Who will eat me and how fast will I be out-competed? Questions about the future for eucalyptus seedlings in a kangaroo world. Read more in Early View paper “Associational refuge in practice: can existing vegetation facilitate woodland restoration?” by Rebecca S. Stutz and co-workers. Below is their own summary of the study:

The characteristics of plant patches influence whether and how herbivores search for, detect and consume particular focal plants. Neighbouring plants may disrupt this foraging process at any phase, providing associational plant refuge for a focal plant. If we understand how and why this occurs, we may be able to improve revegetation efforts by planting strategically amongst existing vegetation to maximise their chances of escape from herbivory. We tested the capacity of existing vegetation in a degraded area of Booderee National Park, eastern Australia, to provide refuge for eucalypt seedlings from abundant mammalian herbivores. We quantified a suite of variables at large and small patch scales and used field cameras to confirm which herbivore species was responsible for seedling consumption.

Swamp wallabies were the principal browsers of seedlings. When they detected a seedling, they almost always decided to consume it, usually completely. At the larger patch scale, seedlings escaped browsing by swamp wallaby for longer in patches with fewer browsed plant species and those dominated by ferns rather than grasses. Higher understorey cover provided refuge for seedlings at the small patch scale. These characteristics are all consistent with disruption to the search and detection phases of the foraging process, and therefore the occurrence of associational plant effects. Lower canopy cover at the large scale also reduced browsing but the mechanism may be through its influence on microclimate, probability of finding seedlings below-canopy, or perceived predation risk. Our study demonstrates that existing patch characteristics can both provide associational plant refuge and influence patterns of herbivore foraging more generally.

A swamp wallaby discovers a eucalypt seedling.

Decades of ecological research have focused on interactions between herbivores and the chemical defenses of plants. However, far less is known about how effective physical defenses (spines, thorns, etc.) are against mammalian herbivores. It has been argued that co-evolution between plant physical defenses and herbivores might underly the confusing results across many studies.

Therefore, we conducted a study, now published Early View in Oikos “Evolutionary irony: evidence that ‘defensive’ plant spines act as a proximate cue to attract a mammalian herbivore”,  focused on the interaction between the white-throated woodrat (Neotoma albigula) and the cactus on which it specializes. There is great variation in how heavily-defended the cactus plants are, ranging from almost spineless to very spiny in the area where we study these animals (Castle Valley, UT, USA),

A white-throated woodrat (Neotoma albigula)

Woodrats collect large amounts of plant material in their nests that they feed on later. Interestingly, we noticed that the woodrat nests were covered mostly in heavily defended, spiny cacti. This phenomenon caused us to ask whether woodrats preferred spiny cacti, and why that might be.

A cactus plant collected from a woodrat nest. The bottom has been eaten by the woodrat.

We performed a number of feeding trials and choice experiments to show that indeed, woodrats do prefer spiny cacti to experimentally despined cacti. This result suggested that woodrats use the cactus spines as a cue for feeding. Nutritional analysis revealed that spiny cacti are lower in indigestible fiber and higher in protein than spiny cacti. We hypothesize that the woodrats may be using the signals of spines to collect a more nutrient-rich plant that they then feed on later.

Our results demonstrate that physical defenses can be overcome by specialist mammalian herbivores. Further, they show that mammalian herbivores can use obvious, visual clues to select plants that they want to consume.

The authors, through Kevin Kohl

As announced in the August issue, Oikos is publishing meta-analyses at an increasing rate, and similar to the transformative capacity of the Forum section, a dedicated section associated with formalized, replicable systematic reviews and meta-analyses will also advance discovery and integration via effective curation. Chris Lortie will act as EiC for this section, and we strive to make all decisions and reviews with one month (provided referees respond in a timely manner), and referees will be selected to review not only the topic explored but also the elements of synthesis included. These efforts will be open-access published as editor’s choice to stimulate positive practices in our field more broadly and to facilitate longitudinal cross-study contrasts of ecological syntheses. Ecology is a very diverse discipline, and big-science ecology needs big bridges between our synthetic discoveries. Granda and colleagues’ meta-analysis on the physiological responses of woody plants to extreme climatic conditions was therefore selected as EiC for November. Understanding responses of species to winter cold and summer drought extremes is especially relevant in face of ongoing climate change. The authors compiled the existing literature on these responses of woody plants from temperate zone and show that that deciduous angiosperms were most sensitive to climatic stress and that evergreen species show less pronounced seasonal responses in both leaves and stems than deciduous species.

The October issue has been dedicated to a set of integrative research papers that bring synthesis on the functioning of soil food webs brought together by one of our editors Ulrich Brose. You can read more on this here. We jointly published with this special issue the forum paper of Fabrizio and colleagues as editor’s choice. They provide a concise synthesis on the role of top predators in food webs. Ecological research on the role of top predators in food webs is becoming increasingly important and popular in terrestrial (see for instance Boersma et al) and marine systems (e.g. Goyert et al; Rizzari et al. ) but also from a more theoretical point of view (e.g. Berg et al.). This exponentially expanding literature is, however, strongly associated with a rapid disintegration into specialized, disconnected subfields for study (e.g. vertebrate predators versus invertebrate predators, community ecology versus biological control etc.). The authors argue that this results in a loss of coherent, integrated understating of the role and importance of these species in ecosystems.