Papers by Marcelo Sternberg
Journal of Applied Ecology, 2000
1. A 4-year study was conducted in a Mediterranean herbaceous community in north-eastern Israel t... more 1. A 4-year study was conducted in a Mediterranean herbaceous community in north-eastern Israel to investigate the eects of cattle grazing management on the structure and composition of the community. Understanding the eects of grazing on the dynamics of Mediterranean herbaceous communities is important in formulating rational management plans for both conservation and sustainable animal production. 2. The relationships among plant functional groups were studied in the context of inter-annual variation in rainfall. Treatments included manipulations of stocking rates (moderate, heavy and very heavy) and grazing regimes (continuous vs. seasonal), in a factorial design. 3. The herbaceous community was rich in species, with 166 species recorded at the site, of which 74% were annuals. Plant cover was dominated by 10 species that accounted for 75% of the total cover. 4. Inter-seasonal rainfall variation was a dominant factor in the expression of different grazing treatments on the structure of the plant community. Grazing eects were stronger in wet years than in dry years. 5. Paddocks under continuous grazing were higher in number of species compared with paddocks subjected to seasonal grazing, independently of grazing intensity. 6. Functional group analyses showed that reduction in cover of tall grasses was correlated with an increase in cover of prostrate annual legumes and less palatable groups such as annual and perennial thistles, crucifers and forbs. 7. Cover of functional groups composed of hemicryptophytic species was less variable (lower coecient of variation) in response to grazing treatments and interannual variation in climatic conditions compared with functional groups with annual species. 8. The persistence of the dominant species and the relatively small amplitude of change in plant cover of the functional groups suggest that the community was rather stable in spite of wide variation in grazing regimes and climatic conditions. East-Mediterranean grasslands appear to be adapted to grazing due to their long history of human association.
Purpose Climate models predict shifts in precipitation patterns characterized by increased precip... more Purpose Climate models predict shifts in precipitation patterns characterized by increased precipitation amount and decreased frequency for semi-arid grasslands in northeast China. However, under these novel climatic conditions, potential differences in plant biomass and its allocation among different degraded grasslands remain unclear.Methods We conducted a mesocosm experiment to test the effects of higher precipitation amount (increased by 50% from the long-term mean) and lower frequency (decreased by 50%) on plant biomass and allocation in the lightly degraded (LDG), moderately degraded (MDG), and severely degraded grasslands (SDG).Results Lower precipitation frequency promoted belowground biomass (BGB), while reducing aboveground biomass (AGB) allocation through enhancing soil water variability. Higher precipitation amount enhanced AGB in LDG and MDG, but not in SDG due to less soil inorganic nitrogen. Lower precipitation frequency weakened the positive effects of higher precipi...
I had the great honor of being one of Imanuel Noy-Meir’s Ph.D. students at The Hebrew University ... more I had the great honor of being one of Imanuel Noy-Meir’s Ph.D. students at The Hebrew University of Jerusalem during the early 90s of the last century. Therefore, it is a privilege for me to serve as Guest Editor of this special issue, which aims to honor his memory and legacy through the inclusion of manuscripts from a small group of researchers who collaborated with Imanuel. The compendium includes a wide range of topics, representing but a small proportion of the broad areas of interest to which Imanuel dedi cated himself during his professional and academic life as an ecologist. Imanuel was a man of many interests and sharp thoughts. Noam Seligman, Eddy van der Maarel, and Sandra Diaz (Seligman et al., 2011, this issue) reflect in their obituary on Imanuel’s wide range of active participation in ecological research that led to the development of a broad spectrum of ecological theory and thought, combining field work and applied issues in ecology. Within this spirit, Imanuel, joi...
Species diversity in Mediterranean grasslands could be seriously affected in the proximate future... more Species diversity in Mediterranean grasslands could be seriously affected in the proximate future by significant changes in climate, as predicted by climate change models for the Mediterranean basin. These models forecast a reduction in precipitation, changes in seasonal rainfall distribution and a decrease in predictability. These changes can also affect the structure, production and composition of Mediterranean grasslands, particularly those that serve as rangelands. Here we present a long-term study (16 years) in Mediterranean grassland in Israel that aimed to evaluate the responses of plant species, plant functional groups and the plant community to different management regimes of cattle grazing. We examined the effects of precipitation change on the structure of the herbaceous community in order to understand the potential role of climate change. The results showed: (i) a decrease in peak standing biomass with decreasing annual rainfall; (ii) rainfall distribution and quantity ...
Planta
MAIN CONCLUSION The dead husk is a vital component of the dispersal unit whose biochemical proper... more MAIN CONCLUSION The dead husk is a vital component of the dispersal unit whose biochemical properties can be modified following exposure to drought. This might affect seed performance and fate, soil properties and consequently plant biodiversity. We investigated the effects of extreme drought on the dispersal unit (DU) properties of winter wild oat (Avena sterilis L.) in the Mediterranean ecosystems focusing on a commonly ignored component of the DU, namely the dead floral bracts (husk). DUs were collected from a climate change experimental research station in the Judean Hills, Israel, simulating extreme drought and from two additional sites differing in the rainfall amounts. Our results showed that drought conditions significantly affected A. sterilis reproductive traits displaying reduced DUs and caryopses weights. The husk contributes profoundly to seed performance showing that germination from the intact DUs or the intact florets 1 was higher, faster and more homogenous compared to naked caryopses; no effect of drought on germination properties was observed. The husk stored hundreds of proteins that retain enzymatic activity and multiple metabolites including phytohormones. Changes in rainfall amounts affected the composition and levels of proteins and other metabolites accumulated in the husk, with a notable effect on abscisic acid (ABA). The husk of both control and drought plants released upon hydration substances that selectively inhibited other species seed germination as well as substances that promoted microbial growth. Our data showed that the dead husk represents a functional component of the DU that have been evolved to nurture the embryo and to ensure its success in its unique habitat. Furthermore, drought conditions can modify husk biochemical properties, which in turn might affect seed performance and fate, soil microbiota and soil fertility and consequently plant species diversity.
5. Synthesis: The effect of the seed bank on the temporal variability of the vegetation in annual... more 5. Synthesis: The effect of the seed bank on the temporal variability of the vegetation in annual communities depends on site conditions and time scale. While the year-to-year variability of the seed bank is similar to the vegetation, the soil seed bank can buffer long-term trends.
Israel Journal of Plant Sciences, 2009
We studied the effects of different environmental conditions on morphological and genetic variati... more We studied the effects of different environmental conditions on morphological and genetic variations in the Mediterranean geophyte Asphodelus aestivus in Israel. The study included six populations, ranging from mesic Mediterranean to arid ecosystems. The results showed important differential morphological traits in one population of the Mediterranean ecosystem (M1). They included longer leaves, longer inflorescences-stalks, and larger number of flower buds than those found among the other populations. We used RAPD analysis to get a genetic profile for all studied populations: 30 loci revealed by the use of 11 primers were studied on 30 plants from each study site. No unique allele was found. Nevertheless, the MI population was always different from the others in several molecular markers, and even created a different clade on the phylogenetic tree. Abiotic factors were considered to have caused the differentiation of the M1 population. A contingency χ 2 test for heterogeneity of RAPD frequencies across all locations revealed significant differences in 17 RAPD loci (57%). The estimated genetic diversity within populations was 0.287 according to Nei's gene diversity and 0.432 according to Shannon's genetic diversity index. Differentiation among six populations of the RAPD loci (G ST) ranged from 0.014 to 0.354 with a mean of 0.096. Principal coordinate analysis indicated the presence of genetically distinct sub-regional groups. Genetic and geographical distances among A. aestivus populations along the environmental gradient were found to be correlated, with the exception of the M1 population. In the present study, levels of gene variability within populations were higher than those between populations. Nevertheless, if we discard the unique M1 population, a clear genetic pattern linked to aridity and geographical distance was discerned.
Agronomy
The conversion from primary forest to agriculture drives widespread changes that have the potenti... more The conversion from primary forest to agriculture drives widespread changes that have the potential to modify the hydroclimatology of the Xingu River Basin. Moreover, climate impacts over eastern Amazonia have been strongly related to pasture and soybean expansion. This study carries out a remote-sensing, spatial-temporal approach to analyze inter- and intra-annual patterns in evapotranspiration (ET) and precipitation (PPT) over pasture and soybean areas in the Xingu River Basin during a 13-year period. We used ET estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) and PPT estimates from the Tropical Rainfall Measurement Mission (TRMM) satellite. Our results showed that the annual average ET in the pasture was ~20% lower than the annual average in soybean areas. We show that PPT is notably higher in the northern part of the Xingu River Basin than the drier southern part. ET, on the other hand, appears to be strongly linked to land-use and land-cover (LULC) patte...
&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;Human activities are directly and indirectly generating major environmental pressures on ecosystems worldwide through climate change, pollution and other global changes. Altogether, these changes result in a rapid erosion of biodiversity and a perturbation of ecological and agricultural systems and services, prompting urgent societal questions on how to retain or promote sustainable ecosystem services in a global change context. Understanding the responses of ecosystems to such pressures and perturbations, and developing adaptation strategies critically requires state-of-the-art experimental facilities that are able to simulate multiple global change factors. AnaEE (Analysis and Experimentation on Ecosystems) brings together such facilities in a European-wide infrastructure for experimental research on managed and unmanaged terrestrial and aquatic ecosystems. It assists and integrates four types of national platforms (Open-air, Enclosed, Analytical, and Modelling) and provides support to scientists who wish to engage in research projects using these platforms or the data they generate. These services are organised through the Central Hub and three Service Centres (Technology, Data and Modelling, Interface and Synthesis). This integrated approach improves the quality and availability of data and projections on ecosystem responses to global changes, enabling policy makers and stakeholders to make fact-based&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#160; decisions on how to sustainably manage ecosystem services. As an example, we shortly discuss the new open air FATI-platform (UAntwerp) in which ecosystems can be exposed to various combinations of precipitation change and warming, and present first results of a study on the impacts of precipitation regime changes on temperate grassland.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;
Journal of Vegetation Science
Questions: What are the effects of extreme drought on above-ground and below-ground net primary p... more Questions: What are the effects of extreme drought on above-ground and below-ground net primary production (ANPP and BNPP, respectively) of an annual plant community in a Mediterranean shrubland? How do annual plant communities in Mediterranean shrublands respond to extreme drought, in terms of changes in their species composition, species richness, and species diversity? Location: A Mediterranean shrubland in the Judean Hills, Israel. Method: Rainout shelters were used to simulate a 66% reduction in annual rainfall, preceded by a baseline year when no treatments were applied. Above-ground and below-ground (i.e., root) biomass was harvested and species surveys were performed following one growing season. Results: Above-ground primary production was significantly reduced by drought, while below-ground production remained mostly stable. Consequently, the shoot:root ratio was reduced by drought, indicating either increased community resource allocation to root production at the expense of shoots or stable root biomass production in the face of drought. Community diversity increased in droughted plots, and significant changes were detected in species composition and dominance patterns. Conclusions: Extreme drought had a profound effect at the ecosystem and community level on the studied Mediterranean shrubland. Extreme drought seems to increase species diversity and evenness in the short term, likely due to release from competition. We predict this effect to be countered by low biomass production and individual species abundance if extreme drought persists a sufficiently long time, leading to significant changes in long-term plant dominance patterns and community structure.
Ecology Letters
Biodiversity can buffer ecosystem functioning against extreme climatic events, but few experiment... more Biodiversity can buffer ecosystem functioning against extreme climatic events, but few experiments have explicitly tested this. Here, we present the first multisite biodiversity × drought manipulation experiment to examine drought resistance and recovery at five temperate and Mediterranean grassland sites. Aboveground biomass production declined by 30% due to experimental drought (standardised local extremity by rainfall exclusion for 72-98 consecutive days). Species richness did not affect resistance but promoted recovery. Recovery was only positively affected by species richness in low-productive communities, with most diverse communities even showing overcompensation. This positive diversity effect could be linked to asynchrony of species responses. Our results suggest that a more context-dependent view considering the nature of the climatic disturbance as well as the productivity of the studied system will help identify under which circumstances biodiversity promotes drought resistance or recovery. Stability of biomass production can generally be expected to decrease with biodiversity loss and climate change.
Conservation Ecology, 2002
Introduction Materials and Methods The grass species Planting and harvesting procedures Defoliati... more Introduction Materials and Methods The grass species Planting and harvesting procedures Defoliation treatments Handling of the harvested biomass Field sampling Statistical analysis Results for Triticum dicoccoides Results for Hordeum bulbosum Discussion Responses of an annual and of a perennial grass Defoliation and tillering Management implications Responses to this Article Acknowledgments Literature Cited
ABSTRACT Background/Question/Methods Soil seed banks are of crucial importance in highly variable... more ABSTRACT Background/Question/Methods Soil seed banks are of crucial importance in highly variable and unpredictable environments. They play a determinant role in plant community dynamics, as differential plant germination strategies buffer against inter-annual variability in growing conditions. Thus, understanding the role of soil seed banks in determining the composition and structure of plant communities under future climatic scenarios becomes an important task in order to understand future global changes. Natural climatic gradients, which are represented by changes in environmental conditions provides an excellent framework for studying the effects of climate change on the factors that regulate the structure and dynamics of soil seed banks. Particularly, the strong climatic gradient in Israel, provides an excellent opportunity to test predictions regarding the effects of global climate change on plant community dynamics. This climatic gradient runs from mesic Mediterranean ecosystems in the North to arid desert ecosystems in the South. Climate change scenarios are experimentally tested with manipulations of rainfall amount using rainout shelters and irrigation systems. Results/Conclusions The results indicated significant differences in seedling densities among the study sites along the aridity gradient. Seedling density increased with increasing rainfall conditions. Significant differences were also noted when comparing seed density between habitats (open gaps vs. shrub understory). Higher seedling densities were observed at the shrub understory at the arid part of the gradient while the opposite was noted at the mesic part (i.e. higher seedling density at the open gaps between shrubs). This phenomenon indicated shrub facilitation effects at the arid part of the gradient and competitive exclusion at the more humid part of the gradient. Moreover, important differences among years were clearly noted as response of rainfall conditions of the year when seeds were produced. The results showed important differences in the germinable seed bank along the gradient The results collected showed no clear response of the seed bank to the rainfall manipulations. According to our expectations we should have observed a decreased in seed density under droughting conditions and a higher number following increasing rainfall through irrigation. The results were not consistent and in some cases opposite to expected. The detected short-term resistance on the seed bank density does not necessarily imply resistance to long-term rainfall manipulations. Continuation of the experiments and monitoring is necessary to shed more light on short-term vs. long-term resistance and provide stronger evidences about the potential effects of climate change on soil seed bank dynamics.
Current trends of emissions of greenhouse gases are expected to cause the global temperature to r... more Current trends of emissions of greenhouse gases are expected to cause the global temperature to rise faster over the present and next century than during any previous period (Houghton et al., 1996, 2001; Zweirs, 2002). Climate models for the Middle East predict an increase in winter temperatures combined with changes in rainfall amounts and distribution (Ben-Gai et al., 1998; Black, 2009, Klafe and Bruins, 2009). These changes may alter ecosystem functioning, with direct effects on ecosystem, community and population processes such as plant litter decomposition, nutrient cycling, primary productivity, biodiversity, plant recruitment and survival (e.g.,
Global Change Biology, 2016
This document is the author's final manuscript version of the journal article, incorporating any ... more This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.
Egu General Assembly Conference Abstracts, May 1, 2010
Abstract The availability of phosphorus (P) to plants, severely limits their growth in many natur... more Abstract The availability of phosphorus (P) to plants, severely limits their growth in many natural and managed ecosystems. Tracking the soil P transformations is hard since both immobilization and mineralization occur simultaneously. In this respect, stable isotopes ...
Ecological Research, Jun 1, 2001
This study investigates the effects of slope aspect on plant community characteristics such as pl... more This study investigates the effects of slope aspect on plant community characteristics such as plant cover, species composition and above-ground biomass production in Mediterranean trees and shrubs in two climatological regions. Two experimental sites were selected in a climatic gradient that runs from the foothills of the Judean Hills to the northern Negev desert in Israel. In each site, 16 quadrats of 10 m ¥ 10 m (eight south-facing and eight north-facing slopes) were established and the vegetation was recorded. Dominant tree and shrub species were measured using allometric parameters of area and volume, and representative branches were cut and weighed. Species studied were Quercus calliprinos, Phillyrea latifolia, Pistacia lentiscus, Cistus creticus, Coridothymus capitatus, and Sarcopoterium spinosum. The results showed that slope aspect had significant effects on the composition, structure and density of the plant communities developing in both sites. Vegetation structure within a site changed significantly in the short distance separating the north and south-facing slopes, and that pattern remained generally constant when comparing the two sites along the rainfall gradient. The data collected here provides new insight into the slope aspect effects on biomass allocation of different woody life forms of eastern Mediterranean plant communities.
Geoderma, Feb 2, 2014
Forest fires are a major environmental concern, especially in the semiarid Mediterranean regions,... more Forest fires are a major environmental concern, especially in the semiarid Mediterranean regions, where the long dry and hot summers and mild winters favor outbreaks of wildfires. The objective of this work was to study the effects of different fire treatments on physical, chemical, and physicochemical properties of Pale rendzina, and their impact on infiltration rate (IR), runoff and soil loss under consecutive rainstorms. After a wildfire in a forest located in northern Israel, soil samples were taken from an area that was directly exposed to fire (direct fire treatment) and from adjacent unburned (unburned soil treatment). Part of the unburned soil was heated in a muffle at 300°C (heated soil treatment). Runoff, soil loss and IR values were measured for the various samples using a laboratory rainfall simulator, and aggregate stability was determined using slaking and dispersion values. The organic matter, clay, and sand content, and cation exchange capacity were significantly lower in the heated soil than in the unburned soil. The CaCO 3 content in the heated soil was significantly higher than in the unburned and direct fire soils. In general, the IR values were highest, intermediate, and lowest and the runoff and soil loss amounts were lowest, intermediate, and highest in the heated, direct fire, and unburned soils, respectively. However, these differences decreased with progression of the consecutive rainstorms. Heating the soil to 300°C enhanced soil-structure stability, most likely due to increased dehydration of 2:1 clay minerals and transformation of iron and aluminum oxides which acted as cementing agents. In addition, soil heating increased the electrical conductivity (EC) and decreased the sodium adsorption ratio in the heated soil solution in the first rainstorm. These processes limited clay dispersion and seal formation in the heated soil, leading to high IR values and low runoff and soil loss. In the second and third rainstorms, EC of the soil solution decreased, which in turn increased clay dispersion. This lessened the differences in the IR values and runoff and soil loss amounts between the fire treatments in these rainstorms compared to the first rainstorm.
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Papers by Marcelo Sternberg