Influence of Anthropogenic Disturbances on Stand Structural Complexity in Andean Temperate Forests: Implications for Managing Key Habitat for Biodiversity

Caviedes, Julián; Ibarra, José Tomás

doi:10.1371/journal.pone.0169450

Cited by 52 publications

(58 citation statements)

References 94 publications

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“…More than 75% of the tree trunks were more than 20 years old, about 60% were between 25 and 50 years old, and only about 15% were more than 50 years old. This might suggest the existence of a secondary forest that is probably more recent at Achada das Furnas, Lombadas and Pinhal da Paz, due to human disturbance [59] and somewhat older at Povoação, Sete Cidades and Tronqueira. At Tronqueira and Povoação stands, we found what appears to be older remains of a laurel forest with a general higher density/cover of endemic tree species.…”

Section: Laurel Forest In São Miguel Islandmentioning

confidence: 99%

Linking Dendrometry and Dendrochronology in the Dominant Azorean Tree Laurus azorica (Seub.) Franco

Matos

Silva

Camarinho

et al. 2019

Forests

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As in many archipelagos, the Azorean primary forest was largely cleared and replaced by secondary forest and grassland, the Azorean tree Laurus azorica (Seub.) Franco being one of the dominant trees in the remaining natural forests. Dendrochronological and dendrometric studies in the Azores mainly focused on non-indigenous trees, either used for timber (e.g., Cryptomeria japonica D. Don) or considered as invasive (Pittosporum undulatum Vent.). Therefore, this study aims to describe the growth ring anatomy of L. azorica, and to understand the relationship between dendrometric traits (e.g., trunk diameter at breast height; tree height), and the number of growth rings. Growth ring anatomy was accessed by wood anatomical preparation of microcore samples while tree age estimation was based on growth ring counts in wood cores taken at breast height and at base. A total of 145 trees were sampled, resulting in 262 increment cores, at six representative stands of laurel forest in São Miguel Island (Azores). The wood anatomical analysis confirmed the presence of clear annual ring boundaries, and a high structural similarity towards Laurus novocanariensis Rivas Mart., Lousã, Fern.Prieto, E.Días, J.C.Costa & C.Aguiar. Age at tree base averaged 33 years, with 60% of the trees between 25 and 50 years old, and only about 15% above 50 years old. This suggests the existence of a secondary forest that is more recent than expected, probably due to human disturbance. The allometric models showed best fit when calculated by stand, suggesting the effect of local environmental conditions on growth rate. Radial growth rate was estimated at 0.68 cm.year−1. Given the known dominance of this species and the threats affecting natural forests, this baseline study will allow a better understanding of forest distribution and dynamics, and support a more effective forest management approach.

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Section: Laurel Forest In São Miguel Islandmentioning

confidence: 99%

Linking Dendrometry and Dendrochronology in the Dominant Azorean Tree Laurus azorica (Seub.) Franco

Matos

Silva

Camarinho

et al. 2019

Forests

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“…The total amount and the attributes of CWD in managed forests could be modified by anthropogenic disturbance [58,59].…”

Section: Components Of Cwdmentioning

confidence: 99%

Coarse Woody Debris Variability Due to Human Accessibility to Forest

Behjou

Monaco

Tavankar

et al. 2018

Forests

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Coarse woody debris (CWD) plays an important role in supporting biodiversity and assisting ecological processes. Sometimes local people intervene modifying the expected distribution of CWD components, harvested as fuel wood. The effect of the human accessibility (HA) on the volume and characteristics of CWD (snag, downed log and stump) was investigated in the natural uneven-age mixed hardwood stands of the Hyrcanian forests of Iran to quantify the impact on CWD. The HA was classified into three classes (easy, medium and difficult) on the basis of slope class, slope direction to the nearest road and road type. As expected, a negative relationship between the degree of accessibility was found with respect to the main qualitative and quantitative indices referring to CWD. The results showed that the volume of CWD decreased with an increase in human accessibility class (HAC), thus the mean volume of CWD in the difficult, medium and easy accessibility classes were 14.87 m 3 ha −1 , 8.84 m 3 ha −1 and 4.03 m 3 ha −1 , respectively. The decrease in CWD volume was more associated with the decreasing volume of small diameter of low decayed downed logs. The ratio of snag volume to standing volume, the ratio of downed log volume to the volume of trees and the ratio of CWD volume to standing volume increased with a decrease in HAC, while the ratio of downed log volume to snag volume decreased with a decrease in HAC. No selective behaviour on the botanical species of CWD was recorded. For ecological forest management, the effect of HAC on CWD should be considered. A constant supply of snags and downed logs must be preserved to assure a high level of biodiversity. To balance social needs and biodiversity requirements, an increased level of CWD retention might be needed in areas with easy accessibility. The obtained results may be useful when ecological and socio-economical needs have to be taken into consideration in future policy-making decisions.

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“…According to some authors, in small seed species (~3 mm long, such as the studied species), a microsite may be no more than a few centimeters in diameter (Fowler, 1988). Microsites do not form a continuum in a forest, and differences in micro environmental variables will arise due to forest complexity at different scales, which can occur naturally but also, they can be influenced by some silvicultural practices and disturbances (Caviedes and Ibarra, 2017;Martínez-Orea et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Germination Response of Two Shrub Species Under Controlled Conditions and to Secondary Vegetation Removal (Weeding) in the Magdalena River Basin, Mexico

et al. 2019

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Temperate forests are heterogeneous because of their variable topography which causes that environmental variables are different between slopes. The availability of microsites for seed germination is crucial for natural regeneration. Secondary vegetation removal (weeding) is practiced in Central Mexico's forests as part of silvicultural practices. To evaluate its effects on germination we performed an experiment with microsite types of different orientations South/North (S/N) and with/without secondary vegetation (Undisturbed/Perturbed) (US, UN, PS, PN). Light (global site factor [GSF] and red/far-red [R/FR] ratio), soil temperature, moisture, pH, nitrogen (Ni) and germination of two shrub species were measured at 24 microsites. Results were analyzed with generalized linear models, variation coefficients and Kruskal-Wallis tests. Light values exhibited higher values at US because South-facing sites receive higher solar radiation than North-facing ones and because canopy gaps were larger. R/FR ratios were significantly different between U and P, and N and S microsites; the highest values were registered at PS microsites because of their orientation and because of the absence of understory vegetation, which filters light. Soil temperature was the highest at PS and PN. Soil moisture was the highest at UN and US because secondary vegetation avoids soil moisture loss. Germination percentages of both species were the highest at US because secondary 137 species have high light and soil moisture requirements. pH, soil moisture and GSF had a significant effect on Ageratina glabrata, while pH, Ni, soil temperature and moisture were significant for Senecio angulifolius. This practice can have negative effects on shrubs species germination. We do not recommend weeding, because it can have negative effects on shrub species germination. RESUMEN:Los bosques templados son heterogéneos por su topografía variable lo que causa que las variables ambientales sean diferentes entre laderas. La disponibilidad de micrositios para la germinación es crucial para la regeneración natural. La remoción de vegetación secundaria (chaponeo, deshierbe) se practica en bosques del centro de México como parte de las prácticas silvícolas. Para evaluar sus efectos en la germinación establecimos micrositios de diferente orientación (Sur/Norte), con/sin vegetación secundaria (Sin Disturbio U/Perturbado P) (US, UN, PS, PN). La luz (factor de sitio global [GSF], tasa de luz rojo/rojo lejano), temperatura, humedad, pH, Nitrógeno (Ni) del suelo y germinación de dos arbustos fueron medidos en 24 micrositios. Se utilizaron modelos lineales generalizados, coeficientes de variación, pruebas de Kruskal-Wallis para el análisis. La luz fue mayor en US porque los sitios orientados al Sur reciben mayor radiación solar que aquellos al Norte y porque los claros del dosel fueron mayores. R/FR varió significativamente entre micrositios U y P, y entre N y S; los mayores valores se registraron en PS por su orientación y ausencia de vegetación secundaria, que filtra la luz....

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Influence of Anthropogenic Disturbances on Stand Structural Complexity in Andean Temperate Forests: Implications for Managing Key Habitat for Biodiversity

Cited by 52 publications

References 94 publications

Linking Dendrometry and Dendrochronology in the Dominant Azorean Tree Laurus azorica (Seub.) Franco

Linking Dendrometry and Dendrochronology in the Dominant Azorean Tree Laurus azorica (Seub.) Franco

Coarse Woody Debris Variability Due to Human Accessibility to Forest

Germination Response of Two Shrub Species Under Controlled Conditions and to Secondary Vegetation Removal (Weeding) in the Magdalena River Basin, Mexico

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