Yarrow (Achillea millefolium) for low-input lawns in the Mediterranean environment

In recent years, environmental concerns have created a desire for the sustainable care of grass swards, with a specific goal of reducing resources needed for turfgrass maintenance by utilising low-input species best adapted to specific local environmental conditions. A two-year field experiment was conducted to compare the aesthetic or ornamental quality, and function potential, of different swards. The treatments consisted of four monostands of white clover (Trifolium repens L.), yarrow (Achillea millefolium L.), strong creeping red fescue (Festuca rubra L. ssp. rubra Gaudin), and tall fescue (Festuca arundinacea Schreb. = Schedonorus arundinaceus Schreb. Dumort.), three two-species mixtures of white clover + yarrow, white clover + strong creeping red fescue, and yarrow + strong creeping red fescue, and one three-species mixture of white clover + yarrow + strong creeping red fescue. Within each plot, a botanical survey was performed each spring to estimate species relative abundance by determining the proportions of different species present. All plots were evaluated every two weeks during the growing period for visual quality and normalised difference vegetative index. Vegetation canopy height in each plot was measured before each biweekly mowing event, and clippings were collected to measure vegetative dry matter. Relative abundance of yarrow, strong creeping red fescue, and tall fescue was stable throughout the entire study period. The mixtures including yarrow displayed sufficient or higher quality ratings (≥6) in all seasons with the exception of winter, however, yarrow + strong creeping red fescue compensated each other's defects by maintaining their relative abundance (≥ 80%) over time as well suppressing or prevent significant weed invasion (relative abundance <15%). Moreover, yarrow or strong creeping red fescue monostands, or yarrow + strong creeping red fescue could be maintained with lower number of mowing events, due to their lower vertical growth. In conclusion, alternative plant species to turf-type grasses produced a visual quality equal to or better than tall fescue maintained under low fertilisation and mowing frequency. All swards that included yarrow produced better visual quality, exhibited better weed control, had lower vertical growth rate, and provided an aesthetically pleasant, persistent, and sustainable vegetative ground cover than other swards, and can be utilised as a low-input species.     

Additive and synergistic effects of land cover,land use and climate on insect biodiversity

Context

We address the issue of adapting landscapes for improved insect biodiversity conservation in a changing climate by assessing the importance of additive (main) and synergistic (interaction) effects of land cover and land use with climate.

Objectives

We test the hypotheses that ant richness (species and genus), abundance and diversity would vary according to land cover and land use intensity but that these effects would vary according to climate.

Methods

We used a 1000 m elevation gradient in eastern Australia (as a proxy for a climate gradient) and sampled ant biodiversity along this gradient from sites with variable land cover and land use.

Results

Main effects revealed: higher ant richness (species and genus) and diversity with greater native woody plant canopy cover; and lower species richness with higher cultivation and grazing intensity, bare ground and exotic plant groundcover. Interaction effects revealed: both the positive effects of native plant canopy cover on ant species richness and abundance, and the negative effects of exotic plant groundcover on species richness were greatest at sites with warmer and drier climates.

Conclusions

Impacts of climate change on insect biodiversity may be mitigated to some degree through landscape adaptation by increasing woody native vegetation cover and by reducing land use intensity, the cover of exotic vegetation and of bare ground. Evidence of synergistic effects suggests that landscape adaptation may be most effective in areas which are currently warmer and drier, or are projected to become so as a result of climate change.

     

Solar radiation intensity influences extensive green roof plant communities

Two studies were conducted on a third-story rooftop to quantify the effect of solar radiation (full sun versus full shade) on several US native and non-native species for potential use on extensive green roofs. In the first study, plugs of six native and three non-native species were planted in May 2005 on substrates of two different depths (8.0 and 12.0 cm) both in sun and shade. Absolute cover (AC) was recorded using a point-frame transect during the growing season beginning in June 2005 and every 2 weeks thereafter for a period of 4 years. By week 174 (23 September 2008), most species exhibited different AC within a depth between sun and shade. However, when all species were combined, overall AC did not differ between sun and shade within a depth. This indicated that while species make-up was changing among solar radiation levels, that overall coverage was not significantly different between sun and shade. For all substrate depths and solar levels, the most abundant species were Sedum acre, Allium cernuum, Sedum album ‘Coral Carpet’, and Talinum calycinum. Less abundant species included Talinum parviflorum, Carex flacca, Sedum stenopetalum, and Sedum divergens, which all exhibited 0 or near 0 AC regardless of depth or solar radiation levels. With the exception of T. calycinum, native species were less abundant than non-native species.In the second study, six common extensive green roof species of Sedum established from seed in May 2005 on a 10.0 cm (3.9 in) substrate depth were compared in both sun and shade over four growing seasons. AC was evaluated as in the previous study. Solar radiation did not affect AC, but overall species composition differed between sun and shade levels. The most abundant species in full sun were S. acre (0.57 AC) and S. album ‘Coral Carpet’ (0.51 AC). Sedum kamtschaticum (0.57 AC) and Sedum spurium ‘Coccineum’ (0.35 AC) performed the best in the shade. For both solar levels, the least abundant species at week 174 were Sedum pulchellum (0.0 AC) and S. album ‘Coral Carpet’ (0.1 AC).     

A tale of two wildfires; testing detection and prediction of invasive species distributions using models fit with topographic and spectral indices

Context

Developing species distribution models (SDMs) to detect invasive species cover and evaluate habitat suitability are high priorities for land managers.

Objectives

We tested SDMs fit with different variable combinations to provide guidelines for future invasive species model development based on transferability between landscapes.

Methods

Generalized linear model, boosted regression trees, multivariate adaptive regression splines, and Random Forests were fit with location data for high cheatgrass (Bromus tectorum) cover in situ for two post-burn sites independently using topographic indices, spectral indices derived from multiple dates of Landsat 8 satellite imagery, or both. Models developed for one site were applied to the other, using independent cheatgrass cover data from the respective ex situ site to test model transferability.

Results

Fitted models were statistically robust and comparable when fit with at least 200 cover plots in situ and transferred to the ex situ site. Only the Random Forests models were robust when fit with a small number of cover plots in situ.

Conclusions

Our study indicated spectral indices can be used in SDMs to estimate species cover across landscapes (e.g., both within the same Landsat scene and in an adjacent Landsat scene). Important considerations for transferability include the model employed, quantity of cover data used to train/test the models, and phenology of the species coupled with the timing of imagery. The results also suggest that when cover data are limited, SDMs fit with topographic indices are sufficient for evaluating cheatgrass habitat suitability in new post-disturbance landscapes; however, spectral indices can provide a more robust estimate for detection based on local phenology.

     

Landscape simplification promotes weed seed predation by carabid beetles (Coleoptera: Carabidae)

Weeds constitute major constraints for farmers by reducing crop yield and quality. However, weeds are managed effectively using herbicides, but this may cause harmful effects on human health and the environment. In an experiment on weed seed predation, we tested the biological control potential of carabid beetles to combat weeds in the absence of herbicides. Seeds from three common weed species were placed in cereal fields on conventional and organic farms located along a landscape complexity gradient (area annual crops within 1 km) in two distinct regions in Sweden. Carabid beetles were sampled in the same fields using pitfall traps. Neither carabid species richness nor seed removal was related to organic farming. Seed removal was significantly related to carabid species richness and both carabid species richness and seed removal was higher in landscapes with large total area of annual crops, although the evenness of the carabid communities was lower. The carabid genera with strongest positive relationship to seed removal differed between regions (Trechus in Uppland and Pterostichus in Scania), as did the preference for the different weed seed species. This study concludes that carabid species richness contributes to weed seed predation and that large scale landscape context explains more variation in the carabids’ responses than local farming practices.     

How deforestation pattern in the Amazon influences vertebrate richness and community composition

The effects of habitat configuration on species persistence are predicted to be most apparent when remaining habitat cover is below 30%. We tested this prediction by comparing vertebrate communities in 21 landscapes located in the southern Amazonia, including 7 control landscapes (~100% of forest cover) and 14 fragmented landscapes (4?×?4?km). The fragmented landscapes retained similar proportions of forest (~25%), but had contrasting configurations, resulting from two different deforestation patterns: the ??fish-bone pattern?? common in small properties, and the large-property pattern generally used by large ranchers. Vertebrates were surveyed in all landscapes in February?CJuly 2009 with interviews (n?=?150). We found a significant difference in reported species richness among the fish-bone, large-property, and control areas (mean?=?29.3, 38.8 and 43.5 respectively). Control areas and large-properties tended to have a higher number of specialist species (mean?=?13.7, and 11.7, respectively), when compared with the fish-bone pattern (5.1). Vertebrate community composition in the control and large-properties was more similar to one another than to those of the fish-bone landscapes. The number of fragments was the main factor affecting the persistence of species, being negatively associated with specialist species richness. Species richness was also positively related with the size of the largest fragment structurally connected to the studied landscapes (i.e., a regional scale effect). Our results demonstrated that the large-property pattern, which results in less fragmented landscapes, can maintain a more diverse community of large vertebrates, including top predators, which are considered fundamental for maintaining ecosystem integrity. These results support the hypothesis that landscape configuration contributes to the persistence and/or extirpation of species.     

The effect of constant and alternating temperatures,rinsing, stratification and fertilizer on germination of some weed species

The effect of constant and alternating temperatures, rinsing, stratification and application of a fertilizer solution on germination of 4 weed species was studied.The seeds of Matricaria chamomilla L. (mayweed) and Poa annua L. (annual meadow grass) achieved almost 100% germination under any condition. For Solanum nigrum L. (black nightshade) an alternating temperature was necessary for germination. The germination percentage of this species was also improved by a cold pretreatment. For Thlaspi arvense L. (stinkweed) a high germination percentage was obtained only when stratification, alternating temperature and a fertilizer solution were applied.     

Exploring the use of edible and evergreen perennials in living wall systems in the Scandinavian climate

We have performed a field experiment to investigate the survival and vitality of perennial plants in a living wall installed in an industrial area in Malmö, southern Sweden. The main aim of the study was to investigate the possibility of growing edible and evergreen perennial plants in living wall systems in the Scandinavian climate. We conclude that the edible perennial plants Allium schoenoprasum, Calamintha nepeta, and Fragaria vesca are feasible in living wall systems in the Scandinavian climate. Thymus vulgaris is sensitive to the Scandinavian climate, and performed equally poorly in Rockwool panels and in soil-filled containers (controls). We also conclude that the evergreen perennial plant species Chamaecyparis pisifera, Euonymus fortuneii, Euphorbia polychroma, Vinca minor, and Waldsteinia ternata can be grown in green walls, and that the edible evergreen plant Vaccinium vitis-idea is highly suitable for living walls in this climatic region. A. schoenoprasum, C. pisifera, E. fortuneii, I. crenata, L. sylvatica, V. minor, and V. vitis-idea showed 100% survival rates, however, the visual quality of e.g. I. crenata and L. sylvatica was not acceptable for ornamental purposes.     

Rooftop temperature reduction from unirrigated modular green roofs in south-central Texas

Modular green roofs were investigated to better understand surface and membrane level temperature expectations of unirrigated green roofs during hot summer conditions in south-central Texas. We used three succulent monocultures, Sedum kamtschaticum, Delosperma cooperi, Talinum calycinum syn. Phemeranthus calycinus and one unplanted control module, each replicated 3 times. Media surface and below media temperatures were monitored, as well as soil water content and general weather conditions (RH, air temperature). Temperatures at the surface and below the media surface were compared with temperatures of a standard roof surface. We found that diurnal surface temperature reductions were very stable throughout the summer. Much larger temperature reductions were achieved below the modules than at the soil surface. Temperature reductions at the soil surface were predominantly driven by soil volumetric water content (VWC) and, to a lesser degree, air temperature while species and percent cover had small modifying effects through interactions with VWC and air temperature. Temperature reductions below the modules were driven by surface soil temperature, while increasing VWC led to a small decrease in temperature reductions at the membrane level. Mean daily temperature reductions achieved were 18.0 °C at the soil surface and 27.5 °C below the module, thus demonstrating that unirrigated, succulent-based green roofs can provide significant rooftop temperature reductions during hot, dry summer conditions.     

Incidence of competitors and landscape structure as predictors of woodland-dependent birds

Globally, modification of landscapes for agriculture has had a strong influence on the distribution and abundance of biota. In particular, woodland-dependent birds are under threat across agricultural landscapes in Britain, North America and Australia, with their decline and extirpation attributed to the loss and fragmentation of habitat. Other native species have become over-abundant in response to anthropogenic landscape change and have strong interactive effects on avian assemblage structure. In eastern Australia, the hyper-aggressive noisy miner (Manorina melanocephala) often dominates woodlands in agricultural landscapes through interspecific competition, resulting in declines of species richness of woodland-dependent birds. We aimed to determine the relative influence and importance of interspecific competition, in situ habitat structure and landscape structure for woodland-dependent bird species at the landscape level. We recorded species-specific landscape incidence of woodland-dependent birds in 24 agricultural-woodland mosaics (25 km²) in southern Queensland, Australia. We selected extensively cleared landscapes (10–23 % woodland cover) where fragmentation effects are expected to be greatest. We applied generalised linear models and hierarchical partitioning to quantify the relative importance of the landscape-level incidence of the noisy miner, mistletoe abundance, shrub cover, woodland extent, woodland subdivision and land-use intensity for the incidence of 46 species of woodland birds at the landscape-scale. The landscape-level incidence of the noisy miner was the most important explanatory variable across the assemblage. Both in situ habitat structure and landscape structure were of secondary importance to interspecific aggression, although previous research suggests that the increasing incidence of the noisy miner in fragmented agricultural landscapes is itself a consequence of anthropogenic changes to landscape structure. Species’ responses to fragmentation varied from positive to negative, but complex habitat structure had a consistently positive effect, suggesting in situ restoration of degraded habitats could be a conservation priority. Landscape wide conservation of woodland-dependent bird populations in agricultural landscapes may be more effective if direct management of noisy miner populations is employed, given the strong negative influence of this species on the incidence of woodland-dependent birds among landscapes.     

Effect of co-cultivation and crop rotation on corm rot disease of Gladiolus

Field and pot experiments were conducted to evaluate the effect of co-cultivation and crop rotation on the growth and corm rot disease of gladiolus (Gladiolus grandiflorus sect. Blandus) cv. Aarti caused by Fusarium oxysporum f.sp. gladioli (Massey) Snyd. and Hans. In the field experiment, gladiolus was co-cultivated with 10 agricultural/horticultural crops viz. Allium cepa L., Brassica campestris L., Capsicum annuum L., Eruca sativa Mill., Helianthus annuus L., Tagetes erectus L., Zea mays L., Vinca rosea L. and Rosa indica L., in a soil infested with F. oxysporum. All the crops except V. rosea and R. indica reduced disease incidence. The effect of H. annuus and T. erectus was significant and more pronounced than other co-cultivated crops. In general, root and shoot dry biomass, corm fresh weight, number of cormlets and number of flowers per spike decreased as compared to the un-inoculated monoculture gladiolus treatment (negative control) but these parameters enhanced as compared to the F. oxysporum inoculated monoculture gladiolus treatment (positive control). In a pot experiment, all the crops of the field experiment except V. rosea and R. indica were sown in rotation with gladiolus. Pot grown plants of different species were harvested at maturity and the soil was inoculated with F. oxysporum. Gladiolus was cultivated 1 week after inoculation. Disease incidence was significantly suppressed in all the treatments ranging from 29% to 53%. The highest suppression of disease incidence was recorded in T. erectus (53%) followed by B. campestris (49%). The effect of preceding crops on various vegetative parameters was similar in the pot experiment to that of the field experiment. The present study suggests that corm rot disease of gladiolus can be managed by mixed cropping of H. annuus and T. erectus or cultivation of T. erectus and B. campestris in rotation.     

Genetic characterization of asparagus doubled haploids collection and wild relatives

The genus Asparagus is very large consisting of around 150 species found as herbaceous perennials, tender woody shrubs and vines. The cultivated species (Asparagus officinalis L., diploid) is a highly prized vegetable, grown in different environments ranging from cool temperate zones to deserts, Mediterranean climates and tropical areas. As a consequence, Asparagus breeders have developed different cultivars that differ for their morpho-agronomic traits, habit and ploidic status (few triploid and tetraploid cultivars are used). Several breeding methods are used for developing cultivars, among which a well developed in vitro anther culture technique produces homozygous clones useful for F₁ hybrids constitution. A fluorescent based AFLP (amplified fragment length polymorphism) technique were applied with the aim to assess genetic diversity among a collection of 173 doubled haploid (DH) androgenetic clones, five Asparagus wild species and interspecific hybrids obtained among the cultivated species and two wild relatives. The average number of AFLP fragments generated per primer set was 105, varying in size from 50 to 550 bp. A total of 1054 AFLP fragments were detected, 20% of which were polymorphic. Genetic similarity based on DNA polymorphisms, showed that a few number of AFLP primer combinations are able to distinguish the cultivated DH clones from the wild species. Indeed, from one DH clone for each anther donors and the wild species were used to construct a dendrogram using Dice's coefficient and the unweighted pair group method with the arithmetic mean (UPGMA). Genetic distances among all DH clones were calculated using the C.S. Chord distance; and a neighbour-joining (NJ) consensus tree was constructed in order to support the breeder for parental genotype choice for asparagus hybrid constitution.     

Fine-scale effects of habitat loss and fragmentation despite large-scale gene flow for some regionally declining woodland bird species

Habitat loss and associated fragmentation effects are well-recognised threats to biodiversity. Loss of functional connectivity (mobility, gene flow and demographic continuity) could result in population decline in altered habitat, because smaller, isolated populations are more vulnerable to extinction. We tested whether substantial habitat reduction plus fragmentation is associated with reduced gene flow in three ??decliner?? woodland-dependent bird species (eastern yellow robin, weebill and spotted pardalote) identified in earlier work to have declined disproportionately in heavily fragmented landscapes in the Box-Ironbark forest region in north-central Victoria, Australia. For these three decliners, and one ??tolerant?? species (striated pardalote), we compared patterns of genetic diversity, relatedness, effective population size, sex-ratios and genic (allele frequency) differentiation among landscapes of different total tree cover, identified population subdivision at the regional scale, and explored fine-scale genotypic (individual-based genetic signature) structure. Unexpectedly high genetic connectivity across the study region was detected for ??decliner?? and ??tolerant?? species. Power analysis simulations suggest that moderate reductions in gene flow should have been detectable. However, there was evidence of local negative effects of reduced habitat extent and structural connectivity: slightly lower effective population sizes, lower genetic diversity, higher within-site relatedness and altered sex-ratios (for weebill and eastern yellow robin) in 10 × 10?km ??landscapes?? with low vegetation cover. We conclude that reduced structural connectivity in the Box-Ironbark ecosystem may still allow sufficient gene flow to avoid the harmful effects of inbreeding in our study species. Although there may still be negative consequences of fragmentation for demographic connectivity, the high genetic connectivity of mobile bird species in this system suggests that reconnecting isolated habitat patches may be less important than increasing habitat extent and/or quality if these need to be traded off.     

Trade-offs between tree cover, carbon storage and floristic biodiversity in reforesting landscapes

This study explores the relationships between an increase in tree cover area (i.e., natural and planted-tree land covers) and changes in forest carbon storage and the potential of a landscape to provide habitat for native floristic biodiversity. Four areas experiencing an increase in tree cover were analyzed. We developed a metric estimating the potential to support native biodiversity based on tree cover type (plantation or natural forests) and the landscape pattern of natural and anthropogenic land covers. We used published estimates for forest and plantation carbon stocks for each region. Focus regions in northwestern Costa Rica, northern Vietnam, southern Chile and highland Ecuador all showed an increase in tree cover area of 390?%, 260?%, 123?% and 418?%, respectively. Landscapes experiencing increases in natural secondary forest also experienced an increase in carbon stored above and below ground, and in the potential to support native floristic biodiversity. Study landscapes in Chile and Ecuador experiencing an expansion of exotic plantations saw their carbon stock decrease along with their potential to support native floristic biodiversity. This study shows that an increase in forest area does not necessarily imply an increased provision of ecosystem services when landscapes are reforesting with monoculture plantations of exotic tree species. Changes in the support of native biodiversity and the carbon stored in pulp rotation plantations, along with other ecosystem services, should be fully considered before implementing reforestation projects.     

Quality assessment of three warm-season turfgrasses growing in different substrate depths on shallow green roof systems

In an effort to increase the accessibility and functionality of shallow green roof systems, the ability of warm-season grasses to provide acceptable growth needs to be further investigated. In the current study, which was conducted during 2011 and 2012, three warm-season grasses (hybrid bermudagrass, Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy ‘MiniVerde’; seashore paspalum, Paspalum vaginatum Swartz ‘Platinum TE’ and zoysiagrass, Zoysia japonica Steud. ‘Zenith’) were established in outdoor lysimeters. The lysimeters were equipped with all necessary green roof layers placed below a coarse-textured substrate that comprised pumice, thermally treated attapulgite clay, peat, compost and zeolite. Half of the lysimeters had a substrate depth of 15 cm, while the other half had a substrate depth of 7.5 cm. Irrigation was applied at crop evapotranspiration (ET_c). Measurements included determination of substrate moisture content, green turf cover (GTC) and leaf stomatal resistance. Significant differences were observed in the values of GTC among the three turfgrass species and the two substrate depths. Zoysiagrass exhibited the best adaptation at the lower depths of shallow green roof systems. At 15 cm substrate depth, zoysiagrass managed to sustain green coverage for the two study periods. In addition, it was the only turfgrass species that managed to perform well at the substrate depth of 7.5 cm. Seashore paspalum exhibited limited green cover at both substrate depths, while hybrid bermudagrass could provide acceptable green coverage only at 15 cm substrate depth.     

Effects of land-use history and the contemporary landscape on non-native plant invasion at local and regional scales in the forest-dominated southern Appalachians

Determining what factors explain the distribution of non-native invasive plants that can spread in forest-dominated landscapes could advance understanding of the invasion process and identify forest areas most susceptible to invasion. We conducted roadside surveys to determine the presence and abundance of 15 non-native plant species known to invade forests in western North Carolina, USA. Generalized linear models were used to examine how contemporary and historic land use, landscape context, and topography influenced presence and abundance of the species at local and regional scales. The most commonly encountered species were Microstegium vimineum, Rosa multiflora, Lonicera japonica, Celastrus orbiculatus, Ligustrum sinense, and Dioscorea oppositifolia. At the regional scale, distance to city center was the most important explanatory variable, with species more likely present and more abundant in watersheds closer to Asheville, NC. Many focal species were also more common in watersheds at lower elevation and with less forest cover. At the local scale, elevation was important for explaining the species’ presence, but forest cover and land-use history were more important for explaining their abundance. In general, species were more common in plots with less forest cover and more area reforested since the 1940s. Our results underscore the importance of considering both the contemporary landscape and historic land use to understand plant invasion in forest-dominated landscapes.     

Sooty canker,a destructive disease of banyan (Ficus benghalensis L.) trees in landscapes of Kish Island (Iran)

Ficus benghalensis L (banyan tree) has been planted as ornamental tree in parks, landscapes as well as along roads and streets in many southern cities of Iran. During field surveys conducted in Kish Island (Hormozgān province) an unusual decline was noticed on F. benghalensis. Affected trees exhibited bark necrosis, peeled off bark and cankers on branches and aerial roots, yellowing and defoliation, branch dieback and eventually death. A black sooty mass of fungal spores under the bark as well as wood discoloration in cross sections were also observed on infected parts of trees and pruning wood debris. Samples were collected from all affected parts of trees showing disease symptoms, pruning wood debris as well as rove arthropods in close proximity to the trees for the presence of fungal inoculum. In this study 239 Botryosphaeriaceae-like isolates were obtained from discoloured wood tissues, pruning wood debris and from the bodies of collected arthropods. Based on morphological characteristics and DNA sequence data of ITS and tef-1α gene regions, isolates were identified as Lasiodiplodia theobromae and Neoscytalidium dimidiatum. Pathogenicity of both species was performed on the branches of banyan trees and L. theobromae was more virulent, based on the length of necrotic lesions in the wood, than those of N. dimidiatum. This study is the first report of N. dimidiatum associated with sooty canker and dieback of F. benghalensis worldwide. Our study showed for the first time that L. theobromae and N. dimidiatum can also be associated with some arthropods. Our outcomes can improve the management strategies of trunk diseases caused by Botryosphaeriaceae species on ornamental trees in landscapes.     

Landscape composition is the strongest determinant of bird occupancy patterns in tropical forest patches

Context

Biodiversity in tropical region has declined in the last decades, mainly due to forest conversion into agricultural areas. Consequently, species occupancy in these landscapes is strongly governed by environmental changes acting at multiple spatial scales.

Objectives

We investigated which environmental predictors best determines the occupancy probability of 68 bird species exhibiting different ecological traits in forest patches.

Methods.

We conducted point-count bird surveys in 40 forest sites of the Brazilian Atlantic forest. Using six variables related to landscape composition and configuration and local vegetation structure, we predicted the occupancy probability of each species accounting for imperfect detections.

Results

Landscape composition, especially forest cover, best predicted bird occupancy probability. Specifically, most bird species showed greater occupancy probability in sites inserted in more forested landscapes, while some species presented higher occurrence in patches surrounded by low-quality matrices. Conversely, only three species showed greater occupancy in landscapes with higher number of patches and dominated by forest edges. Also, several species exhibited greater occupancy in sites harbouring either larger trees or lower number of understory plants. Of uttermost importance, our study revealed that a minimum of 54% of forest cover is required to ensure high (> 60%) occupancy probability of forest species.

Conclusions

We highlighted that maintaining only 20% of native vegetation in private property according to Brazilian environmental law is insufficient to guarantee a greater occupancy for most bird species. We recommend that policy actions should safeguard existing forest remnants, expand restoration projects, and curb human-induced disturbances to minimise degradation within forest patches.

     

Detecting hot and cold spots in a seagrass landscape using local indicators of spatial association

Eelgrass (Zostera marina) is an important feature of coastal ecosystems in Atlantic Canada, providing a suite of valuable ecosystem services. These services, and its sensitivity to stressors, have prompted efforts to characterize the spatial and temporal dynamics of eelgrass landscapes in order to facilitate management and monitoring of coastal ecosystem health. Current methods for broad-scale mapping of eelgrass rely on aerial remote sensing and may not be appropriate in certain types of landscapes, particularly in turbid waters and areas lacking distinct boundaries. This study takes a novel approach to the quantification and analysis of seagrass landscape structure at multiple spatial scales using acoustic data and local spatial statistics. Data from a single-beam acoustic survey in Richibucto, New Brunswick, Canada were analyzed with geostatistical techniques and the Getis-Ord G _i ^* local spatial statistic in order to detect statistically significant zones of high and low cover in an estuarine seagrass bed. Results showed distinct and significant patterns in seagrass cover at multiple spatial scales within a region of apparently continuous spatial cover. Boundaries between areas of high and low cover were also detected. This study demonstrates how acoustic data and local spatial statistics can be used to quantify landscape pattern and to further the application of landscape techniques in the marine environment.     

Two potent allelopathic substances in cucumber plants

Since cucumber plants are mostly discarded as large waste after crop harvesting, allelopathy of cucumber plants was investigated for possible weed management options and utilization of the waste. Two potent growth inhibitory substances were isolated from an aqueous methanol extract of cucumber (Cucumis sativus L. cv. Phung Tuong) plants. These substances were determined as 9-hydroxy-4,7-megastigmadien-9-one (HMO) and (6S,7E,9S)-6,9,10-trihydroxy-4,7-megastigmadien-3-one (THMO) by the analysis of MS, ¹H NMR spectra and optical rotation. HMO inhibited the growth of cress (Lepidium sativum L.) and Echinochloa crus-galli (L.) Beauv seedlings at concentrations greater than 0.3 and 1 μM, respectively. THMO inhibited the growth of cress and E. crus-galli seedlings at concentrations greater than 1 and 3 μM, respectively. The concentrations required for 50% growth inhibition on roots and shoots of cress and E. crus-galli were 2.4–29.3 μM for HMO and 8.1–52.2 μM for THMO. The endogenous levels of HMO and THMO in cucumber plants were 31.8 and 43.5 μg g⁻¹ dry weight, respectively. These results suggest that HMO and THMO may be the causal factors for the growth inhibitory effect of cucumber plants. Therefore, cucumber plants may be potentially useful for weed management options in an agricultural setting, such as a cover crop and soil admixture, which should be investigated further in the field.