Quality and quantity of publications are among the most important measures determining the success of ecologists. The past 50 years have seen a steady rise in the number of researchers and collaborative manuscripts, and a corresponding increase in multi‐authored articles. Despite these increases, there remains a shortage of useful and definitive guidelines to aid ecologists in addressing authorship issues, leading to a lack of consistency in what the term “author” really means. Deciding where to draw the line between those who have earned authorship and those who are more appropriately credited in the acknowledgments may be one of the more challenging aspects of authorship. Here, we borrow ideas from other scientific disciplines and propose a simple solution to help ecologists who are making such decisions. We recommend improving communication between co‐authors throughout the research process, and propose that authors publish their contributions to a manuscript in a separate byline.
Summary1. Theories of plant succession are poorly developed in arid lands, hindering our understanding of how long communities may take to recover after disturbances such as fire. In desert landscapes vulnerable to fire, information about vegetation recovery is important when deciding whether land managers should facilitate vegetation recovery. The deserts of the southwestern USA are increasingly subject to unprecedented fires, facilitated by fuel from exotic grasses, yet management strategies are unclear. 2. We evaluated post-fire recovery patterns of perennial plant species richness and diversity, compared the rate and direction of succession between two major community types, and explored the relationship of time since fire (TSF) and other environmental factors with vegetation recovery. We sampled perennial plant communities and environmental variables (e.g. soil N) on 32 burns, ranging from 2 to 29 years TSF and each paired with their own unburned area, within a 1AE8 million ha landscape in the Mojave Desert, USA. 3. Species richness, diversity and composition exhibited different post-burn recovery patterns, and recovery rates differed between community types. Specifically, diversity in Coleogyne ramosissima communities was greater in burned than unburned areas, but diversity did not differ in Larrea tridentata communities. Species composition in Larrea communities exhibited trajectories that indicate convergence with unburned community composition after 19 years TSF. Conversely, burned and unburned Coleogyne communities lacked convergence irrespective of TSF. Environmental variables (e.g. soil texture and P) accounted for 79-83% of the variation in burned species composition, suggesting environmental characteristics in part control recovery patterns. 4. Synthesis and applications. The results indicate that geographically similar vegetation types within the same landscape can have markedly different post-disturbance successional rates and trajectories. Furthermore, the persistence of fire effects varied depending on the community measure, with fire effects on species composition more long-lasting than the effects on species diversity. This work supports (i) the use of post-disturbance successional analyses for helping to prioritize management where it is most needed (e.g. communities not recovering naturally) and (ii) the need to assess whether persistent, early successional desert communities meet functional management objectives.
Plant communities are often structured by interactions among species, such as competition or facilitation. If competition is an important factor that controls the presence and absence of species within intact communities, then a competitive hierarchy, a ranked order from competitive dominant to competitive subordinate, should predict the composition of intact communities. We tested whether a competitive hierarchy derived from pairwise comparisons accurately predicts species abundances within a constructed polyculture community consisting of seven species common to old-field plant communities. We first conducted a pot experiment in field conditions wherein we grew the species in all possible combinations, then created a competitive hierarchy derived from both competitive effect and competitive response for each species. Concurrently, at the same site in native field soil, we constructed polycultures consisting of the same seven species and calculated an abundance hierarchy based on foliar cover, biomass, and an index of species performance. The competitive hierarchy was not concordant with the abundance hierarchy, indicating that simple pairwise comparisons may not account for other factors that influence the abundance of species within relatively complex communities.
The majority of flowering plants require animals for pollination, a critical ecosystem service in natural and agricultural systems. However, quantifying useful estimates of pollinator visitation rates can be nearly impossible when pollinator visitation is infrequent. We examined the utility of an indirect measure of pollinator visitation, namely pollen receipt by flowers, using the hummingbirdpollinated plant, Ipomopsis aggregata (Polemoniaceae). Our a priori hypothesis was that increased pollinator visitation should result in increased pollen receipt by stigmas. However, the relationship between pollinator visitation rate and pollen receipt may be misleading if pollen receipt is a function of both the number of pollinator visits and variation in pollinator efficiency at depositing pollen, especially in the context of variable floral morphology. Therefore, we measured floral and plant characters known to be important to pollinator visitation and/or pollen receipt in I. aggregata (corolla length and width and plant height) and used path analysis to dissect and compare the effect of pollinator visitation rate vs. pollinator efficiency on pollen receipt. Of the characters we measured, pollinator visitation rate (number of times plants were visited multiplied by the mean percentage of flowers probed per visit) had the strongest direct positive effect on pollen receipt, explaining 36% of the variation in pollen receipt. Plant height had a direct positive effect on pollinator visitation rate and an indirect positive effect on pollen receipt. Despite the supposition that floral characters would directly affect pollen receipt as a result of changes in pollinator efficiency, corolla length and width only weakly affected pollen receipt. These results suggest a direct positive link between pollinator visitation rate and pollen receipt across naturally varying floral morphology in I. aggregata. Understanding the relationship between pollinator visitation rate and pollen receipt may be of critical importance in systems where pollinator visitation is difficult to quantify.
Fire has become more extensive in recent decades in southwestern United States arid lands. Burned areas pose management challenges and opportunities, and increasing our understanding of post-fire plant colonization may assist management decision-making. We examined plant communities, soils, and soil seed banks two years after the 2005 Loop Fire, located in a creosote-blackbrush community in Red Rock Canyon National Conservation Area in southern Nevada's Mojave Desert. Based on a spring sampling of 20, 0.01-ha plots, live + dead cover of the exotic annual Bromus rubens averaged nine times lower on the burn than on a paired unburned area. Perennial species composition shifted from dominance by late-successional native shrubs (e.g., Coleogyne ramosissima) on the unburned area, to dominance by native perennial forbs (e.g., Sphaeralcea ambigua, Baileya multiradiata) on the burn. Species richness of live plants averaged 26% (100 m 2 scale) and 239% (1 m 2 scale) greater on the burn compared to the unburned area. Only 5% of Larrea tridentata individuals resprouted, compared to 64% of Yucca schidigera and baccata. Fire and microsite (interspace, below L. tridentata, or below Yucca) interacted to affect several 0-5 cm soil properties, with higher pH, conductivity, and total P and K on burned Yucca microsites. Bromus rubens density in 0-5 cm soil seed banks was four times lower on the burn, and its distribution among microsites reversed. Below-shrub microsites contained the most B. rubens seeds on the unburned area, but the least on the burned area. Intense fire below shrubs may have increased seed mortality, an idea supported by .3-fold decreases we found in emergence density after heating seed bank samples to 100uC. Our study occurred after a post-fire period of below-average precipitation, underscoring a need for longer term monitoring that characterizes moister years.
Habitat modification (i.e., disturbance) and resource availability have been identified as possible mechanisms that may influence the invasibility of plant communities. In the Mojave Desert, habitat disturbance has increased dramatically over the last 50 years due to increased human activities. Additionally, water availability is considered to be a main limiting resource for plant production. To elucidate the effects of soil disturbance and water availability on plant invasions, we created experimental patches where we varied the levels of soil disturbance and water availability in a fully crossed factorial experiment at five replicated field sites, and documented responses of native and non-native winter annuals. The treatments did not significantly affect the density (seedlings m -2 ) of the non-native forb, Brassica tournefortii. However, the relationship between silique production and plant height differed among treatments, with greater silique production in disturbed plots. In contrast to Brassica, density of the non-native Schismus spp. increased in soil disturbed and watered plots, and was greatest in disturbed plots during 2009 (the second year of the study). Species composition of the native annual community was not affected by treatments in 2008 but was influenced by treatments in 2009. The native forb Eriophyllum sp. was most dense on water-addition plots, while density of Chaenactis freemontii was highest in disturbed plots. Results illustrate that habitat invasibility in arid systems can be influenced by dynamics in disturbance regimes and water availability, and suggest that invasiveness can differ between non-native annual species and among native annuals in habitats undergoing changing disturbance and precipitation regimes. Understanding the mechanistic relationships between water availability and non-native plant responses will be important for understanding the effects of shifting precipitation and vegetation patterns under predicted climate change in arid ecosystems.
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