Grass Areas Research Articles

An improved indicator of simulated grassland production based on MODIS NDVI and GPP data: A case study in the Sichuan province, China

Grassland monitoring is important for both global change research and regional sustainable development. Gross primary production (GPP) is one of the key factors for understanding grass growing conditions. Methods for estimating GPP are plentiful, and the light use efficiency (LUE) model based on remote sensing data is widely used. The MODIS GPP product, which is employed by the National Aeronautics and Space Administration (NASA), is calculated using the LUE model and the surface reflection data from the Moderate Resolution Imaging Spectroradiometer onboard the Terra/Aqua satellite. The MODIS GPP product harbors its own uncertainties arising from the sources and parameters, such as FPAR and light use efficiency (ɛ). In this study, we propose an improved indicator for monitoring grassland based on MODIS GPP and NDVI data. Fractional vegetation coverage and the percentage of grass area (1km2) were used to reduce the mixed pixel effect. A function of NDVI was used to simulate the light use efficiency and FPAR. The modified GPP data were calculated and validated with in situ measured data from the Sichuan province, China, 2011. The results indicated that the modified GPP data were a more accurate indicator for monitoring grassland than previous indicators, and the precision of grass production simulated by SsGPPndvi reached 85.6%. Spatial statistic results were consistent with the practical condition in most cases. Since MODIS data are available twice a day, the improved indicator can meet the actual requirement of grassland monitoring at regional scale.

Preliminary study of N<sub>2</sub>O emission and denitrification at early exposure period in Pengxi River drawdown area, Three Gorges Reservoir

Soil N2O emission and denitrification in the wetland( water level drawdown) area of reservoirs are critical pathways in the N biogeochemistry cycles. The intact soil core-acetylene inhibition technique was applied to investigate the N2 O emission and denitrification rates on grass land,cultivated area and background group in Lake Gaoyang drawdown area of Pengxi River,a tributary in the Three Gorges Reservoir,from March to April in 2013. Environmental impact factors,e. g. p H,oxidation-reduction potential,temperature,organic matter,total nitrogen,ammonium nitrogen,nitrate nitrogen and water-filled pore space,were measured simultaneously. The grass land had a mean N2 O emission rate of 9. 88 ± 6. 49 g N /( ha·d),and a mean denitrification rate of 58. 94 ± 52. 84 g N /( ha·d). The mean N2 O emission rate and denitrification rate of cultivated area were 7. 71 ± 4. 44 g N /( ha·d) and 30. 70 ± 25. 68 g N/( ha·d),respectively. The difference of N2 O emission rate in different land use types was significant. The N2 O emission and denitrification processes were greatly affected by the soil oxygen content,water content and nitrogen content of soils. An increase in soil oxygen content stimulated the N2 O emission in grass area and inhibited the denitrification process in a certain extent. Larger water content in the cultivated area,comparing with that in the grass area,probably lead to a smaller N2 O emission rate. Soil nitrogen content had a positive relationship with the decline of denitrification rate in the drawdown area.

Migration patterns and land use by immigrants under a changing frontier society in the Peruvian Amazon

One of main factors identified as explaining forest loss and degradation in the Selva (the Peruvian Amazon) is the migration of people from the Sierra (Andes highlands), where agricultural conditions are severe, to forest areas in the Selva in search of new land. This paper aims at clarifying the characteristics and process of migration based on interviews with local people near Pucallpa, Ucayali Department, where forest loss and degradation has advanced in recent decades. In the study area, forest loss and degradation progressed by commercial logging after construction of a road connecting between Lima and Pucallpa in 1943. After logging, stock-farming companies and immigrants entered the area, and land uses other than high forest have been expanding. Today, the study area is occupied by people who have immigrated since the 1960s. Many of them earned income by logging until the 1980s, while today almost of them make a livelihood by agriculture, stock farming, or tree planting. As a result of these economic activities, there are substantial areas of mixed shrubs and grass in the study area today. This paper clarifies two points. First, the majority of immigrants were born not in the Sierra, but in the Selva, for instance as part of the expanding population in the Departments of San Martin and Amazonas. The main stream of migration is from parts of the Selva where immigrants had started reclamation in earlier days to other parts of the Selva with still abundant forests (such as the study area). Second, most migrants were not born in a rural area, but in Pucallpa, a developing urban area in the Selva. Pucallpa is also an important place for step migrants who stayed there for a while and worked temporarily before immigrating to the study area. The urban area has gained an important role in migration to forests in the Selva as a place of birth of migrants and for its function in step migration.

Mortality of native grasses after a summer fire in natural temperate grassland suggests ecosystem instability

SummaryThe exclusion of regular fire and the introduction of livestock grazing have altered native grassland composition on Victoria's volcanic plains, commonly resulting in spear‐grass and wallaby‐grass pastures replacing Kangaroo Grass grasslands. The effect of reintroducing fire to these pastures is currently unknown, although it may be an important part of restoring this ecosystem. We measured the changes in basal area of the dominant grasses in a mixed Spear‐grass/Wallaby‐grass pastures after a summer wildfire, which we assume burnt a relatively homogenous grass sward. We found a 90–95% reduction in the basal area of live spear‐grass tussocks in burnt plots compared with unburned controls, due to the mortality of tussocks. This suggests that caution and structured experimentation should be applied when using fire to manage spear‐grass‐dominated grasslands.

Questioning key conclusions of FAO publications ‘Livestock's Long Shadow’ (2006) appearing again in ‘Tackling Climate Change Through Livestock’ (2013)

The accusation by the United Nations Food and Agriculture Organisation (FAO) that domestic animals contribute 18% (Livestock's Long Shadow) or 14.5% (Tackling Climate Change Through Livestock), respectively, to anthropogenic greenhouse gas (GHG) emissions) caused considerable damage to the reputation of animal husbandry in general, and in particular to the grassland-based production systems. This rebuttal highlights the following: – The publications mentioned ignore the uncertainties associated with the climate sensitivity of GHGs. – Baseline scenarios over time and space for livestock-borne methane and nitrous oxide emissions are elided. – There are deficits in the methodological treatment of emissions deriving from land use change (deforestation). – It is not acknowledged that there is virtually no livestock signal discernible in global methane distribution and historical methane emission rates. – The loss of energy through methane emissions by enteric fermentation in ruminants is considered as damaging to production. However, livestock-borne methane might be the price to be ‘paid’ for the effective transformation of high-fibre diets from crop residues and vast areas of grass- and rangelands marginal to agriculture into valuable food for humans (meat and milk). Consequently, the mentioned publications highly overstate livestock contribution to climate change in its extent and impact.

Representation of canopy snow interception, unloading and melt in a parsimonious snowmelt model

Recent improvements in the Utah Energy Balance (UEB) snowmelt model are focused on snow–vegetation–atmosphere interactions to understand how different types of vegetation affect snow processes in the mountains of Western USA. This work presents field work carried out in the Rocky Mountains of Northern Utah to evaluate new UEB model algorithms that represent the processes of canopy snow interception, sublimation, mass unloading and melt. Four years' continuous field observations showed generally smaller accumulations of snow beneath the forest canopies in comparison with open (sage and grass) areas, a difference that is attributed to interception and subsequent sublimation and redistribution of intercepted snow by wind, much of it into surrounding open areas. Accumulations beneath the denser forest (conifer) canopies were found to be less than the accumulation beneath the less dense forest (deciduous) canopies. The model was able to represent the accumulation of snow water equivalent in the open and beneath the deciduous forest quite well but without accounting for redistribution tended to overestimate the snow water equivalent beneath the conifer forest. Evidence of redistribution of the intercepted snow from the dense forest (i.e. conifer forest) to the adjacent area was inferred from observations. Including a simple representation of redistribution in the model gave satisfactory prediction of snow water equivalent beneath the coniferous forest. The simulated values of interception, sublimation and unloading were also compared with previous studies and found in agreement. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of Thermal Environment of Forest and Grass Area on Human Physiological Response - Focused on the University Students at Keumkang Arboretum -

Effect of Thermal Environment of Forest and Grass Area on Human Physiological Response - Focused on the University Students at Keumkang Arboretum -

The effect of light availability on leaf area index, biomass production and plant species composition of park grasslands in Warsaw

How light conditions affect development of park grasslands is a question that has not been satisfactory addressed. The aim of this study was therefore determination of the level to which unfavorable light conditions influence grassy parks area and relationships between parameters which determine state of turf grasses. Researches were conducted in two parks in Warsaw, in various light conditions and included measurement of: leaf density, sward height, leaf area index (LAI), and botanical composition of the communities. The leaf density of shaded areas did not exceed 70%. LAI value varied from 0.5 to 0.9-fold lower than in the areas in half-shade and in sun. The participation of basic lawn species at Skaryszewski Park was higher under shade, while at Łazienki Królewskie was higher in full-sunlight areas. The state of tested grassy areas in limited solar radiation does not satisfy the requirements of recreational and representational functions. The development processes of vegetation coverage were inhibited at the sites of lower solar radiation. LAI was influenced by both leaf coverage and sward height. Agrostis stolonifera and Poa trivialis may be recommended to create grass areas under limited solar radiation.

Measurement of tritium in the free water of milk : spotting and quantifying some biases and proposing ways of improvement

As one of the three natural isotopes of hydrogen, tritium is ubiquitous and may potentially be present in any water or organic molecule that constitutes a biological matrix. Milk is one of the most frequently monitored foodstuffs in the vicinity of chronic release of radionuclides, as it is a very common food product and also because it integrates deposition on large areas of grass or crops at a local scale. Different parameters have been studied to assess their impact on the reliability of tritium measurements in the free water of milk. The volume of the sample, the technique used to extract the water and the level of dehydration modulate the results but in different ways: dispersion of results and under- or over-estimation of the tritium activity. The influence of sample storage and preparation has also been investigated. Methodological improvements of tritium measurements in the free water of milk are proposed. An original fractionation effect during distillation of milk is also described.

Climate and exotic pasture area in landscape determines invasion of forest fragments by two invasive grasses

To date, there has been a focus on biological aspects of invasion rather than landscape-scale processes within human-modified landscapes. Applying a multi-scale approach may improve predictive models of invasion in fragmented landscapes as well as management. We tested a priori models of the relative importance of landscape (10 000 to 30 000 ha), site-scale (<0·3 ha) factors and climate gradients, and their interactions, on the cover of exotic grasses in forest fragments. We tested the models for two exotic pasture grasses Cenchrus ciliaris and Panicum maximum in fragmented agricultural landscapes of subtropical eastern Australia. Mixed-effect models were applied to quantify the multi-scale effects of land use, forest area and fragmentation, vegetation structure, soil and climate attributes and their interactions on the ground cover of the two exotic grasses. We used model averaging to account for model and parameter uncertainty and tested for spatial autocorrelation and the model fit in model residuals. There was strong evidence that the area of exotic pasture grass in the landscape and climate gradients had a strong influence on cover observed at the site scale, but the climate influence was species specific. Cenchrus ciliaris cover was higher in forest sites within landscapes converted to exotic pastures and with high mean minimum temperatures and sites with low canopy cover. In contrast, P. maximum cover was primarily influenced by high mean annual rainfall, with moderate positive effects from area of exotic pasture in the landscape and high minimum temperatures. Synthesis and applications. This study highlights several key issues that need to be considered when prioritizing management of invasive species in fragmented landscapes. First, the propagule supply in the landscape and climate gradients are key factors influencing the spread of exotic grasses into forest fragments. Second, managing canopy cover is critical to enhancing C. ciliaris invasion resistance, but not for P. maximum. We conclude that a multi-scale approach provides the conceptual and applied basis for an improved understanding and management of plant invasions in fragmented landscapes.

Sorghum grain yield, forage biomass production and revenue as affected by intercropping time

Sorghum is an excellent alternative to other grains in poor soil where corn does not develop very well, as well as in regions with warm and dry winters. Intercropping sorghum [Sorghum bicolor (L.) Moench] with forage crops, such as palisade grass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] or guinea grass (Panicum maximum Jacq.), provides large amounts of biomass for use as straw in no-tillage systems or as pasture. However, it is important to determine the appropriate time at which these forage crops have to be sown into sorghum systems to avoid reductions in both sorghum and forage production and to maximize the revenue of the cropping system. This study, conducted for three growing seasons at Botucatu in the State of São Paulo in Brazil, evaluated how nutrient concentration, yield components, sorghum grain yield, revenue, and forage crop dry matter production were affected by the timing of forage intercropping. The experimental design was a randomized complete block design. Intercropping systems were not found to cause reductions in the nutrient concentration in sorghum plants. The number of panicles per unit area of sorghum alone (133,600), intercropped sorghum and palisade grass (133,300) and intercropped sorghum and guinea grass (134,300) corresponded to sorghum grain yields of 5439, 5436 and 5566kgha−1, respectively. However, the number of panicles per unit area of intercropped sorghum and palisade grass (144,700) and intercropped sorghum and guinea grass (145,000) with topdressing of fertilizers for the sorghum resulted in the highest sorghum grain yields (6238 and 6127kgha−1 for intercropping with palisade grass and guinea grass, respectively). Forage production (8112, 10,972 and 13,193Mg ha−1 for the first, second and third cuts, respectively) was highest when sorghum and guinea grass were intercropped. The timing of intercropping is an important factor in sorghum grain yield and forage production. Palisade grass or guinea grass must be intercropped with sorghum with topdressing fertilization to achieve the highest sorghum grain yield, but this significantly reduces the forage production. Intercropping sorghum with guinea grass sown simultaneously yielded the highest revenue per ha (€ 1074.4), which was 2.4 times greater than the revenue achieved by sowing sorghum only.

Estimating the Extent of Impervious Surfaces and Turf Grass across Large Regions

AbstractThe ability of researchers to accurately assess the extent of impervious and pervious developed surfaces, e.g., turf grass, using land‐cover data derived from Landsat satellite imagery in the Chesapeake Bay watershed is limited due to the resolution of the data and systematic discrepancies between developed land‐cover classes, surface mines, forests, and farmlands. Estimates of impervious surface and turf grass area in the Mid‐Atlantic, United States that were based on 2006 Landsat‐derived land‐cover data were substantially lower than estimates based on more authoritative and independent sources. New estimates of impervious surfaces and turf grass area derived using land‐cover data combined with ancillary information on roads, housing units, surface mines, and sampled estimates of road width and residential impervious area were up to 57 and 45% higher than estimates based strictly on land‐cover data. These new estimates closely approximate estimates derived from authoritative and independent sources in developed counties.

Effects of heterogeneous competitor distribution and ramet aggregation on the growth and size structure of a clonal plant.

Spatially heterogeneous distribution of interspecific competitors and intraspecific aggregation of offspring ramets may affect the growth and size structure of clonal plant populations, but these have been rarely studied. We conducted a greenhouse experiment in which we grew a population of eight offspring ramets (plants) of the stoloniferous clonal plant Hydrocotyle vulgaris aggregately or segregately in two homogeneous treatments with or without a competing grass Festuca elata and a heterogeneous treatment with a patchy distribution of the grass. In patchy grass treatments, H. vulgaris produced markedly more biomass, ramets and stolons in open patches (without grasses) than in grass patches, but displayed lower size variations as measured by coefficient of variation of biomass, ramets and stolons among the eight plants. In open areas, H. vulgaris produced statistically the same amounts of biomass and even more stolons and showed higher size variations in patchy grass treatments than in open (no grass) treatments. In grass areas, H. vulgaris grew much worse and displayed higher size variations in patchy grass treatments than in full grass treatments. Ramet aggregation decreased the growth of H. vulgaris in open treatments and in both open and grass patches in patchy grass treatments, but had little effect in full grass treatments. Ramet aggregation had little effect on size variations. Therefore, heterogeneous distribution of competitors can affect the growth and size structure of clonal plant populations, and ramet aggregation may decrease population growth when they grow in open environments or heterogeneous environments with a patchy distribution of interspecific competitors.

Urban planning indicators: useful tools to measure the effect of urbanization and vegetation on summer air temperatures

ABSTRACTIn this article, the relationships between some urban planning indicators (GCR, green cover ratio; LCR, Lawn cover ratio; TCR, Tree cover ratio; SCR, street cover ratio; BCR, building cover ratio; BVD, Building volume density) and intra‐urban minimum and maximum average summer temperatures of Florence (Italy) were investigated. These indicators were calculated at different scales (areas of 10 m to 500 m radius) within the urban environment. Results showed that all the indicators can be used to assess the intra‐urban distribution of minimum air temperature values at all scales. Maximum air temperature was affected by GCR and TCR especially near the stations (radius up to 50 m), and by SCR at all scales, and the significance increased with radius. A 10% increase in LCR determined a reduction in minimum summer temperature from 0.14 °C (radius = 10 m; p &lt; 0.05) to 0.53 °C (radius = 500 m; p &lt; 0.01). A 10% increase in SCR determined an increase in minimum summer temperature from 0.22 °C (radius = 10 m; p &lt; 0.01) to 0.66 °C (radius = 400 m; p &lt; 0.01). The analysis of the type of green showed the significant role of forested areas on decreasing maximum temperatures and of grass areas on decreasing minimum temperatures. This research expands our scientific understanding of the effects of urban planning indicators on the intra‐urban thermal regime and can provide useful tools to urban planners and policymakers for the evaluation of the impact of an urban transformation on the thermal regime of the city at different scales.

Urban Fungi-interesting Fungi from Parks and Gardens of West London

In 2011 I carried out a survey for the Royal Borough of Kensington and Chelsea of the main parks in the borough, of which there are nine. As with my previous articles on fungi of the Royal Parks (Overall 2010, 2011a, 2011b), the aim of this article is to highlight some of the more interesting fungi found during the survey. Before doing so, I give a brief description of two of these parks. Seven out of the nine parks are what I would consider to be amenity parks, some of which consist of only one small area of grass bordered by shrubs. People and their dogs heavily utilize all nine parks. Holland Park and Little Wormwood Scrubs are large and composed of various habitat types such as woodland, grass land and water features, as well as possessing a

Analysis of full-waveform LiDAR data for classification of an orange orchard scene

Full-waveform laser scanning data acquired with a Riegl LMS-Q560 instrument were used to classify an orange orchard into orange trees, grass and ground using waveform parameters alone. Gaussian decomposition was performed on this data capture from the National Airborne Field Experiment in November 2006 using a custom peak-detection procedure and a trust-region-reflective algorithm for fitting Gauss functions. Calibration was carried out using waveforms returned from a road surface, and the backscattering coefficient γ was derived for every waveform peak. The processed data were then analysed according to the number of returns detected within each waveform and classified into three classes based on pulse width and γ. For single-peak waveforms the scatterplot of γ versus pulse width was used to distinguish between ground, grass and orange trees. In the case of multiple returns, the relationship between first (or first plus middle) and last return γ values was used to separate ground from other targets. Refinement of this classification, and further sub-classification into grass and orange trees was performed using the γ versus pulse width scatterplots of last returns. In all cases the separation was carried out using a decision tree with empirical relationships between the waveform parameters. Ground points were successfully separated from orange tree points. The most difficult class to separate and verify was grass, but those points in general corresponded well with the grass areas identified in the aerial photography. The overall accuracy reached 91%, using photography and relative elevation as ground truth. The overall accuracy for two classes, orange tree and combined class of grass and ground, yielded 95%. Finally, the backscattering coefficient γ of single-peak waveforms was also used to derive reflectance values of the three classes. The reflectance of the orange tree class (0.31) and ground class (0.60) are consistent with published values at the wavelength of the Riegl scanner (1550nm). The grass class reflectance (0.46) falls in between the other two classes as might be expected, as this class has a mixture of the contributions of both vegetation and ground reflectance properties.

Paleosols, bones, phytoliths, and δ13C signatures of humus and teeth in the alluvial sequence of Axamilpa, Puebla: Inferences for landscape evolution and megafauna paleoecology during MIS 3–2 in Southern Mexico

Abstract Alluvial paleosol–sedimentary sequences containing animal fossils, and paleobotanical and paleopedological archives have a potential for reconstructing Quaternary paleoenvironments in Southern Mexico and for understanding the paleoecology of Pleistocene megafauna. In the section of Axamilpa river four pedostratigraphic units were recognized. The lower Gleyic and Vertic pedological Units are at the end of marine isotopic stage (MIS) 3 while the upper Humic and (most probably) Calcic Units correspond to MIS 2 according to the radiocarbon dates of humus. The micromorphological analysis indicates an incipient development and syn-sedimentary character of paleopedogenesis in the periodically water-saturated environment (indicated by redoximorphic features, hydrogenic carbonates and low values of magnetic susceptibility in most strata). The δ 13 C values of the paleosol humus range from − 22.6 to − 24.7, indicating a C3 vegetation, whereas in the modern soil it is higher (− 15.2) pointing to an abundance of the C4 and CAM plants. The δ 13 C signature of the vegetation inferred from the teeth enamel of the fossil fauna appeared to be less negative than that of humus from corresponding paleosols. The alimentary preferences of the paleofauna which fed on grasses with high proportion of C4 plants explain this difference. The phytolith analysis shows dominance in conifer forms, followed by C4 and C3 grasses. The content of conifer phytoliths is progressively reduced towards the top of the sequence. We interpret the Late Pleistocene landscape of this area as a heterogeneous forest–grassland landscape with the forest shrinking through time and the grass areas increasing. Swampy floodplain meadows (inferred from paleopedological results) could provide a habitat for grassy vegetation. Both isotope and phytolith records demonstrate a contrasting difference between Pleistocene and recent vegetation dominated by xerophytic shrubs and succulents. This vegetation change could play important role in the extinction of Pleistocene megafauna.

Corrigendum to: Impacts of level of utilisation by grazing on an Astrebla (Mitchell grass) grassland in north-western Queensland between 1984 and 2010. 1. Herbage mass and population dynamics of Astrebla spp.

Managing large variations in herbage production, resulting from highly variable seasonal rainfall, provides a major challenge for the sustainable management of Astrebla (Mitchell grass) grasslands in Australia. A grazing study with sheep was conducted between 1984 and 2010 on an Astrebla grassland in northern Queensland to describe the effects of a range of levels of utilisation of the herbage at the end of the summer growing season (April–May in northern Australia) on the sustainability of these grasslands. In unreplicated paddocks, sheep numbers were adjusted annually to achieve 0, 10, 20, 30, 50 and 80% utilisation of the herbage mass at the end of the summer over the ensuing 12 months. Higher levels of utilisation reduced both total and Astrebla spp. herbage mass because of the effects of higher utilisation on Astrebla spp. and this effect was accentuated by drought. The tussock density of Astrebla spp. varied widely among years but with few treatment differences until 2005 when density was reduced at the 50% level of utilisation. A major change in density resulted from a large recruitment of Astrebla spp. in 1989 that influenced its density for the remainder of the study. Basal area of the tussocks fluctuated among years, with increases due to rainfall and decreases during droughts. Seasonal rainfall was more influential than level of utilisation in changes to the basal area of perennial grasses. Drought resulted in the death of Astrebla spp. tussocks and this effect was accentuated at higher levels of utilisation. A series of three grazing exclosures were used to examine the recovery of the density and basal area of Astrebla spp. after it had been reduced by 80% utilisation over the preceding 9 years. This recovery study indicated that, although grazing exclusion was useful in the recovery of Astrebla spp., above-average rainfall was the major factor driving increases in the basal area of perennial grasses. Spring values of the Southern Oscillation Index and associated rainfall probabilities were considered to have potential for understanding the dynamics of Astrebla spp. It was concluded that Astrebla grassland remained sustainable after 26 years when grazed at up to 30% utilisation, while, at 50% utilisation, they became unsustainable after 20 years. Results from this study emphasised the need to maintain the population of Astrebla spp. tussocks.

Rodent-favored cache sites do not favor seedling establishment of shade-intolerant wild apricot (Prunus armeniaca Linn.) in northern China

Seed dispersal by scatter hoarders is widely assumed to involve directed dispersal, in which microhabitats selected for caching also benefit seedling establishment and growth. However, in many systems, this may not be true if animal-favored cache sites do not match the safe sites for plants, or if cache sites benefit the plant in one life stage and not another. Here, we investigated whether cache sites selected by rodents are favorable for seedling establishment and growth of shade-intolerant wild apricot (Prunus armeniaca Linn.) in northern China. We tracked tagged seeds and compared the germination and growth of seedlings from rodent-cached seeds with that of naturally established seedlings in a secondary forest and shrubland stand. Rodents preferred to cache seeds under shrubs with medium canopy cover (31–60 %) in litter substrate in the secondary forest, and under shrubs with high canopy cover (>60 %) in soil or litter substrate in the shrubland stand, neither of which conveyed an advantage for seedling establishment. Although fewer caches were made along shrub edges, or under low canopy cover (≤30 %) in the secondary forest, or along shrub edges, open areas of grass, or under low canopy cover in the shrubland stand, these cache sites consistently contributed to higher survival rates. The microhabitats of grass, soil, or low canopy cover significantly promoted the emergence, survival, and growth of naturally established seedlings. Our results are best explained by the conflicting demands of rodents for caching seeds in more secure sites and P. armeniaca’s high-light requirements for seedling recruitment. We argue that the relationship between favored cache sites for seed hoarders and safe sites for plants will often not match but may still allow a reasonable rate of establishment and regeneration.

Characterization for industrial purposes of the fibre anatomy of perennial ryegrass and tall fescue stem and leaf at three stages in the primary growth

AbstractCharacterization of grass fibre is important in assessing its potential for industrial fibre applications. Stem and leaf sections were sampled from triplicate field plots of two grass species, perennial ryegrass (PRG) and tall fescue at three dates (monthly from 12 May) in the primary growth, and were used to (a) isolate individual fibre cells and (b) prepare transverse sections. Microscopy and image analysis software were used to determine the length and width of individual fibre cells and the proportion of lignified fibre in stem and leaf transverse sections. The length and width of individual fibre cells were greater (P &lt; 0·001) in stem than in leaf sections, while individual fibre cell length was greater (P &lt; 0·01) for tall fescue than PRG. Harvest date and grass species had little effect (P &gt; 0·05) on the proportion of lignified fibre in the transverse‐sectional area. However, there was a greater (P &lt; 0·001) proportion of lignified fibre in the transverse‐sectional area of grass stems than leaves, with tall fescue having a greater (P &lt; 0·05) stem and leaf transverse‐sectional area and area of lignified fibre in transverse section than PRG. Tall fescue harvested at a later stage of growth, with higher proportions of stem than leaf tissue, may be more suitable for industrial fibre applications.