Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.
Abstract. Question: How do functional types respond to contrasting levels of herbage use in temperate and fertile grasslands?
Location: Central France (3°1’E, 45°43’N), 870 m a.s.l.
Methods: Community structure and the traits of dominant plant species were evaluated after 12 years of contrasted grazing and mowing regimes in a grazing trial, comparing three levels of herbage use (high, medium and low).
Results and Conclusions: Of 22 measured traits (including leaf traits, shoot morphology and composition, phenology), seven were significantly affected by the herbage use treatment. A decline in herbage use reduced individual leaf mass, specific leaf area and shoot digestibility, but increased leaf C and dry matter contents. Plants were taller, produced larger seeds and flowered later under low than high herbage use. Nine plant functional response types were identified by multivariate optimization analysis; they were based on four optimal traits: leaf dry matter content, individual leaf area, mature plant height and time of flowering. In the high‐use plots, two short and early flowering types were co‐dominant, one competitive, grazing‐tolerant and moderately grazing‐avoiding, and one grazing‐avoiding but not ‐tolerant. Low‐use plots were dominated by one type, neither hardly grazing‐avoiding nor grazing‐tolerant, but strongly competitive for light.
In the past decades, Brazil made important progress in the conservation of forest ecosystems. Non-forest ecosystems (NFE), in contrast, have been neglected, even though they cover large parts of the country and have biodiversity levels comparable to forests. To avoid losing much of its biodiversity and ecosystem services, conservation and sustainable land use policies in Brazil need to be extended to NFE. A strategy for conservation of Brazil's NFE should encompass the following elements: (1) creation of new large protected areas in NFE; (2) enforcement of legal restrictions of land use; (3) extension of subsidy programs and governance commitments to NFE; (4) improvement of ecosystem management and sustainable use in NFE; and (5) improvement of monitoring of land use change in NFE. If Brazil managed to extend its conservation successes to NFE, it not only would contribute significantly to conservation of its biodiversity, but also could take the lead in conservation of NFE world-wide.
A mosaic of Campos grassland and)H=K?=HE= forest characterizes the vegetation of the Southern Brazilian highland plateau. Palaeoecological evidence indicates that forest expansion over grassland initiated after the mid Holocene, when climate changed towards present day cool and moist conditions. In this paper, we discuss landscape level changes that occurred on vegetation patterns after grazing and fire exclusion in a mosaic of Campos and)H=K?=HE= forest in Southern Brazil. The analysis of aerial photographs from 1974 and 1999 showed alterations on grassland communities under grazing and fire exclusion, especially pronounced shrub establishment near the edge of the forest. Considering the change in the cover of vegetation classes relative to the total altered cover in all classes from 1974 to 1999, the most prominent alterations were: 48% from grassland with tussock grasses dominance (GRA) to grassland with shrubs (GSR), 24% from GRA to grassland with tall shrubs (GTS), 16% from GSR to GTS and 9% from GTS to forest (FOR). Considering the alteration relatively to the vegetation cover in 1974, the most relevant changes were: 44% from GSR to GTS and 94% from GTS to FOR. These observations support a directional forest expansion over grassland under grazing and fire exclusion.
Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land–climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles.
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