The floristic composition of the understory plays a fundamental role in the long-term conservation of the diversity, structure, and function of mountain cloud forests in the Andes. We evaluated the relationship between the understory tree floristic composition of four types of predefined cloud forests and the canopy structure, the light transmitted to the understory, and the effect of topography. Through multivariate analysis, we found an environmental gradient correlated with light penetration into the understory and a gradient associated with the slope and, to a lesser extent, with the elevation. Then, we identified floristically well-differentiated ecological groups in response to environmental conditions; however, the groups only partially coincided with the understory composition of the predefined forests. We found environmental response species groups such as Roupala obovata and Beilschmiedia sulcata that are indicator species of sites with lower light penetration into the understory but with steeper slopes and higher elevation. In comparison, Clusia multiflora and Zanthoxylum quinduense to be the main indicator species from sites with greater light penetration into the understory and lower slope and elevation. These findings support appropriate species selection when implementing restoration strategies in forest landscape restoration plans.

Plantation forests with timber production as the major function are highly fragmented and disturbed regarding the tree species composition and stand area. Their closed canopies also have different microclimatic conditions compared with better studied conservation areas. We studied three beetle families (click, longhorn, and rove beetles) with different ecological demands in lowland plantation forests dominated by Sessile oak and Norway spruce in the Czech Republic. Our main interest was how their species richness, abundance, diversity, body length, rarity, red-list status, species composition and individual species were driven by the main tree species, stand area and canopy openness. We analyzed 3466 individuals from 198 beetle species and the results revealed complex and contrasting responses of the studied beetle families – click beetles mostly preferred sun-exposure and spruce as the dominant tree species, longhorn beetles mainly preferred large stands, whereas rove beetles were mostly influenced by oak as the dominant tree species and increasing area. We also observed that some species had different preferences in plantation forests than is known from the literature. The main conclusions of our results are that the dominance of non-natural spruce plantations and a large stand area (both originating from artificially replanted large clear-cuts) did not affect the majority of the studied taxa as we expected. On the other hand, our results might have been influenced by other factor, such as the current small total area of the former vegetation, which in the past might have led to extinction debt; or a large area of other conifers in the surroundings that might have promoted conifer-associated fauna.

Species-specific traits of trees affect ecosystem dynamics, defining forest structure and understorey development. Ochroma pyramidale is a fast-growing tree species, with life-history traits that include low wood density, short-lived large leaves and a narrow open thin crown. We evaluated forest succession in O. pyramidale-dominated secondary forests, diverse secondary forests, both 10–15 y since abandonment, and rain forests by comparing height, density and basal area of all trees (> 5 cm dbh). Furthermore, we compared species richness of understorey trees and shrubs, and basal area and density of trees of early- and late-successional species (< 5 cm dbh) between forest types. We found that tree basal area (mean ± SD: 32 ± 0.9 m2 ha−1) and height (12.4 ± 1.8 m) of canopy trees were higher, and density (1450 ± 339 ha−1) lower in O. pyramidale forests than in diverse forests, and more similar to rain forest. Understorey shrub diversity and tree seedling density and diversity were lower in O. pyramidale forests than in diverse forests, but these forest types had a similar density of early- and late-successional trees. Canopy openness (> 15%) and leaf litter (> 10 cm) were both highest in O. pyramidale forests, which positively affected density of understorey trees and shrubs and negatively affected density of late-successional trees. In conclusion, O. pyramidale forests presented structural features similar to those of rain forest, but this constrained the establishment of understorey tree species, especially late-successional species, decreasing successional development.

This study investigated the structure, diversity and composition of the regenerating shrub-tree species community along a stretch of riparian vegetation in relation to environmental heterogeneity. In the Environmental Protection Area of Pandeiros River, southeastern Brazil, the regenerating stratum on 70 plots (25 m2) divided into four groups according to their soil characteristics and natural barriers was sampled. For each plot observations were made of variables related to several soil properties, canopy openness and flooding regime. In addition to the traditional calculation of phytosociological parameters and diversity, a canonical correspondence analysis (CCA) to examine the existing relationships between environmental variables and species distribution was performed. The families with the highest species richness were Fabaceae and Myrtaceae and the species with the highest importance value indices were Zygia latifolia, Tapirira guianensis, Butia capitata, Bauhinia rufa and Hirtella gracilipes. The CCA largely confirmed the groups that were originally proposed. The stretch of riparian vegetation studied was highly heterogeneous with regard to both the abiotic variables tested and floristic structure and composition.

The neotropical terrestrial insectivore Henicorhina leucosticta (Troglodytidae) maintains long-term territories through vocalizations and forages among leaf litter trapped in the understorey vegetation and ground litter. The relationship between forest structure and H. leucosticta territory size was studied in La Selva Biological Station, Costa Rica, during the non-breeding season in 2009. Forest structure was measured by assessing canopy openness and leaf area index (LAI) using hemispherical photography, while territory size was estimated with the playback technique using local conspecific vocalizations. Mean territory area was 3.8 ± 2.8 ha (mean ± SD, n = 10). Territory radius length was similar in old-growth forest and abandoned agro-forest plantations. We found that H. leucosticta territory size decreased as median LAI increased. We propose that LAI is related to territory size through the amount of leaf fall and subsequent leaf litter accumulation over the understorey plants, which constitutes an important reservoir of arthropod prey and nest materials for H. leucosticta. The long-term supply of food resources is likely to affect territory size in this species, as well as other insectivorous birds with similar foraging behaviour. These results are congruent with the structural cues hypothesis.

Logged forests form an increasingly large proportion of tropical landscapes but disproportionately few studies have studied the impact of forest disturbance, e.g. lightly vs. heavily logged, on tree and seedling communities simultaneously. We sampled all trees (on 1 ha) and all recently germinated seedlings (on 90 m2) in three lightly and three heavily logged sites in each of the following three East African tropical forests: Budongo Forest and Mabira Forest in Uganda and Kakamega Forest in Kenya. We analysed species richness, diversity, abundance and community composition of late- and early-successional trees and seedlings. We recorded no difference in species richness or diversity of late-successional or early-successional trees between lightly and heavily logged sites. However, the abundance of late-successional species was lower in heavily than lightly logged sites. Moreover, there was no difference in species richness or diversity of trees among the three forests. Yet, abundances of late-successional trees were higher in Budongo Forest than in Mabira Forest and Kakamega Forest. Species richness, diversity and abundance of seedlings did not differ between lightly and heavily logged sites. Only the abundance of seedlings of late-successional species differed among the forests with more individuals in Budongo Forest than in Mabira Forest. This was corroborated by non-metric multidimensional scaling (NMDS) showing clear differences in composition of tree and seedling communities among the three forests. Thus, both, the tree and seedling communities differed significantly among the three forests but not between lightly and heavily logged sites.

The population dynamics of the liana Machaerium cuspidatum (Fabaceae) were studied in an Amazonian forest in Ecuador using a stage-classified matrix model. Growth, mortality and number of new seedlings were recorded over two 1.5-y periods in eight 20 × 250-m transects. The population growth rate (λ) was 1.032, which was significantly higher than 1. The dynamics of the species were most influenced by survival of large plants, which is typical for slow-growing woody species. λ varied little among years or transects in spite of the high seedling production in one period. The importance of canopy openness and crown height for population growth was studied using bootstraps on λ for different subsets of the whole population. The results suggest that the population growth rate was lower in tall forest (height > 10 m) than in the population in general. The population growth rates in areas with shaded understorey and in low forest (≤ 20 m) were the same as for the whole population. A life table response experiment (LTRE) revealed that the lower λ in tall forest resulted from lower growth and survival of large plants in tall forest. These results indicate that the species is shade-tolerant but that it is sensitive to variations in forest dynamics. The dominance of the species and the increasing population size suggest that the forest has had a low disturbance rate for a long time.

Maximum assimilation rate under saturating light level, leaf nitrogen and chlorophyll content and specific leaf mass were measured in forest plants grown under a range of canopy openness. Seedlings from three tree species co-occurring in damar agroforest (Sumatra) were examined: Shorea javanica, Lansium domesticum and Cinnamomum porrectum. A shrub species, Piper hispidum, growing in a different location was also investigated. All species showed pronounced differences in maximum photosynthetic potential when grown under different canopy openness. All tree seedlings showed an increase in maximum assimilation rate (Amax) with canopy openness (CO) until a certain threshold was reached. This saturation threshold varied between species. A steady increase in the maximum assimilation rate over the entire range of canopy openness explored was found only for Piper. Correlation between leaf nitrogen content and Amax was usually highest when expressed on a per unit area basis. However the overall correlation was poor whether expressed per unit mass or per unit area when all species were pooled together questioning the universality of the relationship between both quantities. Potential photosynthetic nitrogen use efficiency, defined as the amount of CO2 uptake per unit leaf nitrogen under saturating light level, was highest in Cinnamomum, supposedly the most light-demanding species, and lowest in Lansium, the understorey specialist.

Tropical Cyclone ‘Rona’ crossed the coast of the Daintree lowlands of northeastern Australia in 1999. This study reports on its impact on forest canopy openness at six lowland rain forest sites with contrasting management histories (old-growth, selectively logged and regrowth). Percentage canopy openness was calculated from individual hemispherical photographs taken from marked points below the forest canopy at nine plots per site 3–4 mo before the cyclone, and at the same points a month afterwards. Before the cyclone, when nine sites were visited, canopy openness in old-growth and logged sites was similar, but significantly higher in regrowth forest. After the cyclone, all six revisited sites showed an increase in canopy openness, but the increase was very patchy amongst plots and sites and varied from insignificant to severe. The most severely impacted site was an old-growth one, the least impacted a logged one. Although proneness to impact was apparently related to forest management history (old-growth being the most impacted), underlying local topography may have had an equally strong influence in this case. It was concluded that the likelihood of severe impact may be determined at the landscape-scale by the interaction of anthropogenic with meteorological, physiographic and biotic factors. In the long term, such interactions may caution against pursuing forest management in cyclone-prone areas.