Changes In Botanical Composition Research Articles

Can mulching or composting be applied to maintain semi-natural grassland managed for biodiversity?

Traditional, extensive management systems in grasslands have played a fundamental role in the formation, maintenance and conservation of grassland of high natural value. Contemporary processes in the agricultural economy make this type of management unprofitable. Simplified management systems are implemented as part of agricultural and environmental programmes and in protected areas, but these can cause changes in botanical composition. An experiment was conducted for six years on grassland in the Carpathian Mountains to compare mulching and compost application with late cutting and biomass removal. In the conditions of mountain grassland of medium fertility, the level of biomass and the species composition of the vegetation were the same following mulching as in the case of cutting and biomass removal. Mulching was only found to affect the temperature of the topsoil. Compost application caused a significant increase in the amount of biomass. The species composition was the same as for the other management types, but there were changes in the proportions of individual species and functional groups. High grasses were dominant, while the proportion of legume plants was small. Moreover, the N:P ratio was lower following the use of compost, indicating a shift from P limitation to N limitation. Mulching can be used as a simplified means of management in the case of certain types of grassland communities, but its effects must be monitored. Compost application would necessitate modification of other elements of management, e.g. increased frequency of cutting.

Spatiotemporal variation in aboveground biomass in a tropical grass pasture over a 22‐year period

AbstractThis study monitored spatiotemporal variation in aboveground biomass of a paddock (1.1 ha) in a sown tropical grass pasture under cattle grazing over a 22‐year period (1995–2016) by nondestructively estimating biomasses of 182 fixed locations (0.5 × 0.5 m each) in the paddock at about monthly intervals during the annual stocking season (May to October or November). The mean aboveground biomass of the paddock varied seasonally and interannually between 33 and 605 g DM/m2 and was explained by a regression model including positive effects of mean air temperature, N fertilizer rate and total precipitation during the preceding 60 days (R2 = 0.311, P < 0.001). The coefficient of variation of aboveground biomass, as an indicator of spatial (within‐paddock) variability, varied seasonally and interannually between 0.16 and 0.94, and was described by a model incorporating a positive effect of cumulative stocking density during the preceding 40 days and negative effects of mean air temperature, total precipitation during the preceding 20 days and N fertilizer rate during the preceding 60 days (R2 = 0.277, P < 0.001). The spatial distribution pattern of aboveground biomass in the paddock was persistent (P < 0.05) or not persistent over the study period, almost without being reversed. In detail, patterns in the mid stocking season tended to maintain mutual similarity in the entire range of the intervals between the measurements (364–7,694 days), whereas those at the beginning and near end of the stocking season lost mutual similarity as the interval increased. There was no indubitable evidence that the changes in botanical composition destabilized the spatial distribution pattern of aboveground biomass. The results indicate the need for assessing how the long‐term stability of the within‐paddock distribution pattern of aboveground biomass affects agronomic and ecological performance of the grazing system.

Effects of fall stocking rates on naturalized cool‐season stockpiled pastures

AbstractThe potential of tall fescue (Schedonorus arundinaceus Dumort) and orchardgrass (Dactylis glomerata L.) as stockpiled forages has been documented; however, limited information describes the characteristics of other species, especially complex mixtures of cool‐season naturalized pastures. A 3‐yr study assessed the herbage mass, forage quality, and botanical composition of mixed cool‐season naturalized pastures [orchardgrass, tall fescue, clover (Trifolium spp.), narrowleaf plantain (Plantago lanceolata L.), and quackgrass (Elymus repens [L.] Gould)] in response to two stocking rates based on daily herbage allowances of 3.5% (low) or 7.0% (high) of heifer bodyweight. The stocking rate for the entire pasture area, including unoccupied paddocks during the grazing period, was 2.4 and 1.3 heifers acre−1 for the low and high treatments, respectively. Stockpiling began in August; grazing began in early November. The initial herbage mass and botanical composition were determined at the end of the stockpiling period. Herbage samples were taken throughout the fall grazing period at intervals of 11 to 19 d. The stocking rate had no effect on changes in botanical composition. Total legume percentage increased from 6% in Year 1 to 31% in Year 3 (P < .05). Herbage mass declined more quickly in Year 3 than in Years 1 and 2 (P < .05), probably because of the high percentage of legumes. As fall grazing progressed, crude protein content and in vitro true dry matter digestibility declined, and neutral detergent fiber content increased. Mixed cool‐season naturalized pastures could be used for stockpiling and grazed intensively without detrimental effects on subsequent stockpiling periods.

Természetvédelmi célú botanikai, takarmányozástani és talajtani vizsgálatok a Tapolcai és Káli-medence szürkemarha és bivaly legelőin

In the present work we introduce the coenological and pedological results of examination on the Balaton Upland (Badacsonytördemic, Csobánc, Káptalantóti and Kővágóőrs). Grass management plays an important role in nature conservation, rural development thus in the viability of rural population. Soil and water suffer from extreme degradation and pollution, partly because of agricultural activities, growing settlements and mining activity. We evaluated the changes in species composition and coverage, the possibly occurring regeneration or degradation and the effects of botanical composition changes on forage values, especially in case of economically valuable species. Investigations show strengths and weaknesses of having animals on grasslands. Sample sites were in Balaton Upland National Park, Hungary. Results proved that among the plants there are either weeds and/or poisonous and/or prickly species, too. We examined how important grasses and pulses appeared or disappeared, how did the number of overgrazing tolerant species changed and how did the species composition of the grazed and non-grazed land differed. Based on the results the characteristics of the examined pastures show the effects of overgrazing. With the decrease of the number of the animals, nature conservation and economical values could be increased. The examined areas had totally different soil characteristics, pH, soil thickness and nutrient content varied greatly. In the Gyulakeszi area even a small catena was found on a single pasture. The high soil organic matter and nutrient content ensure the good grass yield thus the areas are suitable for grazing and for grass cutting, too.

Plant biodiversity of mountain grasslands as influenced by dairy farm management in the Eastern Alps

It has been widely demonstrated that farm management affects the plant species composition of grassland. The present study aimed to investigate the effect of farm management on plant species richness and composition in forty-nine small-scale farms breeding dairy cattle, located in the Eastern Italian Alps at two levels of precision: plot and farm levels. Data on housing system, quality scheme, farm productivity, income from milk yield and livestock density were collected through interviews with farmers. In each farm, botanical surveys were carried out in different plots representing the botanical composition of the farmland vegetation. Elevation, slope, type of use, number of hay cuts and type of fertilisation were also recorded. The botanical surveys of the plots on each farm were analysed to describe plant composition at the plot level, then merged to describe plant composition at the farm level. At both levels, grassland botanical composition was found to be affected by farm management. At the plot level, meadows cut 2 and 3 times per year did not exhibit any differences in plant richness, but they differed in plant species, botanical family and phytosociological class composition, with a general simplification of botanical composition. We found fewer phytosociological classes but not fewer plant species or botanical families in plots fertilised with slurry than in plots fertilised with manure or not fertilised, and a change in the botanical composition due to changes in the relative abundance of plant species. At the farm level, we observed a decrease in the number of plant species and phytosociological classes, and changes in plant composition, with increasing milk yield and livestock density. Changes in botanical composition were less evident at the farm level than at the plot level. However, protecting farms and their economic viability is a means of maintaining biodiversity at the plot level.

Modelling seasonal pasture growth and botanical composition at the paddock scale with satellite imagery

Abstract Seasonal pasture monitoring can increase the efficiency of pasture utilization in livestock grazing enterprises. However, manual monitoring of pasture over large areas is often infeasible due to time and financial constraints. Here, we monitor changes in botanical composition in Tasmania, Australia, through application of supervised learning using satellite imagery (Sentinel-2). In the field, we measured ground cover and botanical composition over a 12-month period to develop a supervised classification approach used to identify pasture classes. Across seasons and paddocks, the approach predicted pasture classes with 75–81 % accuracy. Botanical composition varied seasonally in response to biophysical factors (primarily climate) and grazing behaviour, with seasonal highs in spring and troughs in autumn. Overall, we demonstrated that 10-m multispectral imagery can be reliably used to distinguish between pasture species as well as seasonal changes in botanical composition. Our results suggest that farmers and land managers should aim to quantify within-paddock variability rather than paddock average cover, because the extent and duration of very low ground cover puts the paddock/field at risk of adverse grazing outcomes, such as soil erosion and loss of pasture biomass, soil carbon and biodiversity. Our results indicate that satellite imagery can be used to support grazing management decisions for the benefit of pasture production and the improvement of environmental sustainability.

Season‐long, mixed stocking of a cool‐temperate pasture

AbstractMixed‐species grazing offers a means to diversify livestock production systems for cool‐temperate regions typified by the Appalachian plateau of the USA. Our objective was to determine how mixed grazing influenced herbage and animal production, and sward botanical composition of three grazing systems including cattle and sheep. Three replicated systems were as follows: (A) cattle only with winter grazing; (B) cattle and sheep with winter grazing; and (C) cattle and sheep without winter grazing. Herbage mass and growth rate differed by grazing period; system C had the lowest growth rate and showed an interaction of system and grazing period. The proportion of grass in the sward differed by period, and the legume component was influenced by an interaction of system and period. Forbs and dead were influenced by period and sampling location. Herbage crude protein was not influenced by treatment. Herbage fiber components and lignin were consistently higher during the second grazing period. Steers performed similarly in all systems, but total gains varied with year. Lambs in the system without a winter grazing component were heavier than lambs in the system with a winter grazing component. Live weight gains were modest. Lamb fecal egg count was higher in the system with a winter grazing component; however, the fecal egg count per gram was relatively low throughout the experiment. Animal productivity differed with year and tended to be slightly greater for the system without a winter grazing component. Our findings suggest that livestock production systems that included mixed‐species grazing and extended‐season grazing practices contributed to desirable changes in botanical composition and improved herbage productivity patterns, especially in years with ample precipitation. The practices could be used to drive pasture composition by modifying relative abundance of various plant functional groups.

Enhancement of palatable perennial grasses by disturbance and seed addition in degraded native grasslands of the dry pampas in Central Argentina

Land use has changed the original composition of the natural grasslands in the dry pampas of central Argentina, to the detriment of palatable perennial grasses (PPG). Long-term elimination of anthropogenic disturbances has not been enough to effectively recover the PPG, which suggests that availability of seeds and/or habitats may be limiting their recruitment. Therefore, our objectives in a degraded grassland site were to assess: (1) the germinable soil seed bank and (2) changes in botanical composition after addition of PPG seed following canopy disturbance. In autumn 2015, we randomly selected 10-paired plots, measured the aboveground biomass and took soil samples to assess the germinable soil seed bank. Afterwards, we disturbed the resident vegetation in each paired plot and either added PPG seeds or left the plot without any seed addition as a control. We quantified the seedling density of seeded and spontaneous species in the spring of 2015 and 2016, and the aboveground biomass at the end of 2017. Annual grasses and forbs (AGFS) dominated the soil seed bank, while PPG and unpalatable perennial grasses (UPG) occurred at low seed density and richness. Addition of PPG seeds resulted in the successful establishment of one key seeded PPG (Poa ligularis). In the spring 2017, the aerial biomass of PPG was highest in the seeded plots, where P. ligularis accounted for 94%. Our results showed that PPG were poorly represented in the soil seed bank of the degraded grassland and that disturbance of the resident vegetation combined with PPG seed addition enabled successful recruitment of a key PPG. So, enhancement of the pastoral value of degraded dry pampas grasslands would be possible through disturbance of the resident vegetation and addition of PPG seed.

Dry matter yield of dryland and irrigated mixtures of Caucasian clover, white clover and perennial ryegrass over 5 years at Lincoln University

This experiment investigated the effects of Caucasian clover (CC), white clover (WC), perennial ryegrass (RG) and their mixtures on dry matter (DM) yield under dryland and irrigated conditions over 5 years (1st July-30th June) at Lincoln University. Seven mixtures of the three species (three pure, three binary and one ternary) were sown in November 1999, grown with and without irrigation, and grazed by sheep. Total annual DM yield in Years 2-6 (2000/2001-2004/2005) was analysed. Clover-RG mixtures yielded more than the average monoculture yields of their constituent species (over-yielding). This diversity effect was 1.8-7.0 t DM/ha for WC-RG over all 5 years and 2.7-4.6 t DM/ ha for CC-RG in Years 3-6. There was no additional yield benefit from the three-species mixture. Diversity effects were due to synergistic interactions between the clovers and RG, which were similar for CC and WC once established. The interspecific interactions persisted despite changes in botanical composition across irrigation levels and years.

Grassland renovation has important consequences for C and N cycling and losses

AbstractSward degradation is a serious threat to the functioning of agricultural grassland and the provision of ecosystem services. Renovation measures are frequently applied to restore degraded swards. The success is highly variable, and substantial trade‐offs can be related to the process of renovation. This paper starts with a general classification of renovation measures and then investigates the processes that are directly related to renovation and lead to a change in botanical composition and affect soil functions and C and N fluxes. These processes are strongly interrelated and dependent on site, climate, and management condition as well as on the timescale. The more an existing and degraded sward is deliberately disturbed prior to a renovation measure, for example, by ploughing, the stronger will be the change in sward composition, and the stronger will be the potential yield and quality advantage. However, the risk of a release of soil organic C and N emissions to the environment will also increase. These emissions will usually decrease in time, but so will the positive effects on sward composition. This demonstrates that the renovation of swards is normally the second best solution and a proper and well‐adapted grassland utilization and management should be adopted to avoid degradation in the first place.

Yield and nutritional value of permanent grassland forage under simulated rotational grazing

A cutting experiment was conducted to test the changes in botanical composition, yield and nutritional value of forage, obtained in conditions of simulated rotational spring grazing on permanent grassland. The experiment was carried out on permanent pasture in vicinity of Sabac, Serbia in 2015 included three cuttings as a simulated rotational spring grazing. The highest share of grasses was noted in the first cut and decreased in the second and third cut, with increased forbs participation, and relatively constant percentage of legumes. The highest dry matter (DM) yield was obtained for the first harvest, followed by the second cut, and the lowest forage production was determined for the third harvest, with only 11.04 and 17.42% of the first and second cut yield. There were not found the significant differences between cuts for herbage DM and crude protein content. Markedly lower value for non-protein N concentration (p<0.05) was determined in the third cut. The fiber content increased during the grazing season (p<0.05), with the highest value determined in the herbage obtained in the second cut. The highest energy values (p<0.05) had the herbage produced in the first cut (DM basis), wherein the lowest values were found in the forage from the second harvest. These results indicate that especially herbage yield of analyzed grassland as chemical composition and nutrition value are highly variable during the growing season. The accurately defined optimal period for using is necessary to provide the high-quality forage for grazing animals.

Herbage intake of dairy cows in mixed sequential grazing with breeding ewes as followers.

This study aimed to evaluate the hypothesis that mixed sequential grazing of dairy cows and breeding ewes is beneficial. During the seasons of spring-summer 2013 and autumn-winter 2013-2014, 12 (spring-summer) and 16 (autumn-winter) Holstein Friesian cows and 24 gestating (spring-summer) and lactating (autumn-winter) Pelibuey ewes grazed on six (spring-summer) and nine (autumn-winter) paddocks of alfalfa and orchard grass mixed pastures. The treatments "single species cow grazing" (CowG) and "mixed sequential grazing with ewes as followers of cows" (MixG) were evaluated, under a completely randomized design with two replicates per paddock. Herbage mass on offer (HO) and residual herbage mass (RH) were estimated by cutting samples. The estimate of herbage intake (HI) of cows was based on the use of internal and external markers; the apparent HI of ewes was calculated as the difference between HO (RH of cows) and RH. Even though HO was higher in CowG, the HI of cows was higher in MixG during spring-summer and similar in both treatments during autumn-winter, implying that in MixG the effects on the cows HI of higher alfalfa proportion and herbage accumulation rate evolving from lower residual herbage mass in the previous cycle counteracted that of a higher HO in CowG. The HI of ewes was sufficient to enable satisfactory performance as breeding ewes. Thus, the benefits of mixed sequential grazing arose from higher herbage accumulation, positive changes in botanical composition, and the achievement of sheep production without negative effects on the herbage intake of cows.

Ecological functions provided by dung beetles are interlinked across space and time: evidence from 15 N isotope tracing.

Maintaining multiple ecological functions ("multifunctionality") is crucial to sustain viable ecosystems. To date most studies on biodiversity-ecosystem functioning (BEF) have focused on single or few ecological functions and services. However, there is a critical need to evaluate how species and species assemblages affect multiple processes at the same time, and how these functions are interconnected. Dung beetles represent excellent model organisms because they are key contributors to several ecosystem functions. Using a novel method based on the application of 15 N-enriched dung in a mesocosm field experiment, we assessed the role of dung beetles in regulating multiple aspects of nutrient cycling in alpine pastures over appropriate spatial (up to a soil depth of 20cm) and temporal (up to 1yr after dung application) scales. 15 N isotope tracing allowed the evaluation of multiple interrelated ecosystem functions responsible for the cycling of dung-derived nitrogen (DDN) in the soil and vegetation. We also resolved the role of functional group identity and the importance of interactions among co-occurring species for sustaining multiple functions by focusing on two different dung beetle nesting strategies (tunnelers and dwellers). Species interactions were studied by contrasting mixed-species to single-species assemblages, and asking whether the former performed multiple functions better than the latter. Dung beetles influenced at least seven ecological functions by facilitating dung removal, transport of DDN into the soil, microbial ammonification and nitrification processes, uptake of DDN by plants, herbage growth, and changes in botanical composition. Tunnelers and dwellers were found to be similarly efficient for most functions, with differences based on the spatial and temporal scales over which the functions operated. Although mixed-species assemblages seemed to perform better than single-species, this outcome may be dependent on the context. Most importantly though, the different functions were found to be interconnected sequentially as reveled by analyzing 15 N content in dung, soil and vegetation. Taken together, our current findings offer strong support for the contention that the link between biodiversity and ecosystem functions should be examined not function by function, but in terms of understanding multiple functions and how they interact with each other.

Holocene carbon and nitrogen accumulation rates in a boreal oligotrophic fen

The contemporary role of mires in carbon exchange with the atmosphere is intensely debated. Thus, understanding the variation in Holocene peat accumulation is particularly important. We investigated carbon (C) and nitrogen (N) accumulation rates and their potential controls during the Holocene at the oligotrophic fen Degerö Stormyr (64°11′N, 19°33′E, 270 m a.s.l.), Sweden. The peat stratigraphy was dominated by remains of Eriophorum spp. and oligotrophic–mesotrophic Sphagnum spp. The long-term rate of C accumulation (LORCA) was 13.7 ± 5.5 (SD) g C m−2 yr−1, while the long-term rate of N accumulation (LORNA) was 0.28 ± 0.14 (SD) g N m−2 yr−1. Carbon and N accumulation rates exhibited similar variations that coincided with major changes in botanical composition. The botanical composition of the peat also had a major impact on the percentage of amorphous peat (a proxy for degree of decomposition). Bulk δ13C values increased with decreasing C content, which probably reflected the relative increase of 13C depleted compounds in the peat during decomposition. Different plant groups exhibited different relationships, likely due to different δ13C signatures of initial litters from Eriophorum spp. and Sphagnum spp. The δ15N values increased significantly with decreasing C:N ratio in bulk peat, likely reflecting preferential uptake of 14N by plants concomitant with nitrogen mineralization. Here, we demonstrate the importance of botanical composition in affecting C and N accumulation rates under a changing climate and suggest that primary production drives the variation in rates of accumulation. Furthermore, we point out the importance of including 13C and 15N signatures in the analysis of peat stratigraphies to advance interpretation of Holocene peat growth and decay.

Selective grazing modifies previously anticipated responses of plant community composition to elevatedCO2in a temperate grassland

Our limited understanding of terrestrial ecosystem responses to elevated CO2 is a major constraint on predicting the impacts of climate change. A change in botanical composition has been identified as a key factor in the CO2 response with profound implications for ecosystem services such as plant production and soil carbon storage. In temperate grasslands, there is a strong consensus that elevated CO2 will result in a greater physiological stimulus to growth in legumes and to a lesser extent forbs, compared with C3 grasses, and the presumption this will lead in turn to a greater proportion of these functional groups in the plant community. However, this view is based on data mainly collected in experiments of three or less years in duration and not in experiments where defoliation has been by grazing animals. Grazing is, however, the most common management of grasslands and known in itself to influence botanical composition. In a long-term Free Air Carbon Dioxide Enrichment (FACE) experiment in a temperate grassland managed with grazing animals (sheep), we found the response to elevated CO2 in plant community composition in the first 5years was consistent with the expectation of increased proportions of legumes and forbs. However, in the longer term, these differences diminished so that the proportions of grasses, legumes and forbs were the same under both ambient and elevated CO2 . Analysis of vegetation before and after each grazing event showed there was a sustained disproportionately greater removal ('apparent selection') of legumes and forbs by the grazing animals. This bias in removal was greater under elevated CO2 than ambient CO2 . This is consistent with sustained faster growth rates of legumes and forbs under elevated CO2 being countered by selective defoliation, and so leading to little difference in community composition.

Effect of Phosphorus Doses and Application Time on The Yield and Quality of Hay and Botanical Composition of Clover Dominant Meadow in Highlands of T

This study was conducted at the AtatUN 8niversity¶V farm in Erzurum over 2 years to evaluate the effects of phosphorus doses and application season on the dry matter production, botanical composition and crude protein, ADF and NDF content of an alsike clover-dominated natural hay meadow. The experiment was planned in a Randomized Complete Block Design with split-plot arrangement of application seasons (autumn and spring) was considered as a main plot and five phosphorus doses (0, 11, 22, 33 and 44 kg P ha-1)as subplots. P fertilization significantly affected the dry matter yield while the application season had no effect on dry matter yield. P application increased the legumes and decreased the other families¶ percentage in the botanical composition, whereas it did not affect the grasses percentage. Due to the nature of alsike cover, the proportion of the legumes decreased and the proportion of grasses increased significantly in the second year. P application had no effect on the crude protein and ADF content of hay, while NDF content was affected by both doses and the season of P application. Depending on changes in botanical composition between years, the chemical content of the hay changed between years. The results indicate that P fertilizer has positive effects on dry matter production and no serious effect on the forage quality of meadows and there are no significant differences between autumn and spring application. Therefore, an 11 kg ha-1 application of P in the spring can be suggested for sustainable dry matter production in legumes-dominated natural hay meadows in highland areas

Changes in botanical composition on three farmlets subjected to different pasture and grazing management strategies

As part of the Cicerone Project’s farmlet experiment, conducted on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006, this study assessed the effects of varying soil fertility, pasture species and grazing management on the botanical composition of three 53-ha farmlets subjected to different management strategies. Starting with the same initial conditions, the farmlets were managed to reach different target levels of soil phosphorus (P) and sulfur (S); Farmlet A aimed at 60 mg/kg of Colwell P and 10 mg/kg S (KCl40) whereas Farmlets B and C both aimed at 20 and 6.5 mg/kg of P and S, respectively. Pastures were renovated on six out of eight paddocks on Farmlet A, but only one paddock of each of Farmlets B (typical management) and C (intensive rotational grazing) was renovated. Flexible rotational grazing was employed on Farmlets A and B (each of eight paddocks) while Farmlet C used intensive rotational grazing over its 17 major paddocks, which were further subdivided into 37 subpaddocks. This paper focuses on the botanical composition dynamics observed across all three farmlets and the explanatory variables associated with those changes. Eight assessments of botanical composition were carried out at approximately annual intervals across each of the 37 major paddocks distributed across the farmlets and the results for each of 49 species were aggregated into seven functional groups for analysis. The strongest correlation found was a negative curvilinear relationship between sown perennial grasses (SPG) and warm-season grasses (WSG). The most significant factors affecting the functional group changes were soil P, sowing phase, paddock and date. These factors led to significant increases in SPG and correspondingly lower levels of WSG on Farmlet A compared with Farmlet B. Farmlets B and C experienced similar, declining levels of SPG, and increasing levels of WSG suggesting that intensive rotational grazing did not lead to substantial changes in botanical composition, compared with flexible rotational grazing, in spite of the fact that intensive rotational grazing had much longer grazing rests and shorter graze periods than the other two farmlets. Soil P levels were also significantly associated with levels of cool-season annual grasses, legumes and herbs, especially on Farmlet A. In general, the largest differences in botanical composition were between Farmlet A and the other two farmlets; these differences were most closely associated with those plants categorised as sown, introduced, C3 pasture species. The levels of legume were generally low on all farmlets, due largely to the dry seasons experienced over most of the trial. Efforts to increase the legume composition on all farmlets were more successful on Farmlet A than on the other two farmlets due, presumably, to higher soil fertility on Farmlet A. Farmlet C, with its long rest periods and short graze periods, had a small proportion of legumes, due to the competitive effects of the accumulated tall grass herbage between grazings. The ‘typical’ management of Farmlet B also resulted in low levels of legume as well as increased ‘patchiness’ of the pastures and increased numbers of thistles.

Variation of botanical composition, forage production and nutrient values along a grassland degradation gradient in the alpine region of Qinghai-Tibet Plateau

The alpine grassland in the Qinghai-Tibet Plateau is an extensive rangeland ecosystem sustaining a sparse population of traditional nomadic pastoralists in China. However, global climate change and anthropologic disturbances have severely degraded the alpine grasslands, and the consequences of this degradation are largely unknown. Forage is the only food source for livestock in the alpine region, and livestock is the major income source for nomadic herders. Therefore, it is critical to assess the forage quantity and quality along the current grassland degradation gradient. In this study, we examined the botanical composition, biomass of different functional groups, and forage grass nutritive values, and classified forage grasses according to their biological condition: lightly degraded, moderately degraded, heavily degraded and severely degraded grasslands. A sharp reduction in vegetative production and variations in botanical composition, plant coverage and nutritive values were associated with increasing degrees of degradation of the alpine grassland. Changes in botanical composition resulted in lower nutritive values in more than in less degraded alpine forage grasses. Given the productive importance of the alpine grassland, urgent action is extremely essential to protect it from degradation.

Decomposition and nitrogen transformation rates in a temperate grassland vary among co-occurring plant species

Decomposition of organic matter varies depending upon interactions between the composition of the organic matter and the source of the microbial community, with differences in these interactions among vegetation types leading to the Home Field Advantage (HFA) hypothesis whereby decomposition of litters is faster in soils previously conditioned by them. It is possible that HFA operates on smaller scales within plant communities with ecosystem processes responding to subtle changes of plant community dominance. Using field measurements and laboratory incubations, we found a strong plant species effect on nitrogen availability and transformations and the relative importance of autotrophic and heterotrophic processes to nitrification. We found that the origin of the soil microbial community had little influence on litter decomposition when litter quality was high but was important with low-quality litter, most of which was root material. Our results demonstrate that plant species identity has a substantial impact on both litter decomposition and N cycling even within a single vegetation type and on an extremely local scale via both litter chemistry and specificity of the associated soil microbial community. Therefore, changes in botanical composition could alter decomposition and nutrient release altering ecosystem productivity and carbon sequestration potential.

Long-term productivity of Mediterranean herbaceous vegetation after a single phosphorus application

Question: What is the mechanism that underlies long-term maintenance of high herbaceous productivity after a single application of phosphorus (4.5 gP m−2 and 9 gP m−2) in a hilly Mediterranean environment in a phosphorus-deficient ecosystem? Location: Inland, 15 km E of the Mediterranean coast, W Galilee, Israel (35°15′E, 33°01′N; 500 m asl). Methods: The experiment was established in 1988. Multi-year data on above-ground biomass, botanical composition, P content of vegetation and soil, and the grazing management context of the experiment were integrated to construct a feasible account of the P dynamics of the ecosystem. Results: The productivity of the herbaceous component already responded to P application in the first year. The effect on the shrubby component of the ecosystem was marginal. The available (bicarbonate extractable) P in the upper soil layer peaked in the year after application of P and then declined to the original level within 7 years. Despite the decline in available soil P, a high, fluctuating level of herbaceous biomass production was maintained for 20 years. Legume species (Fabaceae) became a prominent constituent of the herbaceous vegetation after the P pulse. Conclusions: The long-term shift in productivity of the herbaceous component of the grazed ecosystem was triggered by a nutritional pulse that induced a feedback loop based on changes in botanical composition of the herbaceous vegetation, the animal–vegetation interaction, grazing and supplementary feeding regimen of the cattle.