Impacts of cattle grazing on forest structure and raptor distribution within a neotropical protected area

Piana, Renzo P.; Marsden, Stuart J.

doi:10.1007/s10531-013-0616-z

Cited by 47 publications

(27 citation statements)

References 44 publications

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“…Assim, quando comparados aos valores encontrados na literatura, os valores encontrados para estoque de carbono na vegetação no presente estudo apontam para uma condição mais próxima de regeneração do que de floresta madura propriamente. A inferioridade dos valores encontrados deve-se provavelmente aos impactos sofridos na área, como trilhas e presença de gados, que causam variações na densidade e biomassa de indivíduos entre as parcelas amostrais (Piana & Marsden, 2014;Pereira et al, 2015), e pode estar relacionada também a questões metodológicas envolvidas nas estimativas de carbono (método indireto de determinação).…”

Section: Resultsunclassified

Relação Espacial do Carbono da Vegetação e Matéria Orgânica do Solo na Serra da Mantiqueira

Terra

Mello

2015

Floresta Ambient.

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RESUMOO presente trabalho objetivou analisar o comportamento espacial do estoque de carbono presente no fuste da vegetação (ECV) e da matéria orgânica do solo (MO) em uma floresta ombrófila densa na Serra da Mantiqueira, no Estado de Minas Gerais, por meio de krigagem. Pretendeu-se também testar a utilização da MO superficial como variável auxiliar na predição do ECV com o uso da cokrigagem. Para isso, foram analisados dados georreferenciados de 25 pontos amostrais de MO em três profundidades, 0-20 cm (P1), 20-50 cm (P2) e 50-100 cm (P3), e de 12 parcelas amostrais de 400 m 2 de vegetação. As variáveis apresentaram estrutura de dependência espacial (maior em ECV e menor em MO em P1) e o semivariograma cruzado refletiu a correlação espacial entre ECV e MO em P1. O mapa de interpolação gerado por cokrigagem foi satisfatório na detecção de tendências da variável ECV, conservando os mesmos padrões do mapa gerado por krigagem ordinária para essa variável. Considera-se que, na área estudada, MO em P1 pode ser utilizada como covariável na caracterização espacial geral do ECV, em situações de subamostragem de ECV.Palavras-chave: mata atlântica, geoestatística univariada, geoestatística multivariada. Spatial Relationship of Vegetation Carbon Stock and Soil Organic Matter at Serra da Mantiqueira ABSTRACTWe aimed to analyze the spatial behavior of carbon present in the stems of trees (ECV) and soil organic matter (OM) in a dense ombrophilous forest at Serra da Mantiqueira, MG, using kriging. Also we tested the use of superficial organic matter as auxiliary variable in predicting ECV by cokriging. In order to achieve this, we analyzed georeferenced data from 25 sampling points of soil organic matter in three depths, 0-20 cm (P1), 20-50 cm (P2) and 50-100 cm (P3) and 12 vegetation sample plots of 400 m 2 . All variables presented spatial dependence structure (higher ECV and lower OM at P1). The cross semivariogram reflected the spatial correlation between ECV and OM at P1. The interpolation map generated by cokriging provided good notion of general ECV trends keeping the same patterns as the one generated by ordinary kriging for this variable. Our findings pointed that in our studied area, OM at P1 can be used as a covariate for ECV prediction of where ECV is under sampled.

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Section: Resultsunclassified

Relação Espacial do Carbono da Vegetação e Matéria Orgânica do Solo na Serra da Mantiqueira

Terra

Mello

2015

Floresta Ambient.

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“…In Ecuador, deforestation has removed ∼95% of the original forest cover in the Tumbesian zone and hence the risk of extinction for Gray‐backed Hawks in this country might be high (Dodson and Gentry ). Although known to occur in degraded forests, it is not known if they breed in these areas (Piana and Marsden ). Further study is needed in degraded areas in Peru and Ecuador where the species is still present to evaluate nest productivity and reproductive success in fragmented and deforested landscapes within the Tumbesian zone.…”

Section: Discussionmentioning

confidence: 99%

“…Plots were located randomly without stratification in all areas of the study site except the TNR. Six 1‐km 2 plots were located there to examine the effects of intense cattle grazing (Piana and Marsden ). A few plots were too remote to allow safe access so plots up to 2 km closer to existing trails were substituted for these (Thiollay ).…”

Section: Methodsmentioning

confidence: 99%

“…The global population of this species derived from field counts is unknown, but has been estimated to be between 250 and 999 individuals and decreasing (BirdLife International ). The main reasons for this decline are habitat destruction and fragmentation from agriculture and cattle ranching in northwest Peru and Ecuador, and direct persecution in Ecuador because they are thought to prey on poultry (Vargas , BirdLife International , Piana and Marsden ).…”

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Potential distribution, absolute density, and population size of Gray-backed Hawks (Pseudastur occidentalis) in a protected area in northwest Peru

Piana

2016

J. Field Ornithol.

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Estimates of density and population size are fundamental in assessing population trends and ultimately in informing conservation management. Although the abundance of raptors is often expressed as indices of relative abundance, these can be poor correlates of absolute density. In 2008–2009, I calculated the absolute density and population size of Gray‐backed Hawks (Pseudastur occidentalis), an endangered species and Tumbesian endemic, using line transect counts in four different habitat types in a protected area in northwestern Peru. The absolute density of Gray‐backed Hawks in northwest Peru was estimated to be 0.65 individuals km−2, and the most suitable habitat for the species was located in the provinces of Manabí, Guayas, and Santa Elena in Ecuador, and Tumbes and Piura departments in Peru. The population of Gray‐backed Hawks in my study areas in Tumbes was estimated to be 136, with 94% occurring in dry deciduous and deciduous forest. Because ∼60% of all detections in my study were made outside strictly protected areas, including the recently created Angostura‐Faical Regional Conservation Area, conservation of the remaining, non‐protected forests patches in Peru and Ecuador should be a high priority. The current global population of Gray‐backed Hawks has been estimated to be between 250 and 999 birds and declining due to ongoing habitat destruction and fragmentation. Small populations in small habitat fragments, like those in my study area, have high conservation potential, provided that populations are not isolated, and hence should be the focus of constant monitoring.

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“…Other forms of extraction of woody biomass such as lopping of tree branches affects canopy structure. Livestock grazing also simplifies the understory forest structure and reduces regeneration, foliage density, canopy height, and vegetation cover (Tasker andBradstock 2006, Piana andMarsden 2014). Such loss of structural components and alteration of floristic diversity in forests ultimately affects populations of many species reliant on forest habitat (Díaz et al 2005, Berry et al 2008, Lee and Carroll 2014.…”

Section: Introductionmentioning

confidence: 99%

Effects of habitat extent and forest disturbance on bird communities in lowland nepal

Dahal¹

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Habitat loss and degradation are recognized as the major contributors to species decline and extinction, and therefore represent a key conservation challenge for biodiversity conservation. Key to the protection of biodiversity is acquisition of ecological knowledge about how anthropogenic forest disturbances affect species and how species respond to emergent landscape characteristics.Furthermore, it is also important to assess how different management approaches and land tenures influence retention of the biota of particular sites and of landscapes. However, this crucial ecological knowledge is yet to be obtained for the threatened lowland landscapes of Nepal.Protected areas cover only a small proportion of forests in lowland Nepal; the majority of forests outside the protected areas (off-reserve) have been managed by the state government. However, in recent years, community forestry programs have been increasingly popular as attempts to protect biodiversity while permitting consumptive forest use by people. It is therefore important to understand effectiveness of different forest management tenures for avifaunal conservation. I compared species richness, abundance, diversity and community composition of birds among sites in community forests, state forests and protected areas. Although sites in protected areas had the greatest richness of birds, community forests and state managed forests had complementary assemblages, supporting species not represented in protected areas. Vegetation characteristics such as large tree density, tree canopy cover and shrub density were also greater in community forests than in state-managed forests. The findings suggest that the community forestry approach appears to improve habitat quality compared to state-managed forests, and therefore can be an alternative tenure type for conservation of off-reserve forests and avifauna in the region.Subsistence forestry practices such as logging, lopping, and grazing are sources of forest disturbance in lowland Nepal. Such activities do not reduce forest area, but change habitat characteristics, potentially affecting biodiversity directly, and through interactions with landscape characteristics. I examined effects of forest use practices on species richness and abundance of forest birds, and whether landscape context such as the extent of forest cover moderates disturbance effects on birds. I found that extraction of forest products reduced forest structural complexity and altered the avifaunal community of a site. At the site level, large tree density, tree canopy cover and shrub density were important habitat characteristics, while the extent of forest cover in the landscape had the greatest influence on richness of birds. The effects of forest disturbance (livestock grazing and logging) intensity on birds depended on the extent of forest in the surrounding landscape, with strongest effects in sites with less surrounding forest. Thus, although iii site-level vegetation structure is important, maintenance of forest extent in the lan...

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Impacts of cattle grazing on forest structure and raptor distribution within a neotropical protected area

Cited by 47 publications

References 44 publications

Relação Espacial do Carbono da Vegetação e Matéria Orgânica do Solo na Serra da Mantiqueira

Relação Espacial do Carbono da Vegetação e Matéria Orgânica do Solo na Serra da Mantiqueira

Potential distribution, absolute density, and population size of Gray-backed Hawks (Pseudastur occidentalis) in a protected area in northwest Peru

Effects of habitat extent and forest disturbance on bird communities in lowland nepal

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