Plant-pollinator biodiversity and pollination services in a complex Mediterranean landscape

Mediterranean landscapes comprise a complex mosaic of different habitats that vary in the diversity of their floral communities, pollinator communities and pollination services. Using the Greek Island of Lesvos as a model system, we assess the biodiversity value of six common habitats and measure ecosystemic ‘health’ using pollen grain deposition in three core flowering plants as a measure of pollination services. Three fire-driven habitats were assessed: freshly burnt areas, fully regenerated pine forests and intermediate age scrub; in addition we examined oak woodlands, actively managed olive groves and groves that had been abandoned from agriculture. Oak woodlands, pine forests and managed olive groves had the highest diversity of bees. The habitat characteristics responsible for structuring bee communities were: floral diversity, floral abundance, nectar energy availability and the variety of nectar resources present. Pollination services in two of our plant species, which were pollinated by a limited sub-set of the pollinator community, indicated that pollination levels were highest in the burnt and mature pine habitats. The third species, which was open to all flower visitors, indicated that oak woodlands had the highest levels of pollination from generalist species. Pollination was always more effective in managed olive groves than in abandoned groves. However, the two most common species of bee, the honeybee and a bumblebee, were not the primary pollinators within these habitats. We conclude that the three habitats of greatest overall value for plant-pollinator communities and provision of the healthiest pollination services are pine forests, oak woodland and managed olive groves. We indicate how the highest value habitats may be maintained in a complex landscape to safeguard and enhance pollination function within these habitats and potentially in adjoining agricultural areas.     

Flora and plant genetic resources of ancient olive groves of Apulia (Southern Italy)

A floristic study of vascular flora of ancient olive groves of Apulia (Italy) was carried out from 2009 to 2011. Research was made in the fields and in the ecological infrastructures of four olive groves, located in protected areas: National Park of Gargano, Park of Dune Costiere, State and Marine Natural Reserve of Torre Guaceto and of Le Cesine. Floristic analysis was carried out by Raunkiaer and Braun-Blanquet. Biological forms and chorological types were named according to Raunkiear. Overall, 408 taxa were identified, of which 332 species, 73 subspecies and 3 varieties, belonging to 275 genera and 74 families. A small segment of 18 taxa, out of 408, was considered of conservation interest. For these taxa the topography of the collecting site, plant community, population density, degree of vulnerability and habitats were recorded, according to the Directive 92/43/EEC. Another segment of 111 taxa, out of a total of 408, was considered important for usage, which for the sake of presentation has been divided in five arbitrary categories: food crops, fodder crops, medicinal, aromatic and officinalis, crop wild relatives and edible wild species. For each of these taxa, an attempt to provide relevant information was made. Only two taxa, i.e., Muscari parviflorum and Aegilops uniaristata are common to both segments. The work was carried out within the competence of the LIFE+ CENT.OLI.MED. (LIFE07 NAT/IT/000450) project, with the aim to gather information for improving conservation and management of olive groves of Apulia, as well as of their related wild life.     

Determinants of Woody Plant Species Richness in Abandoned Olive Grove Ecosystems and Maquis of Central Greece

The present study aimed to compare the woody plant species richness and cover (%) of five abandoned olive groves and five maquis ecosystems in central Greece and to describe the relationship between woody plant species richness and a set of environmental variables [soil pH, nitrogen (N), phosphorus (P), potassium (K), and organic matter; air temperature and humidity; altitude; slope; type of ecosystem; and presence of leaf litter]. Although woody plants are abundant in the abandoned olive groves, the number of species and amount of cover (%) are significantly greater in maquis. According to principal component analysis, woody plant species richness was positively correlated with soil organic matter, plant litter, and soil P and K in maquis. Also, woody plant species richness was positively correlated with slope in the abandoned olive groves. Olive grove ecosystems abandoned for at least 12 years have developed species compositions similar to the corresponding features of neighboring maquis, although the number of species and amount of cover (%) are significantly greater in maquis.     

Effect of Land-Use History on Soil Carbon and Nitrogen in a Mediterranean Catchment

The impact of land use on soil organic matter was investigated. Five land cover types (pine forest, olive groves, wheat, wheat/maize cultivation systems, and a shrub pasture) belonging to three land-use categories from the same catchment in the island of Lesvos, Greece, were used. The soils developed under similar pedogenetic processes and accepted similar agricultural practices for at least 30 years. The results showed that the land-use and cover types ranged according to their total soil carbon (C) content as follows: forest > double cultivation > wheat > olive > pasture. Crop plantations contained 31 to 40% less C at their upper 0- to 45-cm layer than forest. Pasture had shallow soils with a small C accumulation but high C concentration, whereas olive groves had the lowest concentrations of both soil C and nitrogen (N). Olive grove soils were the most prone to degradation but possessed the greatest potential for C sequestration.     

Soil properties in organic olive groves compared with that in natural areas in a mountainous landscape in southern Spain

This study evaluates soil properties in organically managed olive groves and natural zones in a mountainous area of Andalusia, Spain. Two soil types (Eutric Regosol and Eutric Cambisol) and the most common soil management methods (tillage and two intensities of grazing) were studied. Both soil types in the groves had values not much lower than those in the natural areas. Average (±SE) values in the groves were 1.58 ± 0.71% for organic carbon, 323 ± 98 g kg^?1 for macroaggregate stability, 1.11 ± 0.16 g cm^?3 for bulk density, 3.5 ± 1.6 mm h^?1 for saturated hydraulic conductivity and 1209 ± 716 mg CO₂ kg^?1 for soil respiration. Overall, these values tended to be lower in the tilled compared with that in the grazed groves. The average phosphorus soil content (5.83 ± 5.22 mg kg^?1) was low for olive production and within adequate ranges for N (0.12 ± 0.05%) and K (142 ± 81 mg kg^?1). Soil erosion was high in the tilled groves (35.5 ± 18.2 t ha^?1 year^?1) with soil loss correlating with indicators of soil degradation such as organic carbon content and water stable macroaggregates. In the grazed groves, soil loss was moderate with no clear indications of soil degradation. Overall, there was significant farm‐to‐farm variability within the same soil and land management systems. Olive production had a moderate effect on soil degradation compared with natural areas and olive cultivation could be sustained in future if cover crop soil management replaced tillage, especially in the most sloping areas.     

Mycorrhizal,nutritional and virgin olive oil parameters affected by groundcovers

Management of olive groves faces the challenge of reconciling yield, soil degradation and virgin olive oil (VOO) quality. We evaluated the effect of replacing tillage management by vegetal groundcovers (GC) on the relationships between mycorrhizal symbiosis, olive nutritional status, and VOO quality under field rainfed conditions. The experiment was set up in 2014 in an existing Cornicabra olive orchard with a Haplic Gypsisol soil under a Mediterranean semiarid climate. Four treatments were replicated four times and consisted of: (1) annual cover of bitter vetch, (2) permanent Brachypodium distachyon, (3) spontaneous vegetation cover (mainly Brassicaceae species), and (4) tilled soil. The use of bitter vetch GC increased the olive root colonization by 50% compared with the tillage treatment. The effect of tillage on VOO differed from that of GC use. Tillage treatment decreased maturity index and its VOO had lower polyphenol content and less luminosity than that from the GC treatments. Olive root colonization, together with changes in nutrients such as Cu, B and other elements resulting from GC use, seems to play an important role in explaining the variability of VOO quality parameters. Although tillage may lead to higher yield by controlling competition for water and nutrients, the introduction of GC in olive groves led to higher polyphenol contents, enhancing VOO quality and, at the same time, protecting soil from erosion.     

Olive mill waste and glyphosate‐based herbicide addition to olive grove soils: effects on microbial activities and their responses to drying–rewetting cycles

The objective of this experimental study was to determine the effect of agronomic practices usually implemented in olive groves (addition of olive mill waste and herbicides) on soil microbial communities and to test whether drought enhanced such effects. For that purpose, mesocosms containing soil cores from olive groves were incubated for 5 months under either of the three treatments: (i) addition of olive mill waste (OMW), (ii) addition of glyphosate‐based herbicide (Gly treatment) and (iii) both treatments. Half of the mesocosms were subjected or not (controls) to drying–rewetting cycles (D/Rw) for 1 month (1 D/Rw) or 3 months (3 D/Rw). In the controls, 2 months after the Gly treatment, higher lipase activities were observed compared with no practice treatment as well as a significant change in catabolic profiles of cultivable microbial communities. Three months later, lipase activities significantly decreased under the Gly treatment. Addition of OMW together with Gly treatment counteracted the negative effect of the herbicide on lipase activities. After three D/Rw cycles, Gly treatment modified catabolic profiles and induced a decrease in functional diversity. Overall, the combination of glyphosate‐based herbicide with OMW was a conservative practice that maintained soil functioning and led to a better response to D/Rw cycles.     

Mulching as best management practice to reduce surface runoff and erosion in steep clayey olive groves

No-tillage and soil mulching with pruning residues,applied in olive groves of the semi-arid Mediter-ranean environment,as erosion control practices still practi...     

黄土丘陵沟壑区退耕坡地不同植物群落的土壤侵蚀特征

黄土高原地区水土流失造成严重的农业和生态环境问题,而植被能从根本上控制黄土高原的水土流失.以安塞县典型退耕坡地不同植物群落为研究对象,采用侵蚀针法,结合2012-2015年降雨数据及不同植物群落特征的分析,研究不同植被恢复坡地的土壤侵蚀特征.结果表明:研究期间,不同年份植被群落土壤侵蚀强度为丰水年＞平水年＞枯水年.不同植被类型群落防治土壤侵蚀的能力不同,具体为自然恢复灌木群落＞自然恢复草本群落＞人工灌木群落＞人工乔木群落.灰色关联度显示,降雨量与坡度是影响植被群落土壤侵蚀最重要的因素,乔灌木群落坡度＞降雨量,草本群落降雨量＞坡度.自然恢复植被群落枯落物盖度＞植被盖度,人工植被群落植被盖度＞枯落物盖度;因此,在当前植被条件下,未受到扰动的群落可有效减少降雨对土壤侵蚀的影响;在进行植被恢复时,应优先进行植被自然修复,适时适地引入乔灌木进行植被恢复人工调控,尽早促进乔木群落的林下植被发育,保护其林下灌草层和枯落物层,同时减少人为干扰.     

Modelling the event-based hydrological response of olive groves on steep slopes and clayey soils under mulching and tillage management using the SCS-CN,Horton and USLE-family models

The SCS-CN, Horton and USLE-family models are used worldwide, but few examples are available for olive groves on steep and clayey soils under mulching of pruning residues. We evaluate the accuracy in predicting runoff and soil loss of a steep (20%) and clayey olive grove subject to three soil conservation practices: mechanical tillage (MT), mulching with pruning residues (NTR) and standard protection (SP), measured at plot scale in Southern Italy during 30 months under natural rainfall. The models were calibrated by adjusting the Curve Numbers (for the SCS-CN model) and the C-factors (MUSLE and USLE-M); the Horton model was not calibrated. The model performance was assessed by qualitative and quantitative procedures. In all practices, the SCS-CN was more accurate for runoff predictions (mean difference of 7% compared with corresponding observations) compared with the Horton (mean difference of 30%). For soil erosion, the MUSLE showed better performance in soils subject to MT or total protection (differences lower than 10%), while the USLE-M was more reliable to simulate soil loss in mulched plots (differences of 8%). A set of Curve Numbers (95 for MT, 70 for SP and 85 for NTR) and C-factors (0.4 for MT, 0.2 for SP and 0.1 for NTR) are proposed for applications in steep slope and clayey soil olive orchards using the SCS-CN and USLE proposed models, respectively. Validation exercises in other environmental experimental conditions would enhance the export these models for runoff and erosion control in agricultural soils treated with mulching.     

Influence of two-phase olive mill waste application to soil on terbuthylazine behaviour and persistence under controlled and field conditions

Purpose  

Terbuthylazine is one of the most common herbicides used to control weeds in olive groves. Application of two-phase olive mill waste (OW) to soils may play a fundamental role in the management of leaching losses of pesticides, especially in Mediterranean areas where soils are characterized by low organic matter levels. We evaluated the impact of OW amendments on the sorption–desorption, degradation, leaching, and persistence of the herbicide terbuthylazine in a representative olive grove soil from Portugal.     

Fertilizer application during primary succession changes the structure of plant and herbivore communities

Fertilization of secondary successional communities generally increases biomass but reduces diversity; its impact on primary successional communities is less well understood. Following applications of a balanced fertilizer to naturally established vegetation on slate quarry waste, effects on tree growth, ground flora species and foliar invertebrates were monitored over two years. Fertilization increased tree growth, with stem basal area increasing by 130% over two growing seasons compared with a 50% increase in unfertilized trees. Several dominant ground flora species increased in cover as a result of fertilization. In contrast, cover of bryophytes was not increased. Fertilization favoured plant species associated with drier habitats, but disadvantaged less-competitive ruderal species. Tree foliar invertebrates were less abundant on the trees on slate waste than on trees in established woodland. Fertilization made tree leaves more palatable by increasing nitrogen and reducing soluble polyphenol concentrations, and increased the abundance of sap-sucking invertebrates, without changing foliar invertebrate diversity. Overall, fertilizing this primary successional site was beneficial for biodiversity; it increased abundance of dominant plant species and foliar invertebrate herbivores, yet few taxa were adversely affected during this period. Increases in tree biomass and invertebrate abundance are likely to favour the establishment of other taxa. Where the biodiversity conservation interest is principally in closed-canopy vegetation, applying fertilizer is a cheap, comparatively non-intrusive and effective way to increase biodiversity on denuded sites. However, plant species characteristic of open and infertile habitats (particularly bryophytes) and their obligate herbivorous invertebrates are likely to decrease in abundance.     

Bradford-reactive soil proteins and aggregate stability under abandoned versus tilled olive groves in a semi-arid calcisol

Glomalin, a substance produced by arbuscular mycorrhizal fungi, is reported to play a role in soil aggregation, but this role has been questioned in soils rich in calcium carbonate. We studied the relationship between aggregation stability and glomalin in a Haplic Calcisol comparing abandoned and active cultivation of olive groves. Abandonment was associated with increases in soil organic carbon, the percentage of water stable aggregates (WSA_1-2mm), and easily extractable and total Bradford-reactive soil protein. WSA_1-2mm was strongly positively correlated with both easily extractable and total Bradford-reactive soil protein. While easily extractable Bradford-reactive soil protein measured in both stable and unstable aggregates did not show any significant differences, Bradford-reactive soil protein was twice as high in stable than in unstable aggregates under both tillage and abandonment. Our results suggest that Bradford-reactive soil protein influences aggregate stability, even in soils with low organic matter and high calcium carbonate contents. However, more research is needed to elucidate the role of easily extractable Bradford-reactive soil protein in soil aggregation.     

Rainfall and Vegetation Effects on Temporal Variation of Topographic Thresholds for Gully Initiation in Mediterranean Cropland and Olive Groves

Topographical threshold conditions (s ≥ k a ^−b), expressed by local slope (s) and drainage area (a), have been widely used to predict gully incision locations. However, little attention has gone to the variation of the thresholds over time. Rainfall variability and changing land use or vegetation cover can potentially lead to important shifts in established thresholds. In this study, we determine topographic thresholds for gullies forming under olive groves and herbaceous crops between 1956 and 2013 in a catchment in Southern Spain. For ten different time periods, we then analysed the impact of rainfall, land use and vegetation cover on the variation of these thresholds. The results show similar topographic thresholds for olive groves and herbaceous crops. However, important variations were found over time. Rainfall indexes, in particular rainy day normal, were generally best correlated. Finally, although overall no effect of land use was obtained, the results did show a significant effect of vegetation cover, but mainly in those years where rainfall was low. This seems to indicate that during years with high rainfall, topographic thresholds are primarily controlled by rainfall, while vegetation cover seems to exert a secondary control. Copyright © 2017 John Wiley & Sons, Ltd.     

Surface control of desert pavement pedologic process and landscape function,Cima Volcanic field,Mojave Desert,California

Desert pavement is a distinctive feature widespread across arid lands of the world. It plays a dynamic role in geomorphic, hydrologic, and ecologic processes. Where desert pavement predominates, infiltration is limited and rainfall is delivered as runoff to nearby bare ground areas where shrubs cluster. Desert pavement surfaces may appear monotonously flat and barren, but we have found, instead, that they are a complex association of landscape and hydrologic elements governed by their surface characteristics. Previously, we identified six unique surface mosaic types that accurately capture the subtle, but distinct, variations in surface clast arrangements for a desert pavement landscape formed on a single-aged basalt flow in the Mojave Desert. We now report that these surface mosaics predict the spatial distribution of fundamental desert vegetation and soil characteristics. Characteristics of soil morphology and texture, the leaching depth of soluble salts, percent plant cover, and shrub species diversity are remarkably consistent for each mosaic type across a 580,000-year-old basalt flow even when measured >1 km apart. Hydrologic character is distinctly different between desert pavement and bare ground regions and vegetation distributions reflect the spatially heterogeneous soil moisture. Where desert shrubs cluster on the three bare ground surface mosaics, leaching is deep, removing most soluble salts to below the 50-cm depth. Where shrubs are absent or few, on the three desert pavement mosaics, leaching depths are shallow, with soluble salt depth distributions as well as desert shrub percent cover precisely controlled by the percent clast cover of the surface.     

巴丹吉林沙漠高大沙山区植被特征与地貌形态的关系

通过对巴丹吉林沙漠伊和吉格德湖高大沙山区野外植被考察,研究了该地区的生物多样性,并分析了该地区植被-沙山地貌形态之间的关系。结果表明,研究区植被种类较少,以旱生物种为主,植被群落分布的垂直特征及差异明显。该区植物种共计6科9属9种,沿沙山上部至底部依次为:草本群落-灌木群落-草本或半灌木群落。沙多分布在背风坡,碟果虫实及白莎蒿多分布在迎风坡。总体群落多样性测度结果,沙山两坡中部多样性指数高,背风坡上部及迎风坡中部均匀度指数高。分层次群落多样性测度结果,由于草本种类单一,草本群落多样性及均匀度指数差别不大,迎风坡中部灌木群落多样性指数最高。高大沙山植被群落特征受整体沙山地貌形态影响,迎风坡植被分布及多样性变化特征与沙山第1和第2序列地貌形态有良好的对应关系。在更为广泛的沙漠发育时期,沙山表面稀疏的植被通过影响输沙率进而拦截沙粒,在维持沙山高度方面具有更为重要作用。     

Historical impacts on linear habitats: The present distribution of grassland species in forest-edge vegetation

In highly fragmented agricultural landscapes, abandoned forests and dense coniferous plantations established on former semi-natural grassland remain potentially suitable sites for the restoration of grassland communities. The roadside vegetation along the edges of these remnant forests could be a key landscape component, because these communities retain pools of grassland species that are maintained by regular mowing alongside public roads to improve traffic safety. We evaluated the effect of land-use history and the proportion of suitable surrounding habitats on the present distribution of grassland species in roadside forest-edge vegetation. The average number of grassland species was significantly lower at sites that had been cultivated since the 1950s, but it did not differ between uncultivated sites and sites cultivated during the 1880s. Positive effects of the proportion of suitable habitats around the sites were detected at specific spatial scales (500- and 700-m squares), and these effects were indistinct at sites that had lost populations to cultivation. In addition to the present habitat conditions (e.g., forest type), the best-fit model for explaining the present distribution of grassland species at a site included both the site’s land-use history and the past proportion of suitable habitat around the sites. Even in remnant linear habitats such as forest-edge vegetation along roads, historical patterns of site conditions and the landscape matrix at optimum scales can provide useful knowledge to improve explanations of the present distributions of grassland species. These information can help identify abandoned or planted forest sites potentially suitable for restoration with grassland species.     

Soil degradation processes and plant colonization in abandoned terraced fields overlying pumice tuffs

The state of soil degradation/regeneration in abandoned agricultural terraced fields over pumiceous tuffs has been assessed in this paper. In an initial stage, the relationships between soil types, surface microfeatures as indicators of soil degradation, physicochemical properties, plant colonization and vegetation structure were studied by means of multivariate statistical analyses (PCA, DCA, CCA and TWINSPAN®). Aerial photographs interpretation, DEMs and field surveys allowed us to identify 47 different environments for abandoned fields along 7 altitudinal transects (33 abandoned field terraces). In each study site, an inventory of the existing plant species and of morphological surface microfeatures were also made, by the line‐intercept method. Plant colonization in the field plots studied relates to the variation of soils properties according to a climatic altitudinal gradient. The soil properties most closely related to the abandonment age (decrease of soil salinity and clay content, and increase of soil alkalinity and total organic C and N), have contributed to the growth of plant communities with a high degree of climacity. The protection degree offered to the soils by the different vegetation types as a function of their structure and life‐forms strongly determines the occurrence of the different soil surface microfeatures as indicators of soil degradation or recovery. The acceleration of the early stages of succession by active planting of seeds from shrub species in the lower and upper areas, followed by reforestation in the latter ones, may be the best improvement practices to achieve an effective ecological recovery of the fields and simultaneously to attenuate soil degradation. The reassuming of agriculture may be desirable in those fields placed in middle heights, provided they show the best soil and climate conditions. Copyright © 2006 John Wiley & Sons, Ltd.     

The effects of soil moisture variability on the vegetation pattern in Mediterranean abandoned fields (Southern Spain)

The demographic pressure decrease in Southern Spanish Mediterranean mountainous areas in the mid twentieth century led to the abandonment of agriculture and rupture in the geo-ecosystem balance which had existed until then. Since then, different phases of recovery have been put into action to return the landscape to its earlier natural condition according to climate and soil degradation state after the abandon. In Mediterranean climatic conditions (between subhumid and semi-arid regimes), degraded soil recovery has followed different tendencies rendering the landscape in heterogenic and complex one. This heterogeneity has manifested in the vegetation pattern of abandoned fields. In this paper, we analyze the state of three abandoned fields situated under different Mediterranean climatic conditions from the recovery point of view by means of monitoring the effects of spatial and temporal variability of soil moisture in the vegetation pattern over a period of two years sampling (Nov. 2002–Nov. 2004). The results showed that: i) more annual rainfall volume did not guarantee success in the biological recovery of the system due to the influence of other factors such as the degradation state of the soil post-abandonment or the steep slope gradient; ii) soil moisture variability tended to play a more important role in affecting vegetal cover in semi-arid conditions; and iii) in dry climatic conditions the system demonstrated greater signs of recovery (greater biodiversity).