Non-leguminous Forbs (non-leguminou + forb)

Distribution by Scientific Domains

Selected Abstracts

Long-term enhancement of agricultural production by restoration of biodiversity

Summary 1Experimental manipulations have shown positive impacts of increased species richness on ecosystem productivity, but there remain some questions about this relationship. First, most studies last < 4 years, which raises issues about whether diversity,productivity relationships are maintained in mature communities. Secondly, the conservation relevance of many studies is debatable. We addressed both issues using long-term experimental studies of the agriculturally relevant hay yield of recreated species-rich grasslands. 2Grasslands were recreated within replicated experiments in ex-arable fields at two sites in southern England by using either species-poor or species-rich seed mixtures. The species-poor mixture comprised seven grasses as recommended for grassland creation in English agri-environment schemes. The species-rich mixture comprised 11 grasses and 28 forbs and was designed to recreate a typical southern English hay meadow. 3After 8 years the plots sown with species-rich mixtures resembled target diverse community types. The plots sown with species-poor mixtures had been colonized by a number of forbs but had lower numbers of grasses, legumes and other forbs than the species-rich plots. Increased hay yield of the species-rich plots in the first years of the experiments have been described in an earlier paper, and these differences were maintained after 8 years. 4In the eighth year the species-rich plots had an average 43% higher hay yield than the species-poor plots. Regression analysis showed that the variation in hay yield was related to differences in the number of non-leguminous forbs and showed no relation to grass or legume numbers. This suggests increased hay yield is an effect of the greater range of life forms exhibited by forbs rather than a simple fertilizing effect of legumes. 5The nitrogen content and phosphorus content of the hay showed complex treatment effects over time. However, the nutritional value of the hay was above the minimum requirements for livestock. 6Synthesis and applications. The aims of conservationists and farmers can often be in conflict. This study has shown that the recreation of diverse grasslands of conservation value can have a positive impact on hay yield, which benefits the farm business, and this is repeated across differing sites. Because the effect is maintained over time, farm income will be increased in the long term. [source]

Ecosystem properties determined by plant functional group identity

Jennie R. McLaren
Summary 1.,Ecosystem properties may be determined by the number of different species or groups of species in a community, the identity of those groups, and their relative abundance. The mass ratio theory predicts that the effect of species or groups of species on ecosystem properties will be dependent on their proportional abundance in a community. 2.,Single plant functional groups (graminoids, legumes, non-leguminous forbs) were removed from a natural grassland in northern Canada to examine the role of group identity in determining both ecosystem properties and biomass compensation by remaining species. Removals were conducted across two different environmental treatments (fertilization and fungicide) to examine the context dependency of functional group identity effects. 3.,The degree of biomass compensation in the first 4 years after removal was influenced by the identity of the functional group removed and also of those remaining. When graminoids were removed, none of the remaining functional groups compensated for the loss of biomass. Graminoids partially compensated for the removal of forbs or legumes, with the degree of compensation depending on environmental treatments. 4.,Light interception, soil moisture and soil nutrients were all influenced by functional group identity, with graminoids having a greater impact than expected based on their biomass contribution to the community. Legumes, in contrast, had very little effect on any of the ecosystem properties measured. 5.,For most ecosystem properties measured, the role of plant functional groups was not context dependent; functional groups had the same effect on ecosystem properties regardless of fertilization or fungicide treatments. 6.,Synthesis. We have shown that the effects of losing a functional group do not solely depend on the group's dominance. In this northern grassland, there are greater effects of losing graminoids than one would predict based on their biomass contributions to the community, and functional group identity plays a critical role in determining the effects of diversity loss. [source]

Linkages between plant functional composition, fine root processes and potential soil N mineralization rates

Dario A. Fornara
Summary 1Plant functional composition may indirectly affect fine root processes both qualitatively (e.g. by influencing root chemistry) and quantitatively (e.g. by influencing root biomass and thus soil carbon (C) inputs and the soil environment). Despite the potential implications for ecosystem nitrogen (N) cycling, few studies have addressed the linkages between plant functional composition, root decay, root detritus N dynamics and soil N mineralization rates. 2Here, using data from a large grassland biodiversity experiment, we first show that plant functional composition affected fine root mass loss, root detritus N dynamics and net soil N mineralization rates through its effects on root chemistry rather than on the environment of decomposition. In particular, the presence of legumes and non-leguminous forbs contributed to greater fine root decomposition which in turn enhanced root N release and net soil N mineralization rates compared with C3 and C4 grasses. 3Second, we show that all fine roots released N immediately during decomposition and showed very little N immobilization regardless of plant composition. As a consequence, there was no evidence of increased root or soil N immobilization rates with increased below-ground plant biomass (i.e. increased soil C inputs) even though root biomass negatively affected root decay. 4Our results suggest that fine roots represent an active soil N pool that may sustain plant uptake while other soil N forms are being immobilized in microbial biomass and/or sequestered into soil organic matter. However, fine roots may also represent a source of recalcitrant plant detritus that is returned to the soil (i.e. fine roots of C4 and C3 grasses) and that can contribute to an increase in the soil organic matter pool. 5Synthesis. An important implication of our study is that the simultaneous presence of different plant functional groups (in plant mixtures) with opposite effects on root mass loss, root N release and soil N mineralization rates may be crucial for sustaining multiple ecosystem services such as productivity and soil C and N sequestration in many N-limited grassland systems. [source]

Floristic composition of a Swedish semi-natural grassland during six years of elevated atmospheric CO2

Mark Marissink
Krok & Almquist (2001) Abstract. A semi-natural grassland in Sweden was exposed to an elevated CO2 concentration during a six-year open-top chamber experiment. Vegetation composition was assessed twice a year using the point-intercept method. The field had been grazed previously, but when the experiment started this was replaced with a cutting regime with one cut (down to ground level) each year in early August. From the third to the sixth year of the study the harvested material was divided into legumes, non-leguminous forbs and grasses, dried and weighed. Elevated CO2 had an effect on species composition (as analysed by Principal Component Analysis) that increased over time. It also tended to increase diversity (Shannon index) in summer, but reduce it in spring. However, the effects of the weather and/or time on species composition and diversity were much more prominent than CO2 effects. Since the weather was largely directional over time (from dry to wet), with the exception of the fifth year, it was difficult to distinguish between weather effects and changes caused by a changed management regime. In all treatments, grasses increased over time in both mass and point-intercept measurements, whereas non-leguminous forbs decreased in mass, but not in point-intercept measurements. Legumes increased in the point-intercept measurements, but not in biomass, at elevated CO2, but not in the other treatments. Overall, we found that elevated CO2 affected species composition; however, it was only one of many factors and a rather weak one. [source]