Greater Percent Cover Research Articles

Microhabitat use by white-footed mice Peromyscus leucopus in forested and old-field habitats occupied by Morrow’s honeysuckle Lonicera morrowii

Abstract We quantified microhabitat use by white-footed mice Peromyscus leucopus in forest and old-field habitats occupied by Morrow’s honeysuckle Lonicera morrowii, an invasive exotic shrub imported from Japan. Microhabitat characteristics were compared between trails used by mice (n = 124) and randomly selected trails (n = 127) in 4 study plots located at Fort Necessity National Battlefield, Farmington, Pennsylvania, USA. We compared 10 microhabitat variables between used and random trails using non-metric multidimensional scaling (NMDS) and classification and regression tree (CART) analysis. Trails used by mice were statistically different from randomly selected trails in both forested plots (P < 0.008) and old-field plots (P < 0.001). In the forested plots, trails of white-footed mice were more often associated with a greater percent cover (% cover) of coarse woody debris (CWD) than were randomly selected trails. In the old-field plots, mouse trails were commonly characterized by having a lower % cover of exotic herbaceous vegetation, a greater % cover of shrubs, and a greater % cover of Morrow’s honeysuckle than randomly selected trails. Our study indicates that white-footed mice do not move randomly and prefer areas of high structural complexity, thereby showing significant microhabitat preference. The preference of white-footed mice for areas with a relatively high percent cover of Morrow’s honeysuckle could 1) be a factor in the aggressive nature of the exotic honeysuckle shrub’s spread throughout the Battlefield or 2) cause the shrub to spread even faster into adjacent areas not yet occupied by Morrow’s honeysuckle.

Food choice of an Algerian population of the spur‐thighed tortoise, Testudo graeca

The diet of an Algerian population of spur‐thighed tortoise (Testudo graeca) was studied with the aims of exploring: (i) the variation in diet among males, females and juveniles, (ii) the relationships between consumption and relative availability of the plant species, and (iii) which plant tissues, vegetative or reproductive, are eaten by tortoises. We recorded more than forty plant species at the study area, with monocot species (n = 7) having a greater percent cover than that of dicot species (n = 31 species) or Gymnospermae (n = 2). Tortoise diet was studied by categorising 4422 plant and animal fragments in faecal pellets of 20 males, 16 females and eight juveniles. Tortoises ate a wide variety of plant species, including 13 dicots and three monocots, and occasionally invertebrates. The number of fragments for a plant species was correlated with plant species cover, and plant vegetative tissues exceeded plant reproductive tissues in the faeces. Dicots (Fabaceae, Composeae, Primulaceae, and Caryophyllaceae) accounted for over 70% of the diet (faecal fragments). The high dietary (niche) overlap, and null model analysis (RA3 algorithm with 30,000 Monte Carlo simulations), indicate that males, females and juveniles did not partition food resources; all three groups ate the same plant species.

Nitrogen in litterfall and precipitation and its release during litter decomposition in the Chilean piedmont matorral

Parts of the nitrogen cycle involving two dominants (Lithraea caustica and Quillaja saponaria) in the Chilean piedmont matorral have been studied over a 15-month period. Analyses showed that 8.2 kg N ha - 1 yr - 1 entered the system in rainfall and dry deposition, though impaction of N-containing compounds on vegetation (not measured) may elevate this value. 1. caustica, by virtue of its greater percent cover, contributed more leaf litter than did Q. saponaria to the system (1089, vs 737 kg dry matter ha -I yr- I, respectively), although on an individual basis Q. saponaria produced more litter (640, vs 350 g dry leaflitter m - 2 yr- 1 r 1. caustica). This plus the greater nitrogen release of 1. causlica leaf litter during decomposition (2.61, vs 0.60g N kg dry litter-I yr- I for Q. saponaria) and Q. saponaria's higher N-content of dropped leaves (0.54, vs 0.37% N for 1. caustica) may indicate a more external cycling of nitrogen in Q. saponaria relative to that in 1. caustica. These two species may therefore represent two different strategies of individual nitrogen cycling, external and internal.