Cattle affect regeneration of the palm species Attalea princeps in a Bolivian forest–savanna mosaic

Abstract

Attalea princeps is an important palm species that shapes the forest–savanna mosaic in Beni, Bolivia, as it dominates the two principal forest landscape elements (forest islands and gallery forest), and provides a vital microhabitat, food, and nesting source for numerous plant and animal species. The forest–savanna mosaic is used for extensive grazing, and the palm population is declining on the forest islands due to a low regeneration rate, which threatens the maintenance of this landscape. We therefore examined the (a)biotic factors that influence the population structure of Attalea in the centers and edges of forest islands and gallery forests. Ninety‐one 0.1‐ha plots were established, and 500 palm adults and 3,700 juveniles were measured for their size, health condition, and fire damage. For each plot, habitat characteristics, such as landscape position, grazing pressure, and soil conditions, were measured. Attalea population density was significantly lower on the forest islands than in the gallery forests, especially in the juvenile life stage. A structural equation model showed that juvenile density is positively related to the health condition of juveniles and amount of fruits present, where the amount of fruits is positively affected by the condition of adults. Juvenile density is negatively influenced by grazing, affecting the health condition of the juvenile, as well as organic matter and phosphate availability in the soil. Therefore, it is recommended to decrease the grazing pressure by decreasing livestock densities, fencing off vulnerable forest islands, or by rotating cattle.Abstract in Spanish is available with online material.

First systematic sampling approach to estimating the global population size of the Critically Endangered Blue-throated MacawAra glaucogularis

“…Studying the movement ecology of Blue-throated Macaws through telemetry would contribute to a more accurate analysis and interpretation of population survey data. Finally, expansion of nest box programmes especially to the north-western subpopulation along with restoration of palm forest islands impacted by cattle ranching (see Hordijk et al 2019) probably are the two most important conservation actions to ensure the species' long-term recovery.…”

Restoration of gallery forest patches improves recruitment of motacú palms (Attalea princeps) while diversifying and increasing wildlife populations

“…The dung provides a mechanical barrier to bruchid beetle oviposition [ 62 , 63 ] leading to reduced rates of infestation [ 34 , 62 ] that may otherwise limit seedling growth in areas where fruits are densely deposited, e.g. carpets under parent trees [ 32 , 64 ]. Cattle could thus facilitate motacú germination by reducing seed mortality and assisting with dispersal away from parent trees [ 65 ].…”

“…Recent research has linked ranching to habitat degradation in Beni, through negative impacts on the regeneration of, motacú palms ( Attalea princeps) [ 32 ]. Motacú palms are a dominant component of Beni’s galley forests and forest islands, and play a key role in shaping their structure, microclimate and ecology [ 21 , 31 , 34 , 35 ].…”

Multiple External Seed Dispersers Challenge the Megafaunal Syndrome Anachronism and the Surrogate Ecological Function of Livestock

“…The habitat in these areas shows a variable degree of fragmentation and defaunation (especially hunting pressure for bush meat and parrot poaching for the pet trade) depending on its inclusion within protected areas, human population density, nearness to inhabited nuclei, and their influences on the frequency of fires and livestock density (Silva et al, 2006;de Carvalho and Mustin, 2017;Mistry et al, 2019; see Table S1 for details). The study area within the Beni savannas are characterized by wide areas of seasonal flooded grasslands dotted with forest islands dominated by palms and semi-deciduous groves used historically by indigenous human communities (Langstroth and Riding, 2011;Hordijk et al, 2019). The study area in San Matías, Ángel Sandoval (Bolivia) correspond to a transition between the Bolivian Pantanal, with roughly 80% of its floodplains submerged during the rainy season, and the Chiquitano dry forest characterized by shrublands, gallery forests, and dry forests (Power et al, 2016;de Carvalho and Mustin, 2017).…”

“…Although the viability of palm seeds dispersed after rumination or spitting without swallowing remains unknown, these different mechanisms for exploiting fruit can have important implications on seed dispersal distances (Castañeda et al, 2018;Delibes et al, 2019). Dispersal of A. totai seeds by cows mostly occurred below the source plant, as demonstrated the high density of seeds regurgitated in resting places within palm patches where plant recruitment is hindered by trampling, grazing and soil compaction (Montúfar et al, 2011;Smith, 2015;Baños-Villalba et al, 2017;Hordijk et al, 2019), or in locations unsuitable for germination outside palm patches within the dry Cerrado vegetation matrix. The frequency of regurgitations (all of A. totai seeds) decreased as the distance from the palms increased, with maximum dispersal distances of up to about 400 m in unsuitable sites, even though cow movement capability allows much longer daily travel distances.…”