The functional structures of communities respond to environmental changes by both species replacement (turnover) and within-species variation (intraspecific trait variability; ITV). Evidence is lacking on the relative importance of these two components, particularly in response to both short- and long-term environmental disturbance. We hypothesized that such short- and long-term perturbations would induce changes in community functional structure primarily via ITV and turnover, respectively. To test this we applied an experimental design across long-term mown and abandoned meadows, with each plot containing a further level of short-term management treatments: mowing, grazing and abandonment. Within each plot, species composition and trait values [height, shoot biomass, and specific leaf area (SLA)] were recorded on up to five individuals per species. Positive covariations between the contribution of species turnover and ITV occurred for height and shoot biomass in response to both short- and long-term management, indicating that species turnover and intraspecific adjustments selected for similar trait values. Positive covariations also occurred for SLA, but only in response to long-term management. The contributions of turnover and ITV changed depending on both the trait and management trajectory. As expected, communities responded to short-term disturbances mostly through changes in intraspecific trait variability, particularly for height and biomass. Interestingly, for SLA they responded to long-term disturbances by both species turnover and intraspecific adjustments. These findings highlight the importance of both ITV and species turnover in adjusting grassland functional trait response to environmental perturbation, and show that the response is trait specific and affected by disturbance regime history.

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is the case for the giant root-rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root-rats on various ecosystem features within a 3.5-ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in 2 periods of a year. The root-rats altered plant species composition, reducing the dominant forb, Alchemilla abyssinica, while enhancing Salvia merjame and a few other species, and reduced vegetation cover, but not the fresh plant biomass. Where burrows were abandoned by root-rats, other rodents took them over and A. abyssinica increased again. Root-rat burrowing created small-scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments. Less compacted soil tended to be rich in nutrients, including carbon, nitrogen and phosphorus, which likely affected the plant growth on sites where the vegetation has been reduced as a result of root-rat foraging and burrowing.

Rodents adjust their activity to environmental conditions. The adjustment can be especially pronounced in climatically challenging environments. We studied activity patterns in the free-living giant root rat (Tachyoryctes macrocephalus), a large fossorial rodent endemic to the Afro-alpine ecosystem of the Bale Mountains, Ethiopia, by means of radio telemetry. We radio-tracked 17 adults during two periods of a dry season differing in temperature and food supply. In both periods, root rats spent a large part of the day (around 79%) in their underground nests. The proportion of time the animals were active aboveground decreased from 6.9 to 3.8% between the early and late dry season, which contradicts our prediction that aboveground activity would increase under lower food supply. We propose that there are thermoregulation advantages of prolonged aboveground activity during warm hours in the colder early dry season. In both periods, the root rats displayed diurnal activity with a unimodal pattern positively related to the temperature at the soil surface. Unlike in some other burrowing rodents, there was no tendency to decrease activity in the warmest part of the day even in the relatively warm late dry season.

Mammalian space-use patterns are largely determined by the resources utilized as well as by given habitat characteristics, as can be illustrated by rodents displaying predominantly subterranean activity. These rodents are largely limited in their use of space by their burrow systems. This results in smaller home ranges than is usual for rodents of a similar size. However, there is little information regarding how stable these home ranges are over time. We studied space use in the giant root-rat, Tachyoryctes macrocephalus, a large fossorial rodent endemic to the Bale Mountains of southern Ethiopia where it is the principal prey of the Ethiopian wolf Canis simensis. We radio-tracked 22 root-rats during a period of 36 days in the early dry season and 17 of them once again during a period of 37 days in the late dry season. The root-rats occupied very small (around 100 m 2) home ranges which were often tightly packed, especially on a wetland shore that was a part of the study locality, but displayed little overlap. Almost 30% of the radio-collared rootrats of either sex dispersed (80-428 m from their original home range) during the 5 months of the study, mostly in a period between the early and late dry season characterized by a decreasing food supply and the soil becoming dry and hard. Individuals who did not disperse during this time usually shifted their home range. Root-rats living on the wetland shore, which were the largest and therefore likely competitively strongest individuals, shifted their home ranges into the wetland, likely for the purpose of increasing their food supply.