Aquatic plant community composition and distribution along an inundation gradient at two ecologically-distinct sites in the Pantanal region of Brazil

In spite of its size and biological significance, we know little about the ecology of the Pantanal, a 140,000 km² floodplain in west-central Brazil. Increasing human pressures make this lack of understanding particularly critical. Using transects and 1 m² circular plots, we documented floristic composition and interacting-environmental conditions associated with littoral herbaceous vegetation along inundation gradients at two ecologically-distinct sites in the Pantanal. We recorded water depth and percent cover for each species in Baía Piuval, a bay in the Bento Gomes River (Mato Grosso), and in a bay in the Acurizal Reserve (Mato Grosso do Sul). Baía Piuval and Acurizal plots contained a total of 22 and 18 macrophyte species, respectively. At both sites Eichhornia azurea and Salvinia auriculata occurred most frequently as dominant or co-dominant species. Chi² analysis, used to quantify zonations along depth gradients, generated four different groups of species ( p < 0.05) for Baía Piuval. For Acurizal, two significantly different groups ( p < 0.05) occurred with an intermediate assemblage of species that could be assigned to either group. Canonical correspondence analysis, used to analyze species distributions, showed a pattern consistent with the Chi² results for Baía Piuval but not for Acurizal. Higher species richness and diversity occurred where dry season and low water levels coincided and richness was generally highest in proximal plots where water depths were lowest. Our results are consistent with the few other plant ecological studies reported for the Pantanal. This study can be considered additive to needed baseline data on biota and ecology of this region of South America.This revised version was published online in March 2005 with corrections to the issue cover date.     

Dung beetle communities as biological indicators of riparian forest widths in southern Brazil

Riparian forests provide important habitat for many wildlife species and are sensitive to landscape change. Among terrestrial invertebrates, dung beetles have been used to investigate the effects of environmental disturbances on forest structure and diversity. Since many studies demonstrated a negative response of dung beetle communities to increasing forest fragmentation, and that most dung beetle species had a more pronounced occurrence during warmest seasons, three hypotheses were tested: (1) Scarabaeinae richness, abundance, diversity and evenness are lower in thinner riparian zone widths than in wider widths during the warmest seasons; (2) Scarabaeinae richness and abundance are positively influenced by leaf litter coverage and height and canopy cover; and (3) Scarabaeinae composition varies with the reduction in riparian vegetation and among annual seasons. We selected four fragments with different riparian zone widths in three secondary streams in southern Brazil. In each fragment, four sampling periods were carried out seasonally between spring 2010 and winter 2011. We collected dung beetles using pitfall traps with two types of bait. We collected 1289 specimens distributed among 29 species. In spring and summer, dung beetle richness was higher in fragments with the widest riparian zone than in those with a thinner riparian zone, and it did not vary between fragments in fall and winter seasons. Dung beetle abundance did not differ among fragments with different riparian zone widths, but it was higher in spring and summer than fall and winter. Richness and abundance were positively influenced by leaf litter. While dung beetle diversity was higher in fragments with wider riparian zone widths than in those with thinner widths, the evenness was similar among fragments. Dung beetle composition differed between the fragments with the widest and thinnest riparian zones, and it also varied among the seasons. Our results suggest that decreased riparian zones affect negatively to dung beetle community structure in southern Brazil. Fragments with thinner riparian zones had lower beetle richness in warmest seasons and an altered community composition. In this sense, the dung beetles are potentially good indicators of riparian forest fragmentation since some species were indicators of a particular riparian zone width. From a conservation perspective, our results demonstrate that the new Brazilian Forest Code will greatly jeopardize not only the terrestrial and aquatic biodiversity of these ecosystems, but also countless other ecological functions.     

Tree species distribution in canopy gaps and mature forest in an area of cloud forest of the Ibitipoca Range,south-eastern Brazil

The tree community of both canopy gaps and mature forest was surveyed in a 5 ha plot of cloud forest in the Ibitipoca Range, south-eastern Brazil, aiming at: (a) comparing the tree community structure of canopy gaps with that of three strata of the mature forest, and (b) relating the tree community structure of canopy gaps with environmental and biotic variables. All saplings of canopy trees with 1–5 m of height established in 31 canopy gaps found within the plot were identified and measured. Mature forest trees with dbh 3 cm were sampled in four 40×40 quadrats laid on the four soil sites recognised in the local soil catena. All surveyed trees were identified, measured and distributed into three forest strata: understorey (<5 m of height), sub-canopy (5.1–15 m) and canopy (15.1–30 m). The following variables were obtained for each gap: mode of formation, age, soil site, slope grade, size, canopy openness and abundance of bamboos and lianas. A detrended correspondence analysis indicated that the tree community structure of gaps in all soil sites was more similar to that of the mature forest understorey, suggesting that the bank of immatures plays an important role in rebuilding the forest canopy and that gap phases may be important for understorey shade-tolerant species. There was evidence of gap-dependence for establishment for only one canopy tree species. Both canonical correspondence analysis and correlation analysis demonstrated for a number of tree species that the distribution of their saplings in canopy gaps was significantly correlated with two variables: soil site and canopy openness. The future forest structure at each gap is probably highly influenced by both the present structure of the adjacent mature forest and the gap creation event.     

塔河源荒漠河岸林群落物种组成、结构与植物区系特征

为了更好地了解荒漠河岸林植被动态与生物多样性维持机制,于塔里木河干流源头荒漠河岸林内建立6个1 hm 2样地,对群落物种组成、数量特征和空间格局等进行综合分析。结果表明,塔河源荒漠河岸林群落结构简单、物种多样性低,共有物种12科15属16种,杨柳科重要值最大(28. 97%),是群落优势建群科。取样面积在0. 04 hm 2时,包括了87. 5%的物种;样地内稀有种和偶见种均占所有物种的12. 5%。植物区系贫乏,单种科、属多,温带成分占绝对优势,古地中海成分也占有重要地位,具典型温带区系性质。样地内 DBH ≥ 1 cm 的活木本个体有2497株,灰胡杨多度占92. 95%,胸高断面积和重要值最大,在群落中占绝对优势地位。群落内科、属、种的数量随植株高度级的增加而减少,垂直结构层次分明,由乔木层、灌木层和草本层构成。样地内所有树种平均胸径15. 57 cm,径级与高度级结构均呈偏正态分布,缺乏高度≤ 2 m的个体,群落更新不良。优势种灰胡杨、胡杨径级结构均呈单峰型,其中胡杨幼树出现断层,灰胡杨幼苗向幼树发展过程中死亡率极高(92. 56%),均为衰退型种群。两个优势种空间格局呈聚集分布,不同生境下随径级增大空间分布格局变化不同;且两个优势种在空间上相互排斥而占据不同生境,暗示着种间竞争与生境异质性是影响荒漠河岸林物种空间分布格局和物种共存的重要因素。     

Structure and composition of riparian forests with special reference to geomorphic site conditions along the Tokachi River,northern Japan

The structure and composition of riparian forests were examined along the Tokachi River, northern Japan. Both the hydrogeomorphic gradient and the temporal gradient were analyzed in attempt to explain the present pattern of riparian forests. The stability of floodplain surfaces was estimated on the basis of the elevation above the riverbed and the distance from the river channel. The characteristics of the substratum on which trees were established were also examined by excavation of buried sediment. The results indicated that soil moisture and organic content increased while the size of particles in the substratum decreased with increased elevation and distance from the river channel. Gradient analysis was employed to examine the distribution of dominant species, such as Alnus hirsuta, Toisusu urbaniana, Populus maximowiczii, Picea jezoensis and Abies sachalinensis. The relative dominance of each could be arrayed across the elevation gradient. Although the three broad-leaved pioneers dominated bars and floodplains near the river channel, their modes shifted from lower to higher elevation and amplitudes of distribution curves decreased in the following order: A. hirsuta, T. urbaniana, P. maximowiczii and conifers, which were located on the highest floodplains. Sites could be divided into three classes in terms of stability. There were fewer species at active sites, which favored the three pioneer species, but species richness and diversity increased with stand age. Semi-active and stable sites were more diverse with the establishment of conifers and other broad-leaved trees, which included upland species. However, species richness peaked and then decreased after trees reached 50 to 60 years of age. The growth of dwarf bamboo and the development of conifer-dominant stands impeded the establishment of other species, thereby reducing species richness and diversity in mature stands. Chronologically, floodplains could be differentiated into high- and low-frequency zones of flood disturbance, with pioneer species occupying the former, and late successional species found largely in the latter.     

塔河源荒漠河岸林群落物种组成、结构与植物区系特征

为了更好地了解荒漠河岸林植被动态与生物多样性维持机制,于塔里木河干流源头荒漠河岸林内建立6个1 hm²样地,对群落物种组成、数量特征和空间格局等进行综合分析。结果表明,塔河源荒漠河岸林群落结构简单、物种多样性低,共有物种12科15属16种,杨柳科重要值最大（28.97%）,是群落优势建群科。取样面积在0.04 hm²时,包括了87.5%的物种;样地内稀有种和偶见种均占所有物种的12.5%。植物区系贫乏,单种科、属多,温带成分占绝对优势,古地中海成分也占有重要地位,具典型温带区系性质。样地内DBH ≥ 1 cm的活木本个体有2497株,灰胡杨多度占92.95%,胸高断面积和重要值最大,在群落中占绝对优势地位。群落内科、属、种的数量随植株高度级的增加而减少,垂直结构层次分明,由乔木层、灌木层和草本层构成。样地内所有树种平均胸径15.57 cm,径级与高度级结构均呈偏正态分布,缺乏高度≤ 2 m的个体,群落更新不良。优势种灰胡杨、胡杨径级结构均呈单峰型,其中胡杨幼树出现断层,灰胡杨幼苗向幼树发展过程中死亡率极高（92.56%）,均为衰退型种群。两个优势种空间格局呈聚集分布,不同生境下随径级增大空间分布格局变化不同;且两个优势种在空间上相互排斥而占据不同生境,暗示着种间竞争与生境异质性是影响荒漠河岸林物种空间分布格局和物种共存的重要因素。     

Effects of microenvironmental heterogeneity on the seed-to-seedling process and tree coexistence in a riparian forest

In a temperate riparian forest, the effects of substrate types, canopy gaps and conspecific seedfall density were investigated on the seed-to-seedling process for the five dominant species (Aesculus turbinata, Fagus crenata, Acer mono, Pterocarya rhoifolia and Cercidiphyllum japonicum). Densities of seedfall and subsequent seedling recruits were measured in the stand over a period of 6 years. A model assuming that local density of seedling recruits is proportional to seedfall density in the preceding year significantly explained a spatial variation in seedling recruits for all species. Several environmental factors were then added. Substrate composition had a positive effect on P. rhoifolia and C. japonicum. P. rhoifolia was favored by gravel substrate, which also explained the adult distribution of this species in this forest. C. japonicum appeared to be facilitated by a mineral-soil substrate. However, the distributions of this substrate and adults of C. japonicum did not follow each other closely. A. mono was negatively affected by gaps, and F. crenata was negatively affected by conspecific seedfall density. In contrast, A. turbinata was not significantly affected by any of the environmental factors tested. The microenvironmental heterogeneity in this forest explained species coexistence to a limited extent in the context of seed-to-seedling processes. Performances at later stages of the life-cycle and/or catastrophic disturbances (e.g. landslides) might have a stronger influence on species coexistence in this forest.     

Structure and species distribution in Coringa mangrove forest,Godavari Delta,Andhra Pradesh,India

Coringa mangrove forest is located in the Godavari delta, Andhra Pradesh, India. The mangrove community consisted of more than 13 species of mangrove and other plants in the present study area. The following three dominant mangrove plants,Avicennia marina, Excoecaria agallocha andSonneratia apetala were found to be present on the banks of a major channel of the Godavari river running through the forest. The structure and species distribution of mangrove, in the Channel Nagathana Kalaya has been described. The area behind the belt consisting ofAcanthus ilicifolius andMyriostachya wightiana is generally colonized byE. agallocha andA. marina. The zone has been called theAvicennia andExcoecaria zone. Adjacent to this zone species likeAegiceras corniculatum andA. officinalis were the common species. In the flat clayey soil,Suaeda maritima was found to grow. In areas of high elevation, devoid of inundation of tidal seawater during the high tidal period, species such asM. wightiana andAcanthus were found to colonize both the banks of the channels.An analysis of species diversity, indicated a definite trend in the distribution of mangrove from the mouth of the estuarine region to the inland waters.The levels of atmospheric pollutants such as sulphur dioxide (SO₂), oxides of nitrogen (NO_x), ammonia (NH₃) and suspended particle matter (SPM) were within the legal limits.     

Soil Mapping in the Pantanal of Mato Grosso, Brazil, using Multitemporal Landsat TM data

Keywords Multitemporal data sets from the Landsat Thematic Mapper (TM) were used to evaluate their applicability for exploratory soil mapping in the floodplain of the Northern Pantanal of Mato Grosso, Brazil. Fifty-four soil profiles were classified into 21 soil units according to the FAO–UNESCO system. Information layers of vegetation types and dynamics of flooding were elaborated by applying supervised hierarchical classification rules. Geomorphologic units were mapped by visual image interpretation. Multinomial logistic regression was applied to test relations between thematic layers and soil units as well as aggregated soil clusters, developing a statistical mapping model. Northern Pantanal floodplain soils show a high variability as a function of age and granulemetry of underlying sediments, as well as soil moisture and flooding regimes. GIS layers of nine vegetation formations, three geomorphologic units and three multi-temporal moisture types were elaborated. Cross-tabulations and multinomial logistic regression models indicate significant relations between FAO–UNESCO soil units and GIS layers. As soil sampling density had been low, a final predictive model was developed for the mapping of six aggregated soil clusters, obtaining a high significance level (p<0.05) for prediction. Applied methodology was found to be appropriate to develop models on soil–landscape relationships and improve information on spatial distribution of soil groupings in the Northern Pantanal.     

长白山落叶阔叶混交林的物种多样性、种群空间分布格局及种间关联性研究

根据在吉林省蛟河实验管理局1 hm²落叶阔叶混交林样地调查结果,对落叶阔叶混交林的群落结构、物种多样性、主要树种的空间分布格局以及树木种群的种间关联进行了研究.结果表明,树木种群优势程度不明显;乔木、灌木、草本的均匀度指数、生态优势度指数都较低.对5个主要乔木种群的空间格局均呈现聚集分布;15个主要树种之间有14个种对存在着显著的种间关联,一个种独立;树种之间正关联的种对少,关联强度低,而负关联多且较高,群落结构组成不稳定,处于软阔叶林向硬阔叶林直至红松阔叶林过渡的阶段.     

长白山落叶阔叶混交林的物种多样性、种群空间分布格局及种间关联性研究

根据在吉林省蚊河实验管理局1hm^2落叶阔叶混交林样地调查结果,对落叶阔叶混交林的群落结构、物种多样性、主要树种的空间分布格局以及树木种群的种间关联进行了研究．结果表明,树木种群优势程度不明显;乔木、灌木、草本的均匀度指数、生态优势度指数都较低．对5个主要乔木种群的空间格局均呈现聚集分布;15个主要树种之间有14个种对存在着显著的种间关联,一个种独立;树种之间正关联的种对少,关联强度低,而负关联多且较高,群落结构组成不稳定,处于软阔叶林向硬阔叶林直至红松阔叶林过渡的阶段．     

Relationship between vegetation and environmental conditions in the northern Pantanal of Mato Grosso, Brazil

This paper analyses the relationship between the distribution of tropical floodplain vegetation and environmental factors such as the soil types, their physical‐chemical properties and inundation dynamics in the northern Pantanal of Mato Grosso, Brazil. Fifty‐four soil profiles of the four principal geomorphologic units of the lowland were classified into twenty‐one units of the FAO‐UNESCO system and related to eight vegetation formations. Under the deciduous and semideciduous woodland and forest formations on flood free riverbanks and relict dunes Arenosols, Solonetz and Alisols dominate. Inundation forests grow on a large variety of soil groupings such as Alisols, Solonetz, Fluvisols, Gleysols and Cambisols, mainly on fluvial deposits. Under the grassland formations of periodically flooded spreadings and depressions Planosols, Acrisols, Alisols, Fluvisols, Arenosols and Cambisols were cored, while Gleysols are common on swamps bearing Thalia geniculata or Cyperus giganteus. Canonical Correspondence Analysis was applied to study the influence of monitored environmental factors on spatial distribution of vegetation formations. Water regime and soil texture were found to define the grassland‐forest boundaries as well as the transition between different grassland formations and between seasonal as well as evergreen forests.     

Changes in avian species composition following surface mining and reclamation along a riparian forest corridor in southern Indiana

Data on the response of bird communities to surface mining and habitat modification are limited, with virtually no data examining the effects of mining on bird communities in and along riparian forest corridors. Bird community composition was examined using line transects from 1994 to 2000 at eight sites within and along a riparian forest corridor in southwestern Indiana that was impacted by an adjacent surface mining operation. Three habitats were sampled: closed canopy, riparian forest with no open water; fragmented canopy, riparian forest with flood plain oxbows; and reclaimed mined land with constructed ponds. Despite shifts in species composition, overall bird species richness, measured as the mean number of bird species recorded/transect route, did not differ among habitats and remained unchanged across years. More species were recorded solely on mined land than in either closed forest or forested oxbow habitats. Mined land provided stopover habitat for shorebirds and waterfowl not recorded in other habitats, and supported an assemblage of grassland-associated bird species weakly represented in the area prior to mining. A variety of wood warblers and other migrants were recorded in the forest corridor throughout the survey period, suggesting that, although surface mining reduced the width of the forest corridor, the corridor was still important habitat for movement of forest-dependent birds and non-resident bird species in migration. We suggest that surface mining and reclamation practices can be implemented near riparian forest and still provide for a diverse assemblage of bird species. These data indicate that even narrow (0.4 km wide) riparian corridors are potentially valuable in a landscape context as stopover habitats and routes of dispersal and movement of forest-dependent and migratory bird species.     

Effects of natural disturbance on the regeneration of riparian forests in a Chichibu Mountains,central Japan

Disturbances in the riparian area had a large effect on each stage of regeneration in riparian forests dominated by Fraxinus platypoda in the Chichibu Mountains, central Japan. F. platypoda adapted well to various disturbances in frequency and size such as landslides and canopy gap formation.The spatial distribution and age structure of F. platypoda were studied in relation to the disturbance regime of the riparian zone. The bell-shaped size and age distributions of F. platypoda suggest that F. platypoda trees were established synchronously in a large disturbance site caused by an earthquake landslide about 200 years ago. For the past 200 years, the topography has been stable and the canopy gap has been recovered by advance regenerated saplings.The distribution of F. platypoda saplings was restricted to an abandoned channel and part of a floodplain. These topographical sites formed by gravel provided safe sites for saplings because stream disturbances did not occur for a long time. Channel bars were under low shade stress because of the lack of herbs and a litter layer, which represents a safe site for seedling establishment. However, the seedling bank could have been destroyed by high frequent flooding caused by large typhoons and the establishment of seedlings might have been prevented for a long time.The regeneration process of F. platypoda was explicated based on the gap dynamics theory during the stable period of topography. On the other hand, an even-aged forest was established in a large scale disturbance site.Nomenclature: Ohwi & Kitagawa (1992)     

Vegetation and environmental heterogeneity relationships in a Neotropical swamp forest in southeastern Brazil (Itirapina, SP)

Patterns in substrate, canopy openness, tree species composition and structure were studied in a swamp forest in southeastern Brazil (Itirapina, SP), using a fine spatial scale (∼0.05 km²). Sixty quadrats of 10 m × 10 m were divided into three sample plots, located in the centre and at both ends of the forest remnant (upstream and downstream), encompassing different environmental conditions. In each quadrat we quantified and identified individuals with CBH (circumference at breast height) ≥ 10 cm, the chemical properties of the soil, the drainage (flooded area) and the percentage of canopy openness. We keep 5124 individuals distributed over 37 species and 25 families. The downstream site presented a lower frequency of flooding, canopy openness, species richness (15 species) and density of individuals. In the central site we found different patterns of drainage and light incidence, the greatest species richness (31 species) and density of individuals, but smaller trees both in height and in diameter. The upstream site was subject to higher frequency of flooding, with intermediate values for density and species richness (27 species). Floristic and structural variation between and within sites reflects the different environmental conditions related to substrate and canopy openness. However, a larger number of species were correlated with drainage pattern (21 species) rather than with canopy openness (14 species), suggesting that the main factor responsible for the spatial organization of the plant community in swamp forests is soil drainage.     

南亚热带森林群落种-多度的对数正态分布模型研究

通过对地处南亚热带的广东省黑石顶自然保护区森林群落的定点研究结果的分析表明：当用１,２,３,…分组每种个体数ｒ时,５个不同类型的群落样地的种一多度分布的直方图都呈明显的倒Ｊ－形;经Ｐｒｅｓｔｏｎ“倍程（ｏｃｔａｖｅｓ）”法分组ｒ后,其种－多度都服从对数正态分布。由种－多度模型可以推出另一新的模型一个体一多度分布模型,即Ｉ（Ｒ）＝２R0ＳＯＥＸＰ［［１ｎ２）２／４ａ２〕ＥＸＰ｛－ａ２（Ｒ－（ＲＯ＋１ｎ２／２ａ２）］２｝,它也符合对数正态分布。另外,还运用积分方法推导出估计总体（整个群落）中总种数Ｓ*和总个体数Ｉ*理论值的公式,用此公式估计的结果较为合理。     

Effect of flooding regime and understorey bamboos on the physiognomy and tree species composition of a tropical semideciduous forest in Southeastern Brazil

The interrelationship between river flooding regime, topography, soil properties and the distribution of tree and bamboo species was analysed in an area of tropical semideciduous forest on the margins of the Rio Grande, in Madre de Deus de Minas, Southeastern Brazil. A survey was carried out in a single forest plot (1.597 ha, 71 adjacent 225 m² quadrats) located in the inner side of a river bend and extending from the point bar to the top of the slope. All trees (5 cm diameter at the base of the trunk) and bamboo culms were registered. Soil samples were collected and analysed for their properties and the river level was monitored during a two year period. In the point bar the forest was dominated by only two tree species, Salix humboldtiana and Inga affinis, that tended to occur in distinct areas. Differences in soil properties between these areas suggest variation in sedimentation dynamics. In the sloping part of the plot, a canonical correspondence analysis (CCA) indicated that the floristic composition was significantly correlated with three topographic sectors and their corresponding flood regimes. The Lower Slope corresponds to the sharp transition to the point bar forest, endures partial and annual floods and shows a very distinct flora that includes many light-demanding species. The Middle Slope is only occasionally reached by exceptional river floods and is characterised by a high density of the bamboo Merostachys neesii. The comparatively low density and basal area of trees, particularly for the smaller ones, provide evidence that the bamboos are problably interfering with the trees by restricting their recruitment. The Ridgetop lies entirely above the highest flooding level registered. The density of bamboos is lower and the understorey trees abundant.     

黔中喀斯特次生林优势物种空间分布格局及关联性

以黔中天龙山2 hm²喀斯特次生林为对象,采用成对相关函数g(r)结合完全随机模型(CSR)研究重要值前4位优势树种的空间分布格局及其关联性。结果表明: 样地树种的径级结构呈倒“J”型分布,在优势树种窄叶石栎和圆果化香的影响下,第Ⅴ径级(≥10 cm)的数量较多。窄叶石栎呈现倒“J”型分布,种群更新良好,处于生长发育初级阶段;而圆果化香和云南鼠刺随着径级的增大数量逐渐递增,成年树、大树数量远多于幼树、小树,表明该种群更新不足,处于生长发育的中后期并逐渐衰退。除窄叶石栎外,其余优势树种整体呈现出在较大尺度上聚集分布,聚集程度随着尺度的增大逐渐下降并趋于随机分布,此规律在幼树径级中表现得尤为突出;而受各种因素的影响,各个树种不同径级呈现出不同的空间分布格局。在种间关联上,4个优势树种之间大多呈现负关联或者无关联关系,树种重要值越高与其他优势树种关联程度越低,呈现负关联的2个树种在小尺度上关联程度最低,随着尺度的增大负关联程度逐渐降低并趋向于无显著关联。     

Relationship between leaf characteristics, tree sizes and species distribution along a slope in a warm temperate forest

The relationships between some leaf characteristics, tree size and species distribution were investigated for evergreen tree species along a slope in a warm temperate forest in Japan. Tree species were classified into three groups based on their dominance on the slope: ridge species that were aggregated in an uppersite, valley species that were aggregated in a lowersite, and uniform species that were distributed almost uniformly. The ridge species had a more positive leaf carbon isotope ratio than the valley species, which suggests that the ridge species have larger water use efficiency than the valley species. This may give some advantage to the ridge species over the valley species in the uppersite where water availability would be limited. However, the ridge species had smaller leaf nitrogen content on a mass basis and larger leaf mass per area than the valley species, which suggests that the ridge species had a smaller mass-based leaf photosynthetic capacity than the valley species. This may be disadvantageous to ridge species in the lowersite, because smaller leaf photosynthetic capacities cause lower leaf carbon gain and thus lower growth than the valley species. These differences in leaf characteristics between the ridge and the valley species were affected by microenvironments, and were also partly affected by the difference in species specific responses to microenvironments on the slope.     

Activity of a specialized insectivorous mammal (Myrmecophaga tridactyla) in the Pantanal of Brazil

The purpose of this study was to correlate the activity and habitat use of a large and ecologically specialized mammal ( Myrmecophaga tridactyla ) with the time of day and minimum daily temperature in Brazil's Pantanal wetland. Seven giant anteaters were fitted with very high frequency (VHF) radio transmitters and monitored from March to December 2001. The animal's state of activity or rest, time and ambient temperature were recorded in different patches of the study site, which were covered by a mosaic of vegetation types and several ponds. Whenever a giant anteater was inside a forest patch, the temperature inside and outside of the patch was also recorded. The temperatures throughout the day were recorded by the meteorological station at the study site. The period of greatest activity of giant anteaters started at 18:00 h on hot days, but whenever the daily minimum temperature declined, the species' activity began earlier. Giant anteaters use predominantly forest habitats for rest and open habitats for activity. The forest patches work as a temperature buffer, because they are cooler than the matrix of open habitats during the hot hours of the day and warmer than the matrix during the cold hours. Although the giant anteater is known to be associated with open habitats, this study indicates the need of preserving forest patches for the conservation of this species.