Are Sage-Grouse Fine-Scale Specialists or Shrub-Steppe Generalists?

Sage-grouse (Centrocercus spp.) are influencing rapidly evolving land management policy in the western United States. Management objectives for fine-scale vegetation characteristics (e.g., grass height >18 cm) have been adopted by land management agencies based on resource selection or relationships with fitness proxies reported among numerous habitat studies. Some managers, however, have questioned the appropriateness of these objectives. Moreover, it remains untested whether habitat–fitness relationships documented at fine scales (i.e., among individual nests within a study area) also apply at scales of management units (e.g., pastures or grazing allotments), which are many orders of magnitude larger. We employed meta-analyses of studies published from 1991 to 2019 to help resolve the role of fine-scale vegetation structure in nest site selection and nest success across the geographic range of greater sage-grouse (C. urophasianus) and evaluate the validity of established habitat management objectives. Specifically, we incorporated effects of study design and functional responses to resource availability in meta-regression models linking vegetation structure to nest site selection, and used a novel meta-analytic approach to simultaneously model vegetation structure and its relationship to nest success. Our approach tested habitat relationships at a range-wide extent and a grain size closely matching scales at which agencies make management decisions. We found moderate, but context-dependent, effects of shrub characteristics and weak effects of herbaceous vegetation on nest site selection. None of the tested vegetation characteristics were related to variation in nest success, suggesting nesting habitat–fitness relationships have been inappropriately extrapolated in developing range-wide habitat management objectives. Our findings reveal surprising flexibility in habitat use for a species often depicted as having very particular fine-scale habitat requirements, and cast doubt on the practice of adopting precise management objectives for vegetation structure based on findings of individual small-scale field studies. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

喀斯特山区不同植被类型土壤有机碳的变化

研究了贵州西南部典型喀斯特山区不同植被类型下常规土壤及小生境土壤中有机碳及不同粒径土壤颗粒有机碳的变化.结果表明:不同植被类型下,常规及小生境土壤有机碳含量均表现为:裸地＜草丛＜灌木林＜乔木林,常规土壤变幅在7.18 ～43.42 g·kg-1,土面和石坑土壤有机碳变幅分别为6.62 ～46.47 g· kg-1和9.01 ～52.07 g·kg-1;颗粒有机碳(POC)/矿物结合态有机碳( MOC)值均为:裸地＜草丛＜乔木林＜灌木林,同一植被类型下,与常规及土面相比,石坑中土壤POC/MOC值最高;植被在由裸地-草丛-灌木林-乔木林的变化过程中,不同粒径土壤颗粒有机碳含量增加,而土壤有机碳主要以砂粒及粉砂粒有机碳形式存在,说明喀斯特地区土壤的固碳能力及有机碳稳定性较弱,土壤易受外界干扰而引发有机碳流失,土壤质量存在下降或退化的风险.     

Microhabitat selection by sea turtles in a dynamic thermal marine environment

1. Reproductive fitness is often compromised at the margins of a species' range due to sub-optimal conditions. 2. Set against this backdrop, the Mediterranean's largest loggerhead sea turtle (Caretta caretta) rookery at Zakynthos (Greece) presents a conundrum, being at a very high latitude for this species, yet hosting a high concentration of nesting. 3. We used visual surveys combined with global positioning system (GPS) tracking to show that at the start of the breeding season, individuals showed microhabitat selection, with females residing in transient patches of warm water. As the sea warmed in the summer, this selection was no longer evident. 4. As loggerhead turtles are ectothermic, this early season warm-water selection presumably speeds up egg maturation rates before oviposition, thereby allowing more clutches to be incubated when sand conditions are optimal during the summer. 5. Active selection of warm waters may allow turtles to initiate nesting at an earlier date.     

不同空间尺度下的肉果植物扩散过程和机理

肉果植物扩散的生态学过程在最近得到生态学者们的广泛关注,其扩散过程包括果实搬运、果实消耗、种子雨、种子取食、种子库动态、萌发和幼苗定居等。许多过程涉及到果食性动物和肉果植物之间的互惠的协同进化关系。对最近15a关于肉果植物扩散的研究论文进行了综述,探讨在生境、微生境、景观和区域等常用的空间尺度上,肉果植物扩散和定居过程的格局与机理。     

Foraging requirements of the endangered long-fingered bat: the influence of micro-habitat structure, water quality and prey type

Myotis capaccinii is one of the most endangered Mediterranean bats. We radio tracked 21 adult individuals to assess foraging range and analyse micro-habitat selection around a nursery roost in central Italy. Habitats were characterized by development of riparian vegetation, distance between banks, degree of water clutter and levels of water pollution (expressed by macro-benthic bioindicators). Diet was also analysed to see whether prey rarity might account for species decline. Myotis capaccinii proved highly mobile: the maximum straight line distance between roost location and the farthest foraging fix recorded on one night was c . 21 km, whereas this variable averaged 7.5 km for the entire study. In general, the species preferred calm waters bordered by well-developed riparian vegetation and large (>5 m) inter-bank distances. Such factors determined the overall quality of foraging sites. Although diet was dominated by pollution-tolerant insects such as Chironomus midges, bats preferred less polluted waters. Our study also confirmed the occurrence of piscivory in this bat. Of the factors potentially responsible for species endangerment, the most likely are general habitat degradation, that is alteration of riparian vegetation and pollution, and cave roost loss. Given the large ecological niche overlap, increasing Myotis daubentonii may be outcompeting M. capaccinii . The most urgent actions to preserve M. capaccinii are extensive restoration of riparian vegetation and strict roost protection. Our study offers indications about where, and how, restoration of riparian vegetation may translate into best conservation results.     

Differences in Field Gas Exchange and Water Relations Between a C3 Dicot (Plantago Asiatica) and a C4 Monocot (Eleusine Indica)

Field gas exchange and water potential in the leaves of a C₃ dicot, Plantago asiatica L., and a C₄ monocot, Eleusine indica Gaertn., which dominate in trampled vegetation in eastern Japan were surveyed during the growing periods for two consecutive years. Net photosynthetic rate (P _N) of E. indica increased with photosynthetic photon flux density (PPFD) and leaf temperature (T_L). P _N was not saturated at PPFDs above 1500 μmol m⁻² s⁻¹ and at T_L above 30 °C. On a sunny day in mid summer, maximum P _N was two times higher in E. indica than in P. asiatica [42 vs. 20 μmol(CO₂) m⁻² s⁻¹], but their transpiration rate (E) and the leaf water potential (Ψ_L) were similar. Soil-to-leaf hydraulic conductance, which probably plays a role in water absorption from the trampled compact soil, was higher in E. indica than in P. asiatica. The differences in photosynthetic traits between E. indica explain why E. indica communities more commonly develop at heavily trampled sites in summer than the P. asiatica communities. This revised version was published online in June 2006 with corrections to the Cover Date.     

Soil micro-habitat effects on fine roots of Chamaecyparis obtusa Endl.: A field experiment using root ingrowth cores

Ingrowth cores in the field were used to compare fine root characteristics of hinoki cypress (Chamaecyparis obtusa) among rooting substrate in the form of needle leaf litter, decomposing organic material, and mineral soil. Fine root growth, morphology, arbuscular mycorrhizal (AM) associations, and tissue C and N concentration were determined. The inorganic N leaching from each soil substrate was taken as a measure of N availability. Although there was no significant difference in total N leaching among substrates, more NH ₊ ⁴ -N leached from the decomposing organic material than other substrates. Rapid fine root production was observed in the organic material, whereas root production in the litter substrate was suppressed. Annual net fine root productions in litter, organic material, and mineral soil were 51, 193, and 132 g m⁻², respectively. In the leaf litter substrate, AM colonization was suppressed and specific root length was higher than in the other substrates, indicating severe nutrient limitation in the litter. These responses of hinoki cypress roots seemed to be a soil exploitation pattern whereby absorptive fine roots were arranged to maximize nutrient acquisition.     

Importance of scrub–pastureland mosaics for wild-living cats occurrence in a Mediterranean area: implications for the conservation of the wildcat (Felis silvestris)

The European wildcat (Felis silvestris) is a threatened species in Europe. Suitable management of forests has been considered crucial for its conservation in Europe. However, this recommendation may not be general due to the lack of studies that test these hypotheses in the Mediterranean area, where landscapes are very different from those of central-north Europe. In this study, wild-living cat habitat associations were analyzed by means of scat surveys in 78 areas distributed in the four main vegetation types of the Mediterranean area of central Spain, where feral cat populations are probably scarce and restricted. Results show higher occurrences of wild-living cats in landscapes covered by scrub–pastureland mosaics rather than forests. Several applied recommendations are given: (1) to include the scrub–pastureland mosaics as protected habitats for wildcats; (2) to encourage further studies about the importance of this habitat in other areas; (3) to avoid the extensive scrubland removal associated with management practices against fires or infrastructure development; and (4) to promote land management practices that enhance these mosaics, and to use shrub species in the reforestation programmes founded by the European Agricultural Policy.