The forgotten habitats in conservation: early successional vegetation

Abstract

Conservation efforts in terrestrial environments have focused on preserving patches of natural habitats and restoring disturbed habitats, with the main goal of transforming them into forests or habitats that resemble the original conditions. This approach tends to overlook the importance of conserving early successional vegetation (e.g., riverside vegetation, natural regeneration, young secondary forests), which often includes a large number of species (e.g., plants and animals) associated with or restricted to these habitats. In this paper we want to bring to attention the importance of preserving early successional vegetation, and to encourage scientists to investigate, e.g., the diversity, distribution, and species interactions occurring in these habitats. To address these goals, we focus on two main objectives: (1) to identify the common types of early successional vegetation in the Costa Rican Central Valley; and (2) to use some case studies to draw attention to the importance that such areas have as reservoirs of a large portion of the diversity unique to early successional stages. We first include an example to show the diversity of plants in small forest patches immersed in a large urbanized area. We provide general information on the insects that occur in early successional vegetation in urban areas, and in further detail examples of butterflies. Additionally, we provide examples of birds and mammals that are restricted to early successional vegetation, and how the reduction of this vegetation type affects species conservation. Finally, we encourage scientists to investigate these early successional habitats, particularly those species exclusive to early successional stages. Special attention should be paid to endemic species and those with a restricted distribution. Information of this type will make conservation of the diversity contained in these habitats possible.

Urbanization has opposite effects on the territory size of two passerine birds

“…These results are important for urban management practices because they provide evidence about the habitat structure (proportion of urban and natural surface) and size necessary for the conservation of species with different degree of tolerance to urban development. Our results also highlight the relevance of dense thicket, a habitat generally underappreciated, but important for the conservation of urban adapter and avoider species alike (Sandoval et al 2019). For an urban avoider species such as White-eared Ground-Sparrow whose natural habitat includes dense understories (Sandoval and Mennill 2012;Sandoval et al 2016), dense thickets inside urban areas constitute an irreplaceable trophic substratum for roosting, breeding and feeding.…”

“…For an urban avoider species such as White-eared Ground-Sparrow whose natural habitat includes dense understories (Sandoval and Mennill 2012;Sandoval et al 2016), dense thickets inside urban areas constitute an irreplaceable trophic substratum for roosting, breeding and feeding. This habitat also provides resources for other species of birds, mammals, and arthropods specialized or restricted to this habitat inside urban areas to survive (Sandoval et al 2019).…”

Genetic structure in neotropical birds with different tolerance to urbanization

“…A large proportion of the original habitat occupied by white-eared ground-sparrows in Costa Rica is now located within the Greater Metropolitan Area (GAM), characterized by a recent, rapid, and unplanned urban development 36 . For the earlier half of the twentieth century, a large portion of the GAM was covered by coffee plantations and second growth vegetation, but recent urban development has reduced coffee plantations and natural vegetation cover to small, isolated fragments 1 , 26 . Hence, the preferred habitat of the white-eared ground-sparrow has been constantly reduced; threatening the viability of this species’ populations 25 , 37 , 38 .…”

“…The white-eared ground-sparrow ( Melozone leucotis ) inhabit thickets, coffee plantations and secondary forest edges 21 – 23 . Historically, coffee plantations expanded in the early twentieth century, and presumably provided greater connectivity for white-eared ground-sparrow; but in recent years, this habitat type has been gradually transformed into urban settlements and the remaining habitat of the white-eared ground-sparrows has been converted into fragments that vary in isolation 1 , 24 – 26 . On the contrary, the second species included in this study, the house wren ( Troglodytes aedon ), is commonly found in open and semi-open areas, forest edges and it has presumably benefited from urban development 21 , 27 , 28 .…”

Pollen analysis as an ecological proxy for the assessment of habitat use of the endangered Black-polled Yellowthroat (Geothlypis speciosa) and sympatric Common Yellowthroat (G. trichas)

“…Marked differences in pollen loads between seasons, shown by equitability resource-use, suggest that food resources (insects) can be more evenly distributed across a wider area or plant substrates during the dry season, potentially increasing bird visitation to different habitats (see Sandoval et al 2019), likely to secondary vegetation. Pollen from plants in secondary vegetation are generally heavier, relying on insect dispersal, which in turn suggests necessary bird movements outside or near the edges of the lake where such vegetation is present (Rojas-Moreno and Novelo-Retana 1995).…”