Ecosystem recovery in terra firme forests after cutting and burning: a comparison on species richness, floristic composition and forest structure in the Jaú National Park, Amazonia

Six hectares, three in a primary forest and three in a 40 year old secondary forest were inventoried for all trees with Diameter at Breast Height (DNH) of 10 cm or greater in a terra firme forest 200 km north-east of Manaus, central Amazonia in order to compare the difference between structure, species richness and floristic composition. Both species richness and tree density were significantly higher in the upland forest than in the secondary forest. The forest structure pattern analysed (DBH, basal area and estimated dry biomass) did not differ significantly between the two forest types. Similarity indices at species level were only 14%. In the 3 ha of primary forest the number of species varied from 137 to 159, the number of individuals from 639 to 713, total basal area from 32.8 to 40.2 m² and estimate total of above-ground dry biomass (AGBM) from 405 to 560 tons per ha. In the 3 ha of secondary forest, the number of species varied from 86 to 90, the number of individuals from 611 to 653, total basal area from 28.8 to 39.9 m² and estimated total AGBM from 340 to 586 tons per ha. Family Importance Value (FIV) is the sum of relative density, dominance and richness of a family. The most important families in relation to FIV were Burseraceae, Chrysobalanaceae, Lecythidaceae, Myristicaceae, Bombacaceae, Fabaceae and Mimosaceae in the 3 ha of primary forest, while Burseraceae, Lecythidaceae, Sapotaceae, Arecaceae and Cecropiaceae were the most important families in the 3 ha of secondary forest. Importance Value Index (IVI) is the sum of relative density, dominance and frequency of a species. Alexa grandiflora (Caesalpiniaceae), Sckronema micranthum (Bombacaceae) and Pourouma guianensis (Cecropiaceae) were the most important species in relation IVI, in the primary forest, while Eschweilera grandiflora (Lecythidaceae), Protium apiculatum (Burseraceae) and Bertholletia excelsa (Lecythidaceae) were the most important species in the secondary forest. We conclude that species richness was significandy different between the two forests, but that forest structure patterns analysed in this study (DBH, basal area and dry biomass) were similar. This demonstrates that 40 years was sufficient time for the secondary forest to recover the original structure of the primary forest, but not the original species richness. The low species similarity between the two forests indicates that the floristic composition was quite distinct and that the mixture of primary forest and disturbed forest has led to an increase in total species diversity.     

Palm species richness,abundance and diversity in the Yucatan Peninsula,in a neotropical context

Species richness, abundance and diversity patterns in palm communities in the Yucatan Peninsula were compared at three sites with different forest types (semi‐deciduous, semi‐evergreen and evergreen), as well as different precipitation, geomorphology and soil depth. All individual palms, including seedlings, juveniles and adults, were identified and counted in forty‐five (0.25 ha) transects. A total of 46 000 individual palms belonging to 11 species from nine genera and two subfamilies were recorded. Palm richness, diversity and abundance were highest in the evergreen forest. Species from the subfamily Coryphoideae dominated the semi‐deciduous and semi‐evergreen forests while species from the subfamily Arecoideae dominated the evergreen forest. Seven species were found only in the evergreen forest. Chamaedorea seifrizii and Sabal yapa were found in all three forest types, while Thrinax radiata was found in the semi‐deciduous and semi‐ evergreen forests and Cocothrinax readii only in the semi‐evergreen forest. Compared to other neotropical palm communities, the richness and diversity in the Yucatan Peninsula are lower than in the western Amazon basin. Although palm richness and diversity on the Yucatan Peninsula were positively associated with precipitation, other variables, in particular soil depth and fertility as well as habitat heterogeneity (microtopography and canopy cover), need to be considered to better understand the observed patterns.     

Diversity of understory plants in undisturbed and disturbed tropical lowland forests of Little Andaman Island, India

Species richness and density of understory plants were investigated in eight 1 ha plots, distributed one each in undisturbed and disturbed tropical evergreen, semi-evergreen, deciduous and littoral forests of Little Andaman island, India, which falls under one of the eight hottest hotspots of Biodiversity in the world viz. the Indo-Burma. One hundred 1 m⁻² quadrats were established in each 1 ha plot, in which all the understory plants (that include herbs, undershrubs, shrubs and herbaceous climbers) were enumerated. The total density of understory plants was 6,812 individuals (851 ha⁻¹) and species richness was 108 species, representing 104 genera and 50 families. Across the four forest types and eight study plots, the species richness ranged from 10 to 39 species ha⁻¹. All the disturbed sites harbored greater number of species than their undisturbed counterparts. Herbs dominated by species (63%) and density (4,259 individuals). The grass Eragrostis tenella (1,860 individuals; IVI 40), the invasive climber Mikania cordata (803; IVI 20) and the shrub Anaxagorea luzonensis (481; IVI 17.5) were the most abundant species. Poaceae, Asteraceae, Acanthaceae, Orchidaceae and Euphorbiaceae constituted the species-rich families represented by 6 species each. The species-area curves attained an asymptote at 0.8 ha level except in sites DD and DL, indicating 1 ha plot is not sufficient to capture all the understory species in disturbed forests. The alien weeds formed about one-fourth of the species richness (31 species; 28%) and density (1,926 individuals; 28.3%) in the study sites, indicating the extent of weed invasion and the attention required for effective conservation of the native biodiversity of the fragile island forest ecosystem.     

Cryptogamic epiphytes in primary and recovering upper montane oak forests of Costa Rica – species richness,community composition and ecology

Species richness, community composition and ecology of cryptogamic epiphytes (bryophytes, macrolichens) were studied in upper montane primary, early secondary and late secondary oak forests of the Cordillera de Talamanca, Costa Rica. Canopy trees of Quercus copeyensis were sampled with the aim of getting insight in patterns and processes of epiphyte succession and recovery of diversity in secondary forest following forest clearing. Species richness of cryptogamic epiphytes in secondary and primary forests were nearly the same, showing that primary forests are not necessarily more diverse than secondary forests. High species richness of secondary forests was presumed due to the closed canopy, resulting in permanently high atmospheric humidity in these forests. Similarity in species composition of secondary and primary forests increases with forest age, but after 40 years of succession one third (46 species) of primary forest species had not re-established in the secondary forest. Community composition in primary and secondary forests differed markedly and indicates that a long time is needed for the re-establishment of microhabitats and re-invasion of species and communities adapted to differentiated niches. Genera and species exclusive to primary forests are relevant as indicator taxa and conservation targets. Forty percent (68 species) of all species recorded are restricted to secondary forests, indicating the important contribution of secondary forest diversity to total species richness of the oak forests of Costa Rica.     

Species diversity and community structure in sal (<Emphasis Type="Italic">Shorea robusta</Emphasis>) forests of two different rainfall regimes in West Bengal,India

Knowledge on the structure and composition of the plant communities has enormous significance in conservation and management of forests. The present study aimed to assess the community attributes, viz., structure, composition and diversity in the moist and dry sal (Shorea robusta) forests in the West Bengal province of India and compare them with the other sal forests of India. The phytosociological data from these forests were quantitatively analysed to work out the species richness, diversity, evenness, dominance, importance value, stand density and the basal area. The analysis showed that plant richness and diversity in moist sal forests of northern West Bengal are higher than the dry sal forests of south-west Bengal; a total of 134 tree (cbh ≥30 cm), 113 shrub and 230 herb species were recorded in the moist sal forest compared to 35 tree, 41 shrub and 96 herb species in dry sal forest. Papilionaceae was observed to be the dominant family. Dry sal forests had higher tree dominance (0.81) and stand density (1,006 stems ha⁻¹) but lower basal area (19.62 m²ha⁻¹) while moist sal forest had lower tree dominance (0.18) and stand density (438 stems ha⁻¹) but higher basal area (56.52 m²ha⁻¹). Tree species richness and stem density across girth classes in both the types decreased from the smallest to largest trees, while the occurrence rate of species increased with increase in girth class. A t-test showed significant differences in species richness, basal area and the stand density at 95% confidence level (p = <0.05) in the two forest types. The CCA indicated very low overall match (canonical correlation value = 0.40) between the two sets of variables from moist and dry sal types. The differences in these forests could be attributed to the distinct variations in climatic conditions- mainly the rainfall, disturbance regimes and the management practices.     

Patterns in woody species diversity, richness and partitioning of diversity in forest communities of tropical deciduous forest biome

The regressive succession model hypothesizes tropical savanna-woodlands to be a degraded stage of primary deciduous forests. Species diversity, richness and evenness of woody species in savanna-woodlands, secondary deciduous forests and mature deciduous forests of central India were compared to test if the regressive succession explained pattern in species richness, diversity, functional diversity and basal area. At the plot scale (0.1 ha) secondary deciduous forests and savanna-woodlands had similar species diversity, a pattern not consistent with the regressive model of deciduous forest succession, and mature deciduous forests had greater species diversity and richness (p<0.05). When examined at a larger scale or community scale by pooling all plots within a community type, the trend in diversity persisted even with greater effort allocated to sampling of secondary deciduous forests. Species richness at the community scale was greatest in secondary deciduous forest as expected from species area relationship. The communities shared 28 woody species but the species composition was significantly different between the communities. I suggest that conservation of tropical deciduous forests based on regressive succession model is problematic.     

川西亚高山森林不同恢复途径物种组成和群落结构动态变化

川西亚高山森林作为西南林区主体,是长江上游的生态屏障,该区域植被恢复方式主要为人工恢复和自然恢复,比较不同恢复方式下森林的物种组成和群落结构动态变化,对于川西亚高山森林恢复与重建有重要的意义,可以为制定合理的森林管理策略提供科学依据。基于茂县山地生态系统定位研究站不同恢复模式形成的的华山松人工林、油松人工林和自然恢复的次生林野外调查数据,分析了2005-2020年乔、灌、草三个层次的群落结构特征和多样性。结果表明:(1)不同恢复途径下,乔木层物种数都呈现增加趋势,华山松人工林、油松人工林、自然恢复的次生林乔木层物种数分别增加了11种、7种、8种;(2)华山松人工林中华山松重要值从48.06%降低到31.1%,乡土阔叶树种四川蜡瓣花进入乔木层,2020年重要值增大至21.62%,油松人工林中油松重要值逐渐降低,从43.59%降至29.76%;自然恢复的次生林中,乡土树种锐齿槲栎逐渐成为第一优势种,2020年重要值增至19.9%。(3) 华山松人工林、油松人工林和自然恢复的次生林中,温带区系成分分别占总属数的71.43%,80.77%和84%,温带区系特征明显。(4)华山松人工林和油松人工林乔木层径级结构均为偏正态分布;而自然恢复的次生林径级分布呈倒"J"形,以小径级个体为主。(5)不同林型的乔木层高度在15年间呈现增加的趋势,具体表现为油松人工林>华山松人工林>自然恢复的次生林。(6)乔木层Shannon-wiener指数和 Simpson指数均表现为自然恢复的次生林显著大于两个人工林,丰富度指数和均匀度指数表现为油松人工林最大;灌木层4个多样性指数均表现为油松人工林最大;草本层的丰富度指数、Shannon-wiener 指数和 Simpson 指数均表现为油松人工林较大,均匀度指数没有显著差异。结论:人工林恢复速度大于自然恢复的次生林,但自然恢复的次生林更新能力更强,且更有利于多样性的保存。两个人工林逐渐由常绿针叶林演替为以常绿针叶树为主的针阔混交林,自然恢复的次生林演替为以常绿阔叶树为主的针阔混交林。     

Anthropogenic disturbances and plant biodiversity in forests of Uttaranchal,central Himalaya

Eight forest types varying in disturbance frequencies were identified along an elevational gradient in Uttaranchal, central Himalaya. Low elevation forests were close to human habitation and had high disturbance frequency, while high elevation forests were situated far from the human habitation and had low disturbance. The dominant tree species at low elevation were Pinus roxburghii and Quercus leucotrichophora, while Q. floribunda and Q. semecarpifolia dominated the high elevation forests. Pyracantha crenulata was the shrub present in all the forests except in Q. semecarpifolia forest and Anaphalis contorta, a herb species, was present in all the forests. Disturbance decreased the dominance of single species and increased the plant biodiversity by mixing species of different successional status. Species richness and diversity for all the vegetation layers were higher in low elevation–high disturbance forests. Mean tree density decreased from high to moderate and increased in low disturbance. The shrub density decreased from high to low disturbance while the reverse occured for herbs. High proportion of early successional species in disturbed forests indicated that disturbance induces succession. The mean number of young individuals increasing from high to low disturbance indicates that disturbance adversely affects regeneration. But, however, the high number of young individuals of Coriaria nepalensis, a small non-leguminous nitrogen fixing tree, in disturbed forests shows that the forest is regenerating. This species could be helpful in the re-establishment of original vegetation through triggering the regeneration of these forests. High elevation–low disturbed forests separated from low elevation–high disturbed forests. Forest type and elevation may have more influence on tree richness while shrub and herb richness may be more sensitive to disturbance and forest types.     

The small mammal community of Mukogodo Forest, Kenya

Species richness and diversity of rodents and insectivores were investigated at relict forest patches of Mukogodo, Laikipia, Kenya using Sherman's live traps and pitfall traps. Two hundred and nineteen individuals were captured in 3021 trap‐nights. There were eleven species in two taxonomic groups, Rodentia and Insectivora. Two other rodent species were sighted but not captured. Thirteen bats belonging to four species (Epomophorous wahlbergi, Pipistrellus kuhlii, Scotophilus dingani and Nycteris thebaica) were opportunistically trapped using mist nets. Two of the four species accumulation curves for forest patches did not reach an asymptote. Species richness and diversity were highest at Kurikuri compared with other patches because of habitat variability. The results support the prediction that forest disturbance and degradation lead to an increase in generalist species as compared with specialists and highlight the importance of relict afromontane forests in the conservation of small mammals in Kenya.     

北京松山自然保护区森林群落物种多样性及其神经网络预测

物种多样性是群落结构和功能复杂性的一种度量,物种多样性的空间分布格局受许多环境因子的影响.运用多样性指数,多层感知器网络,分析了松山保护区森林群落物种多样性与群落类型、结构和生境之间的关系.结果表明:(1)大果榆+山杨混交林、油松+青杨混交林物种丰富度、多样性和均匀度均较高,而大果榆林、华北落叶松林的各项指数值均较低.Patrick指数和Shannon-Weiner指数在森林群落中均表现为草本层＞灌木层＞乔木层;Pielou指数在榆林中表现为草本层＞乔木层＞灌木层,而在其他森林群落中表现为灌木层＞草本层＞乔木层.(2)功能层物种多样性在海拔梯度上的变化趋势不同,在乔木层,丰富度、多样性和均匀度随海拔的升高逐渐降低;在灌木层,丰富度、多样性和均匀度均呈比较明显的单峰曲线变化趋势;在草本层,丰富度和多样性随海拔的升高都呈下降趋势,而在草本层,均匀度变化不大.(3)用多层感知器网络预测功能层多样性效果很好,结果发现坡向对乔木层和灌木层物种多样性的影响最大,而海拔高度对草本层物种多样性的影响最大.     

Effects of rain forest logging on species richness and assemblage composition of small mammals in Southeast Asia

Aim The effects of logging and habitat degradation on the richness and abundance of small mammals in Asian rain forests are largely unknown. This work compares the species richness, dominance and evenness of small non‐volant mammals between logged and unlogged forests, and assesses whether assemblage variability (β‐diversity) is similar between forest types. Location Southeast Asia, northern Borneo (Sabah, Malaysia), Sunda‐shelf. Methods We surveyed species‐rich assemblages of small non‐volant mammals in three unlogged and three logged forests for 2 years. At each forest site, we sampled a permanently marked transect and two additional sites in three trapping sessions. All analyses were performed at both levels to include the effects of local abundances and point estimates, separately from the relative abundances of species on a more regional scale. Results We trapped a total of 1218 individuals of 28 species. Eleven common species accounted for 95% of all captures. Species richness and diversity were significantly higher in unlogged forest (27 species) than in logged forest (17 species). This was mainly attributable to the smaller number of rarely recorded species in logged forest (five compared with 16 in unlogged forest, with a total of fewer than 10 captures). However, all common species were present in both logged and unlogged forests, and our analyses revealed similar patterns of dominance, evenness and fluctuations in abundance. Hence overall assemblage composition in multivariate space did not differ greatly between forest types. Assemblages of Muridae and Tupaiidae showed similar population fluctuations in space and time, indicating that the ecology of these taxa may be partially driven by the same environmental factors. Main conclusions Although species were distributed patchily within sites, analyses at local and regional scales revealed similar patterns in diversity and assemblage variability, suggesting that effects of forest modification did not differ extensively locally and regionally, but had a profound effect on rare species. Our results emphasize the importance and conservation value of logged forest stands that are able to hold a large proportion of the small mammals also found in unlogged forests. Rare and more specialized species are more vulnerable to forest degradation than commonly caught species, resulting in the complete loss, or a decrease in numbers, of certain groups, such as arboreal small mammals and Viverridae.     

Influence of urbanization on riparian forest diversity and structure in the Georgia Piedmont, US

Riparian forests are increasingly threatened by urban expansion and land use change worldwide. This study examined the relationships between landscape characteristics and woody plant diversity, structure, and composition of small order riparian corridors along an urban-rural land use gradient in the Georgia Piedmont, US. Riparian plant diversity, structure, and composition were related to landscape metrics and land use. Species richness was negatively associated with impervious surfaces and landscape diversity, and positively associated with forest cover and largest forest patch index. Shannon species diversity was strongly related to the biomass of non-native species, especially for the regeneration layer. Urban sites were characterized by high richness of non-native and pioneer species. Developing sites were dominated by the non-native shrub, Ligustrum sinense Lour., and several native overstory trees, mainly Acer negundo L. While agricultural and managed forest sites were composed of ubiquitous species, unmanaged forest sites had a structurally distinct midstory indicative of reduced disturbance. Urban and agricultural land uses showed decreased native stem densities and signs of overstory tree regeneration failure. Results from this study highlight the impact of the surrounding landscape matrix upon riparian forest plant diversity and structure.     

基于结构方程模型分析林分空间结构对草本物种多样性的影响

林分空间结构的改变直接影响林下草本物种的多样性。以针叶纯林、针阔混交林和常绿阔叶林为研究对象,采用结构方程模型研究了林分空间结构对林下草本物种多样性的影响,并探讨了林分水平空间结构,垂直空间结构以及林木竞争态势对林下草本物种多样性的影响的相对重要性。结果表明,林分水平空间结构对林下草本的物种多样性指数和物种均匀性指数均存在极显著的影响（P < 0.001）,影响系数高达0.96和0.89,对林下草本物种丰富度存在显著影响（P < 0.01）,影响系数为0.22;林分垂直空间结对林下草本丰富度和物种均匀性指数均存在极显著的影响（P < 0.001）,影响系数分别为0.86和0.43,对林下草本物种多样性指数存在显著影响（P < 0.01）,影响系数为0.16;林木竞争指数与林下草本丰富度和物种多样性指数也均存在极显著的影响（P < 0.001）,但影响系数较小,分别为-0.47和-0.30,而对林下草本物种均匀性指数未达到显著影响作用（P > 0.05）,影响系数仅为-0.04。整体上看,林分水平空间结构、垂直空间结构和林木竞争态势均对林下草本物种多样性有较强的影响作用,但从影响系数看,林分水平空间结构的影响作用最大,垂直空间结构次之,林木竞争态势的影响作用最小。因此,欲维持或改善林下草本物种多样性,应采取调整林分水平空间结构为主,垂直空间结构调整为辅,并适当降低林木竞争程度的综合经营措施。     

The Bromeliad Microcosm and the Assessment of Faunal Diversity in a Neotropical Forest1

The faunas of tank bromeliads were sampled over two years in three forest types at different elevations in the Luquillo Experimental Forest, Puerto Rico, and the diversity of their animal communities compared. Bromeliad plants behaved as islands in that, within forests, the species richness and abundance of their animal communities were significantly and positively correlated with increase in plant size. The amount of canopy debris they accumulated was similarly correlated with increase in plant size. Overall diversity was lowest in the dwarf forest, where plants were uniformly small. Animal communities were stable from year to year, and could be characterised for each forest type and for compartments within the plant. They showed a pattern of high dominance, which increased with elevation (Mc-Naughton index 37, 54, and 73, respectively, for the tabonuco, palo Colorado, and dwarf forest). Alpha-diversity for sites sampled in each year reflected net primary productivity (NPP) of the forest, declining with increasing elevation when animal abundance measures were used (jackknife estimates of Simpson's diversity index 6.54 & 11.04 [tabonuco], 3.53 & 6.22 [palo Colorado], and 2.75 & 2.17 [dwarf forest]). Species richness over the two years, however, was highest in the intermediate palo Colorado forest (187 species), compared to 146 and 88 in the tabonuco and dwarf forests, respectively. These figures were close to jackknife estimates of maximum species richness. The difference in species richness between tabonuco and palo Colorado forests was significant in one year only. In addition to NPP, other factors, such as litter quality and the structural complexity of the habitat in the palo Colorado forest, may have influenced species richness. The most abundant species in individual plants were also the most widely occurring, confirming known patterns of abundance and distribution in other functional groups. Diversity within bromeliad microcosms at different elevations supported known relationships between diversity, productivity, and habitat complexity along gradients and was not related to differences in the total bromeliad habitat available for colonization.     

系统发育多样性与系统发育结构在岛屿植物群落保护中的意义——以蜈支洲岛为例

为探讨系统发育多样性和系统发育结构在岛屿植物群落保护决策制定中的作用,以海南三亚蜈支洲岛被子植物群系为例,分析物种丰富度和系统发育多样性的相关性。结果表明,蜈支洲岛植被可分为10种群系类型,22个样方的物种丰富度与系统发育多样性呈显著正相关,但系统发育多样性与物种丰富度对植物多样性保护优先顺序的指示有差异。森林群系的物种丰富度和系统发育多样性普遍高于灌木和草本群系,4个森林群系样方表现为系统发育结构发散,3个森林群系样方表现为系统发育结构聚集。灌木群系中露兜树(Pandanus tectorius)灌丛和草海桐(Scaevola sericea)灌丛系统发育多样性较高,草本群系中厚藤(Vitex trifolia)灌草丛系统发育多样性较高,灌木和草本群系大多倾向于系统发育结构聚集。距海或人类活动区较近的群系可能受环境过滤的作用,而远离海和人类活动区的群系主要受竞争排斥作用影响。因此,在岛屿植物多样性保护策略制定中应当综合考虑物种和系统发育维度,以及环境、演替阶段及用岛方式等因素的影响。     

Non-woody life-form contribution to vascular plant species richness in a tropical American forest

We provide total vascular plant species counts for three 1-ha plots in deciduous, semi-deciduous and evergreen forests in central Bolivia. Species richness ranged from 297 species and 22,360 individuals/ha in the dry deciduous forest to 382 species and 31,670 individuals/ha in the evergreen forest. Orchidaceae, Pteridophyta and Leguminosae were among the most species-rich major plant groups in each plot, and Peperomia (Piperaceae), Pleurothallis (Orchidaceae) and Tillandsia (Bromeliaceae), all epiphytes, were the most species-rich genera. This dominance of a few but very diverse and/or widespread taxa contrasted with the low compositional similarity between plots. In a neotropical context, these Central Bolivian forest plots are similar in total species richness to other dry deciduous and humid montane forests, but less rich than most Amazonian forests. Nevertheless, lianas, terrestrial herbs and especially epiphytes proved to be of equal or higher species richness than most other neotropical forest inventories from which data are available. We therefore highlight the importance of non-woody life-forms (especially epiphytes and terrestrial herbs) in Andean foothill forest ecosystems in terms of species richness and numbers of individuals, representing in some cases nearly 50% of the species and more than 75% of the individuals. These figures stress the need for an increased inventory effort on non-woody plant groups in order to accurately direct conservation actions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ungulate browsers promote herbaceous layer diversity in logged temperate forests

Ungulates are leading drivers of plant communities worldwide, with impacts linked to animal density, disturbance and vegetation structure, and site productivity. Many ecosystems have more than one ungulate species; however, few studies have specifically examined the combined effects of two or more species on plant communities. We examined the extent to which two ungulate browsers (moose [Alces americanus]) and white‐tailed deer [Odocoileus virginianus]) have additive (compounding) or compensatory (opposing) effects on herbaceous layer composition and diversity, 5–6 years after timber harvest in Massachusetts, USA. We established three combinations of ungulates using two types of fenced exclosures – none (full exclosure), deer (partial exclosure), and deer + moose (control) in six replicated blocks. Species composition diverged among browser treatments, and changes were generally additive. Plant assemblages characteristic of closed canopy forests were less abundant and assemblages characteristic of open/disturbed habitats were more abundant in deer + moose plots compared with ungulate excluded areas. Browsing by deer + moose resulted in greater herbaceous species richness at the plot scale (169 m²) and greater woody species richness at the subplot scale (1 m²) than ungulate exclusion and deer alone. Browsing by deer + moose resulted in strong changes to the composition, structure, and diversity of forest herbaceous layers, relative to areas free of ungulates and areas browed by white‐tailed deer alone. Our results provide evidence that moderate browsing in forest openings can promote both herbaceous and woody plant diversity. These results are consistent with the classic grazing‐species richness curve, but have rarely been documented in forests.     

Bryophyte Species Diversity in Secondary Forests Dominated by the Introduced Species Spathodea campanulata Beauv. in Puerto Rico

The introduced tree species Spathodea campanulata (Bignoniaceae) forms novel forests in Puerto Rico, these having emerged after the abandonment of fields in the mid‐20th century and resulting in forests with a new species composition. We assessed bryophyte species richness in these novel forests and sought correlations with geological substrate, past land use, forest edge and patch area, forest structure, elevation, microhabitat diversity, tree species richness, and microclimatic conditions. Transects were established (edge and forest interior) in nine moist forest patches dominated by Spathodea in north‐central Puerto Rico. These Spathodea forest patches ranged from 0.6 to 9 ha. ANOVA, Chi‐square, correlation, and cluster analyses were used in data analyses. We found 57 bryophyte species. There was a significant difference in bryophyte richness among patches. Those on karst exhibited highest bryophyte richness due to microhabitat diversity, past land use, and shorter hydroperiods. Alluvial sites scored lowest in bryophyte species richness, and forest structure was important for bryophyte communities on these sites. Significant differences in temperature, relative humidity, and light intensity were observed between edge and forest interior. These appeared important for establishing bryophyte species cover but not richness and composition. Microhabitat diversity, patch area, and forest age were more related to bryophyte species richness than elevation, exposed edge, and tree species richness, regardless of geologic substrate. Collectively, Spathodea patches were similar to mature forests on the Island with respect to bryophyte species richness and composition. Novel Spathodea forests have conservation value due to their habitat suitability for bryophyte communities.     

Seasonally flooded,and terra firme in northern Congo: Insights on their structure,diversity and biomass

In the Congo basin, considerable uncertainty remains about the amount and spatial variation of carbon stocks. We studied two types of seasonally flooded forests (dominated by Guibourtia demeusei and Lophira alata) and nearby terra firme forests in northern Congo. We sampled 1.25 ha per forest type and a total of 1,400 trees ≥5 cm diameter. AGB ranged from 207–343 Mg/ha, with no significant differences between forest types. Few significant differences were observed in vegetation structure or tree diversity between forest types. Species richness and stem density of small trees were lower, and dominance was higher in Guibourtia plots, which are subject to greater flooding than Lophira plots. Guibourtia was absent from smaller diameter class in Guibourtia forests; and Uapaca spp. were more abundant in terra firme than in seasonally flooded plots. We show that both types of seasonally flooded forests store important quantities of AGB and should also be considered in forest conservation programmes. We recommend more research on seasonally flooded forests, on larger geographical extent, which assesses flood depth and duration, and measures tree height in the field, as we took a conservative approach to AGB estimates, and AGB could be even greater than we report here.     

Tree species composition and diversity gradients in white-water forests across the Amazon Basin

Aim Attention has increasingly been focused on the floristic variation within forests of the Amazon Basin. Variations in species composition and diversity are poorly understood, especially in Amazonian floodplain forests. We investigated tree species composition, richness and α diversity in the Amazonian white‐water (várzea) forest, looking particularly at: (1) the flood‐level gradient, (2) the successional stage (stand age), and (3) the geographical location of the forests. Location Eastern Amazonia, central Amazonia, equatorial western Amazonia and the southern part of western Amazonia. Methods The data originate from 16 permanent várzea forest plots in the central and western Brazilian Amazon and in the northern Bolivian Amazon. In addition, revised species lists of 28 várzea forest inventories from across the Amazon Basin were used. Most important families and species were determined using importance values. Floristic similarity between plots was calculated to detect similarity variations between forest types and over geographical distances. To check for spatial diversity gradients, α diversity (Fisher) of the plots was correlated with stand age, longitudinal and latitudinal plot location, and flood‐level gradient. Results More than 900 flood‐tolerant tree species were recorded, which indicates that Amazonian várzea forests are the most species‐rich floodplain forests worldwide. The most important plant families recorded also dominate most Neotropical upland forests, and c. 31% of the tree species listed also occur in the uplands. Species distribution and diversity varied: (1) on the flood‐level gradient, with a distinct separation between low‐várzea forests and high‐várzea forests, (2) in relation to natural forest succession, with species‐poor forests in early stages of succession and species‐rich forests in later stages, and (3) as a function of geographical distance between sites, indicating an increasing α diversity from eastern to western Amazonia, and simultaneously from the southern part of western Amazonia to equatorial western Amazonia. Main conclusions The east‐to‐west gradient of increasing species diversity in várzea forests reflects the diversity patterns also described for Amazonian terra firme. Despite the fine‐scale geomorphological heterogeneity of the floodplains, and despite high disturbance of the different forest types by sedimentation and erosion, várzea forests are dominated by a high proportion of generalistic, widely distributed tree species. In contrast to high‐várzea forests, where floristic dissimilarity increases significantly with increasing distance between the sites, low‐várzea forests can exhibit high floristic similarity over large geographical distances. The high várzea may be an important transitional zone for lateral immigration of terra firme species to the floodplains, thus contributing to comparatively high species richness. However, long‐distance dispersal of many low‐várzea trees contributes to comparatively low species richness in highly flooded low várzea.