Impacts of fire severity and cattle grazing on early plant dynamics in old-growth Araucaria-Nothofagus forests

Background: Fire has historically shaped the dynamics of Araucaria araucana-Nothofagus pumilio forests in the Andean region of South America. Nevertheless, human disturbances and stronger drought events have resulted in increased occurrence and severity of wildfires. Regardless of their conservation relevance, the initial response to fire of Araucaria-Nothofagus forests has not been well documented. Through this research we tested the hypothesis that plant composition of Araucaria-Nothofagus forest after fire will initially differ in its recovery depending on fire severity, but over time, plant similarity will increase among areas with different levels of fire severity. The study was carried out in old-growth Araucaria-Nothofagus forests in south-central Chile(38°S) that were burned in 2015. We studied vegetation response to three levels of fire severity(low(LS), moderate(MS) and high(HS) severity), also including an adjacent unburned forest(UN), which were assessed one, two and three years after fire. We also evaluated the impact of cattle on plant recovery after fire. We measured species richness, abundance, plant diversity and origin of all vascular plant species.Results: Species richness and plant abundance responded differently to fire severity. Time-since-fire had a significant effect on plant richness and abundance. Plant composition within LS areas was similar to UN areas, but MS and HS areas were significantly less diverse compared to UN and LS. In absence of other major disturbances, similarity in plant composition tended to increase over time across the different levels of fire severity, becoming more similar to UN. We also found a synergetic effect of cattle and fire on species richness. This interaction promotes the establishment of nonnative species and limits the recovery of native species following fire.Conclusions: Fire severity had a significant impact on the plant community of old-growth Araucaria-Nothofagus forests,especially in areas of high fire severity, where the native tree N. pumilio was completely absent. Nevertheless,plant communities can recover gradually, depending on fire severity, time-since-fire, and the absence of cattle grazing. Management actions should include the exclusion of cattle within fire-affected areas and afforestation with N. pumilio in areas high fire severity due to its unsuccessful recruitment after fire.

A cladistic scenario of Southern Pacific biogeographical history based on Nothofagus dispersal and vicariance analysis

Nothofagus is regarded as a key group for interpreting Southern Pacific biogeographical history.Based on a molecular phylogenetic tree,a quantitative dispersal-vicariance analysis(DIVA) of the genus is presented.The results indicate that the ancestral area of Nothofagus is a broad realm almost including the total extant distribution pattern of the genus rather than a so-named center of origin.Integrated with the paleogeography,the time of origin and subsequent diversification is inferred to have started in the Late Cretaceous.Most vicariance and dispersal events should be contained in that period.Vicariance events versus dispersal events play a dominant rule in speciation.The dispersal events are hypothesized to happen from the Late Cretaceous to Eocene in terms of the geological history.Rich fossils are collected in the Eocene.South America,comprising three subgenera of Nothofagus,should be considered as a diversification region,in which the distribution of the species of subgenus Fuscospora and subgenus Nothofagus are explained by dispersal events during the Late Cretaceous-Late Eocene.

Fossil nothofagaceous leaves from the Eocene of western Antarctica and their bearing on the origin, dispersal and systematics of Nothofagus

Fossil leaves resembling Nothofagaceae have been investigated from the Eocene of western Antarctica and a new form genus Nothofagofolia is proposed for these kinds of fossils. Some new specimens belonging to this form genus are described. They were collected from the Fossil Hill locality of Fildes Peninsula, King George Island, South Shetland Islands, western Antarctica. Two new species, two new combinations and an unnamed species are reported. A number of published Nothofagus leaf fossils from the same locality are discussed and revised. As a result of these studies of Nothofagus leaf morphology, we conclude that (1) Nothofagus probably originated in high latitudes of the Southern Hemisphere during the middle-late Late Cretaceous and diversified, dispersed gradually to the lower latitudes of the same hemisphere; (2) leaf morphological characters are significant for the systematics of the family Nothofagaceae, especially at the intrageneric level; and (3) extant species of Nothofagus known from southern temperate areas have more primitive leaf morphological characters and lower leaf ranks than those from tropical mountains as well as those of the Fagaceae and Betulaceae.

Potential impacts of UV exposure on lichen communities:a pilot study of Nothofagus dombeyi trunks in southernmost Chile

High-latitude terrestrial ecosystems face the triple threats of climate warming,increased exposure to UV arising from polar ozone depletion,and deforestation.Lichen communities of southernmost Chile are recognized for their high diversity,which includes nitrogen-fixing cyanolichens.Such lichens are common on forest trees,contribute nitrogen to forests,and are sensitive to exposure following deforestation(widespread in this region).In a pilot study of exposure effects on tree lichens,using nondestructive imaging methods,we compared lichen communities on trunks of isolated vs.forest tree trunks of southern Chilean beech(Nothofagus dombeyi,Nothofagaceae).We chose trees of similar diameter and trunk lean angle in conserved forest and nearby logged meadow on Navarino Island,XII Region Magallanes and Chilean Antarctica,Chile,within the annual southern ozone hole.Ninety-five percent of cyanolichen records,including Nephroma antarcticum,and 66%of records for other foliose lichens were from the forest,whereas pendulous usneoid lichens dominated N.dombeyi bark at the meadow site.Limitation of cyanolichen growth on isolated trees could affect ecosystem function in this poorly studied habitat.Possible factors contributing to strong community differences were increased light intensity,UV radiation,and wind stress,plus limited ability of lichens to colonize isolated trees in the logged meadow.UV radiation was likely an important stressor for some lichen species but not others.We recommend more extensive monitoring to pinpoint causes of differing lichen communities,and we encourage better protection of bark-dwelling lichens in southern hemisphere regions facing multiple threats.

The influence of canopy-layer composition on understory plant diversity in southern temperate forests

Background： Understory plants represents the largest component of biodiversity in most forest ecosystems and plays a key role in forest functioning.Despite their importance, the influence of overstory-layer composition on understory plant diversity is relatively poorly understood within deciduous-evergreen broadleaved mixed forests.The aim of this work was to evaluate how tree overstory-layer composition influences on understory-layer diversity in three forest types（monospecific deciduous Nothofagus pumilio（Np）, monospecific evergreen Nothofagus betuloides（Nb）, and mixed N.pumilio-N.betuloides（M） forests）, comparing also between two geographical locations（coast and mountain） to estimate differences at landscape level.Results： We recorded 46 plant species： 4 ferns, 12 monocots, and 30 dicots.Canopy-layer composition influences the herb-layer structure and diversity in two different ways： while mixed forests have greater similarity to evergreen forests in the understory structural features, deciduous and mixed were similar in terms of the specific composition of plant assemblage.Deciduous pure stands were the most diverse, meanwhile evergreen stands were least diverse.Lack of exclusive species of mixed forest could represent a transition where evergreen and deciduous communities meet and integrate.Moreover, landscape has a major influence on the structure, diversity and richness of understory vegetation of pure and mixed forests likely associated to the magnitude and frequency of natural disturbances, where mountain forest not only had highest herb-layer diversity but also more exclusive species.Conclusions： Our study suggests that mixed Nothofagus forest supports coexistence of both pure deciduous and pure evergreen understory plant species and different assemblages in coastal and mountain sites.Maintaining the mixture of canopy patch types within mixed stands will be important for conserving the natural patterns of understory plant composition in southern beech mixed forests.

Preliminary study on the spore-pollen assemblages found in the Cenozoic sedimentary rocks in Grove Mountains,east Antarctica and its climatic implications

Glaciogene sedimentary rocks have been found in modem tills of the Grove Mountains, east Antarctica during the 1998 - 1999 Chinese National Antarctic Research Expedition （CHNARE）. Based on the lithilogic and sedimentary features, these sedimentary rocks are correlated with Cenozoic sedimentary strata of the Pagodroma Group in the neighboring Prince Charles Mountains and the Sorsdal Formation in VestFold Hills. Sedimentary clasts contain sparsely Late Tertiary spores and pollens, including ： Toroisporis （ Lygodiaceae）, Osmunda, Granulatisporites （ Pteridaceae？） , Polypodiaceae, Podocarpus , Araucariaceae, Artemisia , Rhus , Nothofagidites , Proteacidites （Proteaceae） , Quercus , Fraxinoipollenites （ Oleaceae ） , Oleoidearumpollenites（ Oleaceae ）, Operculumpollis, and Tricolpopollenites. Most of the pollen and spores contained in these samples originate from local sources according to the conditions of their preservations as well as correlations with the microfossil assemblages found in the neighboring areas. The majority of the pollen assemblages, as represented by Podocarpus and Nothofagus, belong to the Weddellian biogeocenose, however some exotic components from the old sedimentary basement rocks may have been included during erosion of the proximal ice sheet. If the source areas of glaciogenic sedimentary rocks that bear the pollen and spores are assumed to be local, or in the up glacier areas, the pollen assemblages in these samples might represent an inland flora during a warmer period of the ice-sheet evolutionary history. The finding of the Artemisia and Chenopodiaceae in the pollen assemblages implies that they may belong to late Tertiary （most probably Pliocene）. The absence of diatoms in the samples analyzed may indicate that there are no Cenozoic marine strata in the interior of the east Antarctica beyond the Grove Mountains. The significances of the finding of the Nothofagus in these pollen assemblages are discussed on the basis of current knowledge about the age, distribution and ecological conditions of this kind of fossils found in Sirius Group or other strata outcropped in Antarctica. As a preliminary conclusion, we think that the existence of the Cenozoic glaciogenenic rocks and their pollen assemblages present new evidence for a large scale glacial retreat history in Grove Mountains of east Antarctica, and thus support a dynamic East Antarctic Ice Sheet （EAIS）. This is consistent with the interpretations of Webb et al. （1984）.

Analysing changes in spatial point patterns:A proposal using data from a forest thinning experiment

Spatial patterns reveal critical features at the individual and community levels.However,how to evaluate changes in spatial characteristics remains largely unexplored.We assess spatial changes in spatial point patterns by augmenting current statistical functions and indices.We fitted functions to describe unmarked and marked(tree size)spatial patterns using data from a large-scale silvicultural experiment in southern Chile.Furthermore,we compute the mingling index to represent spatial tree diversity.We proffer the pair correlation function difference before and after treatment to detect changes in the unmarked-point pattern of trees and the semivariogram-ratio to evaluate changes in the marked-point pattern.Our research provides a quantitative assessment of a critical aspect of forest heterogeneity:changes in spatial unmarked and marked-point patterns.The proposed approach can be a powerful tool for quantifying the impacts of disturbances and silvicultural treatments on spatial patterns in forest ecosystems.

西南极始新世假山毛榉叶化石新材料——兼论该属的起源、分类及其传播路线

从叶形态学角度,为假山毛榉科(Nothofagaceae)的建立提供了证据.讨论与假山毛榉属的叶相似的印痕化石命名问题,并为这类化石建立了一个形态属——Nothofagofolia gen.nov.描述西南极南设得兰群岛乔治王岛费尔得斯半岛化石山新采集的这类叶化石中的新代表,报道2个新种,2个新组合,1个未定种;讨论和修订了已发表的这个产地的假山毛榉属叶化石.通过叶形态学研究,对假山毛榉属的分类、演化等提出下列看法:(1)支持该属在晚白垩世中晚期起源于南半球高纬度地区,并在那里分化、发展,向低纬度扩散的观点;(2)支持假山毛榉科的建立,并认为叶形态学特征对此科科下等级的分类将具有一定的意义;(3)该属南温带分布的种,具有更为原始的叶形态性状,叶等级低,与其热带山区分布的种以及壳斗科和桦木科等相比,处于更为原始的地位.

Modeling of potential habitat suitability of Hippocamelus bisulcus: effectiveness of a protected areas network in Southern Patagonia

Introduction:Huemul(Hippocamelus bisulcus Molina)is the most threatened flag species of Southern Patagonia,where conservation efforts were not effective to avoid the retraction of its distribution area.Habitat quality modeling can assist to design better management strategies for regional conservation planning.The objective was to elaborate one habitat suitability map for huemul,defining the environmental characteristics at landscape level,and determining the distribution of the suitable habitat inside the current natural reserve network.Methods:We used a database of 453 records and explored 40 potential explanatory variables(climate,topographic,and landscape variables including human-related ones)to develop one habitat suitability map using the Environmental Niche Factor Analysis(ENFA)for Santa Cruz province(Argentina).We combined the outputs in a GIS project using different shapes,including the current natural reserve network.Results:We defined the potential habitat for huemul,where forest edges and ecotone zones(e.g.,mainly alpine environments)were the most important environmental variables,as well as some forest types(e.g.,Nothofagus pumilio).Habitat losses were found in the extreme potential distribution areas(northern and southern areas),probably related to the increasing ranch activities.The current natural reserve network maintains approximately half of the huemul potential habitat in Santa Cruz province,where National Parks presented the similar conservation importance than the Provincial natural reserves.Conclusions:Habitat suitability model for huemul can be used as a decision support system for new management strategies at different landscape levels to improve the current conservation efforts.