The response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change

A reconstruction of past environmental change from Ecuador reveals the response of lower montane forest on the Andean flank in western Amazonia to glacial-interglacial global climate change. Radiometric dating of volcanic ash indicates that deposition occurred ~324,000 to 193,000 years ago during parts of Marine Isotope Stages 9, 7, and 6. Fossil pollen and wood preserved within organic sediments suggest that the composition of the forest altered radically in response to glacial-interglacial climate change. The presence of Podocarpus macrofossils ~1000 meters below the lower limit of their modern distribution indicates a relative cooling of at least 5°C during glacials and persistence of wet conditions. Interglacial deposits contain thermophilic palms suggesting warm and wet climates. Hence, global temperature change can radically alter vegetation communities and biodiversity in this region.     

Comment on "The response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change"

Cárdenas et al. (Reports, 25 February 2011, p. 1055) used the presence of Podocarpus pollen and wood to infer ≥5°C cooling of Andean forests during Quaternary glacial periods. We show that (i) Podocarpus has a wide elevation range in the Neotropics, and (ii) edaphic factors cannot be discounted as a factor governing its distribution. Paleoecologists should therefore reevaluate Podocarpus as a cool-temperature proxy.     

风景园林应对气候变化的创新路径

当前气候变化导致的自然灾害增加以及国家碳达峰碳中和目标为风景园林发展带来了历史机遇,但风景园林在我国气候变化应对中的话语权仍显不足。为提升风景园林在应对气候变化中的学科地位,厘清风景园林在气候变化应对领域的责任和担当,探索风景园林气候设计的创新路径,本研究在综合分析国内外气候变化应对相关文献和政策措施的基础上,从气候变化的减缓和适应两个方面,考察了风景园林能够做出重要贡献的领域。结果显示,风景园林应该面向气候变化适应、灾害治理、碳达峰碳中和等国家需求,加强多学科的交叉融合,一方面通过气候积极性设计在城乡人居环境中固碳增汇、降低碳排放,另一方面通过景观规划设计适应气候变化,降低灾害风险,增强城乡韧性。风景园林气候设计的创新路径包括：标准化定向、空间化定量转向、生态完整性取向、多尺度面向以及教学改革创新。从以上结果可以看出,风景园林在应对气候变化中大有可为,气候设计的创新探索可推动风景园林学科范式转型和创新发展,并为应对气候变化提供中国方案。     

48,000 years of climate and forest change in a biodiversity hot spot

A continuous 48,000-year-long paleoecological record from Neotropical lower montane forest reveals a consistent forest presence and an ice-age cooling of approximately 5 degrees to 9 degrees C. After 30,000 years of compositional stability, a steady turnover of species marks the 8000-year-long transition from ice-age to Holocene conditions. Although the changes were directional, the rates of community change were no different during this transitional period than in the preceding 30,000-year period of community stability. The warming rate of about 1 degrees C per millennium during the Pleistocene-Holocene transition was an order of magnitude less than the projected changes for the 21st century.     

风景园林应对气候变化的实践与气候积极性设计方法

风景园林通过协调人与自然的关系,可以减缓和适应气候变化的负面影响。为构建风景园林应对气候变化的方法体系,提升风景园林应对气候变化能力,进一步发挥风景园林在减少碳排放、提升生物多样性、缓解极端高温天气、培育具有复原力的社区等功能。本文在梳理国内外风景园林应对气候变化的理念和实践基础上,归纳出当前存在的三点不足：对气候变化复杂性认知不足、应对气候变化的理论与实践结合不够、实施保障机制欠缺。研究系统阐述了风景园林气候积极性设计的概念、特点、流程和方法及实施机制等,并构建风景园林气候积极性设计方法和技术体系。结果表明,针对气候变化的复杂影响,风景园林气候积极性设计应采取多策略组合应对和多目标协同的方法,构建相应的价值取向和实施机制,通过多方案比选和优中选优,以取得最为理想的实施效果,更好地发挥风景园林功能,进而促进风景园林学科发展。     

Human evolution out of Africa: the role of refugia and climate change

Although an African origin of the modern human species is generally accepted, the evolutionary processes involved in the speciation, geographical spread, and eventual extinction of archaic humans outside of Africa are much debated. An additional complexity has been the recent evidence of limited interbreeding between modern humans and the Neandertals and Denisovans. Modern human migrations and interactions began during the buildup to the Last Glacial Maximum, starting about 100,000 years ago. By examining the history of other organisms through glacial cycles, valuable models for evolutionary biogeography can be formulated. According to one such model, the adoption of a new refugium by a subgroup of a species may lead to important evolutionary changes.     

Climate change, keystone predation, and biodiversity loss

Climate change can affect organisms both directly via physiological stress and indirectly via changing relationships among species. However, we do not fully understand how changing interspecific relationships contribute to community- and ecosystem-level responses to environmental forcing. I used experiments and spatial and temporal comparisons to demonstrate that warming substantially reduces predator-free space on rocky shores. The vertical extent of mussel beds decreased by 51% in 52 years, and reproductive populations of mussels disappeared at several sites. Prey species were able to occupy a hot, extralimital site if predation pressure was experimentally reduced, and local species richness more than doubled as a result. These results suggest that anthropogenic climate change can alter interspecific interactions and produce unexpected changes in species distributions, community structure, and diversity.     

Impacts of biodiversity loss escalate through time as redundancy fades

Plant diversity generally promotes biomass production, but how the shape of the response curve changes with time remains unclear. This is a critical knowledge gap because the shape of this relationship indicates the extent to which loss of the first few species will influence biomass production. Using two long-term (≥13 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments.     

Forests and climate change: forcings, feedbacks, and the climate benefits of forests

The world's forests influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition. These complex and nonlinear forest-atmosphere interactions can dampen or amplify anthropogenic climate change. Tropical, temperate, and boreal reforestation and afforestation attenuate global warming through carbon sequestration. Biogeophysical feedbacks can enhance or diminish this negative climate forcing. Tropical forests mitigate warming through evaporative cooling, but the low albedo of boreal forests is a positive climate forcing. The evaporative effect of temperate forests is unclear. The net climate forcing from these and other processes is not known. Forests are under tremendous pressure from global change. Interdisciplinary science that integrates knowledge of the many interacting climate services of forests with the impacts of global change is necessary to identify and understand as yet unexplored feedbacks in the Earth system and the potential of forests to mitigate climate change.     

Beyond predictions: biodiversity conservation in a changing climate

Climate change is predicted to become a major threat to biodiversity in the 21st century, but accurate predictions and effective solutions have proved difficult to formulate. Alarming predictions have come from a rather narrow methodological base, but a new, integrated science of climate-change biodiversity assessment is emerging, based on multiple sources and approaches. Drawing on evidence from paleoecological observations, recent phenological and microevolutionary responses, experiments, and computational models, we review the insights that different approaches bring to anticipating and managing the biodiversity consequences of climate change, including the extent of species' natural resilience. We introduce a framework that uses information from different sources to identify vulnerability and to support the design of conservation responses. Although much of the information reviewed is on species, our framework and conclusions are also applicable to ecosystems, habitats, ecological communities, and genetic diversity, whether terrestrial, marine, or fresh water.     

Phanerozoic Earth system evolution and marine biodiversity

The Phanerozoic fossil record of marine animal diversity covaries with the amount of marine sedimentary rock. The extent to which this covariation reflects a geologically controlled sampling bias remains unknown. We show that Phanerozoic records of seawater chemistry and continental flooding contain information on the diversity of marine animals that is independent of sedimentary rock quantity and sampling. Interrelationships among variables suggest long-term interactions among continental flooding, sulfur and carbon cycling, and macroevolution. Thus, mutual responses to interacting Earth systems, not sampling biases, explain much of the observed covariation between Phanerozoic patterns of sedimentation and fossil biodiversity. Linkages between biodiversity and environmental records likely reflect complex biotic responses to changing ocean redox conditions and long-term sea-level fluctuations driven by plate tectonics.     

可可西里1970-2013年气候变化特征及其对景观格局的影响

气候变化对青藏高原景观产生的影响越来越强烈,本文使用1990、2000和2013年3期遥感影像资料,选取具有代表性的6个景观类型,通过ArcGIS 10.0和ERDAS 9.2软件进行数据处理,研究了可可西里国家级自然保护区景观格局变化特征;结合当地1970—2013年气象数据,分析该区气候变化特征及其对景观格局的影响。结果表明:44年间可可西里保护区的降水量以20.3 mm/10年的速率显著上升,年平均温度以0.38 ℃/10年的速率上升,从2000年开始,该区降水量和年平均温度均出现较大幅度增长;但44年间的潜在蒸散量和相对湿度没有明显的趋势性变化。该区冰川和永久积雪、水域、高寒草甸和高寒草原景观格局变化的主要驱动因子分别为年平均温度、降水量、潜在蒸散量和相对湿度。冰川和永久积雪、水域、沼泽湿地景观的变化体现在连续11年间的气候累积效应与该区域气候的波动周期一致;而高寒草甸和高寒草原则受到短时间(2~5年)气候变化的影响,说明可可西里植被的脆弱性。气候变化对可可西里的景观分布具有重要影响。