The little studied Mount Cameroon Francolin Pternistis camerunensis is endangered and strictly endemic to the undergrowth of Mount Cameroon’s primary forest. We surveyed the species in the Mount Cameroon National Park in July–August 2016 using call playback at 86 plots systematically placed along 17 transects in an attempt to assess the occupancy and conservation threats to the species. The study’s three main results are as follows. Firstly, Mount Cameroon Francolin occurred in the stratified vegetation types across the altitudinal range of 1,023–2,186 m. Secondly, the response rates of francolin were 15% in submontane forest (800–1,600 m altitude range); 80.8% in montane forest (1,600–1,800 m); 3.9% in montane scrub (1,800–2,400 m); and nil in the lowland forest (0–800 m). Thirdly, bird abundance significantly increased with latitude, ground vegetation height, presence of Prunus africana and tall grass cover but decreased with the density of small trees and disturbance caused by heavy Prunus exploitation, and also, based on indirect evidence, hunting. We recommend: (1) systematic use of call playback in monitoring the population status of francolins; (2) an increase in patrolling and law enforcement to control illegal hunting, land clearance and burning of the upper slopes; (3) promotion of sustainable harvesting of Prunus and agroforestry practices aimed at curbing land clearance in the park surroundings. Further research priorities and conservation strategies have been suggested based on this study’s emerging results.

Each taxon is characterized by a temperature range over which seed germination is possible and this may vary in space and time in relation to climate and ecological conditions. We used thermal modelling to test the hypothesis that thermal thresholds for seed germination can predict germination timing of Mediterranean species along an altitudinal and environmental gradient. Seeds of 18 species were collected in Sardinia from sea level to 1810 m above sea level, and germination tests were carried out at a range of constant (5 to 25°C) and alternating (25/10°C) temperatures. Different dormancy-breaking treatments [gibberellic acid (GA3), cold (C) and warm (W) stratifications and dry after ripening (DAR)] were applied. The annual pattern of soil temperatures was recorded using 24 data-loggers buried close to the study species. The logged soil temperatures distinguished ‘Mediterranean lowland’ from ‘Mediterranean mountain’ species. Although germination was >50% in untreated seeds of most species, GA3 had a positive effect in all species. C either inhibited or had a neutral effect on germination, W did not enhanced seed germination, while DAR had a positive effect only in species from coastal environments. The thermal time constant (S) for 50% germination ranged from 22 to 357°Cd (degree days) above base temperatures (Tb) of –9 to 9°C, depending on species and treatments. Mediterranean lowland species had lower Tb values compared with upland species. This study revealed significant differences in germination thresholds of Mediterranean lowland and mountain species in relation to Tb and S that probably have an impact on germination timing in the field and niche competitiveness.

To investigate changes in vegetation and climate with altitude, we established forest plots and recorded climatic data at 100-m intervals between 550–1100 m asl on the western slopes of Mount Batilamu, Mount Koroyanitu range, Viti Levu, Fiji. Trees with a dbh ≥10 cm were identified and measured in 21 10 × 10-m plots, starting at 750 m altitude. Temperature and relative humidity sensors were deployed in two habitats, leaf litter and 50 cm above the ground, and two vegetation types, grasslands and forest, at six altitudes over a 48-h period. Two significantly distinct forest types, lowland and montane, were present. Montane forest was found at higher elevations (>950 m asl) and had significantly higher stem density. Mean temperature decreased significantly with altitude and was strongly moderated by vegetation type (lower average and less variation in forest). While average relative humidity significantly increased with altitude, it was strongly moderated by both habitat and vegetation type (higher average and less variation in leaf litter and forest). The lapse rate varied with time of day (higher during the day) and vegetation type (higher in grasslands). Therefore, vegetation and microhabitats create unique microclimates, and this should be considered when investigating current or future climatic patterns along altitudinal gradients on forested mountains.

Patterns in above-ground biomass of tropical forests over short altitudinal gradients are poorly known. The aim of this study was to investigate the variation of above-ground biomass with altitude in old-growth forests and determine the importance of changes in floristic composition as a cause of this variation. We used a dataset from 15 1-ha permanent plots established from lowland (200 m asl) to submontane forests (900 m asl) in the Ngovayang Massif, south-western Cameroon. We analysed variation over altitude in two specific functional traits, the potential maximum tree height and the wood density. Forest above-ground biomass decreased from 500–600 Mg ha−1 in lowland plots to around 260 Mg ha−1 at the highest altitudes. The contribution to above-ground biomass of large-tree species (dbh ≥ 70 cm) decreased with altitude, while the contribution of smaller trees was constant. Contribution of the Fabaceae subfamily Caesalpinioideae decreased with altitude, while those of Clusiaceae, Phyllanthaceae and Burseraceae increased. While potential maximum tree height significantly decreased, wood specific gravity displayed no trend along the gradient. Finally, the decrease in above-ground biomass along the short altitudinal gradient can be at least partially explained by a shift in species composition, with large-tree species being filtered out at the highest altitudes. These results suggest that global change could lead to significant shifts in the properties of montane forests over time.

Not much is known about the nitrogen (N) uptake capacity and N-form preference of tropical trees. In a replicated labelling experiment with 15N-ammonium, 15N-nitrate and dual-labelled glycine applied to saplings of six tree species from southern Ecuadorian montane forests, we tested the hypotheses that (1) the saplings of tropical trees are capable of using organic N even though they are forming arbuscular mycorrhizas, and (2) with increasing altitude, tree saplings increasingly prefer ammonium and glycine over nitrate due to reduced nitrification and growing humus accumulation. Three- to 5-y-old saplings of two species each from 1000, 2000 and 3000 m asl were grown in pots inside the forest at their origin and labelled with non-fertilizing amounts of the three N forms; 15N enrichment was detected 5 days after labelling in fine roots, coarse roots, shoots and leaves. The six species differed with respect to their N-form preference, but neither the abundance of ammonium and nitrate in the soil nor altitude (1000–3000 m asl) seemed to influence the preference. Two species (those with highest growth rate) preferred NH4+ over NO3−, while the other four species took up NO3− and NH4+ at similar rates when both N forms were equally available. After 13C-glycine addition, 13C was significantly accumulated in the biomass of three species (all species with exclusively AM symbionts) but a convincing proof of the uptake of intact glycine molecules by these tropical montane forest trees was not obtained.

Population cycles of the winter moth (Operophtera brumata) in sub-arctic coastal birch forests show high spatiotemporal variation in amplitude. Peak larval densities range from levels causing little foliage damage to outbreaks causing spatially extensive defoliation. Moreover, outbreaks typically occur at or near the altitudinal treeline. It has been hypothesized that spatiotemporal variation in O. brumata cycle amplitude results from climate-induced variation in the degree of phenological matching between trophic levels, possibly between moth larvae and parasitoids. The likelihood of mismatching phenologies between larvae and parasitoids is expected to depend on how specialized parasitoids are, both as individual species and as a guild, to attacking specific larval developmental stages (i.e. instars). To investigate the larval instar-specificity of parasitoids, we studied the timing of parasitoid attacks relative to larval phenology. We employed an observational study design, with sequential sampling over the larval period, along an altitudinal gradient harbouring a pronounced treeline outbreak of O. brumata. Within the larval parasitoid guild, containing seven species groups, the timing of attack by different groups followed a successional sequence throughout the moth's larval period and each group attacked 1–2 instars. Such phenological diversity within parasitoid guilds may lower the likelihood of climate-induced trophic mismatches between victim populations and many/all of their enemies. Parasitism rates declined with increasing altitude for most parasitoid groups and for the parasitoid guild as a whole. However, the observed spatiotemporal parasitism patterns provided no clear evidence for or against altitudinal mismatch between larval and parasitoid phenology.

We conducted a study on small-mammal composition, abundance and diversity across altitudinal and vegetational gradients in the Urucum Mountains (from 150 to 1000 m asl) in western Brazil, a complex biogeographic region. Small mammals were collected in 31 sampling units distributed along altitudinal and vegetational gradients (forest and grassland), totalling 18 112 trap-nights for pitfall and 3500 trap-nights for live-trap. Community variation among sampling units was assessed by randomization tests, setting altitude, vegetation, locality and time as factors, and using presence/absence data. Correlation and logistic regression analyses were run for species and diversity along gradients of altitude and vegetation, according to abundance and presence/absence data. Nineteen species (seven marsupial and 12 rodent) and 355 individuals were recorded. The species composition of small mammals differed according to altitude, vegetation type, locality and time. Species diversity varied significantly according to altitude. Species were influenced solely by altitude or vegetation, or by both vegetation and altitude concomitantly. The small-mammal community was divided in two groups according to biogeographic affinities. The grassland group is capable of invading forest habitats. The results are discussed in light of current hypotheses that attempt to explain community variation along altitudinal gradients around the world.

A soil climate monitoring network, consisting of seven automated weather stations, was established between 1999 and 2003, ranging from Minna Bluff to Granite Harbour and from near sea level to about 1700 m on the edge of the polar plateau. Active layer depth was calculated for each site for eight successive summers from 1999/2000 to 2006/2007. The active layer depth varied from year to year and was deepest in the warm summer of 2001–02 at all recording sites. No trends of overall increase or decrease in active layer depth were evident across the up-to-eight years of data investigated. Average active layer depth decreased with increasing latitude from Granite Harbour (77°S, active layer depth of > 90 cm) to Minna Bluff (78.5°S, active layer depth of 22 ± 0.4 cm), and decreased with increasing altitude from Marble Point (50 m altitude, active layer depth of 49 ± 9 cm) through to Mount Fleming (1700 m altitude, active layer depth of 6 ± 2 cm). When all data from the sites were grouped together and used to predict active layer depth the mean summer air temperature, mean winter air temperature, total summer solar radiation and mean summer wind speed explained 73% of the variation (R2 = 0.73).