A Modified-Whittaker nested vegetation sampling method

A standardized sampling technique for measuring plant diversity is needed to assist in resource inventories and for monitoring long-term trends in vascular plant species richness. The widely used Whittaker plot (Shmida 1984) collects species richness data at multiple spatial scales, using 1 m², 10 m², and 100 m² subplots within a 20 m × 50 m (1000 m²) plot, but it has three distinct design flaws involving the shape and placement of subplots. We modified and tested a comparable sampling design (Modified-Whittaker plot) that minimizes the problems encountered in the original Whittaker design, while maintaining many of its attractive attributes. We overlaid the two sampling methods in forest and prairie vegetation types in Larimer County, Colorado, USA (n=13 sites) and Wind Cave National Park, South Dakota, USA (n=19 sites) and showed that the modified design often returned significantly higher (p<0.05) species richness values in the 1 m², 10 m², and 100 m² subplots. For all plots, except seven ecotone plots, there was a significant difference (p<0.001) between the Whittaker plot and the Modified-Whittaker plot when estimating the total number of species in the 1000 m² plots based on linear regressions of the subplot data: the Whittaker plot method, on average, underestimated plant species richness by 34%. Species-area relationships, using the Modified-Whittaker design, conformed better to published semilog relationships, explaining, on average, 92% of the variation. Using the original Whittaker design, the semilog species-area relationships were not as strong, explaining only 83% of the variation, on average. The Modified-Whittaker plot design may allow for better estimates of mean species cover, analysis of plant diversity patterns at multiple spatial scales, and trend analysis from monitoring a series of strategically-placed, long-term plots.     

Sampling-Design Effects on Properties of Species-Area Relationships – A Case Study from Estonian Dry Grassland Communities

Despite widespread use of species-area relationships (SARs), dispute remains over the most representative SAR model. Using data of small-scale SARs of Estonian dry grassland communities, we address three questions: (1) Which model describes these SARs best when known artifacts are excluded? (2) How do deviating sampling procedures (marginal instead of central position of the smaller plots in relation to the largest plot; single values instead of average values; randomly located subplots instead of nested subplots) influence the properties of the SARs? (3) Are those effects likely to bias the selection of the best model? Our general dataset consisted of 16 series of nested-plots (1 cm²–100 m², any-part system), each of which comprised five series of subplots located in the four corners and the centre of the 100-m² plot. Data for the three pairs of compared sampling designs were generated from this dataset by subsampling. Five function types (power, quadratic power, logarithmic, Michaelis-Menten, Lomolino) were fitted with non-linear regression. In some of the communities, we found extremely high species densities (including bryophytes and lichens), namely up to eight species in 1 cm² and up to 140 species in 100 m², which appear to be the highest documented values on these scales. For SARs constructed from nested-plot average-value data, the regular power function generally was the best model, closely followed by the quadratic power function, while the logarithmic and Michaelis-Menten functions performed poorly throughout. However, the relative fit of the latter two models increased significantly relative to the respective best model when the single-value or random-sampling method was applied, however, the power function normally remained far superior. These results confirm the hypothesis that both single-value and random-sampling approaches cause artifacts by increasing stochasticity in the data, which can lead to the selection of inappropriate models.     

Effects of termite mounds on composition,functional types and traits of plant communities in Pendjari Biosphere Reserve (Benin,West Africa)

Understanding the role of termite mounds in biodiversity and ecosystem functioning is a priority for the management of tropical terrestrial protected areas dominated by savannahs. This study aimed to assess the effects of termite mounds on the diversity of plant functional types (PFTs) and herbaceous’ net aboveground primary productivity (NAPP) in plant communities (PCs) of the Pendjari Biosphere Reserve. PCs were identified through canonical correspondence analysis performed on 96 phytosociological ‘relevés’ realized in plots of 900 m². PFTs’ diversity was compared between savannahs and mounds’ plots using generalized linear models. In each plot, 7 m² subplots were harvested and NAPP was determined. Linear mixed models were performed to assess change in herbaceous NAPP regarding species richness, graminoids’ richness, specific leaf area and termite mounds. There is no specific plant community related to mounds. However, the occurrence of termite mounds induced an increase of woody and forbs diversity while the diversity of legumes and graminoids decreased. These diversity patterns led to decreasing of PCs’ NAPP. This study confirms that termite‐induced resource heterogeneity supports niche differentiation theory and increased savannah encroachment by woody species.     

Community Assembly of Biological Soil Crusts of Different Successional Stages in a Temperate Sand Ecosystem, as Assessed by Direct Determination and Enrichment Techniques

In temperate regions, biological soil crusts (BSCs: complex communities of cyanobacteria, eukaryotic algae, bryophytes, and lichens) are not well investigated regarding community structure and diversity. Furthermore, studies on succession are rare. For that reason, the community assembly of crusts representing two successional stages (initial, 5 years old; and stable, >20 years old) were analyzed in an inland sand ecosystem in Germany in a plot-based approach (2 × 18 plots, each 20 × 20 cm). Two different methods were used to record the cyanobacteria and eukaryotic algae in these communities comprehensively: determination directly out of the soil and enrichment culture techniques. Additionally, lichens, bryophytes, and phanerogams were determined. We examine four hypotheses: (1) A combination of direct determination and enrichment culture technique is necessary to detect cyanobacteria and eukaryotic algae comprehensively. In total, 45 species of cyanobacteria and eukaryotic algae were detected in the study area with both techniques, including 26 eukaryotic algae and 19 cyanobacteria species. With both determination techniques, 22 identical taxa were detected (11 eukaryotic algae and 11 cyanobacteria). Thirteen taxa were only found by direct determination, and ten taxa were only found in enrichment cultures. Hence, the hypothesis is supported. Additionally, five lichen species (three genera), five bryophyte species (five genera), and 24 vascular plant species occurred. (2) There is a clear difference between the floristic structure of initial and stable crusts. The different successional stages are clearly separated by detrended correspondence analysis, showing a distinct structure of the community assembly in each stage. In the initial crusts, Klebsormidium flaccidum, Klebsormidium cf. klebsii, and Stichococcus bacillaris were important indicator species, whereas the stable crusts are especially characterized by Tortella inclinata. (3) The biodiversity of BSC taxa and vascular plant species increases from initial to stable BSCs. There are significantly higher genera and species numbers of cyanobacteria and eukaryotic algae in initial BSCs. Stable BSCs are characterized by significantly higher species numbers of bryophytes and vascular plant species. The results show that, in the investigated temperate region, the often-assumed increase of biodiversity in the course of succession is clearly taxa-dependent. Both successional stages of BSCs are diversity “hot spots” with about 29 species of all taxa per 20 × 20 cm plot. (4) Nitrogen and chlorophyll a concentrations increase in the course of succession. The chlorophyll a content of the crusts (cyanobacteria, eukaryotic algae, bryophyte protonemata) is highly variable across the studied samples, with no significant differences between initial and stable BSCs; nor were ecologically significant differences in soil nutrient contents observed. According to our results, we cannot confirm this hypothesis; the age difference between our two stages is probably not big enough to show such an increase. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Monitoring an Arizona Ponderosa Pine Restoration: Sampling Efficiency and Multivariate Analysis of Understory Vegetation

As monitoring plans for the restoration of Pinus ponderosa forests in the southwestern United States evolve toward examining multifactor ecosystem responses to ecological restoration, designing efficient sampling procedures for understory vegetation will become increasingly important. The objective of this study was to compare understory composition and diversity among thin/burn and control treatments in a P. ponderosa restoration, while simultaneously examining the effects of sampling design and multivariate analyses on which conclusions were based. Using multi‐response permutation procedures (MRPP), we tested the null hypothesis of no difference in understory species composition among treatments using different data matrices (e.g., frequency and cover) for two different sampling methods. Treatment differences were subtle and were detected by an intensive 50, 1‐m² subplot sampling method for all data matrices but were not detected by a less intensive point‐intercept sampling method for any matrix. Sampling methods examined in this study controlled results of multivariate analyses more than the data matrices used to summarize data generated by a sampling method. We partitioned data into plant life form and native/exotic species categories for MRPP, and this partitioning isolated plant groups most responsible for treatment differences. We also examined the effects of number of 1‐m² subplots sampled on mean‐species‐richness/m² estimates and found that estimates based on 10 subplots and based on 50 subplots were highly correlated (r = 0.99). Species–area curves indicated that the 50, 1‐m² subplot sampling method detected the common species of sites but failed to detect the majority of rare species. Additional sampling‐design studies are needed to develop single sampling designs that produce multifactor data on plant composition, diversity, and spatial patterns amenable to multivariate analyses as part of monitoring plans of vegetation responses to ecological restoration.     

Effect of inventory plot patterns in the floristic analysis of tropical woodland and dense forest

This study was set up to examine the effect of plot patterns on the accuracy of phytosociological characterization of tropical vegetation. Fifteen and twenty square plots of 1 ha were demarcated, respectively, in woodland and dense forest in Bénin. Each 1 ha plot was divided into 100 quadrats of one 100 m². Species of trees in each quadrat were identified and recorded. The cost in terms of time required to record tree species in each 1 ha plot and five random quadrats in a 1 ha plot were also recorded to compute the mean inventory effort for a team of three foresters. From the 100 quadrats in a 1 ha plot, fourteen independent subplots of square and rectangular plots with different sizes were considered by grouping together adjacent quadrats of 100 m². Eigenanalysis was carried out to compare the subplots. Moreover, the relationship between the relative loss of accuracy (RLA) and the size of subplots was modelled. Plot size highly influenced the RLA (P < 0.05). Findings indicated that the square plots of 1500 and 1000 m² with an inventory effort of 0.35 and 0.20 man‐days per subplot, respectively in tropical dense forests and woodlands appeared to be the most efficient in the phytosociological characterization of woody vegetation.     

Late-successional biological soil crusts in a biodiversity hotspot: an example of congruency in species richness

Understanding the biodiversity of functionally important communities in Earth’s ecosystems is vital in the apportionment of limited ecosystem management funds and efforts. In southern California shrublands, which lie in a global biodiversity hotspot, biological soil crusts (BSCs) confer critical ecosystem services; however, their biodiversity remains unknown. In this study, six sites (n = 4 each, 25 m²) were established along a mediterranean shrubland environmental gradient in southern California. Here, the biodiversity of all BSC-forming lichens and bryophytes was evaluated, related to environmental traits along the gradient, and compared to species richness among North American ecosystems supporting BSCs (data from previous studies). In total, 59 BSC-forming lichens and bryophytes were observed, including the very rare Sarcogyne crustacea, a rare moss, and five endemic lichen species. Over half (61%) of the species observed were found at a single site. Along the gradient, species evenness of late-successional BSC was related to dew point and elevation, and both evenness and richness were related to distance to coast. Using an ordination analysis, five distinct late-successional BSC communities were identified: Riversidian, Spike moss, Casperian, Alisian, and Lagunian. Twenty-five lichens and 19 bryophytes are newly reported for North American BSC-forming organisms, now comprising ~1/2 of the North American total. BSCs in North American hot and cold deserts were approximately 4.0 and 2.4 times less species rich than BSCs found in southern California shrublands, respectively. Given the anthropogenic impacts on quality and distribution of California mediterranean shrublands, our results show that these sites represent important refugia of BSC species in this globally important region.     

Seeding tallgrass prairie in monospecific patches promotes native species establishment and cover

In tallgrass prairie reconstruction, the way desired seeds are arranged on the landscape may affect species establishment, species persistence, and the establishment and persistence of undesired (nonseeded) species from the local propagule pool. To test effects of species seeding pattern on how grasslands develop spatially, we seeded 20—4 × 4–m bare soil plots with 16 tallgrass prairie species. Treatment plots were divided into 16—1 × 1–m subplots, 64—0.5 × 0.5–m subplots, 256—0.25 × 0.25–m subplots, or 1,024—0.125 × 0.125–m subplots. Each species was hand broadcast into separate subplots (1 m² total area/species) within each plot. An additional treatment included uniformly mixing and broadcasting all seeds across a plot. We recorded species cover at the 0.125 × 0.125–m scale within each plot at the beginning of the second and third growing seasons. While species persistence was greatest within plots seeded with larger subplots, plots with smaller subplots were more spatially diverse and less occupied by nonseeded species over time than larger subplot and mixed plots. As is common in reconstruction efforts, establishment was variable among species and seeding with monospecific subplots enhanced colonization of desired rhizomatous species (e.g., Heliopsis helianthoides, Monarda fistulosa, Elymus virginicus) into unoccupied locations at the expense of species from the local propagule pool. Results suggest that seeding species in smaller, monospecific patches could result in grasslands with a more balanced native species composition than those established with a seed mixture approach.     

Shape matters in sampling plant diversity: Evidence from the field

The identification of shape and size of sampling units that maximises the number of plant species recorded in multiscale sampling designs has major implications in conservation planning and monitoring actions. In this paper we tested the effect of three sampling shapes (rectangles, squared, and randomly shaped sampling units) on the number of recorded species. We used a large dataset derived from the network of protected areas in the Siena Province, Italy. This dataset is composed of plant species occurrence data recorded from 604 plots (10 m × 10 m), each divided in a grid of 16 contiguous subplot units (2.5 m × 2.5 m). Moreover, we evaluated the effect of plot orientation along the main environmental gradient, to examine how the selection of plot orientation (when elongated plots are used) influences the number of species collected. In total, 1041 plant species were recorded from the study plots. A significantly higher species richness was recorded by the random arrangement of 4 subplots within each plot in comparison to the ‘rectangle’ and ‘square’ shapes. Although the rectangular shape captured a significant larger number of species than squared ones, plot orientation along the main environmental gradient did not show a systematic effect on the number of recorded species. We concluded that the choice of whether or not using elongated (rectangular) versus squared plots should dependent upon the objectives of the specific survey with squared plots being more suitable for assessing species composition of more homogeneous vegetation units and rectangular plots being more suited for recording more species in the pooled sample of a large area.     

Langfristige Auswirkungen ehemaliger Bewirtschaftungsvarianten auf die Diversit?t von Blütenpflanzen, Moosen und Flechten eines Kalkmagerrasens

Jeschke M., Kiehl K., Pfadenhauer J. and Gigon A. 2008. Long-term effects of former management on the diversity of vascular plants, mosses and lichens in a calcareous grassland. Bot. Helv. 118: 95 – 109. Long-term effects of grassland management on the species richness of vascular plants, mosses and lichens were studied in a calcareous grassland near Schaffhausen (Switzerland). Experimental plots were treated for 22 years (1977 – 1999) with different mowing regimes, annual burning in late winter, or abandonment. From 2000 onwards, all plots were mown annually in autumn. Five years later (2004), we studied the after-effects of the previous treatments by recording the cover of vascular plants, mosses and lichens in nested plots with sizes from 0.01 m² to 16 m². Vascular plant species richness as well as the number of species characteristic for calcareous grasslands were significantly lower in formerly abandoned or burnt plots than in regularly mown plots, with larger differences on small subplots. There was no significant effect of the previous mowing time (July vs. October) or mowing frequency (annual or every two years) on vascular plants. Mosses and lichens had been eliminated by annual burning between 1977 and 1999, and only few moss species re-colonized the formerly burnt plots until 2004. The species richness of mosses did not differ between formerly abandoned and mown plots, but there were more mesophytic and fewer xerophytic species in the formerly abandoned plots. Mesophytic mosses were also more abundant in plots that used to be mown every second year than in those mown annually. Our data indicate that even after five years of similar management, i.e. annual mowing in autumn, the previous long-term management had strong after-effects on species richness and species composition of calcareous grasslands. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Eingereicht am 19. M?rz 2008, Angenommen am 30. August 2008, Redaktion: Sabine Güsewell     

Does using species abundance data improve estimates of species diversity from remotely sensed spectral heterogeneity?

Different approaches for the assessment of biodiversity by means of remote sensing were developed over the last decades. A new approach, based on the spectral variation hypothesis, proposes that the spectral heterogeneity of a remotely sensed image is correlated with landscape structure and complexity which also reflects habitat heterogeneity which itself is known to enhance species diversity. In this context, previous studies only applied species richness as a measure of diversity. The aim of this paper was to analyze the relationship of richness and abundance-based diversity measures with spectral variability and compare the results at two scales. At three different test sites in Central Namibia, measures of vascular plant diversity was sampled at two scales – 100 m² and 1000 m². Hyperspectral remote sensing data were collected for the study sites and spectral variability, was calculated at plot level. Ordinary least square regression was used to test the relationship between species richness and the abundance-based Shannon Index and spectral variability. We found that Shannon Index permanently achieved better results at all test sites especially at 1000 m², Even when all sites where pooled together, Shannon Index was still significantly related with spectral variability at 1000 m². We suggest incorporating abundance-based diversity measures in studies of relationships between ecological and spectral variability. The contribution made by the high spectral and spatial resolution of the hyperspectral sensor is discussed.     

A nested-intensity design for surveying plant diversity

Managers of natural landscapes need cost-efficient, accurate, and precise systems to inventory plant diversity. We investigated a nested-intensity sampling design to assess local and landscape-scale heterogeneity of plant species richness in aspen stands in southern Colorado, USA. The nested-intensity design used three vegetation sampling techniques: the Modified-Whittaker, a 1000-m² multiple-scale plot (n = 8); a 100-m² multiple-scale Intensive plot (n = 15); and a 100-m² single-scale Extensive plot (n = 28). The large Modified-Whittaker plot (1000 m²) recorded greater species richness per plot than the other two sampling techniques (P < 0.001), estimated cover of a greater number of species in 1-m² subplots (P < 0.018), and captured 32 species missed by the smaller, more numerous 100-m² plots of the other designs. The Intensive plots extended the environmental gradient sampled, capturing 17 species missed by the other techniques, and improved species–area calculations. The greater number of Extensive plots further expanded the gradient sampled, and captured 18 additional species. The multi-scale Modified-Whittaker and Intensive designs allowed quantification of the slopes of species–area curves in the single-scale Extensive plots. Multiple linear regressions were able to predict the slope of species–area curves (adj R ² = 0.64, P < 0.001) at each Extensive plot, allowing comparison of species richness at each sample location. Comparison of species–accumulation curves generated with each technique suggested that small, single-scale plot techniques might be very misleading because they underestimate species richness by missing locally rare species at every site. A combination of large and small multi-scale and single-scale plots greatly improves our understanding of native and exotic plant diversity patterns.     

Hidden crown jewels: the role of tree crowns for bryophyte and lichen species richness in sycamore maple wooded pastures

Tree crowns typically cover the vast majority of the surface area of trees, but they are rarely considered in diversity surveys of epiphytic bryophytes and lichens, especially in temperate Europe. Usually only stems are sampled. We assessed the number of bryophyte and lichen species on stems and in crowns of 80 solitary sycamore maple trees (Acer pseudoplatanus) at six sites in wooded pastures in the northern Alps. The total number of species detected per tree ranged from 13 to 60 for bryophytes, from 25 to 67 for lichens, and from 42 to 104 for bryophytes and lichens considered together. At the tree level, 29 % of bryophyte and 61 % of lichen species were recorded only in the crown. Considering all sampled trees together, only 4 % of bryophyte, compared to 34 % of lichen species, were never recorded on the stem. Five out of 10 red-listed bryophyte species and 29 out of 39 red-listed lichen species were more frequent in crowns. The species richness detected per tree was unexpectedly high, whereas the proportion of exclusive crown species was similar to studies from forest trees. For bryophytes, in contrast to lichens, sampling several stems can give a good estimation of the species present at a site. However, frequency estimates may be highly biased for lichens and bryophytes if crowns are not considered. Our study demonstrates that tree crowns need to be considered in research on these taxa, especially in biodiversity surveys and in conservation tasks involving lichens and to a lesser degree also bryophytes.     

Space-time heterogeneity in the recovery after experimental burning and cutting in a Cistus laurifolius shrubland

Recovery after experimental burning and cutting in a shrubland of Cistus laurifolius in NW Spain has been studied. The community was homogeneous prior to the disturbances, and tended to recover through a process of autosuccession. It was tested whether in a small space (two 100 m² plots) there was a greater similarity among individual subplots (1²) in five consecutive years, or among the five subplots considered in each plot in the same year. By comparing space and time beta diversity using analysis of variance, no significant differences were observed, which indicates that temporal changes are not of a greater magnitude than space heterogeneity, even on such a small scale. Changes in time are characterized by an increase in cover by woody species, mainly Cistus laurifolius, or a decrease in the diversity and richness of species. Space heterogeneity (differences between subplots) does not seem to be determined by environmental gradients, since the sampling surface is very small, and may be due to the effect of some annual or perennial species, which are not dominant and only appear in some subplots, probably due to random dispersal.     

In and out: Effects of shoot- vs. rooted-presence sampling methods on plant diversity measures in mountain grasslands

Plant diversity measures (e.g., alpha- and beta-diversity) provide the basis for a number of ecological indication and monitoring methods. These measures are based on species counts in sampling units (plots or quadrats). However, there are two alternative conventions for defining a vascular plant species as “present” in a plot, i.e. “shoot presence” (a species is recorded if the vertical projection of any above-ground part falls within the plot) and “rooted presence” (a species is recorded only when an individual is rooted inside the plot). Very few studies addressed the effects of the two sampling conventions on species richness and diversity indices. We sampled mountain dry grasslands in Italy across different plot sizes and vegetation types to assess how large is the difference in alpha- and beta-diversity values and in sample-based rarefaction curves between the two methods. We found that the difference is greatly dependent on plot size, being more relevant, both in absolute and percentage values, at smaller grain; it is also dependent on habitat type, being larger in shallow-soil communities, as they have a sparser vegetation structure and host life-form types with a larger lateral spread. At fine spatial scales (<1 m²) the difference is large enough to bias statistical inference, and we conclude that at such scales one should not attempt to compare plant diversity indices if they were not obtained with the same sampling convention.     

Bryophyte and lichen diversity: A comparative study

Abstract We describe the regional species richness, variation in species richness and species turnover of bryophytes and lichens from 36 sites in lowland forests of southeastern Australia. The analyses subdivided the two major taxa into their constituent sub-groups: mosses, liverworts, and crustose, fruticose and foliose lichens. They also explored correlations between selected environmental variables and patterns of diversity. On a regional scale, there were 77 species of bryophytes and 69 species of lichens, giving a total of approximately one-third of the total number of vascular plant species in the region. Mean species richness was higher for lichens than bryophytes. Also, the two taxa were negatively correlated because lichens favoured dry sites and bryophytes favoured moist ones. Species turnover was greater for bryophytes than lichens, largely due to the distribution of liverwort species. Foliose lichens showed higher levels of turnover than crustose lichens. Multiple regression and canonical correspondence analysis showed that both taxa and all sub-groups responded to the same three variables: vascular plant cover, time since last fire and topographic position. Other variables, including time since logging and intensity of logging, explained little variation in bryophyte or lichen diversity. The data suggest that the strategies for the conservation of bryophyte and lichen biodiversity will be different, to reflect the different patterns of species richness and species turnover.     

The effect of plant succession on slope stability

The aim of this field investigation was to study the enrichment of biodiversity of the slope at an early phase of succession, initiated by selected pioneers, and to study how this enrichment related to enhancement of the slope stability. Four experimental plots, with differing plant pioneers and number of species (diversity), were designed in order to assess the effects of plant succession on slope stability. Plant growth pattern was assessed by observing the increment in species diversity (number), species frequency and plant biomass. Higher vegetation biomass in a mixed culture situation (LLSS) in the field with Leucaena leucocephala as a pioneer, marked an increase in species diversity after 24 months of observation. In contrast, G (grasses and legume creepers) plot revealed the slowest rate of succession and the lowest above-ground biomass amongst the plots. The mixed-culture plot without L. leucocephala (SS) had also shown a lower biomass, a similar phenomenon observed in a plot grown by L. leucocephala (LL) with low plant diversity. Consequently, these plant growth patterns gave a positive effect on slope stability where the regression study showed that the shear strength was much affected by plant biomass. Meanwhile, throughout the succession process in LLSS plot, root length density reached the highest value amongst the plots, 23 Km m^?3. In relation to this, the saturation level of the slope indicates the unsaturated condition of the soil which resulted in the enhancement of both soil penetrability and soil shear strength of the plot. These attributes reveal a strong positive relationship between the process of natural succession and the stability of slopes.     

Carbon of Chaillu forests based on a phytosociological analysis in Republic of Congo,more than meets the eye?

The objectives were to quantify aboveground, belowground and dead wood carbon pools near Mayoko in the Chaillu massif of Republic of Congo and explore relationships between carbon storage and plant diversity of all growth forms. A total of 190 plots (25 m by 25 m) were sampled (5072 stems, 211 species) and data analysed using recommended central-African forest allometric equations. Mean stem diameter at breast height was 33.6 cm, mean basal area 47.7 m² ha⁻¹ and mean density of individuals 407 ha⁻¹. Mean aboveground carbon (AGC) ranged from 13.93–412.66 Mg C ha⁻¹, belowground carbon from 2.86–96.97 Mg C ha⁻¹ and dead wood from 0.00–7.59 Mg C ha⁻¹. The maximum AGC value recorded in a plot was 916 Mg C ha⁻¹. The analysis performed using phytosociological association as basis rather than broad vegetation type is unique. AGC values for undisturbed terra firme forest sites featured among the highest recorded for African tropical forests. Considering only tree diversity, a weak, yet significant, relationship existed between AGC and species richness, Shannon-Wiener index of diversity and Fisher's alpha. However, if diversity of all plant growth forms is considered, no relationship between carbon and plant diversity existed.     

Sampling grain influences trends in vegetation composition and diversity with time since fire in Australian heathland

Scale‐dependency of pattern and process is well‐understood for many ecological communities; however, the influence of spatial scale (sampling grain) in detecting temporal change in communities is less well‐understood. The temperate lowland heathlands of south‐east Australia are one of the most fire‐prone ecosystems on earth. Despite the extensive literature documenting the effect of time since fire on heathlands, we know little about how sampling grain influences trends in vegetation variables over time, and whether these trends are scale‐dependent. Using 3500 ha of heathland in the Gippsland Lakes Coastal Park, south‐east Australia, we investigated how above‐ground species composition and diversity, and trends in these variables with increasing time since fire, were influenced by sampling grain (1 m², 10 m², 100 m², 900 m², 1 ha, 4 ha). Sampling grain influenced patterns detected in vegetation variables and in some instances, significantly affected their relationship with time since fire. Richness decreased with time since fire, with mean richness decreasing at three of the four grains, while total richness decreased at half of the sampled grains. Evenness (J) decreased with increasing time since fire for all grains except 1 m². The decline in diversity (H) with time since fire appeared to be independent of scale, as all grains decreased significantly with increasing time since fire. Community heterogeneity demonstrated a weak response to time since fire across most grains. Changes in composition among young (0–6 years since fire), intermediate (9–19 years) and old (23–27 years) sites were dependent on sampling grain, with all grains exhibiting significant differences in composition, apart from the 1 m² grain and the 100 m² grain (presence/absence data). Overall, species composition, richness, evenness, diversity and community heterogeneity were dependent on the scale at which the vegetation was sampled. In addition, trends in many of these vegetation variables with increasing time since fire were scale‐dependent. This work provides strong evidence that sampling at multiple grains contributes substantially to understanding pattern and process in heathlands.