Assessing the functional signature of heathland landscapes via hyperspectral remote sensing

Wall-to-wall information about the state and change of vegetation is needed in many ecological applications, such as the monitoring of large conservation areas. In support of this task, remote sensing can provide valuable information that is complementary to the results from field work. Remote sensing is also well suited for change detection, but the question arises how a rate of change can be expressed in a generalized and objective way that allows comparisons between different areas. We think that true comparability can hardly be achieved by using conventional vegetation classification approaches, which are not transferable if they take account of the individuality of areas. To reach such comparability, an approach would be needed that combines generality with flexibility to adapt to local conditions.Therefore, we propose that the local vegetation is broken down into basic strategy types as proposed by Phil Grime in 1974. He observed general rules in the occurrence of three general plant strategies: competitive ability (C), stress tolerance (S), and ruderal strategy (R). Our research question is whether these strategy types can be used to derive functional signatures of landscapes as a basis for comparison between conservation areas.We used the CSR concept to map plant strategies in a heath landscape based on remote sensing data. Average Grime CSR values of vegetation samples were regressed against airborne hyperspectral imagery, resulting in spatial representations of C, S, and R (val. r² of 0.55, 0.59, and 0.28, respectively). Based on this continuous information we created functional signatures for two subareas of the study site, the ‘CSR-fingerprints’.We found clear differences in the CSR signatures of different parts of the investigated area. We think that similar differences in time can also be assessed using the same approach. This could provide a simple but powerful expression of the state of vegetation that would be comparable across regions and time. We therefore assume that the method is suitable for comparative studies with a focus on vegetation functioning. While it does not explicitly take into account differences in species composition, it can also work as an early warning system with follow-up investigations in areas subjected to change.     

Seed bank diversity in mesic grasslands in relation to vegetation type,management and site conditions

Questions: 1. Do different management types (i.e. hay meadow, silage meadow, meadow‐pasture, pasture) have different impact on the size and composition of the seed bank of mesic grassland (Arrhenatheretalia)? 2. How strong is the effect of management on the seed bank in relation to above‐ground vegetation, edaphic factors and land‐use history? 3. Are there differences in C‐S‐R plant strategy types and seed longevity under different management regimes? Location: Lahn‐Dill Highlands in central‐western Germany. Methods: Above‐ground vegetation and the soil seed bank of 63 plots (at 21 sites) in mesic grasslands were studied. Differences between management types in quantitative seed bank traits and functional characteristics were tested by ANOVA. The impact of management, above‐ground vegetation, site conditions and land‐use history on seed bank composition were analysed by partial CCA. Results: Management had no significant impact on species richness and density of the seed bank but significantly influenced their floristic composition and functional characteristics. CCA revealed that even after adjustment for soil chemical parameters and above‐ground vegetation management still had significant impact on seed bank composition. ANOVA revealed that silage meadows contained higher proportions of R‐strategy compared to hay meadows. In contrast, in hay meadows and meadow‐pastures proportions of S‐strategy were higher than in silage meadows. Conclusions: The type of grassland management has little impact on quantitative seed bank traits. Management types with a high degree of disturbance lead to an increase of species following a ruderal strategy in the seed bank. Irrespective of management type only a limited proportion of characteristic grassland species is likely to re‐establish from the seed bank after disappearance from above‐ground vegetation.     

The phosphorus‐rich signature of fire in the soil–plant system: a global meta‐analysis

The biogeochemical and stoichiometric signature of vegetation fire may influence post‐fire ecosystem characteristics and the evolution of plant ‘fire traits’. Phosphorus (P), a potentially limiting nutrient in many fire‐prone environments, might be particularly important in this context; however, the effects of fire on P cycling often vary widely. We conducted a global‐scale meta‐analysis using data from 174 soil studies and 39 litter studies, and found that fire led to significantly higher concentrations of soil mineral P as well as significantly lower soil and litter carbon:P and nitrogen:P ratios. These results demonstrate that fire has a P‐rich signature in the soil–plant system that varies with vegetation type. Further, they suggest that burning can ease P limitation and decouple the biogeochemical cycling of P, carbon and nitrogen. These effects resemble a transient reversion to an earlier stage of ecosystem development, and likely underpin at least some of fire's impacts on ecosystems and organisms.     

Are plant functional types relevant to describe degradation in arid,southern Tunisian steppes?

Abstract. In the Tunisian arid zone disturbances (e.g. overgrazing and agriculture) and stresses (e.g. aridity, low fertility) drive changes in the structure and functioning of rangelands, with a decrease in perennial plant cover, changes in floristic composition and erosion. Long‐term monitoring requires (1) an understanding of the dynamics of vegetation change and associated ecological processes and (2) identification of relevant indicators. Using data from the arid zone of southern Tunisia we tested the hypothesis that plant functional response types could be used to address these two goals. We identified plant functional response types in response to a gradient of soil and vegetation types characterized by changes in perennial plant cover, dominant species and associated soil types. Vegetation samples were stratified by contrasted vegetation patch types with varying perennial plant cover (1.6 to 22%). We focused our analysis of trait responses within dwarf–shrubs, which are the dominants in typical steppe ecosystems of south Tunisia. Available trait data concerned morphology (plant height, leaf type), regeneration (dispersal mode, phenology and regeneration mode) and grazing value. Although we found it difficult to recognize ‘indicator response types’ that could be used directly to monitor changes in community composition, we were able to identify plant response syndromes that are relevant to long‐term vegetation changes, and in particular degradation processes, in the region. Two main response types were identified: the decreaser type, made up of small or medium chamaephytes with high grazing palatability and the increaser type with medium to tall chamaephytes and low grazing palatability. These response types are proposed as key elements in a state‐and‐transition model of vegetation dynamics in the context of agropastoral disturbances and climatic and edaphic stresses.     

Effects of neighbouring vegetation on eucalypt seedlings at two sites subject to different levels of abiotic stress

Abstract In spite of numerous studies on the effect of nutrient levels and/or standing crop on the intensity of resource competition the debate has not been resolved. Field studies that have used natural productivity gradients have generally supported the argument that competitive intensity and resource availability are positively correlated, whereas studies that have used artificial resource gradients have generally refuted the same argument. Here we report the results from study in which both approaches were used within the same system. We studied two species of eucalypt that occupy contrasting parts of the same landscape: Eucalyptus camaldulensis, found mostly along creek lines and in valleys with deep alluvial soils, and Eucalyptus microcarpa, found on hillsides and ridges with shallow soils. We studied the response of seedlings of the two species to the combined effects of competition and manipulated nutrient levels in a glasshouse experiment, and also investigated their responses to removal of neighbouring plants in the field. Eucalyptus microcarpa was less responsive to increased resource availability, which is consistent with one of the principal assumptions of Grime’s C‐S‐R model. In the glasshouse experiment both species of eucalypt responded in a qualitatively similar fashion to the combined effects of resource availability and competition: release from competition resulted in increased growth, but only in pots that received additional resources. In the field we found that neighbouring vegetation could severely limit the establishment of E. camaldulensis but the removal of neighbouring vegetation did not affect the performance of E. microcarpa seedlings. Eucalyptus camaldulensis seedlings suffered high levels of damage from herbivores. Our results thus generally support the predications of the C‐S‐R model, however, they indicate that the effects of competition and herbivory may be heavily confounded.     

The relationship between soil seed bank,above‐ground vegetation and disturbance intensity on old‐field successional permanent plots

Questions: How does disturbance and successional age influence richness, size and composition of the soil seed bank? What is the potential contribution of the soil seed bank to the plant community composition on sites differing in their successional age or disturbance intensity? Location: Experimental Botanical Garden of Göttingen University, central Germany. Methods: Above‐ground vegetation and soil seed bank were studied on formerly arable fields in a 36‐year‐old permanent plot study with five disturbance intensities, ranging from yearly ploughing via mowing to long‐term uninterrupted succession. We compared species compositions, seed densities and functional features of the seed bank and above‐ground vegetation by using several methods in parallel. Results: The seed bank was mainly composed of early successional species typical of strongly disturbed habitats. The difference between seed bank composition and above‐ground vegetation decreased with increasing disturbance intensity. The species of greatest quantitative importance in the seed bank was the non‐native forb Solidago canadensis. Conclusions: The ability of a plant community to regenerate from the soil seed bank dramatically decreases with increasing time since abandonment (successional age) and with decreasing disturbance intensity. The present study underlines that plant species typical of grasslands and woodlands are limited by dispersal capacity, owing to low capacity for accumulation of seeds in the soil and the fact that most species do not build up persistent seed banks. Rare and target species were almost absent from the seed bank and will, after local elimination, depend on reintroduction for continuation of their presence.     

Numerical reproduction of traditional classifications and automatic vegetation identification

Questions: Is it possible to develop an expert system to provide reliable automatic identifications of plant communities at the precision level of phytosociological associations? How can unreliable expert‐based knowledge be discarded before applying supervised classification methods? Material: We used 3677 relevés from Catalonia (Spain), belonging to eight orders of terrestrial vegetation. These relevés were classified by experts into 222 low‐level units (associations or sub‐associations). Methods: We reproduced low‐level, expert‐defined vegetation units as independent fuzzy clusters using the Possibilistic C‐means algorithm. Those relevés detected as transitional between vegetation types were excluded in order to maximize the number of units numerically reproduced. Cluster centroids were then considered static and used to perform supervised classifications of vegetation data. Finally, we evaluated the classifier's ability to correctly identify the unit of both typical (i.e. training) and transitional relevés. Results: Only 166 out of 222 (75%) of the original units could be numerically reproduced. Almost all the unrecognized units were sub‐associations. Among the original relevés, 61% were deemed transitional or untypical. Typical relevés were correctly identified 95% of the time, while the efficiency of the classifier for transitional data was only 64%. However, if the second classifier's choice was also considered, the rate of correct classification for transitional relevés was 80%. Conclusions: Our approach stresses the transitional nature of relevé data obtained from vegetation databases. Relevé selection is justified in order to adequately represent the vegetation concepts associated with expert‐defined units.     

Plant functional types and climate at the global scale

Abstract. Globally applicable sets of terrestrial plant functional types (PFTs) have been identified as a major need in the development of dynamic global vegetation models for use with global atmospheric models. Global sets of PFTs should represent the world's most important plant types; characterize them through their functional behavior; and provide complete, geographically representative coverage of the world's land areas. Three main schools of thought on PFTs have emerged: (1) a physiological focus on internal function, especially at the level of basic metabolism; (2) an ecological focus on function in relation to plant form and environmental conditions; and (3) a geophysical focus on how plant functions affect the adjacent atmosphere. A structural approach based on pheno-physiognomy permits ready identification of relatively familiar, recognizable plant types. Many of the criteria cited by other approaches also are intimately related to structure and its seasonal changes. An earlier global system of structural-functional PFTs and their climatic relations has been improved, including addition of less well-known plant types, and is briefly described. A more strictly ‘functional’ approach is proposed, in which major aspects of plant function, initially metabolism and water balance, are used to classify functional types and suggest how these are constrained by climate. Such functional considerations, however, are closely linked to structural manifestations - but also require other functional criteria for more completely functional classifications. A recent global model of potential natural vegetation types suggested ca. 15 major plant types as necessary to cover the world's main terrestrial vegetation patterns. These essential types correspond well with a first-cut set of structural types implied by metabolic considerations.     

A hierarchical deductive approach for functional types in disturbed ecosystems

Abstract. We propose a hierarchical approach for plant functional classification in disturbed ecosystems to be used for vegetation modelling and global plant trait comparisons. Our framework is based on the persistence of plants at different levels of organization. We assume that the main parameters to determine persistence in chronically disturbed ecosystems are those related to: I ndividual‐persistence capacity, P ropagule‐persistence capacity (persistence at the population level), C ompetitive capacity (persistence at the community level) and D ispersal capacity (persistence at the landscape level). The IPCD approach is illustrated for fire‐prone and grazed ecosystems from the Mediterranean region and Australia and by assuming a binary classification of the four traits determining persistence which give a total 16 possible functional types. The IPCD framework provides a simple structured and synthetic view from which more elaborated schemes can be developed.     

New aspects of grassland recovery in old‐fields revealed by trait‐based analyses of perennial‐crop‐mediated succession

Classical old‐field succession studies focused on vegetation changes after the abandonment of annual croplands or on succession after the elimination of cultivated crops. Perennial‐crop‐mediated succession, where fields are initially covered by perennial crops, reveals alternative aspects of old‐field succession theories. We tested the validity of classical theories of old‐field succession for perennial‐crop‐mediated succession. We formulated the following hypotheses: (1) functional diversity increases with increasing field age; (2) resource acquisition versus conservation trade‐off shifts toward conservation at community level during the succession; (3) the importance of spatial and temporal seed dispersal decreases during the succession; and (4) competitiveness and stress‐tolerance increases and ruderality decreases at community level during the succession. We studied functional diversity, trait distributions and plant strategies in differently aged old‐fields using chronosequence method. We found increasing functional richness and functional divergence, but also unchanged or decreasing functional evenness. We detected a shift from resource acquisition to resource conservation strategy of communities during the succession. The role of spatial and temporal seed dispersal was found to be important not only at the initial but also at latter successional stages. We found an increasing stress‐tolerance and a decreasing ruderality during succession, while the competitiveness remained unchanged at the community level. Despite the markedly different starting conditions, we found that classical and perennial‐crop‐mediated old‐field successions have some similarities regarding the changes of functional diversity, resource acquisition versus conservation trade‐off, and seed dispersal strategies. However, we revealed also the subsequent differences. The competitive character of communities remained stable during the succession; hence, the initial stages of perennial‐crop‐mediated succession can be similar to the middle stages of classical old‐field succession. Moreover, the occupied functional niche space and differentiation were larger in the older stages, but resources were not effectively utilized within this space, suggesting that the stabilization of the vegetation requires more time.     

Mechanistic studies of sesquiterpene cyclases based on their carbon isotope ratios at natural abundance

During the process of terpene biosynthesis, C–C bond breaking and forming steps are subjected to kinetic carbon isotope effects, leading to distinct carbon isotopic signatures of the products. Accordingly, carbon isotopic signatures could be used to reveal the ‘biosynthetic history’ of the produced terpenoids. Five known sesquiterpene cyclases, regulating three different pathways, representing simple to complex biosynthetic sequences, were heterologously expressed and used for in vitro assays with farnesyl diphosphate as substrate. Compound specific isotope ratio mass spectrometry measurements of the enzyme substrate farnesyl diphosphate (FDP) and the products of all the five cyclases were performed. The calculated δ¹³C value for FDP, based on δ¹³C values and relative amounts of the products, was identical with its measured δ¹³C value, confirming the reliability of the approach and the precision of measurements. The different carbon isotope ratios of the products reflect the complexity of their structure and are correlated with the frequency of carbon–carbon bond forming and breaking steps on their individual biosynthetic pathways. Thus, the analysis of carbon isotopic signatures of terpenes at natural abundance can be used as a powerful tool in elucidation of associated biosynthetic mechanisms of terpene synthases and in future in vivo studies even without ‘touching’ the plant.     

Variation in modern pollen from tropical evergreen forests and the monsoon seasonality gradient in SW India

Abstract. This study analyses the pollen signature of tropical lowland forests (< 1000 m a.s.l.) in the Asian monsoon climate. Its aim is to investigate how well the pollen data can reproduce the vegetation patterns in tropical India, and how the variations in the pollen composition are related to the gradient of decreasing plant moisture availability (measured by the ratio of actual over equilibrium evapotranspiration) that is associated with the strong seasonality of precipitation that characterizes the monsoon climate regime. We used canonical correspondence analysis (CCA) to relate the variations in the pollen composition of 71 surface soil samples from evergreen and semi‐evergreen forests distributed along the western coast of south India (8° 48’ N‐15° 08’ N), with the climate characteristics of the sampling sites. We show that variations in plant moisture availability strongly determine variations in the pollen composition; for example evergreen and semi‐evergreen forests can be distinguished on the basis of their pollen assemblages. Variations in the mean temperature of the coldest month associated with elevation also determine distinct pollen assemblages; for example evergreen forests above 800 m a.s.l. present different pollen signatures than those below this altitude/temperature limit. Variations in the relative abundance of some pollen taxa are strongly related to plant moisture availability and taxa indicators of climate can be identified. Hence, modern pollen assemblages from tropical forests in south India carry considerable information about vegetation patterns and climate. Paleoclimatic changes, notably in the monsoon season, could be quantified.     

Vegetation classification,mapping, and monitoring at Voyageurs National Park,Minnesota: An application of the U.S. National Vegetation Classification

Question: How can the U.S. National Vegetation Classification (USNVC) serve as an effective tool for classifying and mapping vegetation, and inform assessments and monitoring? Location: Voyageurs National Park, northern Minnesota, U.S.A and environs. The park contains 54 243 ha of terrestrial habitat in the sub-boreal region of North America. Methods: We classified and mapped the natural vegetation using the USNVC, with ‘alliance’and ‘association’as base units. We compiled 259 classification plots and 1251 accuracy assessment test plots. Both plot and type ordinations were used to analyse vegetation and environmental patterns. Color infrared aerial photography (1:15840 scale) was used for mapping. Polygons were manually drawn, then transferred into digital form. Classification and mapping products are stored in publicly available databases. Past fire and logging events were used to assess distribution of forest types. Results and Discussion: Ordination and cluster analyses confirmed 49 associations and 42 alliances, with three associations ranked as globally vulnerable to extirpation. Ordination provided a useful summary of vegetation and ecological gradients. Overall map accuracy was 82.4%. Pinus banksiana - Picea mariana forests were less frequent in areas unburned since the 1930s. Conclusion: The USNVC provides a consistent ecological tool for summarizing and mapping vegetation. The products provide a baseline for assessing forests and wetlands, including fire management. The standardized classification and map units provide local to continental perspectives on park resources through linkages to state, provincial, and national classifications in the U.S. and Canada, and to NatureServe's Ecological Systems classification.     

Plant height as a simple predictor of the root to shoot ratio: Evidence from alpine grasslands on the Tibetan Plateau

Question: Since increases in altitude and grazing intensity generally result in decreases in height growth of alpine grasslands, plant height may integrate effects of environmental stress and grazing disturbance and provide better assessments of the variation in root: shoot (R: S) biomass ratio than other variables. However, it is unclear if there is a general relationship between plant height and R:S ratio across grassland ecosystems. Such knowledge would be helpful for root biomass estimation in grasslands. Location: An altitudinal transect in the Gonghe Basin (2880–4040 m a.s.l.), northeast Tibetan plateau. Methods: We measured standing biomass both above‐ground and below‐ground, maximum plant height (MPH) and soil variables across 43 plots. Results: Climatic variables explained the variations in MPH and R: S ratio of undegraded grasslands better than soil variables (46–50% vs < 19%), while those of degraded grasslands generally showed insignificant correlations with climatic and soil variables. There was a general relationship between R: S ratio and MPH (negative, R²= 0.76, P< 0.001) across degraded and undegraded grasslands. The relationship was used to predict R: S ratio in 13 additional plots in steppe grasslands of Inner Mongolia, and good agreement of expected and observed values has been found (R²= 0.87, P < 0.001). Conclusions: MPH, that is relatively easy to measure, can be used to predict R:S ratio at plot to regional scales. It is promising to develop a new method for large‐scale estimation of root biomass in grasslands using MPH and shoot biomass avoiding tedious procedures of physical measuring of above and below‐ground biomass.     

Is New Zealand vegetation really ‘problematic’? Dansereau's puzzles revisited

Over four decades ago, Pierre Dansereau, the noted North American ecologist, proposed six features of New Zealand vegetation as being problematic or unusual in a global context. We examine his propositions in the light of current ecological knowledge to determine whether or not these can still be considered unusual characteristics of New Zealand vegetation. (1) ‘Climatic change is still progressing’ resulting in disequilibrium between species' distributions and the present climate. New data and methods of analysis now available have removed the impression that Dansereau gained of imprecise zonation, unclear vegetation/climate relations and missing vegetation types. Communities cited as having regeneration failure can now be seen as even‐aged stands that developed after major disturbance, although there are other, also non‐climatic, explanations. However, the cause of the Westland ‘Nothofagus gap’ has become more, rather than less, controversial. (2) ‘Continuity of community composition defies classification’ and ‘Very few New Zealand associations have faithful species' are correct observations, but perhaps equally true of vegetation elsewhere. Dansereau's assertion of low species richness in New Zealand is not supported by the comparative data available. (3) ‘Lack of intolerant [i.e. mid‐seral] trees …’ is not evident with newer information. The order of species in succession, seen as unclear by Dansereau, has been determined by a range of approaches, largely confirming each other. (4) ‘Discrepancies of form and function …’ in divaricate shrubs and widespread heteroblasty are still controversial, with many more explanations. Several abiotic explanations have failed to stand up to investigation. Explanations in terms of herbivory have been well supported, although the extinction of the large avian herbivores makes certainty impossible. (5) ‘Incidence of hybridization …’ remains problematic. We do not know whether the incidence is unusually high, as Dansereau alleged, but the limited comparative data available suggest not. (6) The ‘overwhelming … competing power of exotics' is strongly context dependent. They are prominent in many non‐forest habitats. It seems that they are drivers of the vegetation change in some habitats, yet passengers after disturbance in others. Invasions can be slow, and may still be very incomplete in some ecosystem types. Whether exotics will eventually take over in most communities, or whether the native species will ‘laugh them to scorn’ as Cockayne suggested, only time will tell. In conclusion, some aspects of New Zealand's vegetation seem less unusual with increased knowledge, but others remain ‘problems’.     

The effect of landscape pattern on Mediterranean vegetation dynamics: A modelling approach using functional types

Abstract. In the framework of land use changes in the Mediterranean area, I asked to what extent different landscape structures might determine long‐term dynamics in Mediterranean ecosystems. To answer this question, a spatially explicit model was developed (the Melca model), incorporating two functional types of woody species dominant in Mediterranean ecosystems: a resprouter (R) and a non‐resprouter fire‐recruiter (seeders, S). The model was used as a tool for generating hypotheses on the possible consequences of different landscape scenarios. Thus, five different hierarchically structured random landscapes were generated, all having the same cover for the two functional types but different landscape structure (ranging from highly heterogeneous to homogeneous landscapes). After a 100‐yr simulation, plant cover and spatial pattern had changed and the changes were different for the different initial spatial configurations, suggesting that long‐term vegetation dynamics is spatially dependent (the resultant dynamics are sensitive to the initial spatial structure). In the landscapes where R‐type species had a low number of large patches and S‐species had a large number of small patches, the number of R‐patches increased and their size decreased, while the number of S‐patches decreased. In these cases, the final cover of the two types changed little from the initial cover. Landscapes with a large number of small R‐patches interspersed with S‐patches had a decrease in the number of R‐patches, an increase in the number of S‐patches and a decrease in the size of S‐patches. In these landscapes, final cover was significantly changed, increasing in R‐type and decreasing in S‐type species. These results suggest that low spatial autocorrelation (low aggregation) favours R‐type species. Implications for land management are also discussed.     

Synthesis of new C3 symmetric amino acid‐ and aminoalcohol‐containing chiral stationary phases and application to HPLC enantioseparations

We recently reported a new C3‐symmetric (R)‐phenylglycinol N‐1,3,5‐benzenetricarboxylic acid‐derived chiral high‐performance liquid chromatography (HPLC) stationary phase (CSP 1) that demonstrated better results as compared to a previously described N‐3,5‐dintrobenzoyl (DNB) (R)‐phenylglycinol‐derived CSP. Over a decade ago, (S)‐leucinol, (R)‐phenylglycine, and (S)‐leucine derivatives were used as the starting materials of 3,5‐DNB‐based Pirkle‐type CSPs for chiral separation. In this study, three new C3‐symmetric CSPs (CSP 2, 3, and 4) were prepared by combining the ideas and results mentioned above. Here we describe the synthetic procedures and applications of the new C3‐symmetric CSPs (CSP 2–CSP 4).     

Modern pollen–vegetation relationships along transects on the Whangapoua Estuary, Great Barrier Island, northern New Zealand

Aims To quantify pollen–vegetation relationships from saline to freshwater in an estuarine gradient from surface samples of the modern pollen rain, to allow more accurate interpretations of the stratigraphic palynological record. Location Whangapoua Estuary, Great Barrier Island, northern New Zealand. Methods Six transects were laid out along a vegetation sequence running from estuarine mud to freshwater swamp. Along these transect lines, 108 plots were sampled for vegetation and surface sediments from wet sand, mud, plant litter or moss (sand and mud sites are inundated by most tides, other sites less frequently). All sediment samples were analysed for pollen. The relationships between plant species frequency and pollen representation were examined at a community scale using twinspan and ordination analyses, and for individual species using fidelity and dispersibility indices, regression and box‐plot analyses. Results The quantitative relationships between source taxon vegetation frequency and its pollen representation varied between species due to differential pollen production and dispersal. twinspan of the surface pollen samples suggests five vegetation types: (A) mangrove (Avicennia marina); (C) Leptocarpus similis salt meadow; (D) Baumea sedges; (E) Leptospermum shrubland; and (F) Typha/Cordyline swamp forest. The (B) Juncus kraussii community is not represented palynologically owing to the destruction of its delicate pollen grains during acetolysis of samples. Detrended correspondence analysis places these communities on an estuarine‐to‐freshwater gradient. However, pollen assemblages at the seaward end of the salinity gradient are less clearly representative of the associated vegetation than those at the landward end, probably because the open vegetation at the former allows the influx of wind‐ and water‐dispersed pollen from surrounding vegetation. Main conclusions The vegetation pattern (zonation) at Whangapoua is reflected in the pollen rain. When the long‐distance and over‐represented pollen types are excluded, five out of six of the broad vegetation communities can be identified by their pollen spectra. Species with high fidelity and low‐to‐moderate dispersibility indices can be used to identify the vegetation types in the sedimentary sequences. The more open vegetation types at the ‘marine end’ of the sequence tend to be ‘overwhelmed’ by regional pollen, but the nature of the sediments and the presence of discriminatory species (e.g. A. marina, Plagianthus divaricatus, Cordyline australis), even in small amounts, will allow correct identification of the local vegetation represented in sedimentary palynological sequences. A box‐plot analysis indicates that the pollen and spore types A. marina (mangroves), Sarcocornia quinqueflora (salt meadow), P. divaricatus (sedges), Gleichenia (shrubland) and C. australis (swamp forest) are highly discriminatory in relation to vegetation type. These discriminatory palynomorphs help with the interpretation of stratigraphic pollen studies. However, salt marsh vegetation communities in the sediments must be interpreted with caution as the marine sediments are easily affected by erosion, bioturbation and tidal inundation effects.