Passive Restoration of Atlantic Forest Following Pinus taeda Harvesting in Southern Brazil

The understory of exotic tree plantations can have non‐negligible native species richness. Ecological restoration of these sites may include the harvest of trees, depending on the tradeoff between timber income and harvest impacts on biodiversity. This study aimed to investigate how a site can recover from harvest disturbance, by comparing the regeneration of woody species in the understory of two types of 37‐year‐old Pinus taeda plantation (P1 and P2, high and low relative density of pine seedlings in the understory, respectively), with stands that were similar to P2 but subjected to harvest and then abandoned for 15 years (R sites). Secondary forests (SF) were used as references. We sampled three different sites for each stand condition; soil chemical properties, estimations of litter mass, and canopy cover were measured. P1 had low species diversity, and P2 and R had 50 and 46% of SF richness, respectively. The R site contained few pine saplings and was floristically similar to P2; this indicated that 15 years was sufficient for the recovery of plant diversity to near pre‐harvesting levels. Soil fertility was highest in SF and lowest in P1. Thus old plantations of P. taeda with low relative density of pine juveniles can be cost‐effective starting points for restoration. Despite the destructive effects of pine harvest, recovery of native species can occur rapidly. In situations in which clearcutting of pine stands is not planned or possible, modest thinning of P. taeda adults and/or intensive thinning of juveniles could expedite restoration.     

Selecting Species for Passive and Active Riparian Restoration in Southern Mexico

In revegetation projects, distinguishing species that can be passively restored by natural regeneration from those requiring active restoration is not a trivial decision. We quantified tree species dominance (measured by an importance value index, IVI_i) and used abundance–size correlations to select those species suitable for passive and/or active restoration of disturbed riparian vegetation in the Lacandonia region, Southern Mexico. We sampled riparian vegetation in a 50 × 10–m transect in each of six reference (RE) and five disturbed (DE) riparian ecosystems. Those species representing more than 50% of total IVI in each ecosystem were selected, and Spearman rank correlation between abundance and diameter classes was calculated. For eight species, it was determined that passive restoration could be sufficient for their establishment. Another eight species could be transplanted by means of active restoration. Five species regenerate well in only one ecosystem type, suggesting that both restoration strategies could be used depending on the degree of degradation. Finally, two species were determined to not be suitable for restoration in the RE (based on the above selection criteria) and were not selected during this initial stage of our restoration project. The high number of tree species found in the RE suggests that the species pool for ecological restoration is large. However, sampling in both ecosystem types helped us reduce the number of species that requires active restoration. Restoration objectives must guide the selection of which methods to implement; in different conditions, other criteria such as dispersal syndrome or social value could be considered in the species selection.     

Natural history predicts patterns of thermal vulnerability in amphibians from the Atlantic Rainforest of Brazil

In the Brazilian Atlantic Rainforest (AF), amphibians (625 species) face habitat degradation leading to stressful thermal conditions that constrain animal activity (e.g., foraging and reproduction). Data on thermal ecology for these species are still scarce. We tested the hypothesis that environmental occupation affects the thermal tolerance of amphibian species more than their phylogenetic relationships. We evaluated patterns of thermal tolerance of 47 amphibian species by assessing critical thermal maxima and warming tolerances, relating these variables with ecological covariates (e.g., adult macro‐ and microhabitat and site of larval development). We used mean and maximum environmental temperature, ecological covariates, and morphological measurements in the phylogenetic generalized least squares model selection to evaluate which traits better predict thermal tolerance. We did not recover phylogenetic signal under a Brownian model; our results point to a strong association between critical thermal maxima and habitat and development site. Forest species were less tolerant to warm temperatures than open area or generalist species. Species with larvae that develop in lentic environment were more tolerant than those in lotic ones. Thus, species inhabiting forest microclimates are more vulnerable to the synergistic effect of habitat loss and climate change. We use radar charts as a quick evaluation tool for thermal risk diagnoses using aspects of natural history as axes.     

Effects of a Severe Frost on Riparian Rainforest Restoration in the Australian Wet Tropics: Foliage Retention by Species and the Role of Forest Shelter

Restoration of ecological communities that can withstand future climate and land use changes requires information on species responses to various natural disturbances. Frost is an important disturbance that regulates plant species distributions, and although rare in tropical rainforest, it can occur in upland areas, especially where deforestation has occurred. We report the impacts of a severe frost that occurred in June and July 2007 on the Atherton Tablelands, Queensland, Australia and caused extensive damage to riparian restoration plots of upland rainforest species. We estimated proportion foliage retention to (1) compare impacts across 45 species; (2) examine the influence of plant height on frost effects; and (3) determine if plantings under shelterbelts of mature trees received less damage. Species exhibited different levels of foliage retention. Species that were particularly frost resistant included those from riparian habitats and a conifer. Some heavily impacted species are deciduous and may survive frost by shedding leaves; this warrants further investigation. Plant canopy height above ground level was only weakly correlated to foliage retention. Sheltered plants were much less damaged than unsheltered conspecifics, suggesting a useful way to mitigate frost impacts. These principles should help guide the development of resilient ecological communities in frost‐prone areas.     

西双版纳热带雨林下砂仁拔除后的生态恢复

 种植砂仁（Amomum villosum）对西双版纳热带雨林植物多样性的影响引起了人们的关注。通过西双版纳热带雨林下种植的砂仁拔除后的生态恢复两年的研究工作,结果表明砂仁排除后：1）林下植物数量显著增加,超过同等类型的没种过砂仁的原始热带雨林;植物种类、物种多样性和均匀度都有大幅度增加,与原始热带雨林差别不大;群落组成成分仍向着热带雨林演替,优势种不明显,其中,草本和蕨类植物增加显著;2）林下植物生长速率在旱季与原始林差别不大,但在雨季可有较快生长;生物量在两年内可达到(636.1±43.4) g·m-2,超过原始林,特别是草本和蕨类植物生长较快;3）土壤含水量得到提高,与原始林相比差异不显著,并且,涵养水源的能力有所增加;深层土壤有机质的含量增加显著,速效磷含量需要更长时间的植被恢复才能有所提高,速效钾受淋洗作用的影响,地表有大量损失。文中最后讨论指出,热带林下砂仁实现斑块式的轮歇种植是协调保护与发展的较好方法,这在偏远少数民族地区有着较好的可行性。     

Principles of Natural Regeneration of Tropical Dry Forests for Restoration

Tropical dry forests are the most threatened tropical terrestrial ecosystem. However, few studies have been conducted on the natural regeneration necessary to restore these forests. We reviewed the ecology of regeneration of tropical dry forests as a tool to restore disturbed lands. Dry forests are characterized by a relatively high number of tree species with small, dry, wind‐dispersed seeds. Over small scales, wind‐dispersed seeds are better able to colonize degraded areas than vertebrate‐dispersed plants. Small seeds and those with low water content are less susceptible to desiccation, which is a major barrier for establishment in open areas. Seeds are available in the soil in the early rainy season to maximize the time to grow. However, highly variable precipitation and frequent dry spells are important sources of mortality in seeds and seedlings. Collecting seeds at the end of the dry season and planting them when soil has sufficient moisture may increase seedling establishment and reduce the time they are exposed to seed predators. Germination and early establishment in the field are favored in shaded sites, which have milder environment and moister soil than open sites during low rainfall periods. Growth of established seedlings, however, is favored in open areas. Therefore, clipping plants around established seedlings may be a good management option to improve growth and survival. Although dry forests have species either resistant to fire or that benefit from it, frequent fires simplify community species composition. Resprouting ability is a noticeable mechanism of regeneration in dry forests and must be considered for restoration. The approach to dry‐forest restoration should be tailored to this ecosystem instead of merely following approaches developed for moister forests.     

Factors influencing the habitat use by ocelots in one of the last large Atlantic Forest remnants in southeastern Brazil

Ocelots (Leopardus pardalis) are widely distributed throughout the Americas, being dependent on forested areas to survive. Although ocelot ecology is broadly studied throughout the species range distribution, studies concerning factors that may affect ocelot occupancy in the Atlantic Forest are still scarce. We used camera traps to evaluate factors influencing the probabilities of detection and occupancy of ocelots in a protected area of the Atlantic Forest, the Rio Doce State Park (RDSP), southeastern Brazil. To assess ocelot occupancy and detection probabilities, we measured the distances between sampling stations and rivers, lakes, cities, pasture, and Eucalyptus plantations. In addition, we recorded the mean rainfall levels for each sampling occasion, and native grassland areas within a 500 m‐buffer around each sampling station. We found a strong and positive association between ocelot detection and the dry season, which might be due to a higher number of individuals moving through the Park during this season. Moreover, we found a strong and positive association of ocelot detection with native grassland areas around lakes, which may be related to the ocelot behavior of searching for prey in these areas. Conversely, the ocelot occupancy probability was intermediate (Ψ^ = 0.53, 95% CI = 0.36–0.69) and was not strongly associated with the evaluated covariates, which may be explained by the high‐quality of forest habitats and water resources that are homogeneously distributed within the Park. Our study indicates that the RDSP still provides a structurally suitable forest habitat for ocelots, but because of the current worrying scenario of over fragmentation, reduction of forest cover, and weakness of the protective legislation of this biome, the long‐term persistence of the species in RDSP is uncertain.     

Growth ring response of two Atlantic Forest tree species pre- and post-dam operation in Southern Brazil

Hydropower plants are important sources of renewable energy, but the climatic impacts of their constructions remain poorly explored. Considering that tree growth analysis is a useful tool to identify environmental impacts, this study aimed at using climate records and tree-ring chronologies to understand possible local climate changes caused by the construction of a hydropower plant in the 1980s in the State of Paraná, Southern Brazil. Historical climatic data were obtained from the local meteorological station and surrounding municipalities and analyzed using ANOVA and means tests. The Pettitt test was additionally used to identify change-points in the meteorological data. Wood samples from a total of 60 trees from Araucaria angustifolia (Bertol.) Kuntze (Araucariaceae) and Cedrela fissilis Vell. (Meliaceae) were collected, and tree-ring chronologies were built using dendrochronological standard procedures. Chronologies for A. angustifolia and C. fissilis represented time periods from 1800 to 2016 and 1899–2015, respectively. Tree-ring growth responses to climatic variables were evaluated by adjusting generalized mixed linear models and the Spearman correlations. Our results evidenced that the hydropower plant altered the local climate, mostly influencing the hydrological cycle by increasing local rainfall, with monthly rain volumes being statistically higher than in other meteorological stations. Significant responses in the growth of A. angustifolia were found to be associated with the water level increase caused by the dam and of C. fissilis due to the increase in cloud cover.     

Morphological characterization of the asexual reproduction in the acorn worm Balanoglossus simodensis

The acorn worm Balanoglossus simodensis reproduces asexually by fragmentation and subsequent regeneration from the body fragments. We examined the morphogenesis of its asexual reproduction. At first, we collected asexually reproducing specimens and observed their morphogenesis. Then, we succeeded in inducing the asexual reproduction artificially by cutting the worm at the end of the genital region. The process of morphogenesis is completely the same between naturally collected and artificially induced specimens. The stages during morphogenesis were established on the basis of the external features of the asexually reproducing fragments. The internal features of the fragments were also examined at each stage. In a separate phase of the study, the capacity for regeneration of some body parts was also examined by dividing intact worms into about 10 fragments. Although the capacity for regeneration varied among the different body parts, some fragments regenerated into complete individuals in 1 month. The process of regeneration was the same as that in the asexually produced fragments.     

Three New Species of Phytotelm-Breeding Melanophryniscus from the Atlantic Rainforest of Southern Brazil (Anura: Bufonidae)

Three new species of Melanophryniscus are described from the Serra do Mar mountain range of the state of Santa Catarina, southern Brazil. All species are found at intermediate to high altitudes and share phytotelm-breeding as their reproductive strategy. The new species are distinguished from other phytotelm-breeding Melanophryniscus based on different combinations of the following traits: snout-vent length, presence of white and/or yellow spots on forearms, mouth, belly and cloaca, pattern and arrangement of warts, and presence and number of corneous spines. The discovery of these species in a rather restricted geographical area suggests that the diversity of phytotelm-breeding species of Melanophryniscus might be severely underestimated. The conservation status of these species is of particular concern, given that one of them is at risk of extinction not only due to its restricted habitat, but also because of anthropogenic disturbances.     

海南热带雨林国家公园不同植被类型的大型真菌多样性

为揭示海南热带雨林国家公园大型真菌多样性及不同植被类型对真菌群落的影响, 本研究于2020年和2021年湿季对海南热带雨林国家公园内7个管理局辖区开展了大型真菌多样性调查, 比较了不同植被类型(山地雨林、低地雨林、低地雨林次生林、人工林)的大型真菌生活型(共生型、腐生型)组成差异。从设置的58条1 km长的样带内采集到1,869份子实体标本, 根据子实体形态与ITS rDNA序列分析, 从中鉴定出562种真菌, 涉及17目64科174属, 其中80%以上的物种由伞菌目、牛肝菌目、红菇目、多孔菌目、鸡油菌目、锈革孔菌目和炭角菌目构成。大型真菌的营养型以腐生型(占48.2%物种)和共生型(44.8%)为主。每条样带的平均物种丰富度和多度以中海拔的山地雨林最高, 分别为28 ± 5种和33 ± 6个, 而人工林最低, 分别为11 ± 1种和11 ± 2个。植被类型主要影响共生型大型真菌物种丰富度(P = 0.026)和子实体多度(P = 0.019)及Shannon-Wiener多样性(P = 0.028), 但对腐生型大型真菌的影响并不显著。多响应置换过程(multiple response permutation procedure, MRPP)检验结果表明, 不同植被类型对共生型与腐生型大型真菌群落物种组成均有显著影响(腐生型: P = 0.004, 共生型: P = 0.041)。冗余分析(redundancy analysis, RDA)的结果表明, 植被类型对腐生型和共生型真菌群落物种组成差异的解释度均较低(共生型: R² = 0.068, P = 0.004; 腐生型: R² = 0.067, P = 0.004)。海拔仅对腐生型真菌群落物种组成产生微弱影响(R² = 0.029, P = 0.001), 而对共生型真菌影响不显著(R² = 0.024, P = 0.072)。在不同保护地之间, 共生型(R² = 0.148, P = 0.001)与腐生型(R² = 0.123, P = 0.002)真菌物种组成均具显著差异; 基于样带‒真菌矩阵的网络图显示, 海南热带雨林国家公园内尖峰岭、霸王岭、五指山等国家级自然保护区的山地雨林是共生型大型真菌多样性较高区域, 应作为共生型真菌与宿主的优先保护区域。     

滇南勐宋热带山地雨林木质藤本多样性研究

调查滇南勐宋山地雨林沟谷与坡地两种生境中木质藤本种的丰富度、径级分布、攀缘方式以及样地中被藤本缠绕的树木(dbh≥5cm)的数量和比率。结果表明:沟谷与坡地胸径≥1cm的木质藤本平均密度分别为95.7株/0.1hm2、57株/0.1hm2。调查样地内木质藤本共64种,隶属30个科。茎缠绕是最主要的攀缘方式,占总个体数的57%,卷须缠绕种所占比重最小,仅占3%;沟谷与坡地所调查树木被木质藤本缠绕的比例分别为43.7%和28.6%。与亚洲其它热带地区森林相比,勐宋地区藤本的多样性低,但是木质藤本的密度相当高,并且在一些样地中出现了大型木质藤本,这些可能与该地区森林的演替状态有关。     

Dyssochroma viridiflorum (Solanaceae): a reproductively bat-dependent epiphyte from the Atlantic rainforest in Brazil

Few Neotropical plant species seem to depend on the same animal type both for pollination and seed dispersal, and the known instances refer mostly to birds as the agents in these two phases of a plant reproductive cycle. Dyssochroma viridiflorum (Solanaceae), an epiphyte endemic to the Atlantic rainforest in south-eastern Brazil, was found to be visited by phyllostomid bats for nectar as well as for fruits, with the pollination and seed dispersal of the plant ensured by these flying mammals. The greenish flowers open at night and are visited by the nectar-feeding bat Glossophaga soricina, whereas the yellowish-white fruits are consumed by two species of fruit-eating bats, Carollia perspicillata and Sturnira lilium. Only clinging visits, an uncommon behavioural pattern for glossophagine bats while feeding on flowers, were recorded. The small seeds of D. viridiflorum are swallowed along with the fruit pulp and later defecated on the bats' flying pathways. It is suggested that species of Dyssochroma and two other solanaceous bat-pollinated genera, Merinthopodium and Trianaea, form a derived and bat-dependent clade within the Juanulloeae.     

滇南片断热带雨林植物物种多样性变化趋势

采用群落样方（５０×５０ｍ）调查分析法,探讨滇南西双版纳曼仰广龙山片断热带雨林群落中木本植物物种多样性１９５９～１９９１年间的变化趋势。结果表明,该片断森林经３０多年的演化,物种数变化不大,但物种多样性指数降低２４％。在片断热带雨林中,物种的消失率与新增率虽相对平衡,但由于物种的生物学、生态学特性不同,呈现明显的消长变化趋势,即：在群落的不同层次中,物种消失率和新增率都是乔木（Ａ．Ｂ．Ｃ）＜灌木（Ｄ）,在乔木层中则是Ａ＜Ｂ＜Ｃ;就物种的不同确限度而言,消失率和新增率都是特征种＜适宜种＜随遇种＞外来种。此外,本研究认为群落内小气候由“凉湿效应”向“干暖效应”转化,是片断热带雨林物种多样性变化的一个重要环境因素。     

Occasional intraguild predation structuring small mammal assemblages: the marsupial Didelphis aurita in the Atlantic Forest of Brazil

The didelphid marsupial, Didelphis aurita, is suggested as an intraguild predator and as key‐species in small mammal assemblages of the Atlantic Forest of Brazil. The field experiments required to test this hypothesis are complex to implement, but the recent revival of regression methods offers a viable alternative. Here we use the dynamic and static regression methods to determine the importance of D. aurita as a competitor and intraguild predator. Capture–recapture data from two localities in the Rio de Janeiro State were used, Garrafão (municipality of Guapimirim), a coastal forest of the Serra do Mar, and Barra de Maricá, a costal sand dune vegetation. Population and microhabitat variables were monitored from April 1997 to April 2003 in Garrafão, and from January 1986 to July 1990 in Barra de Maricá. Microhabitat variables were related to Canopy, Plant, Litter and Rock covers, Obstruction from 0 to 1.5 m, and Number of logs. Exploitation competition was tested by the dynamic method, which models the effects of D. aurita on the per capita growth rate of a species. Interference by predation or competition was tested by the static method, where the abundance of D. aurita at trap stations was regressed against the abundance of other small mammals, after removal of any variation associated with microhabitat factors. Exploitation competition was not detected, but the interference of D. aurita was pervasive, affecting all small mammals studied in the two localities. The clear avoidance of D. aurita by all small mammals tested in two localities of different physiognomies indicates that it functions as an intraguild predator, even if actual predation by D. aurita is an occasional event.     

Low genetic structure in an epiphytic Orchidaceae (Oncidium hookeri) in the Atlantic rainforest of South-eastern Brazil

BACKGROUND AND AIMS: Oncidium hookeri is a neotropical species of epiphytic Orchidaceae found in the Brazilian Atlantic rainforest at the top of the Mantiqueira Range of mountains. The genetic variation of O. hookeri was studied to assess the distribution of genetic variability within and among six populations localized in Atlantic rainforest remnants. Gene flow among populations and the occurrence of recent bottlenecks were investigated in order to infer the degree of isolation of these populations. METHODS: Thirteen polymorphic loci were used for allozyme electrophoresis. The data were analysed by means of standard statistical approaches, to estimate gene diversity and the genetic structure of the populations. KEY RESULTS: The mean gene diversity and allelic richness were H(e) = 0.099 and A = 1.75, respectively. F-statistics revealed high heterozygote deficiencies in all populations (F(IS) = 0.43-0.82). Several rare alleles were found in all the populations, and three populations presented private alleles. Low genetic differentiation among O. hookeri populations was detected (F(ST) = 0.029); natural selection may be involved in PGM locus differentiation among populations. The genetic differentiation between paired populations was low, bearing no correlation with geographic distance (Mantel test: r = -0.34, P = 0.72). Only two populations showed signs of recent bottlenecks. CONCLUSIONS: The heterozygote deficiency found seems to be caused by pollinator behaviour; the low frequencies of several alleles of different loci can be maintained due to clonal propagation. Despite the stochastic nature of the wind-dispersal of seeds to long distances, this process may promote an effective gene flow among populations, thus avoiding genetic differentiation.     

Asexual and sexual hybrids between Fundulus diaphanus and F. heteroclitus in the Canadian Atlantic region

Levels and origins of clonal diversity in asexual hybrid animals are critical to understanding how they can coexist with their sexual progenitor species. In this study, asexual gynogenetic hybrids between Fundulus diaphanus and Fundulus heteroclitus known from two sites in Nova Scotia (Canada) were characterized using discriminant morphological traits, eight microsatellite loci, and mitochondrial DNA. Fifteen clonal genotypes were uncovered, all bearing the same F. diaphanus maternal haplotye. Each site harboured a different dominant clone along with several rarer clones that all appear to be of recent origin. Unexpectedly, highly introgressed sexually reproducing hybrids (0.25 > q > 0.75) were also detected. Sexual hybrids with maternal ascendance in either species were also found at three other sites in the Atlantic region. Based on a single meristic trait (scale counts), it is shown that asexual clones can be significantly more variable than populations of sexual parental species. Also, species are morphologically more alike when living in sympatry, suggesting that introgression may occur via sexual hybrids. Altogether, these results confirm and refine the available knowledge on this hybrid system, and indicate that hybridization is probably a more widespread phenomenon than suspected, with implications for the phenotypic variability of a widely used model species, F. heteroclitus.     

Soil seed bank in a patchy vegetation of coastal sandy plains in southeastern Brazil

Large seed banks have been found in tropical dry forests and also in habitats with high seasonality in rainfall. However, patchily structured vegetation could induce great spatial variation in the seed bank. We characterized the seed bank in a patchy vegetation of restinga, a common type of coastal vegetation found in the Atlantic forest biome. We also evaluated whether there is any spatial variation between the litter and soil layer, bare sand, and the edge and center of vegetation patches with distinct species dominance. We found 104 seeds/m² in the seed bank using a 5‐cm‐depth sampling. Seven out of 16 species found in the restinga seed bank germinated; two of these were found in the early stages of vegetation patches. We found a higher number of seeds at the edge than in the center of vegetation patches. However, there were no significant differences in the number of seeds in the seed bank between the litter and soil layer, and between vegetation patches with distinct species dominance. Bare sandy soils had lower seed bank densities than vegetation patches. A small seed bank size might be explained by the low proportion of seeds from herbaceous and woody species, which are pioneers in the Atlantic forest. However, seed bank might play an important role in the early stages of the successional process, due to the occurrence of the few species that are able to colonize new young vegetation patches.