The effect of vesicular-arbuscular mycorrhizal inoculation on nutrient uptake and yield of alley-cropped cassava in a degraded Alfisol of southwestern Nigeria

Leaf and root (tuber) nutrient uptake patterns of cassava (Manihot esculenta Crantz) alley-cropped with gliricidia (Gliricidia sepium), leucaena (Leucaena leucocephala), and senna [(Senna (syn. Cassia) siamea] as influenced by vesicular-arbuscular mycorrhizal (VAM) inoculation in a degraded Alfisol were investigated in consecutive years. The cassava plants were mulched with fresh prunings of each hedgerow tree species at 2-month intervals in the second and third years of alley cropping. While VAM inoculation significantly influenced the root uptake of nutrients, the leaf uptake was not affected except for the uptake of P. In most cases, there was no difference in the nutrient concentration between inoculated and uninoculated plants, either in the leaf or in the root, indicating that the productivity of cassava was regulated by the amount of nutrients the roots could absorb. In spite of similar total soil N in all inoculated and uninoculated alley-cropped cassava plots and similar exchange-able soil K contents in inoculated and uninoculated alley-cropped cassava plots with leucaena and senna, greater uptake of N, P, and K and greater concentrations of K were observed in roots of inoculated alley-cropped cassava with gliricidia and leucaena than with senna. These results indicated that greater mineralization and availability of nutrients to cassava roots from prunings of nodulating gliricidia and leucaena than from non-nodulating senna may be important, particularly with efficient VAM inoculation, in these alley-cropping systems. Also, for similar nutrients in the inoculated and uninoculated cassava soils alley-cropped with each hedgerow species, VAM inoculation significantly enhanced cassava root dry weights, indicating that an effective VAM fungus can be an agent of greater nutrient uptake in a competitive environment.     

Decomposition of Subtropical Fruit Tree Leaf Litter at Nelspruit,South Africa

There is limited information about the decomposition of leaf litter from subtropical fruit trees despite their potential for managing soil fertility. The aim of this study was to quantify the effect of quality on decomposition and nutrient-release patterns from leaf litter of avocado, litchi, and mango trees in South Africa. The litterbag technique was used for investigation. The decomposition results over 2 years indicated significant differences in mass loss among the tree species with low rapid loss for litchi (57.3 percent). The annual decomposition rate constant (k) decreased in the order mango (0.82) > avocado (0.76) > litchi (0.69). The concentrations of phosphorus, potassium, manganese, and polyphenols in all species decreased while nitrogen, sulfur, and calcium concentrations increased with time. The nutrient-release pattern of the leaf litter from the three species varied considerably due to different quality characteristics. This had an influence on litter decomposition and thus its management.     

铅锌矿区分离丛枝菌根真菌对万寿菊生长与吸镉的影响

盆栽试验研究了土壤不同施Cd水平(0、20、50 mg kg-1)下,接种矿区污染土壤中丛枝菌根真菌对万寿菊根系侵染率、植株生物量及Cd吸收与分配的影响。结果表明:接种丛枝菌根真菌显著提高了Cd胁迫下万寿菊的根系侵染率和植株生物量;随着施Cd水平提高,各处理植株Cd浓度和Cd吸收量显著增加。各施Cd水平下万寿菊地上部Cd吸收量远远高于根系Cd吸收量,尤其在20 mg kg-1施Cd水平下,接种处理地上部Cd吸收量是根系的3.90倍,对照处理地上部Cd吸收量是根系的2.33倍;同一施Cd水平下接种处理地上部Cd吸收量要显著高于对照。总体上,试验条件下污染土壤中分离的丛枝菌根真菌促进了万寿菊对土壤中Cd的吸收,并增加了Cd向地上部分的运转,表现出植物提取的应用潜力。     

Effects of indigenous and introduced arbuscular mycorrhizal fungi on the growth of Allium fistulosum under field conditions

ABSTRACT

Enhanced phosphorus (P) uptake from the soil and increased plant growth related to arbuscular mycorrhizal (AM) fungi in pot culture, using sterilized soil, are well-known phenomena. However, these enhancements are not widely observed under field conditions because field sterilization is difficult. The aim of this study was to investigate the effects of AM fungi on P uptake and the growth of Allium fistulosum in non-fumigated and fumigated fields, under different levels of P availability. Plants were inoculated with the AM fungus Glomus R-10 and grown in fumigated soil. For the uninoculated treatment, a sterilized inoculum was applied directly. The field was fumigated using dazomet. Superphosphate was applied to the field at the rates of 0 (P0) or 500 (P500) kg P₂O₅ ha^?1. The inoculated and uninoculated plants were transplanted into the fields and sampled three times to measure AM fungal colonization, shoot P concentration, and shoot dry weight of the plants. At the transplanting stage, AM fungal colonization was observed in the inoculated plants (>70%) but not in the uninoculated plants. At the third sampling, irrespective of P treatment, AM fungal colonization was observed both in the uninoculated and inoculated plants in the non-fumigated field, and there was no difference in shoot P content and shoot dry weight between the inoculated and uninoculated plants. AM fungal colonization in the fumigated field was higher in the inoculated than uninoculated plants, irrespective of P treatment; shoot P content and shoot dry weight were both higher in the inoculated plants than in the uninoculated plants with P0. These results suggest that the responses of A. fistulosum to AM fungal inoculation under the low-P and fumigated conditions are similar to those observed in sterilized pot culture conditions.     

Rhizobium and phosphorus influence on lentil seed protein and lipid

Root nodulation by rhizobial bacteria and P fertilization may affect seed protein and lipid composition in plants by altering nitrogen (N) and phosphorus (P) nutrition or by eliciting metabolic responses by the host plant. This study was conducted to determine the effects of rhizobium and P fertilization on seed protein and lipid contents and yield of lentil (Lens culinaris Medik). Lentil was grown to maturity in a greenhouse with P levels of 0 (low) and 50 (high) mg kg^‐1 soil with or without inoculation with Rhizobium bacteria. At the low level of P, protein and lipid concentrations and protein contents were significantly higher in inoculated than in uninoculated plants. Seed dry weight and protein concentrations and contents were higher in inoculated than in uninoculated plants at the high level of P. Seed protein/lipid (Pro/L) concentration ratios varied between inoculated and uninoculated plants at both P levels, and was related to the intensity of root nodulation. Lipid and protein contents were highly correlated with P content in lentil seeds. Seed lipid and protein contents were lower at the high level of P in uninoculated than inoculated plants. The data indicate different patterns of seed P accumulation and different relationships between seed P content and protein and lipid contents in inoculated and uninoculated plants. This might indicate that the intensity of nodulation altered the response of seed protein and lipid metabolism to increasing P availability, which affected protein and lipid ratios.     

AM真菌对田间山银花生长、矿质营养及绿原酸含量的影响

Lonicera confusa, a traditional Chinese medicine herb for treating cold, flu, acute fever, and so forth, is often grown artificially in acidic soils and suffers from phosphorus (P) deficiency. A five-year field experiment was carried out to study the colonization rate, growth, nutrition, and chlorogenic acid content of Lonicera confusa seedlings inoculated with arbuscular mycorrhizal (AM) fungi, Glomus etunicatum and Glomus intraradices. Before transplanting into a field, both AM-inoculated and uninoculated control plants were cultured in nursery beds. In the plants inoculated with the AM fungi, the colonization rate decreased linearly with time and a greater decrease was observed in the plants inoculated with G. intraradices than with G. etunicatum, while the AM colonization increased from 0% to 12.1% in the uninoculated control plants 5 years after transplanting. Plant height, crown diameter, number of new branches, and flower yield increased significantly by AM inoculation as compared to the uninoculated control. Phosphorus concentrations in leaves and flowers increased, and plant uptake of nutrients, e.g., nitrogen (N), P, and potassium (K), was also enhanced significantly by AM inoculation. The Lonicera confusa seedlings had a better response to inoculation of G. intraradices than G. etunicatum in both growth and chlorogenic acid content in flowers. In contrast, both plant P uptake and P concentrations in leaves and flowers were similar between two fungal inoculations. The positive responses of Lonicera confusa to AM inoculation in growth, nutrient uptake, flowering, and chlorogenic acid content in flowers suggested that AM inoculation in nursery beds could promote the plant growth and increase chlorogenic acid content in flowers of Lonicera confusa when grown on acidic and P-deficient soils.     

Effect of vesicular-arbuscular mycorrhizae and zinc application on dry matter and zinc uptake of greengram (Vigna radiata L. Wilczek)

Summary In a greenhouse study we examined the effects of vesicular-arbuscular mycorrhizae (VAM) inoculation, using Glomus macrocarpum and of Zn application on dry matter production and Zn uptake by greengram in two mollisols. The VAM inoculation significantly increased the dry weight of different plant parts and the Zn uptake in both soils. Inoculated plants showed a greater response to the application of Zn at 2.5 and 5.0 mg kg^-1 soil in a Zn deficient clay loam soil. The inoculated plants also absorbed — more water than the uninoculated plants. Mass flow and diffusion were the principal processes by which Zn reached the plant roots; mass flow was particularly important in the absence of VAM in a sandy soil fertilized with higher Zn doses (5 and 10 mg kg^-1 soil). The greater supply of Zn to inoculated roots was attributed to an apparent diffusion process rather than to mass flow of Zn.     

Potential of indigenous bradyrhizobia versus commercial inoculants to improve cowpea (Vigna unguiculata L. walp.) and green gram (Vigna radiata L. wilczek.) yields in Kenya

Limited information is available on reduced cowpea (Vigna unguiculata L. Walp.) and green gram (Vigna radiata L.Wilczek.) yields in Kenya. Declining soil fertility and absence or presence of ineffective indigenous rhizobia in soils are assumptions that have been formulated but still require to be demonstrated. In this study, soils were collected from legume growing areas of Western (Bungoma), Nyanza (Bondo), Eastern (Isiolo), Central (Meru) and Coast (Kilifi) provinces in Kenya to assess indigenous rhizobia in soils nodulating cowpea and green gram under greenhouse conditions. Our results showed that highest nodule fresh weights of 4.63 and 3.32?g plant^?1 for cowpea and green gram were observed in one soil from Isiolo and another from Kilifi, respectively, suggesting the presence of significant infective indigenous strains in both soils. On the other hand, the lowest nodule fresh weights of 2.17 and 0.72?g plant^?1 were observed in one soil from Bungoma for cowpea and green gram, respectively. Symbiotic nitrogen (N) fixation by cowpea and green gram was highest in Kilifi soil with values of 98% and 97%, respectively. A second greenhouse experiment was undertaken to evaluate the performance of commercial rhizobial inoculants with both legumes in Chonyi soil (also from Coast province) containing significant indigenous rhizobia [>13.5?×?10³ Colony Forming Units (CFU) g^?1]. Rhizobial inoculation did not significantly (P?相似文献   

Fertility of tropical soils under different land use systems—a case study of soils in Tabasco,Mexico

Increasing deforestation in Mexico in the past 40 years has led to significant land use changes. It is important to establish land use systems that allow for the necessities of an increasing population and the conservation of soil fertility in the long term. In this study, we investigated the influence of different land use forms on soil fertility in Tabasco, SE Mexico. We chose two different commonly used pastures (Cynodon plectostachyus and Brachiaria decumbens) and a succession forest. We characterised soil fertility by physico-chemical parameters (texture, density, pH, P, Corg., Ntot., cation exchange capacity (CEC)) as well as by biological parameters, such as litter decomposition, microbial biomass and earthworm community. To estimate litter decomposition we used leaves of Gliricidia sepium, a common fodder tree in the region. The three land use systems had very similar soil chemical characteristics. All three can be characterised as acidic (pH between 4.1 and 5.3) with a high content of organic matter and total nitrogen. However, the three land use systems differed significantly with respect to their soil biological characteristics. Earthworm density as well as litter decomposition were significantly lower under B. decumbens than in the other soils. In all land use systems, the participation of macrofauna and mesofauna accelerated litter decomposition rate significantly as compared with decomposition with microfauna and microflora alone.We extracted two components of the pool of data by main component analysis. The acidity component explained mainly the microbial litter decomposition rate. The rate of litter decomposition – with participation of soil meso- and macrofauna – could be explained by the humus component. We assume that biological parameters were more suitable to characterise differences between the different land use systems. The use of C. plectostachyus and succession forest showed a positive effect on soil fertility.     

Response of Sauropus androgynus to soil phosphorus concentration and mycorrhizal colonization

Thirty three‐day‐old seedlings of nonmycorrhizal Sauropus androgynus were transplanted into pots containing a subsurface Oxisol uninoculated or inoculated with Glomus aggregation at three target soil solution phosphorus (P) concentrations. While no evidence of vesicular‐arbuscular mycorrhizal fungal (VAMF) colonization was noticed in the uninoculated soil, sauropus roots were colonized to the extent of 54%, 60% and 38% in the inoculated soil if target soil P concentrations were 0.014, 0.02 and 0.2 mg/L. VAMF colonization led to significant increases in tissue P and shoot dry matter accumulation at the first two soil P concentrations but not at the highest concentration. Root dry matter yield of mycorrhizal sauropus was greater than that of nonmycorrhizal sauropus at all soil P concentrations tested. Although mycorrhizal inoculation effects at soil P concentrations of 0.014 and 0.02 mg/L were comparable, growth of mycorrhizal plants was greater at the latter P concentration than at the former. Growth of mycorrhizal sauropus at this P concentration was also comparable to non‐mycorrhizal growth of the plant at soil P concentration of 0.2 mg/L. Based on the growth responses observed sauropus was classified as a highly mycorrhizal dependent species.     

Establishment of <Emphasis Type="Italic">Bradyrhizobium japonicum</Emphasis> and <Emphasis Type="Italic">B. elkanii</Emphasis> strains in a Brazilian Cerrado oxisol

The competition with established soil populations of Bradyrhizobium able to nodulate soybean has been one of the major constraints to the introduction of more efficient strains in Cerrados soils. The effects of nodulation establishment and persistence of four serologically distinct strains of Bradyrhizobium japonicum (CPAC 15 and CPAC 7, belonging to serogroups USDA 123 and CB 1,809) and B. elkanii (29 W and SEMIA 587, belonging to serogroups 29 W and 587) were examined. These strains were introduced in a dark-red oxisol, without indigenous populations of soybean bradyrhizobia, and were evaluated for 6 years. The experimental design was a completely randomized block with four replicates. In the first year, besides the inoculation treatments, there was also an uninoculated control. In the second year, the main plots were split into three sub-plots and treatments consisted of an uninoculated control, CPAC 7 and CPAC 15. In the third year, the entire area was inoculated with CPAC 7. In the fourth and sixth years, the plots were planted with soybean without inoculation, and in the fifth year the plots were left fallow. The strains introduced in the first year influenced nodule occupancy by strain CPAC 7 until the third successive growing season. By the fourth and sixth years, as a consequence of the dispersal of strains serologically related to serocluster 123 in the entire experimental area, this serogroup dominated the nodulation, occurring, on average, in more than 50% of the nodules of the treatments where it had never been inoculated.     

Changes in the vesicular‐arbuscular mycorrhizal dependency of Albizia ferruginea and Enterolobium cyclocarpum in response to soil phosphorus concentration 1

A greenhouse experiment was conducted to determine the degree to which Albizia ferruginea and Enterolobium cyclocarpum respond to colonization of their roots by the vesicular‐arbuscular mycorrhizal fungus (VAMF) Glomus aggregatum. Plants were grown in pots containing a subsurface ultisol uninoculated or inoculated with the fungus at three target soil solution phosphorus (P) concentrations. VAMF inoculation enhanced pinnule P content of Albizia but not of Enterolobium at the native P concentration of the experimental soil. However, dry matter yield was not affected by VAMF inoculation for either species. Mycorrhizal inoculation effect was either negative or nil at the highest soil solution P concentration tested. The highest mycorrhizal inoculation effect was observed at soil P concentration of 0.02 mg/L. Based on these data, both Albizia and Enterolobium were classified as highly mycorrhizal dependent species.     

Comparisons of the influence of vesicular-arbuscular mycorrhiza on the productivity of hedgerow woody legumes and cassava at the top and the base of a hillslope in alley cropping systems

We investigated the influence of vesicular-arbuscular mycorrhizal (VAM) inoculation on growth and nutrient relationships in two alley-cropping trials, one at the top and the other at the base of a hillslope. Each trial involved three woody hedgerow legumes with cassava (Manihot esculenta Crantz) as the sole intercrop. The hedgerow trees at the base of the slope showed greater survival and higher leaf dry weights than those at the top of the slope, although these parameters were not affected by VAM inoculation, either at the top or the base of the slope. In contrast to survival, the uptake of nutrients, particularly P and N, was higher for inoculated than uninoculated hedgerow trees, both at the top and at the base of slope. Increases in stem and leaf biomass and the uptake of nutrients by the trees were strongly correlated with increases in P uptake, indicating that the improvements were attributable to VAM inoculation. Cassava tuber yields at the base of the slope, from inoculated or uninoculated plants, were significantly greater than the corresponding cassava yields at the top of the slope. These increases at the base of the slope compared to the top of the slope were not attributed to available soil nutrients but to greater VAM spore density. Higher available soil moisture may have been another factor. Increasing the VAM spore density of effective mycorrhiza through proper agronomic practices at the top of a slope may bring about comparable yields on different parts of the slope.     

Response of pineapple to mycorrhizal inoculation and fosetyl‐Al treatment

Abstract

A pot experiment was conducted in the greenhouse to determine the influence of vesicular‐arbuscular mycorrhizal (VAM) inoculation on growth of pineapple (Ananas comosus, cv.’Smooth Cayenne') and its interaction with fosetyl‐Al in a Wahiawa soil (Tropeptic Eutrustox) at soil solution P levels of 0.003, 0.02 and 0.2 mg/L. Pineapple crowns were dipped in a solution of fosetyl‐Al before planting. Inoculation of soil with the fungus Glomus aggregatum (Schenck & Smith emend. Koske) significantly increased VAM colonization of pineapple roots at soil solution P levels of 0.003 and 0.02 mg/L. VAM inoculation also increased mycorrhizal effectiveness measured six weeks after planting. At harvest, pineapple grown in the inoculated soil at the lowest P level had significantly higher D‐leaf P concentration and plant fresh weight than that grown in the uninoculated soil. Fosetyl‐Al appears to have no significant effect on VAM‐pineapple interaction.     

Effects of inoculation with Glomus mosseae, Azorhizobium caulinodans and rock phosphate on the growth of and nitrogen and phosphorus accumulation in Sesbania rostrata

A study was carried out to evaluate the influence of single or dual inoculation with Glomus mosseae and Azorhizobium caulinodans with and without rock phosphate on the growth of and N, P and K accumulation in Sesbania rostrata grown in sterilized soil. Height of plants inoculated with G. mosseae in combination with A. caulinadans and/or rock phosphate was significantly higher than that of uninoculated plants or plants inoculated with A. caulinodans alone before but not after 28 days. However, the oven-dry weight of shoots and roots from all treatments did not vary significantly. Generally, concentration and uptake of N and P but not K in shoots and roots of plants were improved by dual inoculation with G. mosseae and A. caulinodans plus or minus P. Mycorrhizal infection of roots was enhanced significantly by A. caulinodans. Received: 18 March 1996     

Sesbania rostrata as a green manure for lowland rice: Growth,N2 fixation,Azorhizobium sp. inoculation,and effects on succeeding crop yields and nitrogen balance

Summary Root and stem nodulation, nitrogen fixation (acetylene-reducing activity), growth and N accumulation bySesbania rostrata as affected by season and inoculation were studied in a pot experiment. The effects ofS. rostrata as a green manure on succeeding wet-season and dry-season rice yields and total N balance were also studied.S. rostrata grown during the wet season showed better growth, nodulation, and greater acetylene-reducing activity than that grown during the dry season. Inoculation withAzorhizobium caulinodans ORS 571 StrSpc® (resistant to streptomycin and spectinomycin) on the stem alone or on both root and stem significantly increased N₂ fixation by the plants. Soil and seed inoculation yielded active root nodules under flooded conditions. Plants that were not inoculated on the stem did not develop stem nodules. The nitrogenase activity of the root nodules was greater than that of the stem nodules in about 50-day-oldS. rostrata. S. rostrata incorporation, irrespective of inoculation, significantly increased the grain yield and N uptake of the succeeding wet season and dry season rice crops. The inoculated treatments produced a significantly greater N gain (873 mg N pot^–1) than the noinoculation (712 mg N pot^–1) treatment. About 80% of the N gained was transferred to the succeeding rice crops and about 20% remained in the soil. The soil N in the flooded fallow-rice treatment significantly declined (–140 mg N pot^–1) but significantly increased in bothS. rostrata-rice treatments (159 and 151 mg N pot^–1 in uninoculated and inoculated treatments respectively). The N-balance data gave extrapolated values of N₂ fixed per hectare at about 303 kg N ha^–1 per two crops forS. rostrata (uninoculated)-rice and 383 forS. rostrata (inoculated)-rice.     

接种耐铬细菌菌株对二月兰中铬积累及其生长状况的影响

Beneficial interactions between microorganisms and plants, particularly in the rhizosphere, are a research area of global interest. Four cadmium （Cd）-tolerant bacterial strains were isolated from heavy metal-contaminated sludge and their effects on Cd mobility in soil and the root elongation and Cd accumulation of Orychophragmus violaceus were explored to identify the capability of metal- resistant rhizobacteria for promoting the growth of O. violaceus roots on Cd-contaminated soils. The isolated strains, namely, Bacillus subtilis, B. cereus, B. megaterium, and Pseudomonas aeruginosa, significantly enhanced the plant Cd accumulation. The Cd concentrations in the roots and shoots were increased by up to 2.29- and 2.86-fold, respectively, by inoculation of B. megaterium, as compared with the uninoculated control. The bacterial strains displayed different effects on the shoot biomass. Compared with the uninoculated plants, the shoot biomass of the inoculated plants was slightly increased by B. megaterium and significantly decreased by the other strains. B. megaterium was identified as the best candidate for enhancing Cd accumulation in O. violaceus. Thus, this study provides novel insight into the development of plant-microbe systems for phytoremediation.     

Effects of surface fire on litter decomposition and occurrence of microfungi in a Cymbopogon polyneuros dominated grassland

Abstract

Litter decomposition rate, changes in macronutrients such as nitrogen (N), phosphorus (P) and potassium (K) from different grades of litter decomposition and occurrence of soil microfungi were investigated in a Cymbopogon polyneuros-dominated tall grass ecosystem from a burned and an unburned site in southern India. The litter decomposition rate was higher at the burned site than at the unburned site. This rate was also higher when the litter was mixed with the mineral soil material than leaving the litter unaffected on the soil surface. The concentrations of N, P, and K in the litter decreased as a result of progressed litter decomposition. Occurrence of microfungi identified from the different decomposition grades of the Cymbopogon polyneuros litter was higher at the burned site compared to the unburned site. Microfungal species present at both sites showed only minor differences.     

Improvement of crop yield by phosphate-solubilizing Aspergillus species in organic farming

Phosphate-solubilizing fungal strains were isolated from organically managed soil and tested for their ability to solubilize rock phosphate (RP), ferric phosphate and aluminium phosphate. These strains were identified as Aspergillus tubingensis and Aspergillus niger based on internal transcribed spacer sequence analysis. A field study was conducted in two different seasons in organically managed soil to test the efficacy of two strains, A. tubingensis (PSF-4) and A. niger (PSF-7) on the yield and soil fertility. RP was amended at the rate of 59 kg P₂O₅ ha^?1 to study the effect of RP on soil fertility. The maize was grown in rainy season (July–October 2011) and wheat in winter season (November 2011–April 2012). Plant heights, shoot and root dry biomass and phosphorous (P) uptake in roots, shoots and grains were significantly increased due to inoculation in both crops. The yield of maize and wheat were significantly increased when inoculated along with RP fertilization. Organic carbon, P levels and soil enzyme activities were significantly increased due to inoculation. Results of present study suggested that A. tubingensis and A. niger improved the crop yield and soil fertility of organic farm when inoculated with RP fertilization.     

How browsing by red deer impacts on litter decomposition in a native regenerating woodland in the Highlands of Scotland

Herbivores can indirectly affect ecosystem productivity and processes such as nutrient cycling and decomposition by altering the quantity and quality of resource inputs into the decomposer subsystem. Here, we tested how browsing by red deer impacts on the decomposition of, and nutrient loss from, birch leaf litter (Betula pubescens), and tested whether effects of browsing on these measures were direct, via alteration of the quality of leaf litter, or indirect through long term impacts of deer browsing on soil biological properties. This was tested in a microcosm experiment using soil and litter taken from inside and outside three individual fenced exclosures located at Creag Meagaidh National Nature Reserve, Scotland. We found that litter of un-browsed trees decomposed faster than that from browsed trees, irrespective of whether soil was sourced from inside or outside exclosures. These findings suggest that effects of browsing on litter quality, rather than on soil biological properties, are the key determinant of enhanced decomposition in un-browsed areas of this ecosystem. Despite this, we found no consistent impact of browsing on litter C:N, a key indicator of litter quality; however, the rate of litter decomposition was linearly and negatively related to litter C:N when analysed across all the sites, indicating that this measure, in part, contributed to variation in rates of decomposition in this ecosystem. Our findings indicate that herbivores impact negatively on rates of decomposition in this ecosystem, ultimately retarding nutrient cycling rates, and that these effects are, in part, related to changes in litter quality.