Response of subarctic vegetation to transient climatic change on the Seward Peninsula in north-west Alaska

Understanding the response of terrestrial ecosystems to climatic warming is a challenge because of the complex interactions of climate, disturbance, and recruitment across the landscape. We use a spatially explicit model (ALFRESCO) to simulate the transient response of subarctic vegetation to climatic warming on the Seward Peninsula (80 000 km²) in north‐west Alaska. Model calibration efforts showed that fire ignition was less sensitive than fire spread to regional climate (temperature and precipitation). In the model simulations a warming climate led to slightly more fires and much larger fires and expansion of forest into previously treeless tundra. Vegetation and fire regime continued to change for centuries after cessation of the simulated climate warming. Flammability increased rapidly in direct response to climate warming and more gradually in response to climate‐induced vegetation change. In the simulations warming caused as much as a 228% increase in the total area burned per decade, leading to an increasingly early successional and more homogenous deciduous forest‐dominated landscape. A single transient 40‐y drought led to the development of a novel grassland–steppe ecosystem that persisted indefinitely and caused permanent increases in fires in both the grassland and adjacent vegetation. These simulated changes in vegetation and disturbance dynamics under a warming climate have important implications for regional carbon budgets and biotic feedbacks to regional climate.     

The flora of Japan and the implication of global climatic change

The influence of climate change induced by increasing atmospheric CO₂ on the flora and vegetation of Japan is discussed. Nineteen small sized restricted plant-communities are evaluated as communities with a considerable number of species threatened under present scenarios of global climate change.     

植物物候对气候变化的响应

植物物候的变化可以直观地反映某些气候变化,尤其是气候变暖.植物生长节律的变化引起植物与环境关系的改变.生态系统的物质循环（如水和碳的循环）等过程将随物候而改变.不同种类植物物候对气候变化的响应的差异,会使植物间和动植物间的竞争与依赖关系也发生深刻的变化.目前欧洲、美洲、亚洲等许多地区均有关于春季植物物候提前,秋季物候推迟,使植物的生长季延长,从而提示气候变暖的趋势.植物物候的模拟模型构成生态系统生产力模型的重要部分.     

Alien flora of the Korean Peninsula

The Korean Peninsula has been divided into the countries of North and South Korea since 1948. This adoption of different political and socio-economic regimes has significantly changed economic activity and international exchange by those nations, thus affecting the introduction of alien plants. Our study objective was to provide a comprehensive, up-to-date inventory of the alien flora on the Korean Peninsula and to analyse how the partitioning between North and South Korea has influenced the numbers and status of those alien plants. We identified pre-1876 aliens that were brought to the Korean Peninsula before 1876, when Korea opened up to foreign countries, and also determined the post-1876 aliens that were introduced after 1876. Plants in the latter group were further classified into those that arrived before the outbreak of the Korean War in 1950 (1876–1950 aliens) and those introduced since then (post-1950 aliens). We investigated the regions of origin, family compositions, and invasion status of those alien taxa. In total, 504 alien taxa were identified, with 102 taxa being pre-1876 and 117 being 1876–1950 aliens. After the Korean War, the number of alien plants in South Korea more than doubled (276 taxa), whereas the number reported for North Korea was considerably lower (33 taxa). This might be due to enhanced economic activity and a larger human population in South Korea. Climatic differences as well as variations in the recording intensity for alien flora between North and South Korea may also have contributed to the large contrast in numbers of new alien species recorded during the last decades. Coordinated measures between the two nations are necessary if the spread of invasive alien plants onto the Korean Peninsula is to be reduced.     

Phosphate absorption and root respiration of different plant growth forms from northern Alaska

Rate of phosphate absorption measured on field-collected, excised roots of eight species from a tundra site and a taiga forest was more strongly correlated with growth form traits than with type of community. In the taiga forest phosphate absorption rate ranged tenfold among species and was higher in graminoids than in shrubs. In both sites deciduous shrubs tended to have higher rates than evergreens. Phosphate absorption rate was not strongly reduced at low temperature in any species examined and there was a temperature optimum of about 20°C in Eriophorum vaginatum . Phosphate absorption rates were higher in lateral than primary roots, although both root types had substantial respiration rates. At one tundra site, calculations suggest that roots of E. vaginatum require 30–40 d to absorb a quantity of phosphorus equivalent to that required to synthesize the root and another 5–6 d to provide the net phosphorus requirements for the remainder of the plant.     

Reproduction of the common buzzard at its northern range margin under climatic change

A changing climate induces shifts in the location of biomes. Tracing such a shift may pose problems for life history traits adapted to the prior conditions, so that, e.g. the timing of reproduction and the time with sufficient resources for rearing hatchlings do not match. We show that the timing of breeding of Finnish common buzzards Buteo buteo , has advanced with over ten days as a response to the warming of early spring, during 1979–2004. During the same period the isoclines of the onset of breeding have moved about 200 km to the north-east. However, the reproductive performance of the common buzzard has not increased as a response to these changes. Despite increasing temperatures during early spring, the temperatures of early summer have remained the same since the 1970s. Combined, the early onset of breeding and the unchanged temperatures of early summer have lead to decreased post-hatching temperatures. Under these circumstances, common buzzard offspring now face a higher risk to hatch into less favourable weather conditions than three decades ago. Furthermore, summer precipitation, harmful for nestlings, has been predicted to increase in the future, thus possibly further worsening the circumstances for breeding common buzzards. Our results demonstrate that even if common buzzards in Finland breed at the northern limit of the species' distribution, and could therefore be expected to gain advantage from a warming climate, the opposite is the case.     

Extreme climatic events change the dynamics and invasibility of semi-arid annual plant communities

Extreme climatic events represent disturbances that change the availability of resources. We studied their effects on annual plant assemblages in a semi-arid ecosystem in north-central Chile. We analysed 130 years of precipitation data using generalised extreme-value distribution to determine extreme events, and multivariate techniques to analyse 20 years of plant cover data of 34 native and 11 exotic species. Extreme drought resets the dynamics of the system and renders it susceptible to invasion. On the other hand, by favouring native annuals, moderately wet events change species composition and allow the community to be resilient to extreme drought. The probability of extreme drought has doubled over the last 50 years. Therefore, investigations on the interaction of climate change and biological invasions are relevant to determine the potential for future effects on the dynamics of semi-arid annual plant communities.     

The role of land bridges,ancient environments,and migrations in the assembly of the North American flora

Continental‐scale assembly of floras results from past and present in situ diversification in association with several external processes. Among these processes are the making and breaking of connections among landmasses. Connections among landmasses are constantly in flux as are the climates and landscapes along the connection corridors, so that these corridors, or land bridges, may either facilitate or restrict migration at a given time. Across land bridges, changing landscape‐level and organismal factors include the dispersal potential and vectors of propagules, competition, predation, and distributions altered by pathogens. Assembly of a flora is, therefore, the outcome of complex, interacting, temporally‐varying factors that render simplistic explanations unlikely. In the case of North America, the continent experienced ephemeral connections with adjacent regions via five land bridges over the last 100 Ma at different times and under different climates and specific landscape morphologies, including edaphic characteristics. Here, I emphasize the earliest of these connections, Beringia, which probably comprised an initially‐incomplete land bridge during the Cretaceous and Paleocene resulting from compression, fragmentation, and rotation of Asian‐North American sub‐blocks as North America began moving westward from the northern portion of the Mid‐Atlantic Ridge. During the same time, additional land was added to Beringia with accretion of terranes and the subduction of the northern edge of the Pacific Plate beneath the North American‐Asian Plates in the Eocene to form the Aleutian Islands. Other connections between North America and adjacent landmasses were the North Atlantic, the Antilles, Central America, and the Magellan land bridge.     

South from Alaska: a pilot aDNA study of genetic history on the Alaska Peninsula and the eastern Aleutians

The Aleutian Islands were colonized, perhaps several times, from the Alaskan mainland. Earlier work documented transitions in the relative frequencies of mtDNA haplogroups over time, but little is known about potential source populations for prehistoric Aleut migrants. As part of a pilot investigation, we sequenced the mtDNA first hypervariable region (HVRI) in samples from two archaeological sites on the Alaska Peninsula (the Hot Springs site near Port Moller, Alaska; and samples from a cluster of sites in the Brooks River area near Katmai National Park and Preserve) and one site from Prince William Sound (Mink Island). The sequences revealed not only the mtDNA haplogroups typically found in both ancient and modern Aleut populations (A2 and D2) but also haplogroups B2 and D1 in the Brooks River samples and haplogroup D3 in one Mink Islander. These preliminary results suggest greater mtDNA diversity in prehistoric populations than previously observed and facilitate reconstruction of migration scenarios from the peninsula into the Aleutian archipelago in the past.     

雷州半岛的红树林植物组成与群落生态

综述了前人对雷州半岛的红树林的研究;根据作者的调查研究报道了雷州半岛的红树林面积、树种组成、群落类型与结构。     

Assessing the response of plant functional types to climatic change in tropical forests

Abstract. We propose and test a classification of plant functional types for tropical trees based on demography, growth form, phenology, and moisture requirements, using data from a 50-ha forest dynamics plot in Panama. Correlations among demographic variables for individual species - mortality, growth, and the tendency to colonize light gaps - were strong, and a single principal component (PC) accounted for a large fraction of the demographic variability. Most species - shade-tolerants - were clustered at the low end of the PC axis (low growth, low mortality), while the rest were continuously distributed over a wide range. Three demographic guilds could be defined from scores on this axis: we call these pioneer, building phase, and shade-tolerant trees, following earlier terminology. Leaf lifetime correlated negatively with the demographic axis, and there was a weak relationship between demography and moisture-preference: no species with high demographic scores also had high moisture requirements. There was no significant relationship between deciduousness and the demographic axis, but deciduousness was negatively correlated with leaf lifetime and moisture index. Altogether, 11 different combinations of demographic variables, deciduousness, moisture needs, and growth form (canopy vs. understory species) were identified. We evaluated how these functional types changed in abundance between 1982 and 1995. Because of a recent run of dry years and long dry seasons, we predicted that deciduous species, canopy species, pioneers, and drought-tolerant species would be increasing at the expense of their counterparts. Only one aspect of this prediction was borne out: moisture- demanding species declined sharply in abundance relative to drought-tolerant species. Neither deciduousness nor growth form was associated with population change, and pioneer species declined in abundance more often than shade-tolerants. The overall structure of the forest - the density of deciduous, pioneer, and understory species - did not change much, but the decline of the moisture-demanding guild indicates that a change in composition is preceding a structural change.     

An 18 million year record of vegetation and climate change in northwestern Canada and Alaska: tectonic and global climatic correlates

We reconstruct long-term vegetation/paleoclimatic trends, spanning the last 18 million years, in Alaska, Yukon and far western Northwest Territories. Twenty-one average percentage spectra for pollen and spores are assembled from eight surface/subsurface sections. The sections are dated independently or by correlation. Pollen and spore ratios indicate the direction of change in vegetation and climatic parameters — growing season temperature (T_est), tree canopy density (C_est) and paludification at study sites (P_est). A global warm peak ca. 15 Ma is shown by the abundance of thermophilous taxa, including Fagus and Quercus. A temperature decline immediately following 15 Ma parallels climatic reconstructions based on marine oxygen isotopes. Subsequent declines correlate to the Messinian event and the onset of late Pliocene-Pleistocene glaciation. After 7 Ma herbs and shrubs become more important elements of the palynological assemblages, suggesting a more continental, colder/drier climate. However, a late Pliocene warm interval is evident. Vegetation/climatic changes during the early to late Miocene show synchrony with, and are most economically attributable to, global events. After 7 Ma, vegetation/climate change is attributed primarily to latest Miocene-to-Pleistocene uplift of the Alaska Range and St. Elias Mts. The continuing influence of global climatic patterns is shown in the late Pliocene warm interval, despite uplift to the south. The opening of the Bering Strait ca. 3 Ma may have moderated the climate in the study area.     

浙北安吉龙王山维管植物区系分析

浙江北部安吉龙王山共有维管植物１３０８种、６亚种、８１变种。区系成分以温带属为主,占６０３０％;种在国内以长江以南的分布类型为主,占５２２３％。从区系成分、优势科属、生活型等方面看,龙王山维管植物区系与天目山、黄山有密切联系。首次记录了睫毛蕨科（Ｐｌｅｕｒｏｓｏｒｉｏｐｓｉｄａｃｅａｅ）在浙江分布。文中还就华中植物区系通过大别山向华东迁移以及区系研究中若干问题进行了讨论。     

The effects of climatic pattern on lichen productivity: Cetraria cucullata (Bell.) Ach. in the arctic tundra of northern Alaska

Summary The climatic control of productivity for two populations of the lichen Cetraria cucullata (Bell.) Ach. growing in the arctic tundra of northern Alaska (70°28N, 157°23W) was examined. Respiratory losses of carbon vary with tissue temperature, tissue water content, and time since wetting. Potential net photosynthetic gains of carbon are affected by photon flux density, tissue temperature, and water content. The net CO₂ exchange responses of populations growing on ridge tundra and on upland tundra differ and these differences reflect possible adaptation to the normal environmental regimes in the two habitats. Simulation of the lichen's net carbon balance using continuous hourly records of photon flux density, temperature, and water content for the unusually dry period June 28 through July 17, 1977 show that lichen biomass is actually lost during climatic regimes leading to frequent but short periods of lichen metabolic activity. This result is confirmed by the negative relative growth rates measured for C. cucullata over the same monitoring period. This observed loss of biomass may be attributable to depletion of carbon reserves to reactivate dormant metabolism without sufficiently long periods favorable for net photosynthetic activity to replenish the lost reserves. These results illustrate that environmental limits exist on the success of the dormancy strategy characteristic of lichen and moss carbon metabolism.     

A phylogenetically-informed trait-based analysis of range change in the vascular plant flora of Britain

Species distributions are changing, and knowing whether certain character traits predispose species to decline or increase during times of environmental change can shed light on the main drivers of distribution change. Here we conduct a trait-based analysis of range change in the flora of Britain since the 1930s using some of the best plant distribution and trait data available in Europe. We use phylogenetically-informed models based on a recently published, dated, species level plant phylogeny. Traits associated with habitat specialism and competitive ability were related to range change, with more competitive habitat generalists faring better than habitat specialists. We attribute this result to the greater ability of generalists to adapt to environmental perturbation, but also to the negative impacts of agricultural intensification on the flora of Britain, in particular the loss of open, dry habitats. We discovered spatial variation in the main drivers of plant range change and find support for previous evidence that agricultural intensification has been a major driver of distribution change in the flora of Britain over the past 70 years, particularly in southern England.