Understanding the reproductive response of host plants to herbivores is important in grazing ecology and grassland management. Simulated grazing experiments were conducted to determine the influence of different grazing intensities on reproductive performance of a shrub, Caragana microphylla Lam. The total leaf mass, total flower mass, total flower mass allocation, and single flower mass allocation decreased with increased grazing intensity. The total spine mass, single flower mass and total spine mass allocation increased with increased grazing intensity. The stem mass, stem mass allocation and total leaf mass allocation had not significant change with the increasing grazing intensity. Under heavy grazing treatments, the host plants significantly decreased their investment in reproduction and increased investment in physical defense organs. Although there were no significant differences in the number of ovules among different grazing intensities, herbivory negatively affected reproductive performance, including the number of flowers, the number of pollen grains per flower, the number of ripe seeds and the rate of pod-set in host plants. These results indicate that there are trade-offs among vegetative and reproductive and defensive organs. Compared with male reproduction, female reproductive performance was less sensitive to herbivory and grazing intensity. Moreover, pollen grains from heavily browsed plants seemed to be less likely to sire pods and ripe seeds than those from unbrowsed plants, indicating that herbivory not only decreased pollen production, but also adversely affected pollen performance.
Zhen Zhang, Lichao Wang, Jing Liu, Zhaorong Dong, Wei Xu and Shiping Wang
Adiv Gal, David Saltz and Uzi Motro
The effect of food supplement to Lesser Kestrel (Falco naumanni) nests during the nestling period (from hatching to fledging) was studied in two nesting colonies in Israel – Alona and Jerusalem. Our hypothesis, based on diminishing returns considerations, was that food supplement will have a greater effect on fledgling success in the food-limited, urban colony of Jerusalem, than in the rural colony of Alona. Indeed, food supplement had a significantly positive effect on breeding success in both colonies. However, and contrary to our prediction, the decrease in chick mortality between supplemented and control nests in Jerusalem was not larger than in Alona (actually it was numerically smaller, albeit not significantly so). This implies either that additional factors, possibly urbanization associated, other than food limitation, might be responsible for the difference in nesting success of Lesser Kestrels between Alona and Jerusalem, and/or that the amount or the nutritional quality of the additional food provided to supplemented nests (three mice per chick per week), was not enough.
Rida Sultanova, Ildar I. Gabitov, Yulai A. Yanbaev, Fitrat G. Yumaguzhin, Maria V. Martynova, Ivan V. Chudov and Varys R. Tuktarov
The management of beekeeping on forest lands is a vivid manifestation of the multifunctional use of forests, which is based on its target cultivation. The work shows the development of beekeeping, identifies factors affecting the sustainable development of this industry, sets priorities for increasing the efficiency of utilization of forest honey resources of the Southern Urals, including the main melliferous - Tilia cordata Mill. The nature and characteristics of the influence of weather and climatic factors on the growth of bee colonies, their physiological state, composition, age representation of natural melliferous woody plants, the onset dates and the duration of their flowering were determined. It was found that, of the silvicultural and inventory indicators, the composition and age, density and type of forest most strongly influence the yield of honey. The activities of forest care are close to them in terms of importance. A system of organizational measures has been proposed, through which high efficiency of using forest feed resources and sustainable development of beekeeping can be achieved: keeping an optimal number of bee colonies in an apiary - up to 150 hives, based on providing one bee colony of 50-60 thousand individuals with at least 130 kg of nectar; the location of apiaries in the 3-kilometer zone of growth of forest melliferous plants, taking into account the productive emergence of bees in the 2.5-3.0 km; establishing clear nomadic routes based on a geobotanic inventory of forest and agricultural melliferous plants. Increasing the target indicator - the nectar productivity of forests without a gap in their use both in space and in time - can be achieved by growing multi-tiered forests of different age from Tilia cordata Mill.
Shai Meiri, Amos Belmaker, Daniel Berkowic, Kesem Kazes, Erez Maza, Guy Bar-Oz and Roi Dor
Faunal lists are important tools in ecology, biogeography, and conservation planning. Such lists can identify gaps in our knowledge of the distribution and taxonomy of regional faunas, and highlight issues needing further study. We present an up to date list of all land vertebrates occurring in Israel. We identify 786 species, of which 551 are birds, 130 are mammals, 97 are reptiles and eight are amphibians. Of these 369 species breed in Israel (including reintroductions), 199 (mostly birds) are regular visitors and 182 are accidental. Fourteen other species are invasive, and 22 species are extinct. We identify issues with the taxonomy and status of several species, and note recent developments in our understanding the Israeli land vertebrate fauna.
Xin Yin, Wei Qi and GuoZhen Du
A growing body of evidence from diversity-manipulation and natural studies suggests that the stability of community productivity increases with biodiversity; however, few studies have researched this relationship in a non-weeded grassland. To clarify this issue, we established an artificial grassland in 2003 using three common species, Elymus nutans, Festuca sinensis and Festuca ovina, which included seven different community structures (three monocultures, three two-species mixtures and one three-species mixture based on sown species) and two nutrient addition treatments (non-nutrient addition and nutrient addition). Data was collected over a three-year period (2011–2013). Our results showed that the sowing species modified realized species richness (i.e. the number of total species we observed in a community) and species evenness, but had negligible influences on community- and population-level stability. Furthermore, all of these variables were reduced by nutrient addition. These dynamics did not alter the positive influence of realized species richness on community stability, but restricted the stable effect of evenness because this effect was only significant under nutrient addition condition. The potential mechanisms underlying these processes were statistical averaging and species asynchrony, rather than overyielding effect. Conversely, population stability decreased with realized species richness in non-nutrient addition treatments. We conclude that biodiversity contributed to community- and population-level stability even in non-weeded experiment. This process resulted from different mechanisms that observed in weeded experiments. Further studies in other ecosystems (e.g. aquatic ecosystem) are needed to find a more general conclusion.
Chaobin Zhou and Wei Gong
In the arid region of northwest China, H. ammodendron has become the main pioneer species for the restoration of plant communities. However, the breeding system of the plant remains unknown. The floral dynamics and the breeding system characteristics of H. ammodendron were investigated in this study, using a bagging experiment. The results show that anthesis lasted about 22 d. The longevity of individual flowers was 14.1 d. Stigma receptivity lasted about 6 d and there were relatively long periods for the meeting between stamen and stigma. Anther height was slightly greater than that of the stigma. The outcrossing index was 2 and the pollen-ovule ratio was 64,815. The H. ammodendron mating system can be described as a mixed mating system with facultative apomixis; pollination is not necessary for reproduction. The mixed mating system with facultative apomixis could guarantee the reproductive success of H. ammodendron in severe desert conditions with sparse pollinators.
Justin R. St. Juliana, Burt P. Kotler, Berry Pinshow and Noga Kronfeld-Schor
We studied the influence of manipulating predation risk on Allenby’s gerbil ( Gerbillus andersoni allenbyi) held in a large, outdoor enclosure. We measured giving up densities (GUDs), apprehension, time allocation to foraging, harvest strategy (grab and go (GAG) vs. eat at tray (EAT)), and fecal cortisol concentration. First we established the time necessary for cortisol and corticosterone concentrations to change significantly from baseline after a stressful experience. To do this we collected feces from gerbils 2, 4, 6, or 8 hours after being handled (treatment) or not (control). After 8 h, fecal cortisol, but not corticosterone, concentration was significantly higher in treatment animals. We used the results from the hormone time course experiment to design the predation experiment. We used a dog, trained to harass gerbils, to increase predation risk for the gerbils. We predicted that fecal cortisol concentrations would increase directly in the face of predation risk, or indirectly, due to reduced foraging time because of perceived predation risk that, in turn, leads to increased hunger levels. As predicted, in the presence of a predator, GUDs were higher, time allocation lower, and GAG foraging was used more in treatment animals than in controls, but we found no change in apprehension. There was no difference in cortisol concentration between predator present and no-predator treatments. However, individuals that tended to have higher average fecal cortisol concentrations also tended, on average, to spend more time foraging. This indicates a relationship between stress hormones and optimal foraging. This relationship is potentially causal. While nightly changes in behavior may not be related to stress hormones, over course time scales, stress hormones may be driving gerbils to forage more.
Justin R. St. Juliana, Jocelyn L. Bryant, Nadja Wielebnowski and Burt P. Kotler
We evaluated the suitability of a corticosterone enzyme immunoassay (EIA) to monitor excretion of fecal glucocorticoid metabolites (FGM) in response to Adrenocorticotropic hormone (ACTH) and saline injections in three desert rodent species (Gerbillus andersoni allenbyi (GA), Gerbillus nanus (GN), and Gerbilis piridium (GP). We exposed 24 gerbils (N = 9 for GA, N = 7 for GN, N = 8 for GP) to an ACTH and a saline injection at different times. Fecal samples were collected hourly for 24 hours after injection. The average starting concentration (baseline) FGM concentration was 797 ng/g for GA, 183 ng/g for GN, and 749 ng/g for GP. The average peak concentration was 2377 ng/g for GA, 589 ng/g for GN, and 1987 ng/g for GP. We were able to provide a physiological validation for the chosen assay in GAs and GPs, however, our results for GNs were less clear. We found an increase in FGM concentrations on average after 5.5 hours in GA, 3.1 hours in GN, and 3.8 hours in GP. We found a peak in FGM concentration on average after 8.8 hours in GA, 5.6 hours in GN, and 10.3 hours in GP. We determined that FGM concentration returned to starting value on average after 14.4 hours in GA, 9.1 hours in GN, and 15.1 hours in GP. The outcomes of this study can help establish trapping protocols and time frames for FGM monitoring of these wild small mammal populations. The time course for excretion of FGM is similar between the species in this study, and comparable to some non-desert rodents. We found high variation in the time course of excretion within species. This variation needs to be taken into account when monitoring stress responses in the field. By assessing adrenocortical activity using FGM monitoring, stress responses to varying ecological and environmental factors can be reliably examined in the field.
Rachel Schwarz, Gavin Stark and Shai Meiri
The south-facing slopes in canyons, oriented along an east-west axis north of the equator, are often hotter and drier than north-facing slopes, promoting differences in the biotic and abiotic characteristics of the opposing slopes. We studied how diversity and abundance patterns have changed in Oren stream (Carmel Mountains, Israel) during the last 25 years. We tested whether temperature and habitat preferences of reptiles affected observation frequencies, to assess potential effects of global warming on the reptiles. We compared the results of a 1993–1994 survey in Oren stream to a survey we conducted during 2017–2018, using similar methods, survey area and effort. Species composition and abundance in Oren stream did not significantly change between studies, but the proportion of observations differed significantly across slopes for four out of the six most abundant species. The number of observations increased monotonically with increasing temperatures on the south-facing slope, but decreased on the north-facing slope above a temperature of 22°C. The major biome species inhabit globally was unrelated to the number of observations across slopes or studies, but species inhabiting warmer ranges were more frequently observed in the current survey. Our results suggest that as global temperatures rise, reptile species which can tolerate higher temperatures, and those which can avoid the hottest temperatures of the day, may be able to cope better. These results however may also derive from better detection ability of some species over others between study teams.