall,the study area is dominated by the widespread species,the dominant families and genera show marked superiority over the lesser taxa,and there is a distinct lack of endemic species.( 2) The planted forests and hedges have the highest species richness and diversity compared with the other non-agricultural habitats. The evenness and coverage in the ditches,planted forests and hedges are significantly higher than in the field roads. The field roads have the highest β-diversity.( 3) Community similarity analysis shows that the planted forests,hedges and field roads have high inter-community similarity,while the ditches have low inter-community similarity attributable mainly to species characteristics. Given the difference in community coverage and species importance value( IV) of the planted forests,hedges and field roads,we suggest that the results of the similarity analysis reflect the similarity of species occurrence rather than that of ecological functioning. Based on the results of this study,we believe that the planted forests and hedges have an important role in species conservation. The species diversity of planted forests is nearly equal to that of the hedges,indicating that the two habitats have similar abilities for protecting plant species in agro-landscapes. The ditches provide shelters for the hydrophytes and hygrophytes. In the future,we should concentrate on biodiversity characteristics controlling the ecosystem processes that underpin ecosystem functioning and services,investigate the ecological effects and mechanisms of the spatial configuration of the landscape elements,and explore appropriate regulation and management strategies. Furthermore,constructing hedge corridors may be an advisable approach for maintaining agricultural production and ecological functions in the study area. The ecological functions of planted forests may be enhanced by appropriately modifying the forests' structure and species composition to boost species diversity. Further studies are required to understand how agricultural landscapes can be configured to simultaneously maintain agricultural productivity and ecosystem functioning.

Vegetation Analysis and Soil Characteristics on Two Species of Genus &amp;lt;i&amp;gt;Achillea&amp;lt;/i&amp;gt; Growing in Egyptian Desert

The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica. Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na+, K+, Ca++ and Mg++) and PAR.

Estimating above Ground Biomass and Carbon Stock in the Lake Hawassa Watershed, Ethiopia by Integrating Remote Sensing and Allometric Equations

With the increasing concentration of carbon dioxide in the Earth’s atmosphere as the result of deforestation, there is a pressing need to estimate biomass and carbon pools in tropical forests. This is, particularly, essential in Africa where reliable biomass data is lacking. The present study was aimed at classifying land use land cover, estimating above ground biomass using remote sensing data and allometric equations, and determining the importance value of species in Lake Hawassa Watershed. Pantropic allometric equations were used that relate tree variables obtained by non-destructive measurements to the oven dry biomass. Local species specific biomass equations were also used to compare the results. The results indicated that the natural forest had lower mean above ground biomass (200.9 Mg/ha) than the plantation forest (223.6 Mg/ha). The pantropic allometric equations overestimated the above ground biomass by about 13.0% and 20.5% for natural and plantation forests, respectively, compared to the local equations. This variation is likely to be the main source of uncertainty for biomass computed using generalized equations. The species sampled ranged from 1 to 22 per plot and the overall mean stand density was 785 stems/ha. Cupressus lucitanica (60.09%), Grevillea robusta (28.65%), and Eucalyptus citriodora (20.87%) were the species with the highest importance value. The majority of tree species belonged to the diameter at breast height class of 5–25 cm accounting for 79.1% and 73.3% in plantation and natural forests, respectively. The total above ground biomass of the forest in the study area in 2011 was estimated at 1.72 Megatons. Although using generalized allometric equations demonstrated variations in above ground biomass estimates compared to the local species specific equations, results from this research effort can be used in absence of area specific models.

喷灌对藏北高寒草地生产力和物种多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 喷灌对藏北高寒草地生产力和物种多样性的影响 DOI: 10.5846/stxb201403310599 作者: 作者单位: 中国农业科学院农业环境与可持续发展研究所／农业部农业环境与气候变化重点实验室,北京市园林科学研究院,中国建筑设计咨询公司绿色建筑设计研究院／中国建筑设计研究院建筑节能与新能源工程中心,中国农业科学院农业环境与可持续发展研究所／农业部农业环境与气候变化重点实验室,中国农业科学院农业环境与可持续发展研究所／农业部农业环境与气候变化重点实验室,中国农业科学院农业环境与可持续发展研究所／农业部农业环境与气候变化重点实验室,西藏自治区那曲地区草原站,西藏自治区那曲地区草原站,西藏自治区那曲地区草原站 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技支撑课题(2012BAC01B02);国家自然科学基金项目(31170460);西藏那曲地区与中国农业科学院合作项目 Effects of irrigation on alpine grassland Northern Tibet Author: Affiliation: Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences/ Key Laboratory for Agro-Environment Climate Change,Ministry of Agriculture,Beijing Institute of Landscape architecture,China Building Design Consultants COCBDC/China Architecture design Research Group CAG,Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences/ Key Laboratory for Agro-Environment Climate Change,Ministry of Agriculture,Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences/ Key Laboratory for Agro-Environment Climate Change,Ministry of Agriculture,Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences/ Key Laboratory for Agro-Environment Climate Change,Ministry of Agriculture,Nagqu grassland station,Tibet Autonomous Region,Nagqu,Nagqu grassland station,Tibet Autonomous Region,Nagqu,Nagqu grassland station,Tibet Autonomous Region,Nagqu 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:通过3a(2008-2010年)的藏北高寒草地喷灌试验,研究了不同喷灌量对草地群落生产力和物种多样性的影响.结果表明,丰水年灌溉对藏北高寒草地的影响较小;而在相对干旱年份灌溉对高寒草地生产力和物种多样性影响显著.喷灌条件下高寒草地生物量显著提高,最高增幅出现在高水(GS)样地中,达到116%.喷灌明显促进物种重要值提高,其中灌木和阔叶杂草比例增加趋势更为明显.不同喷灌条件下优势物种相对重要值均有不同程度的降低,高水处理降低幅度最大.物种多样性方面,喷灌措施能够明显促进高寒草地Simpson指数和Shannon-weiner指数增加(P < 0.05),E. Pielou均匀度指数无显著变化(P > 0.05).Shannon-weiner指数与生物量之间存在显著正相关关系(P < 0.05).未来降水增多的气候条件可以减少干旱对高寒草地带来的负面影响,有利于提高草地生产力和维持草地物种多样性,促进高寒草地畜牧业健康发展. Abstract:Productivity and species diversity are important indicators of the service functions and basic factors of stability in grassland ecosystems. Precipitation is a main limiting factor of grassland productivity. There is a positive correlation between precipitation and productivity. Species diversity increases under precipitation enhancement; the water availability of the plant community has an important effect on community structure, composition, and species diversity. An increase in soil moisture content not only affects the grassland plant communities directly but also improves soil nutrient availability to promote plant growth. However, drought could lead to a series of negative effects on grassland ecosystems. Therefore, moisture is an important factor for productivity and species diversity, and it even affects the stability and sustainability of grassland ecosystems.Northern Tibet has low ecosystem stability, so external disturbances, such as climate change and human activities, easily result in variation in the pattern, process, and function of ecosystems. In recent years, Northern Tibet has experienced warming and increased precipitation. Increased precipitation will affect grassland productivity and species diversity, and will even influence animal husbandry. As a main measure of the adaptation strategy for climate change, irrigation could be a reasonable pathway to redistribute and make full use of increased precipitation.In this study, we conducted a growing season irrigation experiment in Northern Tibet (between 2008 and 2010) to simulate the precipitation enhancement in this area. We designed 4 irrigation gradients: CK (no irrigation), DS (low irrigation, plus 5% more than the ambient precipitation), ZS (moderate irrigation, plus 10% more than the ambient precipitation), and GS (high irrigation, plus 15% more than the ambient precipitation). We measured plant biomass, community composition, and species diversity under different amounts of irrigation. The results showed that irrigation had greater effects on alpine grassland productivity and species diversity in drought years than in wet years. Under the irrigation conditions, the grassland biomass increased significantly, and the highest increase was up to 116% in a high irrigation plot. Irrigation promoted the species importance values of alpine grasslands; in particular, the proportion of shrubs and broad-leaved forbs was increased. The proportion of dominant species decreased significantly under irrigation conditions, and the decrease was the highest in the high irrigation plot. The Simpson index and Shannon-Wiener index significantly increased under different amounts of irrigation (P < 0.05). The E. Pielou evenness index was not significantly influenced by irrigation (P > 0.05). There was a positive correlation between biomass and the Shannon-Wiener index (P < 0.05). In short, we can project that grassland biomass and species diversity will increase under future precipitation enhancement; this will reduce the negative impact of drought in alpine grasslands and promote the sustainable development of animal husbandry in alpine grasslands. 参考文献 相似文献 引证文献