Culture of Risk in Vulnerable Communities: The Case of Barranquilla,Colombia, in the Context of Globalized (In)Security

This article addresses both the culture of risk as an analytical and intervention category in vulnerable communities. The main objective is to show that risk analysis and intervention is only viable when the cultural values of the communities that face a particular kind of vulnerability are taken into account. We present the results from a study of a representative sample of vulnerable communities in Barranquilla, Colombia, in which various techniques of data collection were applied to identify the perception of risk and its relationship with the cultural typologies developed by Cultural Theory. We explain the causes and effects of perception and response when faced with risk in different contexts.     

Xylem vulnerability to cavitation can be accurately characterised in species with long vessels using a centrifuge method

Vulnerability to cavitation curves describe the decrease in xylem hydraulic conductivity as xylem pressure declines. Several techniques for constructing vulnerability curves use centrifugal force to induce negative xylem pressure in stem or root segments. Centrifuge vulnerability curves constructed for long‐vesselled species have been hypothesised to overestimate xylem vulnerability to cavitation due to increased vulnerability of vessels cut open at stem ends that extend to the middle or entirely through segments. We tested two key predictions of this hypothesis: (i) centrifugation induces greater embolism than dehydration in long‐vesselled species, and (ii) the proportion of open vessels changes centrifuge vulnerability curves. Centrifuge and dehydration vulnerability curves were compared for a long‐ and short‐vesselled species. The effect of open vessels was tested in four species by comparing centrifuge vulnerability curves for stems of two lengths. Centrifuge and dehydration vulnerability curves agreed well for the long‐ and short‐vesselled species. Centrifuge vulnerability curves constructed using two stem lengths were similar. Also, the distribution of embolism along the length of centrifuged stems matched the theoretical pressure profile induced by centrifugation. We conclude that vulnerability to cavitation can be accurately characterised with vulnerability curves constructed using a centrifuge technique, even in long‐vesselled species.     

基于系统保护规划的三江平原湿地保护网络体系优化

综合三江平原湿地不同层次、不同维度的生物多样性特征,在系统保护规划方法(Systematic Conservation Planning,SCP)框架下,以集水区为规划单元,计算研究区域不可替代性指数,确定高保护价值网络体系,通过保护空缺分析对现有保护网络进行优化,并评估优化体系的有效性。结果表明:三江平原湿地高保护价值区域的分布呈现沿河流分布的特点;现有保护区中湖泊和目标物种的保护状态比较好;保护网络体系优化后,沼泽湿地在保护网络中的比重由22.88%重增加到50%以上;河流湿地由16.20%增加到33.92%;地下水资源在现有保护网络中的比重非常低,仅为2.01%,优化后保护网络中保护比重增加到12.05%,因此在今后的保护区规划中,应该重视对地下水资源的保护和管理。另外本研究结合生态脆弱性对高保护价值的空缺设计3个情景方案,并根据生态威胁的种类和强度提出各优先保护方案的保护建议,为保护管理决策提供依据。     

Applying a framework for landscape planning under climate change for the conservation of biodiversity in the Finnish boreal forest

Conservation strategies are often established without consideration of the impact of climate change. However, this impact is expected to threaten species and ecosystem persistence and to have dramatic effects towards the end of the 21st century. Landscape suitability for species under climate change is determined by several interacting factors including dispersal and human land use. Designing effective conservation strategies at regional scales to improve landscape suitability requires measuring the vulnerabilities of specific regions to climate change and determining their conservation capacities. Although methods for defining vulnerability categories are available, methods for doing this in a systematic, cost‐effective way have not been identified. Here, we use an ecosystem model to define the potential resilience of the Finnish forest landscape by relating its current conservation capacity to its vulnerability to climate change. In applying this framework, we take into account the responses to climate change of a broad range of red‐listed species with different niche requirements. This framework allowed us to identify four categories in which representation in the landscape varies among three IPCC emission scenarios (B1, low; A1B, intermediate; A2, high emissions): (i) susceptible (B1 = 24.7%, A1B = 26.4%, A2 = 26.2%), the most intact forest landscapes vulnerable to climate change, requiring management for heterogeneity and resilience; (ii) resilient (B1 = 2.2%, A1B = 0.5%, A2 = 0.6%), intact areas with low vulnerability that represent potential climate refugia and require conservation capacity maintenance; (iii) resistant (B1 = 6.7%, A1B = 0.8%, A2 = 1.1%), landscapes with low current conservation capacity and low vulnerability that are suitable for restoration projects; (iv) sensitive (B1 = 66.4%, A1B = 72.3%, A2 = 72.0%), low conservation capacity landscapes that are vulnerable and for which alternative conservation measures are required depending on the intensity of climate change. Our results indicate that the Finnish landscape is likely to be dominated by a very high proportion of sensitive and susceptible forest patches, thereby increasing uncertainty for landscape managers in the choice of conservation strategies.     

Indirect validation of the Environmental Sensitive Area Index using soil degradation indicators: A country-scale approach

The Environmental Sensitivity Area Index (ESAI) is one of the most used frameworks to monitor land vulnerability to degradation in southern Europe, northern Africa and the Middle East. ESAI outputs were validated on the field at both local and regional scales, but a country or continental scale validation is still missing. Using non-parametric correlations and multivariate statistics, the present study contrasts the spatial distribution of the ESAI over 8100 local municipalities in Italy with 12 soil variables assessing individual soil attributes, soil degradation processes and the overall soil quality. Three supplementary variables assessing elevation, latitude and the urban–rural gradient have been also considered in the analysis. The ESAI correlated with both soil attributes (topsoil organic carbon) and degradation processes (soil contamination risk, landslide risk, grazing pressure and agricultural mechanization, considered a predisposing factor to soil compaction) varying in intensity along the elevation gradient. The approach illustrated provides an indirect evaluation of the reliability of the ESAI as a multi-domain indicator of land vulnerability to degradation in the Mediterranean region.     

A review of new research progress on the vulnerability of xylem embolism of woody plants

Xylem cavitation/embolism is the blockage of xylem conduits when woody plants suffer from water stress under drought and other environmental conditions, the study of embolism has become a hot and key topic under global climate change. Recent researches on the relationship between the vulnerability of xylem embolism and hydraulic architecture/drought tolerance have made some progress, however, scholars reached different conclusions based on results from different regions or different materials. This paper reviews the current achievements and controversial viewpoints, which includes indicator of xylem embolism vulnerability (P₅₀), method of vulnerability curve establishment, the relationship between embolism vulnerability and hydraulic architecture (vessel diameter, vessel length, pit area, wood density, fiber and fiber tracheid) and the relationship between embolism vulnerability and drought tolerance of woody plants. Future studies should use Cochard Cavitron centrifuge and Sperry centrifuge coupled with traditional methods to establish vulnerability curves, calculate P₅₀, analyze the difference among different organisms (root, stem, leaf), and measure physiological and ecological indexes. Future studies should be aimed to explore the relationship between the vulnerability of xylem embolism and hydraulic architecture/drought tolerance and to assess drought tolerance ability of different species under future climate change.     

Morphological and ecophysiological variation of the hybrid oak Quercus subpyrenaica (Q. faginea × Q. pubescens)

Natural hybridization is common among oaks. We studied the variability of morphological and ecophysiological variables in the hybrid Quercus subpyrenaica and its assumed parental species Q. faginea and Q. pubescens, which co-occur in NE Spain. To assess the fitness of these taxa we studied several ecophysiological variables (hydraulic conductivity, K_h; hydraulic specific conductivity, K_s; leaf specific conductivity, LSC; water potential corresponding to a 50% loss of conductivity, PLC₅₀; efficiency of light absorption, E_a). We performed a correspondence analysis (CA) to ordinate seedlings, grown under homogeneous environmental conditions, according to their plant and leaf morphology. The CA axis 1 synthesized intra-taxon variability, while the CA axis 2 summarized inter-taxa variability. Q. subpyrenaica showed a wide spectrum of forms, but they were overall closer to those of Q. faginea. We defined three phenotypes within the hybrid based on morphology, which were: (i) the robur group (Qs-r; auriculate leaf base, rounded lobe apex); (ii) Q. pubescens (Qs-p; rounded leaf base, acute lobe apex); and (iii) Q. faginea (Qs-f; acute leaf base, acute-spiny lobe apex). The mean values of K_s and PLC₅₀ arranged the hybrid groups in the same order as the ordination based on leaf morphology. The Qs-r group showed the highest values of K_s and PLC₅₀, while the Qs-f group showed the lowest. Both morphologically and ecophysiologically, the hybrids showed a wide range of values, which spanned and even exceeded the variation of parental taxa.     

Inter-species variation of photosynthetic and xylem hydraulic traits in the deciduous and evergreen Euphorbiaceae tree species from a seasonally tropical forest in south-western China

The objective of the present study was to examine the functional coordination among hydraulic traits, xylem characteristics and gas exchange rates across three deciduous Euphorbiaceae tree species (Hevea brasiliensis, Macaranga denticulata and Bischofia javanica) and three evergreen Euphorbiaceae tree species (Drypetes indica, Aleurites moluccana and Codiaeum variegatum) from a seasonally tropical forest in south-western China. The deciduous tree species were more vulnerable to water stress-induced embolism than the evergreen tree species. However, the deciduous tree species generally had higher maximal rates of sapwood and leaf-specific hydraulic conductivity (K _S and K _L), respectively. Compared with the evergreen tree species, the deciduous tree species, however, possessed a lower density of sapwood and a wider diameter of xylem vessels. Regardless of leaf phenology, the hydraulic vulnerability and conductivity were significantly correlated with sapwood density and mean vessel diameter. Furthermore, the hydraulic vulnerability was positively correlated with water transport efficiency. In addition, the deciduous tree species exhibited higher maximal photosynthetic rates (A _max) and stomatal conductance (g _max), but lower water use efficiency (WUE). Interestingly, the A _max, g _max and WUE were strongly correlated with K _S and K _L across the deciduous and evergreen tree species. These results suggest that xylem structure, rather than leaf phenology, accounts for the difference in hydraulic traits between the deciduous tree species and the evergreen tree species. Meanwhile, our results show that there is a significant trade-off between hydraulic efficiency and safety, and a strong functional correlation between the hydraulic capacity and gas exchange rates across the deciduous and evergreen tree species.     

Flattening of Caribbean coral reefs: region-wide declines in architectural complexity

Coral reefs are rich in biodiversity, in large part because their highly complex architecture provides shelter and resources for a wide range of organisms. Recent rapid declines in hard coral cover have occurred across the Caribbean region, but the concomitant consequences for reef architecture have not been quantified on a large scale to date. We provide, to our knowledge, the first region-wide analysis of changes in reef architectural complexity, using nearly 500 surveys across 200 reefs, between 1969 and 2008. The architectural complexity of Caribbean reefs has declined nonlinearly with the near disappearance of the most complex reefs over the last 40 years. The flattening of Caribbean reefs was apparent by the early 1980s, followed by a period of stasis between 1985 and 1998 and then a resumption of the decline in complexity to the present. Rates of loss are similar on shallow (<6 m), mid-water (6–20 m) and deep (>20 m) reefs and are consistent across all five subregions. The temporal pattern of declining architecture coincides with key events in recent Caribbean ecological history: the loss of structurally complex Acropora corals, the mass mortality of the grazing urchin Diadema antillarum and the 1998 El Nino Southern Oscillation-induced worldwide coral bleaching event. The consistently low estimates of current architectural complexity suggest regional-scale degradation and homogenization of reef structure. The widespread loss of architectural complexity is likely to have serious consequences for reef biodiversity, ecosystem functioning and associated environmental services.     

生态脆弱性及其研究进展

生态脆弱性已成为当前全球变化与可持续发展研究中的热点问题.有关生态脆弱性的研究,正逐渐从重点考察某单一生态要素发展到关注区域人地系统的整体性响应.当前生态脆弱性研究的内容主要包括系统变化分析、系统自身的敏感性与外部扰动的潜在影响,人地系统的适应性等.主要的研究方法有情景分析法、生态模拟法和指标评价法.目前生态脆弱性研究中存在的问题主要是情景分析与模拟的不确定性、适应性能力与社会经济发展的关系不明晰、自然因素与社会经济因素脆弱性研究相对不足等.生态脆弱性未来研究的重点是推进脆弱性研究多学科、跨尺度的融合,加强脆弱性中自然与人文因素的厘定和耦合研究,并开展基于历史变化史实的生态脆弱性实证分析.而作为脆弱性研究归宿,适应性研究不仅需要探讨能力建设和策略优化,还应深入研究适应性能力阈值与社会经济发展的关系以及国家、区域和群体之间适应性能力的总体协调与管理.最后,需要加强人地系统对极端自然灾害事件的脆弱性的研究.