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opencc-zeroAug 2020View details →

Three eco-physiological strategies of response to drought maintain the form and function of a tropical montane grassland

1. Ecologists seek a general scheme to classify the diversity of plant responses to environmental factors into a few strategies (e.g. competitor -C, stress-tolerant -S, ruderal-R), while plant physiologists seek a mechanistic scheme to explain such different responses (e.g. tolerance, escape, avoidance). So far, few attempts have been made to combine both perspectives into plant eco-physiological strategies. Moreover, the relative contribution of different strategies to maintain both community structure and ecosystem functioning during drought has rarely been assessed. This limits our capacity to predict how extreme events caused by climate change will affect plant communities. 2. Here, we present an integrated framework to identify plant eco-physiological strategies and to estimate their contribution to community originality (diversity of trait-combinations), dominance (species relative frequency), and ecosystem functioning (productivity and evapotranspiration). 3. We applied this framework in a tropical montane grassland and found three co-occurring eco-physiological strategies in this community (S-tolerance/avoidance, CS-escape/tolerance and CR-escape/avoidance). While CS-species contributed more to dominance and functionality, CR- and S-species contributed more to originality. Therefore, all three strategies were important to support the grassland form and function. Synthesis: Plants exhibit different strategies, as well as different contributions to community and ecosystem attributes. We developed an integrated approach to both identify strategies and estimate their relative contribution. Thereby, as droughts intensify, we can better predict which plants are more likely to be lost and how their loss will impact the communities and ecosystem where they occur. This knowledge is necessary for specifying conservation priorities and for developing more efficient conservation practices.

opencc-zeroDec 2020View details →

Data from: Impacts of habitat on butterfly dispersal in tropical forests, parks and grassland patches embedded in an urban landscape

Dispersal distances of 17 species of butterflies in tropical Singapore were significantly greater in forest than in urban habitat. Butterflies in urban plots frequently moved within suitable habitat (park/grassland) patches but rarely crossed non-habitat patches suggesting potential isolation and a need for urban corridors.

opencc-zeroDec 2016View details →

Data from: The present and future effects of land use on ecological assemblages in tropical grasslands and savannas in Africa

The world is currently experiencing a period of rapid, human-driven biodiversity loss. Over the past decade, numerous metrics for biodiversity have been used to create indicators to track change in biodiversity. However, our ability to predict future changes has been limited. In this study, we use two very different models to predict the status and possible futures for the composition and diversity of ecological assemblages in African tropical grasslands and savannas under land-use change. We show that ecological assemblages are affected more by land use in African grasslands and savannas than in other biomes. We estimate that average losses of assemblage composition and diversity are already between 9.7 and 42.0%, depending on the model and measure used. If current socio-economic trajectories continue ('business-as-usual'), the likely associated land-use changes are predicted to lead to a further 5.6–12.3% loss of assemblage composition and diversity. In contrast, a scenario that assumes more efficient use of agricultural areas (thus requiring a smaller total area) could be associated with a partial reversal ‒ of as much as 3.2% ‒ of past losses. While the agriculture that causes the majority of land-use change is an important source of economic growth, projections of the effects of land use on ecological assemblages can allow for more informed decisions.

opencc-zeroJul 2019View details →

Data from: Frost maintains forests and grasslands as alternate states in a montane tropical forest-grassland mosaic; but alien tree invasion and warming can disrupt this balance

1. Forest-grassland mosaics, with abrupt boundaries between the two vegetation types, occur across the globe. Fire and herbivory are widely considered primary drivers that maintain these mosaics by limiting tree establishment in grasslands, while edaphic factors and frosts are generally considered to be secondary factors that reinforce these effects. However, the relative importance of these drivers likely varies across systems. In particular, although frost is known to occur in many montane tropical mosaics, experimental evidence for its role as a driving factor is limited. 2. We used replicated in-situ transplant and warming experiments to examine the role of microclimate (frost and freezing temperatures) and soil in influencing germination and seedling survival of both native forest trees and alien invasive Acacia trees in grasslands of a tropical montane forest-grassland mosaic in the Western Ghats of southern India. 3. Seed germination of both native and alien tree species was higher in grasslands regard-less of soil type, indicating that germination was not the limiting stage to tree establishment. However, irrespective of soil type, native seedlings in grasslands incurred high mortality fol-lowing winter frosts and freezing temperatures relative to native seedlings in adjoining forests where freezing temperatures did not occur. Seedling survival through the tropical winter was thus a primary limitation to native tree establishment in grasslands. In contrast, alien Acacia seedlings in grasslands incurred much lower levels of winter mortality. Experimental night-time warming in grasslands significantly enhanced over-winter survival of all tree seedlings, but increases in recruitment were much greater for alien Acacia than for native tree seedlings. 4. Synthesis: Our results provide evidence for a primary role for frost and freezing temperatures in limiting tree establishment in grasslands of this tropical forest-grassland mosaic. Future increases in temperature are likely to release trees from this limitation and favour tree expansion into grasslands, with rates of expansion of non-native Acacia likely to be much greater than that of native trees. We suggest that studies of frost limitation to plant establishment are needed across a range of tropical ecosystems to re-evaluate the general importance of frost as a driver of vegetation transitions in the tropics.

opencc-zeroDec 2017View details →

Data from: Not seeing the grass for the trees: timber plantations and agriculture shrink tropical montane grassland by two-thirds over four decades in the Palani Hills, a Western Ghats Sky Island

Tropical montane habitats, grasslands, in particular, merit urgent conservation attention owing to the disproportionate levels of endemic biodiversity they harbour, the ecosystem services they provide, and the fact that they are among the most threatened habitats globally. The Shola Sky Islands in the Western Ghats host a matrix of native forest-grassland matrix that has been planted over the last century, with exotic timber plantations. The popular discourse on the landscape change is that mainly forests have been lost to the timber plantations and recent court directives are to restore Shola forest trees. In this study, we examine spatiotemporal patterns of landscape change over the last 40 years in the Palani Hills, a significant part of the montane habitat in the Western Ghats. Using satellite imagery and field surveys, we find that 66% of native grasslands and 31% of native forests have been lost over the last 40 years. Grasslands have gone from being the dominant, most contiguous land cover to one of the rarest and most fragmented. They have been replaced by timber plantations and, to a lesser extent, expanding agriculture. We find that the spatial pattern of grassland loss to plantations differs from the loss to agriculture, likely driven by the invasion of plantation species into grasslands. We identify remnant grasslands that should be prioritised for conservation and make specific recommendations for conservation and restoration of grasslands in light of current management policy in the Palani Hills, which favours large-scale removal of plantations and emphasises the restoration of native forests.

opencc-zeroDec 2014View details →

Data from: Passive restoration of sub-tropical grassland after abandonment of cultivation

Passive restoration of grasslands after the abandonment of cultivation may be a viable restoration option where seed sources from remnant grasslands are available, and if the risk of deflected succession is low. Passive restoration of subtropical grassland in Queensland, Australia was evaluated along a chronosequence of abandoned cultivation (fallow) paddocks. Plant communities in fallow paddocks were compared with nearby remnant grassland. On average, species richness recovers after 60 years of abandonment and floristic composition shows affinities with nearby remnant grassland (Bray-Curtis ˜ 0·6). The risk of deflected succession, such as dominance by exotic grasses, has apparently been low in this ecosystem. Annual grasses and forbs are rapid colonizers of the abandoned fields, and richness of perennial forbs exhibits near-linear recovery. Perennial grasses are relatively slow to establish but all except two species have statistically insignificant differences in abundance between remnant grassland and fallow fields after 20 years. The perennial grasses that recover most rapidly in fallow paddocks have disseminules that are adorned with appendages for wind dispersal including the most important dominant grass, Dichanthium sericeum. The perennial grasses that are slowest to recover are probably less effective dispersers. Synthesis and applications. Passive restoration of grasslands after the abandonment of cultivation can be a viable contribution to grassland conservation where there is an adequate matrix of remnant grasslands in the vicinity of fallows, perennial exotic species do not monopolize fallows and the dominant native grasses are well dispersed.

opennotspecifiedJan 2009View details →

Subspecies and Distribution. P. g. gymnocercus Fischer, 1814 — subtropical grasslands of NE Argentina, SE Brazil, Paraguay, and Uruguay. Pg. antiquus Ameghino, 1889 — Pampas grasslands, monte scrublands, and open woodlands of C Argentina. P. g. lordi Massoia, 1982 — Chaco-montane tropical forest ecotone in NW Argentina (Salta & Jujuy Provinces). The subspecific status of the Pampas Fox from Entre Rios Province in Argentina remains unclear, and there are no data regarding the taxonomic position of Bolivian foxes. in Canidae

Subspecies and Distribution. P. g. gymnocercus Fischer, 1814 — subtropical grasslands of NE Argentina, SE Brazil, Paraguay, and Uruguay. Pg. antiquus Ameghino, 1889 — Pampas grasslands, monte scrublands, and open woodlands of C Argentina. P. g. lordi Massoia, 1982 — Chaco-montane tropical forest ecotone in NW Argentina (Salta & Jujuy Provinces). The subspecific status of the Pampas Fox from Entre Rios Province in Argentina remains unclear, and there are no data regarding the taxonomic position of Bolivian foxes.

opennotspecifiedJan 2009View details →

Subspecies and Distribution. P. g. gymnocercus Fischer, 1814 — subtropical grasslands of NE Argentina, SE Brazil, Paraguay, and Uruguay. P.g. antiquus Ameghino, 1889 — Pampas grasslands, monte scrublands, and open woodlands of C Argentina. P. g. lordi Massoia, 1982 — Chaco-montane tropical forest ecotone in NW Argentina (Salta & Jujuy Provinces). The subspecific status of the Pampas Fox from Entre Rios Province in Argentina remains unclear, and there are no data regarding the taxonomic position of Bolivian foxes. in Canidae

Subspecies and Distribution. P. g. gymnocercus Fischer, 1814 — subtropical grasslands of NE Argentina, SE Brazil, Paraguay, and Uruguay. P.g. antiquus Ameghino, 1889 — Pampas grasslands, monte scrublands, and open woodlands of C Argentina. P. g. lordi Massoia, 1982 — Chaco-montane tropical forest ecotone in NW Argentina (Salta & Jujuy Provinces). The subspecific status of the Pampas Fox from Entre Rios Province in Argentina remains unclear, and there are no data regarding the taxonomic position of Bolivian foxes.

Fig. 4 in Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains

Fig. 4. Chain-length distribution of the very-long-chain (VLC) aliphatic compounds of leaf cuticular waxes of each of the six plant species with two different strategies of foliar water uptake. Data are shown as mean ± SD (n = 3). Bars stand for the contribution of a single chain-length to the total of VLC aliphatic wax load. Dark and grey bars represent plants with fast and slow FWU strategies, respectively. ACL: average-chain-length of the aliphatic wax fraction.

Fig. 5 in Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains

Fig. 5. NMDS plot of leaf cuticular wax composition of each of the six plant species and (A) leaf water uptake speed (parameter k) and (B) maximum leaf water absorption (parameter Cmax).

Fig. 3 in Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains

Fig. 3. Gas chromatographic analysis of cuticular waxes of the six plant species with two different strategies of foliar water uptake (FWU). Data are shown as mean ± SD (n = 3). Different letters indicate significant differences among plant species (P ≤ 0.05, One-Way ANOVA). Note that the x-axis scale is modified after the break.

Fig. 2 in Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains

Fig. 2. Leaf surfaces of the three plant species with fast foliar water uptake strategy under scanning electron microscopy. (A–C) Leandra australis (B) adaxial and (C) abaxial surfaces. (D–F) Byrsonima variabilis (E) adaxial and (F) abaxial surfaces. (G–I) Ocotea pulchella (H) adaxial and (I) abaxial surfaces. St: stomata; T: trichomes. Bars = 10 μm.

Fig. 1 in Cuticular wax composition contributes to different strategies of foliar water uptake in six plant species from foggy rupestrian grassland in tropical mountains

Fig. 1. Leaf surfaces of the three plant species with slow foliar water uptake strategy under scanning electron microscopy. (A–C) Pleroma heteromallum (B) adaxial and (C) abaxial surfaces. (D–F) Trembleya laniflora (E) adaxial and (F) abaxial surfaces. (G–I) Senna reniformis (H) adaxial and (I) abaxial surfaces. Em: emergence; St: stomata; T: trichomes; GT: glandular trichomes. Bars = 10 μm.

publicJul 2019View details →

Data from: Frost maintains forests and grasslands as alternate states in a montane tropical forest-grassland mosaic; but alien tree invasion and warming can disrupt this balance

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