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A leaf-height-seed (LHS) plant ecology strategy scheme is proposed. The axes would be specific leaf area SLA (light-capturing area deployed per dry mass allocated), height of the plant's canopy at maturity, and seed mass. All axes would be log-scaled. The strategy of a species would be described by its position in the volume formed by the three axes. The advantages of the LHS scheme can be understood by comparing it to Grime's CSR scheme, which has Competitors, Stress-tolerators and Ruderals at the corners of a triangle. The CSR triangle is widely cited as expressing important strategic variation between species. The C-S axis reflects variation in responsiveness to opportunities for rapid growth; in the LHS scheme, SLA reflects the same type of variation. The R axis reflects coping with disturbance; in the LHS scheme, height and seed mass reflect separate aspects of coping with disturbance. A plant ecology strategy scheme that permitted any species worldwide to be readily positioned within the scheme could bring substantial benefits for improved meta-analysis of experimental results, for placing detailed ecophysiology in context, and for coping with questions posed by global change. In the CSR triangle the axes are defined by reference to concepts, there is no simple protocol for positioning species beyond the reference datasets within the scheme, and consequently benefits of worldwide comparison have not materialized. LHS does permit any vascular land plant species to be positioned within the scheme, without time-consuming measurement of metabolic rates or of field performance relative to other species. The merits of the LHS scheme reside (it is argued) in this potential for worldwide comparison, more than in superior explanatory power within any particular vegetation region. The LHS scheme avoids also two other difficulties with the CSR scheme: (a) It does not prejudge that there are no viable strategies under high stress and high disturbance (the missing quadrant in the CSR triangle compared to a two-axis rectangle); (b) It separates out two distinct aspects of the response to disturbance, height at maturity expressing the amount of growth attempted between disturbances, and seed mass (inverse of seed output per unit reproductive effort) expressing the capacity to colonize growth opportunities at a distance. The advantage of LHS axes defined through a single readily-measured variable needs to be weighed against the disadvantage that single plant traits may not capture as much strategy variation as CSR's multi-trait axes. It is argued that the benefits of potential worldwide comparison do actually outweigh any decrease in the proportion of meaningful variation between species that is captured. Further, the LHS scheme opens the path to quantifying what proportion of variation in any other ecologically-relevant trait is correlated with the LHS axes. This quantification could help us to move forward from unprofitable debates of the past 30 years, where CSR opponents have emphasized patterns that were not accommodated within the scheme, while CSR proponents have emphasized patterns that the scheme did account for.

A long-term research programme, conducted mainly in northern England, has involved field surveys (1965-77), laboratory screening (1974-96), monitoring of permanent plots (1958 to date) and manipulative experiments (1987 to date). The so-called C-S-R classification of plant functional types developed from all this activity. Patterns of covariation among the traits used in the classification have recently been validated in this journal. The C-S-R classification appears to be applicable to vegetation in general. It thus has considerable potential for interpreting and predicting vegetation and ecosystem properties on a world-wide scale. However, to realize this potential we need to develop simplified procedures to extrapolate the C-S-R system to the many species which have not been the subject of previous ecological investigation. Here we describe a rapid method for attribution of C-S-R type and we test its accuracy in Britain by comparing it with an independent classification based upon more laborious procedures. The new method allocates a functional type to an unknown herbaceous subject using few, simple predictor variables. We have developed spreadsheets to perform all of the necessary calculations. These may be downloaded from the UCPE website at http://www.shef.ac.uk/uni/academic/N-Q/nuocpe, or obtained by direct application to the E-mail address ucpe@sheffield.ac.uk

Some theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2subplots (20 1000-m2modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2subplots (16 1000-m2plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm. At the 1-m2scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2plots was explained by the number of native plant species and the total percentage of soil carbon. At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and biodiversity), are invasible in many landscapes; and (2) this pattern may be more closely related to the degree resources are available in native plant communities, independent of species richness. Exotic plant invasions in rare habitats and distinctive plant communities pose a significant challenge to land managers and conservation biologists.

In this study, flood frequency, productivity, and spatial heterogeneity were correlated with plant species richness (SR) among wetlands on a coastal island in southeast Alaska. Studies of 16 sites in or near the Kadashan River basin demonstrated nonlinear, unimodal relations between flood frequency and SR, productivity and SR, and linear relations between SR and the spatial variation of flood frequencies (SVFF) within a site. SVFF is caused by microtopographic variation in elevation. A nonlinear regression model relating SR to flood frequency and SVFF explained much of the variation in SR between wetland communities. Sites with intermediate flood frequencies and high SVFF were species-rich, while sites frequently, rarely, or permanently flooded and with low SVFF were species-poor. The data suggest that small-scale spatial variation can dramatically alter the impact of disturbances. The data also support Michael Huston's dynamic-equilibrium model of species diversity, which predicts the effects of productivity and disturbance on diversity patterns. Species-rich sites had low to intermediate levels of productivity and intermediate flood frequencies, and species-poor sites had very low or high flood frequencies and low productivity, supporting the model's predictions. The model was tested at contrasting spatial scales (1000 m2and 1 m2) At the 1000-m2scale, Huston's model predicted 78% of the variation in SR. At the microplot scale, relationships between SR and flood frequency were weaker, and the dynamic-equilibrium model predicted only 36% of the variation in SR.

Recent improvements in our understanding of the dynamics of soil carbon have shown that 20-40% of the approximately 1,500 Pg of C stored as organic matter in the upper meter of soils has turnover times of centuries or less. This fast-cycling organic matter is largely comprised of undecomposed plant material and hydrolyzable components associated with mineral surfaces. Turnover times of fast-cycling carbon vary with climate and vegetation, and range from 20 years at low latitudes to 60 years at high latitudes. The amount and turnover time of C in passive soil carbon pools (organic matter strongly stabilized on mineral surfaces with turnover times of millennia and longer) depend on factors like soil maturity and mineralogy, which, in turn, reflect long-term climate conditions. Transient sources or sinks in terrestrial carbon pools result from the time lag between photosynthetic uptake of CO2 by plants and the subsequent return of C to the atmosphere through plant, heterotrophic, and microbial respiration. Differential responses of primary production and respiration to climate change or ecosystem fertilization have the potential to cause significant interrannual to decadal imbalances in terrestrial C storage and release. Rates of carbon storage and release in recently disturbed ecosystems can be much larger than rates in more mature ecosystems. Changes in disturbance frequency and regime resulting from future climate change may be more important than equilibrium responses in determining the carbon balance of terrestrial ecosystems

Natural ecosystems contain many individuals and species interacting with each other and with their abiotic environment. Such systems can be expected to exhibit complex dynamics in which small perturbations can be amplified to cause large changes. Here, we document the reorganization of an arid ecosystem that has occurred since the late 1970s. The density of woody shrubs increased 3-fold. Several previously common animal species went locally extinct, while other previously rare species increased. While these changes are symptomatic of desertification, they were not caused by livestock grazing or drought, the principal causes of historical desertification. The changes apparently were caused by a shift in regional climate: since 1977 winter precipitation throughout the region was substantially higher than average for this century. These changes illustrate the kinds of large, unexpected responses of complex natural ecosystems that can occur in response to both natural perturbations and human activities.

Several studies have suggested the existence of a positive relationship between the Normalized Difference Vegetation Index (NDVI) derived from AVHRR/NOAA satellite data and either biomass or annual aboveground net primary production (ANPP) for different geographic areas and ecosystems. We calibrated a 4-yr average of the ingegral of the NDVI (NDVI-I) using spatially aggregated values of ANPP. We also provided an estimate of the energy conversion efficiency coefficient (ε) of Monteith's equation. This is the first attempt to calibrate a standard NDVI product for temperate perennial grasslands. We found a positive and statistically significant relationship between NDVI-I and ANPP for grassland areas with mean annual precipitation between 280 and 1150 mm, and mean annual temperature between 4⚬ and 20⚬ C. Depending on the method used to estimate the fraction of photosynthetic active radiation, the energy conversion officency coefficient was constant (0.24 g C/MJ), or varied across the precipitation gradient, from 0.10 g C/MJ for the least productive to 0.20 g C/MJ for the most productive sites.

La erosión costera está relacionada directamente con el desbalance sedimentario que afecta las playas a nivel mundial, y tiene el potencial de cambiar las condiciones que requieren las comunidades vegetales. El objetivo de esta investigación es caracterizar la composición del bosque y el gradiente ambiental en dos áreas protegidas con erosión costera en el Caribe Sur de Costa Rica. Se realizaron 70 parcelas circulares de 15 m de diámetro que abarcaron desde los 50 m y hasta los 200 m tierra adentro, ubicados de manera perpendicular a las playas del Parque Nacional Cahuita (PNC) y Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (REGAMA), que han sido identificadas previamente con tendencia erosiva fuerte entre 1960-2023. En cada parcela, se midieron parámetros fisicoquímicos y ambientales, se identificaron las especies de árboles y se analizaron las texturas del suelo. Se evidenció una zonificación que abarca desde los 50 m y hasta los 200 m respecto al mar, principalmente para los análisis fisicoquímicos y la textura del suelo, que inciden en la composición y estructura del bosque. Tanto en el PNC como en el REGAMA se destaca un ensamble básico de especies que funcionan como estabilizadoras de las reservas de sedimento de playas arenosas, que incluyen a Prioria copaifera, Lonchocarpus heptaphyllus, Pterocarpus officinalis, Rhizophora mangle, Laguncularia racemosa y Tabernamontana alba. Se concluye que, en ambas áreas protegidas, la erosión costera tiene efectos sobre la composición del bosque e incide en los gradientes ambientales que se presentan en los primeros metros de la costa. Coastal erosion is directly related to sediment imbalance that affects beaches worldwide and possesses the potential to alter the conditions requisite for plant communities. This research aimed to characterize the forest composition and environmental gradient in two protected areas with coastal erosion in the Southern Caribbean, Costa Rica. Seventy circular plots of 15 m diameter were located perpendicular to the coastal edge and carried out from 50 m from the coastline to 200 m inland in the Cahuita National Park (PNC) and the Gandoca-Manzanillo National Wildlife Refuge (REGAMA), which have been previously identify as those with the stronger erosion tendency between 1960-2023. We collected environmental and physicochemical parameters, identified the tree species, and analyzed the soil texture in each plot. Zoning from 50 m to 200 m from the sea was observed, mainly for physicochemical analysis and soil texture, which affect the composition and structure of the forest. In both the PNC and REGAMA, there is a crude assemblage of species that function as stabilizers of the sediment reserves of sandy beaches, including Prioria copaifera, Lonchocarpus heptaphyllus, Pterocarpus officinalis, Rhizophora mangle, Laguncularia racemosa and Tabernamontana alba. In conclusion, in both protected areas, coastal erosion affects the forest composition and the environmental gradients that occur in the first meters of the coast.

Vegetation is sparsely distributed over Antarctica's ice-free ground, and distinct plant communities are present in each of the continent's 15 recently identified Antarctic Conservation Biogeographic Regions (ACBRs). With rapidly increasing human activity in Antarctica, terrestrial plant communities are at risk of damage or destruction by trampling, overland transport, and infrastructure construction and from the impacts of anthropogenically introduced species, as well as uncontrollable pressures such as fur seal (Arctocephalus gazella) activity and climate change. Under the Protocol on Environmental Protection to the Antarctic Treaty, the conservation of plant communities can be enacted and facilitated through the designation of Antarctic Specially Protected Areas (ASPAs). We examined the distribution within the 15 ACBRs of the 33 ASPAs whose explicit purpose includes protecting macroscopic terrestrial flora. We completed the first survey using normalized difference vegetation index (NDVI) satellite remote sensing to provide baseline data on the extent of vegetation cover in all ASPAs designated for plant protection in Antarctica. Large omissions in the protection of Antarctic botanical diversity were found. There was no protection of plant communities in 6 ACBRs, and in another 6, <0.4% of the ACBR area was included in an ASPA that protected vegetation. Protected vegetation cover within the 33 ASPAs totaled 16.1 km² for the entire Antarctic continent; over half was within a single protected area. Over 96% of the protected vegetation was contained in 2 ACBRs, which together contributed only 7.8% of the continent's ice-free ground. We conclude that Antarctic botanical diversity is clearly inadequately protected and call for systematic designation of ASPAs protecting plant communities by the Antarctic Treaty Consultative Parties, the members of the governing body of the continent. La vegetación se encuentra distribuida escasamente sobre el suelo libre de hielo de la Antártida y están presentes distintas comunidades vegetales en cada una de las 15 Regiones Biogeográficas de Conservación Antártica (RBCA) identificadas recientemente. Con un rápido incremento de la actividad humana en la Antártida, las comunidades de plantas terrestres están en riesgo de ser dañadas o destruidas por el pisoteo, el transporte terrestre, la construcción de infraestructura y el impacto de las especies introducidas por el hombre, así como por presiones incontrolables como la actividad del lobo marino antártico (Arctocephalus gazella) y el cambio climático. Bajo el Protocolo sobre la Protección Ambiental al Tratado Antártico, la conservación de las comunidades vegetales puede promulgarse y facilitarse por medio de la designación de las Zonas Antárticas Especialmente Protegidas (ZAEP). Examinamos la distribución dentro de las 15 RBCA de las 33 ZAEP cuyo propósito explícito incluye la protección de la flora macroscópica terrestre. Completamos el primer censo con el uso de teledetección satelital del índice de vegetación de diferencia normalizada (IVDN) para proporcionar el punto de referencia de datos sobre la extensión de la cobertura vvvegetal en todas las RBCA designadas para la protección de plantas en la Antártida. Se encontraron grandes omisiones en la protección de la diversidad botánica de la Antártida. No hubo protección en las comunidades vegetales de seis RBCA y en otras seis, <0.4% del área de la RBCA estuvo dentro de una ZAEP que protegía a la vegetación. La cobertura de vegetación protegida dentro de las 33 RBCA tuvo un total de 16.1 km² de todo el continente antártico; más de la mitad se ubicó dentro de una única área protegida. Más del 96% de la vegetación protegida se encontró en dos RBCA, las cuales en conjunto contribuyen con sólo el 7.8% del suelo libre de hielo del continente. Concluimos que la diversidad botánica de la Antártida está claramente mal protegida y requiere de una designación sistemática de ZAEP que protejan las comunidades vegetales por parte de las Partes Consultivas del Tratado Antárico, los miembros del cuerpo de gobierno del continente.

Carbon-isotope values of bulk organic matter from high-altitude lakes on Mount Kenya and Mount Elgon, East Africa, were 10 to 14 per mil higher during glacial times than they are today. Compound-specific isotope analyses of leaf waxes and algal biomarkers show that organisms possessing CO2-concentrating mechanisms, including C4 grasses and freshwater algae, were primarily responsible for this large increase. Carbon limitation due to lower ambient CO2 partial pressures had a significant impact on the distribution of forest on the tropical mountains, in addition to climate. Hence, tree line elevation should not be used to infer palaeotemperatures