Editor's choice AprilSubmitted by editor on 10 April 2018.
The first editor’s choice for the April issue is the meta-analysis by Frida Piper and colleagues. The authors present a global analysis on herbivory rates in understorey vegetation from forests. The rationale for the study comes from observations that herbivory in understorey is limited relative to gaps. Since temperature is thought to be a major driver of this process, the differential impact is thought to increase with latitude. Interestingly, the comprehensive global analysis shows –in accordance with earlier work- insect herbivory in gaps to be much higher than in the understorey, but only so in tropical forests. This contradicts hypotheses of temperature constraints and does on the other hand point at resource limitation to be a major factor limiting insect herbivore activity in forest understoreys, especially in the tropics. The authors conclude that the selective influence of insect herbivory on late‐successional tree species is likely overestimated.
The second editor’s choice is the work of Luciano Sgarbi and Adriano Melo (You don’t belong here: explaining the excess of rare species in terms of habitat, space and time). The authors point at the often high prevalence of rare species in samples from ecological communities. While such rare species are widely observed and accepted as part of a natural pattern, it is surprising how little we know about the causes of this rarity. Using a unique dataset on stream macroinvertebrates the authors investigated whether the excess of rare species in three focal communities is rather the consequence of environmental limitation (filtering), spatial limitations or simply phenology. Overall, the authors conclude that the presence in non‐optimum habitat appeared to be a strong determinant of the rarity observed in natural communities. Most rare species are thus rare because of sampling artifacts or because they are accidently trapped in sink habitat.