Regeneration of secondary forests is recognized as an important means for the recovery of native species biodiversity in human‐disturbed tropical lands. Native earthworms are often replaced with exotic species after deforestation. We studied changes in earthworm diversity and community structure along a chronosequence of abandoned tropical pastures in the Cayey Mountains of Puerto Rico. This chronosequence consisted of active pastures, young secondary forests 25–40 years old, and mature secondary forests>77 years old. Earthworm diversity increased along successional stages. The exotic soil‐feeding earthworm Pontoscolex corethrurus dominated the pastures and young secondary forests. Five native earthworm species ( litter feeders Borgesia sedecimsetae, Estherella sp., Onychochaeta borincana, Neotrigaster rufa, and Trigaster longissimus ) were found in the mature forests, together with P. corethrurus. Earthworm density was highest in the active pastures ( 273 individuals/m2 ), decreased as forest regeneration proceeded, and was lowest in the mature forests ( 88 individuals/m2 ). Our results suggest that regeneration of mature secondary forests, and the consequent increase in litter biomass on the forest floor, can promote the recovery of earthworm diversity and native species of earthworms in old tropical pastures.
The choice by the Baya weaver between different plant species as nesting platforms and sources of nesting fibre was analysed on an agricultural study plot at Chorao (15°30'N, 73°50'E), an island in the Mandovi estuary in Goa, India. The bird chose eucalyptus over coconut palms, as shown by a higher ratio of utilised trees to available trees and by the maintenance of significantly higher numbers of total nests (t = 2.92, P < 0.05) and viable nests (t = 3.10, P < 0.05). The wider anchoring area, providing a better display front for the male birds competing for mates, and the protection against monsoon vagaries (such as rains and winds) provided by the extensive drooping canopy of profuse branches seem to have favoured of eucalyptus trees over coconut palms. The choice went against short and medium sized coconut palms and tall eucalyptus trees, as probably the former were more prone to the menace of intruders and the latter were more exposed to strong monsoon winds. The birds exhibited a differential use of nesting fibres to fabricate the different zones of the nest. Sugarcane fibres, which probably provided better anchorage and stability due to their interlocking silicious spicules, were used for the base, stalk and roof of the brood chamber. Fibres from coconut leaves went into the construction of the entrance tube and floor of the brood chamber, probably to provide added comfort to the altricial young and incubating parent and to afford the required resistance against wear and tear owing to frequent movements of the mother bird while ferrying food to the young.
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