Phytomass structure of natural plant communities on spodosols in southern Venezuela: the Bana woodland

Bana, or Low Amazon Caatinga is an evergreen sclerophyllous woodland. It occurs on bleached quartz sands in the lowlands of SW Venezuela, where it occupies relatively small ‘islands’ amidst Tall Amazon Caatinga which is exclusively developed on tropaquods. There is an outer vegetation belt about 20 m in width in which trees over 10 m in height occur (Tall Bana); its structure and floristic composition resemble Tall Amazon Caatinga. Low Bana (maximum tree height usually below 5 m) follows next. The central part is occupied by Open Bana in which even lower trees are very widely spaced. Destructive phytomass sampling was carried out for chemical analyses in seven plots along a 150 m line across the zonation. The total dry matter of living plants including roots of Tall Bana (30–32 kg/m²) compares rather well with 41 kg/m² in Tall Amazon Caatinga. This is only 9–14 kg/m² in Low Bana, and 4–6 kg/m² in Open Bana. The average root % of total phytomass increases from 41% in Tall Bana to 63% in Low Bana, and is 88% in Open Bana. Average total dry dead above-ground phytomass (including standing trees and stumps) declines from 1 kg/m² in Tall Bana to 0.2 kg/m² in Open Bana. An accumulation of dead matter in Low and Open Bana, relative to the above-ground phytomass of living plants, is noted and this contrasts with the general absence of raw humus in the soil. Eighty-two species of woody plants (dbh≥1 cm) were recorded on the total plot area (640 m²); 90% of the species are also known to occur in Tall Amazon Caatinga. The species number declines from 59 in Tall Bana to 18 in Open Bana. Mesophylls sensu strictu dominate in Tall Bana, while notophylls are dominant in Low and Open Bana. Herbaceous species are less numerous: most of them belong to the Araceae, Bromeliaceae, Orchidaceae, Droseraceae, Eriocaulaceae and Xyridaceae.     

Effects of herbaceous plant functional groups on the dynamics and structure of an alpine lichen heath: the results of a removal experiment

Alpine lichen heaths are polydominant, low-productive communities where lichens and, at some localities, the dwarf shrub Vaccinium vitis-idaea prevail. To analyse the role of herbaceous dominants in the structure of alpine heaths, we established a removal experiment. We tested (1) whether dominant graminoids and forbs differ in their effects on species richness, phytomass, and abundance of individual species; and (2) which remaining species are able to replace the removed dominants. Permanent plots were established in 1996 in the Teberda Reserve (the Northwestern Caucasus, Russia) at 2750 m a.s.l. with four treatments: (1) control, (2) forb removal, (3) graminoid removal, (4) graminoid and forb removal. Target species were clipped every year to avoid regrowth. We counted the shoot numbers of all vascular plants yearly from 1996 to 2009. In 2010, we harvested the aboveground phytomass. We used mixed-effects models to assess the responses of the remaining species and phytomass fractions to the removal. The biomass of the removed dominants was almost compensated for by the remaining species, but due to diffuse competition none of the subordinate species became a new dominant. Graminoid removal reduced community weighted mean leaf dry matter content and litter accumulation. Species number per plot completely recovered after graminoid, not forb removal. Shoot numbers of Antennaria dioica, Arenaria lychnidea, Campanula tridentata, Ranunculus oreophilus, and Trifolium polyphyllum showed positive responses to graminoid removal. Anemone speciosa shoot numbers decreased after graminoid removal. In alpine heath, graminoid dominants contribute more to community structure than forb dominants.     

Phylogenetic structure of a palm community in the central Amazon: changes along a hydro-edaphic gradient

The concepts of phylogenetic community structure (PCS) and phylogenetic niche conservatism (PNC) allow ecologists to address the role of species’ evolutionary history in community assembly. It is important to test the role of historical legacies relative to environmental constraints at local scales, where communities are assembled. We studied phylogenetic structure and niche conservatism for palms (Arecaceae) in the 64-km² Ducke Reserve in the central Amazon, near Manaus. The 72 study plots, each covering 0.1 ha, were distributed regularly in a terra firme forest along a hydro-edaphic gradient. We compared the observed palm PCS with assemblages generated by null models. We also analyzed whether morphological and ecological traits are labile or conserved along the phylogeny and quantified the spatial structure of morphological traits in each plot. We found an overall neutral PCS in combination with low PNC (labile traits), suggesting that evolutionary history poses little constraint on palm community assembly in this Amazonian landscape. Still, there was a tendency towards phylogenetic overdispersion in bottomlands, suggesting competitive exclusion among close relatives or, more likely, environmental filtering acting on convergent traits that affect co-occurrence in flood-prone areas. We conclude that (1) PCS of local communities is random as a whole and morphological traits are overall labile, but that (2) the hydro-edaphic gradient within terra firme forests leads to differences in species co-occurrence so that closely related species occur less often than expected in bottomlands due to diffuse competition among close relatives or environmental filtering on convergent traits.     

Nitrogen relations of ruderal communities (Rumicion alpini) in the Northern Calcareous Alps

Summary The total nitrogen and nitrate turnovers of three plots of plant communities typical of cattle resting sites in the Bavarian Alps were investigated. Annual net N mineralisation of the soil and N content of the above-ground phytomass at maximum development are low in the Senecio cordatus dominated community W at 1,450 m altitude (80 and 57 kg N/ha respectively) and highest in the nearly pure Rumex alpinus stand K (1,240 m) (156 and 148 kg N/ha). The subalpine mixed Rumex alpinus community S (1,790 m) is intermediate with low mineralisation but high N content in the aboveground parts (69 and 128 kg N/ha). In general the mineralisation values are below those from other comparable plant communities. The main component of N mineralisation is nitrification in all three plots.The nitrate content in the phytomass at full development increases from 0.1 g/m² in W to 0.3 g/m² in S and to 1.0 g/m² in K. With one exception (Adenostyles alliariae) no species showed a real nitrate accumulation in the leaf laminae towards the end of the growing season.     

A new species of Simaba (Simaroubaceae) from Pará, Brazil,with a key to the species north of the Amazon River

A new species,Simaba cavalcantei, is described and illustrated. It is considered to be intermediate between sectionsGrandiflorae andFloribundae and is distinguished from potentially sympatric species in a key to the species occurring north of the Amazon River.     

Phytomass utilization and deposition of feces by ungulates on steppe pastures of eastern Mongolia

The amount of phytomass removed by a complex of livestock (horses, cattle, sheep, and goats) and wild ungulates (Mongolian gazelle Procapra gutturosa Pall.) grazing in plain and mountain pastures of eastern Mongolia has been estimated by taking account of feces deposited by these animals. The results show that at an animal density of up to 30 head/km², the total annual amount of feces reaches 140 kg/ha (dry weight), with the greater part (up to 90 kg/ha) being deposited by horses. The contribution of Mongolian gazelles in some pastures reaches 20–40 kg/ha per year. Decomposition of feces proceeds very slowly, with the annual loss of their weight averaging only 9–12%. This is evidence for gradual accumulation of nondecomposed matter in the soil. The removal of phytomass by the complex of ungulates, calculated from the amount of feces with regard to their annual loss and forage digestibility, varies in different grazing areas from 240 to 400 kg/ha (25–60% of the total aboveground phytomass). The greatest amount of phytomass is utilized by horses, reaching 200 kg/ha (13%), and Mongolian gazelles utilize up to 86 kg/ha per year. In the growing season, ungulates remove no more than 11–16% of the total aboveground phytomass. It is concluded that the impact of total ungulate stock does not impair the productivity of vegetation in the pastures studied.     

Tree Species Composition, Structure, and Aboveground Wood Biomass of a Riparian Forest of the Lower Miranda River, Southern Pantanal, Brazil

The aboveground wood biomass (AWB) of tropical forests plays an important role in the global carbon cycle, and local AWB estimates provide essential data that enable the extrapolation of biomass stocks to ecosystem or biome-wide carbon cycle modelling. Few AWB estimates exist in Neotropical freshwater floodplains, where tree species distribution and forest structure depend on the height and duration of periodic inundations. We investigated tree species composition, forest structure, wood specific gravity, and AWB of trees ≥10 cm dbh in 16 plots totalling an area of 1 ha in a seasonally inundated riparian forest of the lower Miranda River, southern Pantanal, Brazil. The 443 tree individuals belonged to 46 species. Four species (Inga vera, Ocotea suaveolens, Tabebuia heptaphylla and Cecropia pachystachya) comprised more than 50% of the Total Importance Values (TIV), and floristic similarities between the plots averaged 38%. Although we detected an overall increase in species diversity correlated with decreasing flood levels, the most important tree species had almost identical distribution patterns along the flooding gradient. The stand basal area per plot (±?s.d.) amounted to 3.0?±?1.1 m² (47.8?±?18.1 m²/ha), and the tree heights averaged 10.9?±?1.4 m. Multiplying the individual basal areas by individual tree heights and a form factor of 0.6, we estimated the aboveground wood volume (AWV) for each individual, and for each plot (24.4?±?11.7 m³, 391.1?±?188 m³/ha). Wood specific gravity (SG) varied between 0.39 g/cm³ (Cecropia pachystachya) and 0.87 g/cm³ (Tabebuia heptaphylla), with a stand level average of 0.63?±?0.12 g/cm³. Multiplying the individual AWV with species SG, we estimated the plot AWB to be 16.2?±?6.4 Mg (259.4?±?102 Mg/ha). This value is comparable to that reported for late-successional forest stands of Amazonian floodplain forests, and it is close to the worldwide tropical average AWB. Because tree heights in the present forest were comparatively low when compared to other Neotropical forests, we found that resprouting of stems accounted for comparatively high basal areas. We argue that stem resprouting is an adaptation of tree species originating in non-flooded Cerrado to the seasonal inundations of riparian forests.     

Nutrient dynamics within amazonian forests

Summary Relationships between fine root growth, rates of litter decomposition and nutrient release were analysed in a mixed forest on Tierra Firme, a Tall Amazon Caatinga and a Low Bana on podsolized sands near San Carlos de Rio Negro. Fine root growth in the upper soil layers (root mat+10 cm upper soil) was considerably higher in the Tierra Firme forest (1117 g m^-2 yr^-1) than in tall Cattinga (120) and Bana (235). Fine root growth on top of the root mat was stimulated significantly by added N in Tall Caatinga and Low Bana forests, by P in Tierra Firme and Bana forests, and by Ca only in the Tierra Firme forest. Rate of fine root growth in Tierra Firme forest on fresh litter is strongly correlated with the Mg and Ca content of litter. Rate of litter decomposition was inversely related to % lignin and the lignin/N ratio of litter. Litter contact with the dense root mat of the Tierra Firme increased rates of disappearance for biomass, Ca and Mg as compared with litter permanently separated or lifted weekly from the root mat to avoid root attachment. Nitrogen concentration of decomposing litter increased in all forests, net N released being observed only in Caryocar glabrum and Aspidosperma megalocarpum of the Tierra Firme forest after one year of exposure. Results emphasize the differences in limiting nutrients in amazonian forest ecosystems on contrasting soil types: Tierra Firme forests are particularly limited by Ca and Mg, while Caatinga and Bana forests are limited mainly by N availability.     

Nutrient dynamics within amazonian forest ecosystems

Summary A comparative analysis on the rate of fine litterfall and its associated nutrient fluxes was carried out in a mixed forest on Tierra Firme, a tall Amazon Caatinga and a Bana on podsolized sands near San Carlos de Rio Negro. There was seasonality in leaf fall and total litterfall in mixed forest and tall Amazon Caatinga forest but no definite trend in the Bana. Litterfall curves were significantly correlated among sites indicating common regulating factors in the three forests. Leaf litter from mixed forest on Tierra Firme was richer in N with extremely low Ca and Mg concentrations; tall Amazon Caatinga litter had higher P and Mg concentration, while Bana litter was low in N but K concentration was twice as high as in the other two forests. Annual fine litterfall in Tierra Firme mixed forest was nearly 4 times higher than in Bana, But N flux was 10 times higher, while Ca and Mg fluxes were similar. Tall Amazon Caatinga had Ca and Mg fluxes in litterfall 2–3 times higher than the other two forests. Within-stand efficiency of nitrogen, calcium and magnesium use, as measured by biomass/nutrient ratios, differentiates Tierra Firme from Caatinga and Bana forest: Tierra Firme has the lowest N, but the highest Ca and Mg use efficiencies. Higher P use efficiency was measured in Bana followed by Tierra Firme and Caatinga; while Tierra Firme and Caatinga showed similar higher K use efficiencies than Bana. N/P ratios indicates that Tierra Firme forest is limited by P availability, while low N availability predominates in Caatinga. Bana appears limited by both N and P. These differences probably relate to variations in degree of sclerophylly and leaf duration which determine leaf nutrient concentrations in the ecosystems studied.     

Current state of forage resources and feeding of reindeer (<Emphasis Type="Italic">Rangifer tarandus</Emphasis>) and musk oxen (<Emphasis Type="Italic">Ovibos moschatus</Emphasis>) in the arctic tundras of Wrangel Island

The species composition and aboveground biomass of plant and lichens and the composition of reindeer and musk ox diet in the arctic tundra of Wrangel Island were studied in 2004 to 2007. The above-ground phytomass in different areas of the island varied from 1105 to 2100 kg/ha. The composition of plants consumed by reindeer and musk oxen and their proportions in the diet were determined by standard micro-histological analysis of plant remains in their feces. The results showed that, either in winter or in summer, both species obviously preferred feeding on willows (Salicaceae), which comprised almost half of their diet. Moreover, their feeding was highly selective, especially with respect to sedges and rushes (Cyperaceae + Juncaceae) and legumes (Fabaceae). Although the contributions of these plant groups to the total aboveground phytomass were very small (less than 4 and 8%), their proportions in the diet reached 27 and 24%, respectively. Mosses were not a preferred forage: their proportion in the aboveground phytomass reached 40%, but that in the diets of both species was below 10% in summer and increased to 20% only in the winter diet of reindeer. At a high abundance of lichens (up to 20% of the aboveground phytomass), neither of the animals consumed them during the study period.     

Rapid Simultaneous Estimation of Aboveground Biomass and Tree Diversity Across Neotropical Forests: A Comparison of Field Inventory Methods

A standardized rapid inventory method providing information on both tree species diversity and aboveground carbon stocks in tropical forests will be an important tool for evaluating efforts to conserve biodiversity and to estimate the carbon emissions that result from deforestation and degradation (REDD). Herein, we contrast five common plot methods differing in shape, size, and effort requirements to estimate tree diversity and aboveground tree biomass (AGB). We simulated the methods across six Neotropical forest sites that represent a broad gradient in forest structure, tree species richness, and floristic composition, and we assessed the relative performance of methods by evaluating the bias and precision of their estimates of AGB and tree diversity. For a given sample of forest area, a ‘several small’ (< 1 ha) sampling strategy led to a smaller coefficient of variation (CV) in the estimate of AGB than a ‘few large’ one. The effort (person‐days) required to achieve an accurate AGB estimate (< 10% CV), however, was greater for the smallest plots (0.1 ha) than for a compromise approach using 0.5 ha modified Gentry plots, which proved to be the most efficient method to estimate AGB across all forest types. Gentry plots were also the most efficient at providing accurate estimates of tree diversity (< 10% CV of Hill number). We recommend the use of the 0.5 ha modified Gentry plot method in future rapid inventories, and we discuss a set of criteria that should inform any choice of inventory method.     

Euphorbiaceae responses to chronic anthropogenic disturbances in Caatinga vegetation: from species proliferation to biotic homogenization

Chronic anthropogenic disturbances (CAD) have posed tangible threats to biodiversity-relevant tropical biotas, but community- and ecosystem-level impacts still remain poorly understood. Here we address a 152 km² Caatinga landscape in northeast Brazil in order to investigate how Euphorbiaceae species and these seasonally dry tropical plant assemblages respond to a CAD gradient. Woody plant species were recorded across 26 0.06 ha spatially independent plots exposed to CAD. Euphorbiaceae species accounted for 78.9% of all plants and 21.5% of all species, with some species reaching up to 283 individuals per 0.06 ha or 92% of all recorded plants. Despite such contributions, Euphorbiaceae total and relative abundance, as well as total and relative richness, did not correlate with disturbance intensity at plot scale. At species level, some Euphorbiaceae species responded positively to disturbance, while others declined or did not exhibit a consistence response (i.e., positive, negative, and neutral responses). CAD intensity affected patterns of community similarity considering the whole plant assemblage as follow: first, plot-level disturbance correlated positively with NMDS scores; second, C. sonderianus experienced a 100% increment in terms of relative abundance along the disturbance gradient, and its plot-level abundance correlated positivity with NMDS scores; and finally, cross-plot similarity correlated positively with cross-plot geographical distance. Among others, our results suggest that CAD may favor some particular species (i.e., proliferating taxa), leading to community-level changes, including biotic homogenization as disturbance increases.     

Two new species of Rhynchospora section Psilocarya (Cyperaceae)

Two new species ofRhynchospora sectionPsilocarya are described and illustrated.Rhynchospora eburnea is known from Amazonian Venezuela and nearby Brazil whileRhynchospora waspamensis is known only from eastern Zelaya, Nicaragua. These species are distinguished from most of the species of sectionPsilocarya by means of a key to the species found in the Americas south to and including the Amazon Basin.     

Factors Affecting the Abundance of Leaf-Litter Arthropods in Unburned and Thrice-Burned Seasonally-Dry Amazonian Forests

Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance.     

Site parameters,species composition,phytomass structure and element stores of a terra-firme forest in East-Amazonia,Brazil

Our objective was to asses site parameters, species diversity, phytomass structure and element stores of a Terra-firme forest prior to subsequent studies on nutrient fluxes during forest conversion. The soil was classified as a Xanthic Ferralsol, with a low effective cation exchange capacity (ECEC), low nutrient status and a deeply weathered solum. On 0.75 ha, including all trees with a DBH >7 cm, we identified 222 tree species belonging to 58 families. The above-ground phytomass was estimated using logarithmic regression analysis on two plots of 0.25 ha each. Despite differences in forest structure and species composition, no major differences were found in terms of total phytomass or overall element stores. The mean living above-ground phytomass (LAGP) was 257 Mg ha^–1, and mean quantity of litter 14 Mg ha^–1, while dead wood contributed between 10 to 17% of total above-ground phytomass (32–56 Mg ha^–1). Element store in LAGP was medium to high compared to other studies on tropical forest systems, while LAGP itself was comparatively low. Comparing 26 humid tropical forest stands recorded in literature, no correlation was found between LAGP and the amount of N and base cations stored in LAGP. However, a correlation between LAGP and P storage in LAGP (R ²=0.76) indicates the important role P may play in phytomass accumulation on zonal tropical soils. More then 60% of C, 20% of total N, 10% of total P and 66–88% of total K, Ca and Mg of the system (including the first meter of soil) were concentrated in the above-ground phytomass, including deadwood and litter. Consequently, phytomass destruction in form of forest conversion will lead to major element losses from the system.     

Metarhizium species in soil from Brazilian biomes: a study of diversity,distribution, and association with natural and agricultural environments

Metarhizium is a diverse genus of fungi adapted for different ecologies, including soil saprotrophs, entomopathogens, and endophytes. We characterized the genetic diversity and distribution of Metarhizium species in soils found in native and agricultural landscapes within Brazilian biomes (Amazon, Cerrado, Atlantic Forest, Caatinga, and Pampa). Current species limits were determined with 5′-TEF, and the genetic diversity discerned using MzIGS3 sequences. Metarhizium robertsii, Metarhizium anisopliae, Metarhizium pingshaense, and three other lineages that lie beyond currently recognized species were found. Only soils from the Amazon contained all the species. The diversity of Metarhizium species associated with native vegetation was greater than that identified in annual and perennial crops. M. robertsii was the most abundant species (65%), followed by Metarhizium sp. indet. 1, which exhibited the highest haplotype and nucleotide diversities. Metarhizium sp. indet. 3 was found predominantly in the Caatinga biome. This information increases the knowledge about diversity and belowground species composition of Metarhizium in Brazil.     

Forest and laboratory evaluations of hybridizedApanteles melanoscelus [Hym.: Braconidae], a parasitoid ofPorthetria dispar [Lep.: Lymantriidae]

Hybrids ofApanteles melanoscelus (Ratzeburg) were produced from colonies originating from France, Yugoslavia, and Connecticut. All strains, as well as freshly collected “wild” Connecticut parasitoids of the same species were evaluated in the laboratory for developmental rate, host attack rate, and sex ratios. Development was significantly slower in all the laboratory strains compared to the progeny of forest collected Connecticut females. Progeny production was greater (almost 2X) for the “wild” females and the French-Yugoslavian-Connecticut hybrid than for the laboratory Connecticut strain. The proportion of females collected from the “wild” (Connecticut) strain was higher than that observed in any laboratory strain. A field test was conducted using the triple hybrid in 3 release plots with ca. 6000A. melanoscelus cocoons released per plot in central Connecticut, U.S.A. Weekly collections of gypsy moth larvae showed that the % parasitism was significantly higher in release plots than in the 3 check plots. These results suggest the value of inundative releases ofA. melanoscelus for reduction of sparse gypsy moth populations, but they did not show that hybridization of these strains produced a more effective parasitoid under forest conditions.     

Influence of agricultural practices and seasons on the abundance and community structure of culturable pseudomonads in soils under no-till management in Argentina

Background and aims

Members of the genus Pseudomonas are common inhabitants of rhizospheres and soils, and it is known that soil types and crop species influence their population density and structure. 20?×?10⁶ ha are cultivated under no-tillage in Argentina and there is a need to find new biologically-based soil quality indexes to distinguish between sustainable and non-sustainable agricultural practices. Pseudomonads abundance and community structure were analyzed in no-till soils with different agricultural practices, in productive fields along 400 km of Argentinean Pampas.

Methods

We sampled soils and root systems from agricultural plots in which sustainable or non-sustainable agricultural practices have been applied. Samples were collected in summer and winter during 2010 and 2011. Culturable fluorescent and total pseudomonads were enumerated by plating on Gould’s selective medium S1. Colonies from these plates served as DNA source to carry out PCR-RFLP community structure analysis of the pseudomonads-specific marker genes oprF and gacA.

Results

Abundance of total and fluorescent culturable pseudomonads in bulk soils was influenced by seasonal changes and agricultural practices. Rhizospheric counts from the same crop were affected by agricultural treatments. Also, crop species influenced pseudomonads density in the rhizosphere. Combined PCR-RFLP profile of both genes showed a seasonal grouping of samples.

Conclusions

Sustainable soil management seems to promote pseudomonads development in soils, favoring root colonization of crops from those plots. Crop species influence total pseudomonads load of rhizospheres and its community structure. Total or relative pseudomonads load could function as soil quality indicator of good agricultural practices.     

Modification by an invasive ecosystem engineer shifts a wet prairie to a monotypic stand

At the landscape scale, ecosystem engineers are expected to increase species diversity; however, diversity could decline if the ecosystem engineer is over-abundant. Thus, invasive ecosystem engineers are expected to have strong impacts, due to their high abundances and novel disturbances. An invasive ecosystem engineer, the feral swine (Sus scrofa), is a species that creates intense soil disturbances, altering soil and plant communities. In this study, we examine the effects of this invasive ecosystem engineer on experimental plant plots that had been protected for over a decade. Feral swine avoided recently burned plots and preferred plots with N addition. Rooted plots shifted from a bunchgrass dominated wet prairie to a monotypic stand of the native, Lachnanthes caroliana. Feral swine were also attracted to plots with existing patches of L. caroliana suggesting a potential positive feedback between swine activity and L. caroliana patch expansion that could result in an alternative state.