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1.
Ying Yong Sheng Tai Xue Bao ; 31(1): 45-54, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957379

RESUMEN

Evaluation of landscape aesthetic quality is a key step in the management system of forest resource. Color is an important component of autumn landscape forest, and quantitative analysis of color and scientific evaluation of landscape aesthetic quality are important for the management of autumn landscape forest. We assessed the aesthetic quality of autumn landscape forest using scenic beauty estimation and analyzed the effects of color characteristics on ornamental value of autumn landscape forest based on color composition and color spatial pattern according to human's visual characteristics. The results showed that the overall landscape quality of subalpine region of western Sichuan could be divided into five grades according to beauty value (I to V). About 71.5% of autumn landscape forests could be classified into grade I, II, and III, indicating that autumn landscape forests of subalpine region in western Sichuan had higher ornamental value. According to the scenic beauty estimation value, the landscape aesthetic quality of broadleaved mixed forests was higher than that of coniferous and broadleaved mixed forests and pure forests. In terms of the comprehensive index evaluation system of color elements, the index weight coefficient order was landscape patch heterogeneity factors>autumn main color factors>color saturation and brightness factors>color diversity and evenness factors. With cluster analysis, autumn landscape forests of western Sichuan could be divided into three types. The forests with higher ornamental value showed following characteristics: larger degree of patch fragmentation and heterogeneity, higher percentage of orange and yellow and lower percentage of green in autumn, higher percentage of color saturation and brightness, and higher color diversity and uniformity index. The communities with higher richness, species diversity and evenness index would have higher beauty values. We concluded that species diversity and fragmentation of colors should be considered in the construction of autumn landscape forests, and that aesthetic quality of autumn landscape forest could be improved by planting and cultivating tree species with various and bright autumn leaf colors.


Asunto(s)
Bosques , Árboles , China , Color , Estética , Humanos
2.
Ying Yong Sheng Tai Xue Bao ; 31(1): 55-64, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957380

RESUMEN

The remotely sensed burned area (BA) products can provide continuous and spatiotemporally explicit characteristics of fire patches, which are critical data sources for understanding regional fire regimes. However, their accuracy remains to be improved. In this study, a global BA product (i.e., CCI_Fire) at 250 m resolution was integrated with global forest change (GFC) product at 30 m to generate a refined BA product, named CCI_GFC product, whose accuracy was evaluated through comparing the BA with pre-existing fire patches data. To reveal the characteristics of forest fire in China between 2001 and 2017, we conducted a grid analysis at 0.05°×0.05° spatial resolution based on the refined BA product and the spatial pattern of eco-regions at the macro scale. The results showed that the accuracy metrics including the recognition rate (RR), variance explained (R2), root mean squared error (RMSE), mean absolute percentage error (MAPE) of the CCI_GFC product (i.e., 83%, 0.91, 0.28, and 8.5% respectively) were all superior to the CCI_Fire product (i.e., 74%, 0.86, 0.36, and 11.8% respectively) and the MCD64A1 product (i.e., 35%, 0.78, 0.48, and 17.3% respectively). The total burned area of forest was approximately 12.11 million hm2 for the whole country from 2001 to 2017, while the annual burned area temporally decreased. Forest fires in China were dominated by the low-frequency [0

Asunto(s)
Fuego , Incendios Forestales , China , Bosques , Estaciones del Año , Árboles
3.
Ying Yong Sheng Tai Xue Bao ; 31(1): 65-71, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957381

RESUMEN

China is one of the countries with serious forest fires. Besides the methods of strengthening management of fire source and increasing forest fire monitoring and rescue efforts, improving the ability of forest itself to resist fire is also the key to prevent forest fires. In this study, we examined the characteristics of the bark across 11 main tree species in Korean pine broad-leaved forest at Jiaohe Forestry Experimental Area in Jilin Province. Fire resistance of bark acorss the tree species was evaluated comprehensively with four indices of water content, ash content, calorific value and oxygen index, using the methods of entropy weight, variance analysis and cluster analysis. Results showed that water content of bark was the highest in Phellodendron amurense. Calorific value of bark was the lowest and ash content was the highest in Ulmus davidiana. Oxygen index of bark was the highest in Fraxinus mandshurica. Bark fire resistance of 11 tree species followed the order of U. davidiana > Acer mono > Acer triflorum > Acer mandshuricum > F. mandshurica > Quercus mongolica > P. amurense > Tilia amurensis > Juglans mandshurica > Pinus koraiensis > Betula costata. The tree species in Korean pine broad-leaved forest could be classified to five categories according to bark fire resistance: U. davidiana belonged to the category of strongest fire-resistance; A. mono and A. triflorum belonged to the category of strong fire-resistance; A. mandshuricum, F. mandshurica, Q. mongolica, P. amurense, T. amurensis belonged to the category of common fire-resistance; J. mandshurica and P. koraiensis belonged to the category of weak fire-resistance; and B. costata belonged to the category of poor fire-resistance.


Asunto(s)
Pinus , Árboles , China , Bosques , Corteza de la Planta
4.
Oecologia ; 192(2): 449-462, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31960145

RESUMEN

In forest communities, conspecific density/distance dependence (CDD) is an important factor regulating diversity. It remains unknown how and the extent to which gap creation alters the mode and strength of CDD via changes in the relative importance of pathogens and mycorrhizae. Seeds of two hardwoods (i.e., Acer mono associated with arbuscular mycorrhizae [AM] and Quercus serrata associated with ectomycorrhizae [EM]) were sown reciprocally at four distances from the boundary between Acer- and Quercus-dominated forests towards forest interior in each of forest understories (FUs) and gaps. The causes of seed and seedling mortality, seedling growth and colonization of mycorrhizal fungi were investigated. In Acer, seed and seedling mortality were highest in Acer forests and gradually decreased towards the interior of Quercus forests in FU, mainly due to severe attack of soil pathogens, invertebrates, and leaf diseases. The reverse was true in gaps, due to reduction of damping-off damage caused by distance-dependent colonization of AM. In Quercus, most seeds and seedlings were eaten by vertebrates in FUs. The seedling mortality caused by leaf diseases was not high, even beneath conspecific forests with higher colonization of EM in gaps, suggesting a positive EM influence. In both species, seedling mass was greatest in conspecific forests and gradually decreased towards the interior of heterospecific forests in gaps, due to higher colonization of mycorrhizae near conspecifics. In conclusion, light conditions strongly altered the mode of CDD via changes in relative influence of pathogens and mycorrhizae, suggesting that gap creation may regulate species diversity via changes in the mode of CDD.


Asunto(s)
Acer , Micorrizas , Animales , Bosques , Plantones , Árboles
5.
Ecol Lett ; 23(3): 483-494, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31922344

RESUMEN

A 'resilient' forest endures disturbance and is likely to persist. Resilience to wildfire may arise from feedback between fire behaviour and forest structure in dry forest systems. Frequent fire creates fine-scale variability in forest structure, which may then interrupt fuel continuity and prevent future fires from killing overstorey trees. Testing the generality and scale of this phenomenon is challenging for vast, long-lived forest ecosystems. We quantify forest structural variability and fire severity across >30 years and >1000 wildfires in California's Sierra Nevada. We find that greater variability in forest structure increases resilience by reducing rates of fire-induced tree mortality and that the scale of this effect is local, manifesting at the smallest spatial extent of forest structure tested (90 × 90 m). Resilience of these forests is likely compromised by structural homogenisation from a century of fire suppression, but could be restored with management that increases forest structural variability.


Asunto(s)
Fuego , Tracheophyta , Incendios Forestales , California , Ecosistema , Bosques , Árboles
6.
Nature ; 577(7788): 29, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31892743

Asunto(s)
Árboles , China
7.
Ecol Lett ; 23(2): 336-347, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31802606

RESUMEN

The traditional view holds that biological nitrogen (N) fixation often peaks in early- or mid-successional ecosystems and declines throughout succession based on the hypothesis that soil N richness and/or phosphorus (P) depletion become disadvantageous to N fixers. This view, however, fails to support the observation that N fixers can remain active in many old-growth forests despite the presence of N-rich and/or P-limiting soils. Here, we found unexpected increases in N fixation rates in the soil, forest floor, and moss throughout three successional forests and along six age-gradient forests in southern China. We further found that the variation in N fixation was controlled by substrate carbon(C) : N and C : (N : P) stoichiometry rather than by substrate N or P. Our findings highlight the utility of ecological stoichiometry in illuminating the mechanisms that couple forest succession and N cycling.


Asunto(s)
Ecosistema , Fijación del Nitrógeno , China , Bosques , Nitrógeno , Fósforo , Suelo , Árboles
8.
Mol Genet Genomics ; 295(1): 107-120, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31506717

RESUMEN

The oriental gall wasp Dryocosmus kuriphilus represents a limiting pest for the European Chestnut (Castanea sativa, Fagaceae) as it creates severe yield losses. The European Chestnut is a deciduous tree, having major social, economic and environmental importance in Southern Europe, covering an area of 2.53 million hectares, including 75,000 ha devoted to fruit production. Cultivars show different susceptibility and very few are resistant to gall wasp. To deeply investigate the plant response and understand which factors can lead the plant to develop or not the gall, the study of transcriptome is basic (fundamental). To date, little transcriptomic information are available for C. sativa species. Hence, we present a de novo assembly of the chestnut transcriptome of the resistant Euro-Japanese hybrid 'Bouche de Bétizac' (BB) and the susceptible cultivar 'Madonna' (M), collecting RNA from buds at different stages of budburst. The two transcriptomes were assembled into 34,081 (BB) and 30,605 (M) unigenes, respectively. The former was used as a reference sequence for further characterization analyses, highlighting the presence of 1444 putative resistance gene analogs (RGAs) and about 1135 unigenes, as putative MiRNA targets. A global quantitative transcriptome profiling comparing the resistant and the susceptible cultivars, in the presence or not of the gall wasp, revealed some GO enrichments as "response to stimulus" (GO:0050896), and "developmental processes" (e.g., post-embryonic development, GO:0009791). Many up-regulated genes appeared to be transcription factors (e.g., RAV1, AP2/ERF, WRKY33) or protein regulators (e.g., RAPTOR1B) and storage proteins (e.g., LEA D29) involved in "post-embryonic development". Our analysis was able to provide a large amount of information, including 7k simple sequence repeat (SSR) and 335k single-nucleotide polymorphism (SNP)/INDEL markers, and generated the first reference unigene catalog for the European Chestnut. The transcriptome data for C. sativa will contribute to understand the genetic basis of the resistance to gall wasp and will provide useful information for next molecular genetic studies of this species and its relatives.


Asunto(s)
Fagaceae/genética , Transcriptoma/genética , Avispas/patogenicidad , Animales , Europa (Continente) , Fagaceae/parasitología , Perfilación de la Expresión Génica/métodos , Repeticiones de Microsatélite/genética , Anotación de Secuencia Molecular/métodos , Enfermedades de las Plantas/parasitología , Polimorfismo de Nucleótido Simple/genética , Factores de Transcripción/genética , Árboles/genética , Árboles/parasitología , Regulación hacia Arriba/genética
9.
Int J Phytoremediation ; 22(2): 210-222, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31432685

RESUMEN

Leaf and bark of trees are tools for assessing the effects of the heavy metals pollution and monitoring the environmental air quality. In this study, the possibility of using leaves and bark of two urban trees, namely, Ficus nitida and Eucalyptus globulus as a bioindicator of atmospheric pollution was evaluated by determining the composition of heavy elements in the tree leaves, bark, soil, and the atmospheric dust. Two common tree species, namely, F. nitida and E. globulus were selected in the heavily industrial zone of surrounding Minya governorate, Upper Egypt. Two urban areas with heavy traffic load (sites 1 and 2), three industrial zones (sites 3, 4, and 5) and an uncontaminated area as a control were selected (site 6). Sampling from leaf, bark, soil, deposited dust of trees was carried out in winter and summer seasons (from November 2016 to March 2017). The concentrations of heavy metals in dust, soil, leaves, and bark possess the same trend: Pb>Cu>Cd. The highest concentration of cadmium, lead, and copper was found in the leaf of F. nitida and E. globulus higher than bark samples of the studied species, supporting the idea suggesting that tree leaves can be used as a good indicator of heavy metals accumulation. A high and statistically significant correlation (p < .05) was found between Pb concentrations in the atmospheric dust and those in the leaves of both species throughout the two growing seasons, confirming that the main source of incorporated Pb is the atmospheric dust. Otherwise, the obtained results showed that F. nitida tree does not seem to be a good accumulator of Cu. According to the obtained results, F. nitida and E. globulus trees are more likely to capture cadmium and lead from air, so planting these trees in industrial areas with such atmospheric pollutants would be beneficial.


Asunto(s)
Contaminantes Atmosféricos , Metales Pesados , Contaminantes del Suelo , Bioacumulación , Biodegradación Ambiental , Egipto , Monitoreo del Ambiente , Hojas de la Planta , Árboles
10.
Water Environ Res ; 92(1): 106-114, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31344757

RESUMEN

This study determines the exfiltration rates in six tree boxes with embedded sensors and analyzes their hydrologic performance for 2 years to quantify the effect of different parameters (i.e., water depth, temperature, and age) on the exfiltration rate. Each tree box is 1.5 m wide, 1.5 m long, and 1.8 m deep. A 46-cm-diameter shaft was drilled at the bottom of each tree box to reach the underlying permeable soil layer. The water level inside the shaft rose up to 500 cm. Exfiltration rate increased with water level and exfiltration rate in second year decreased significantly by 27%-37% compared with first year. Overall, in the second year, the decrease in geometric mean exfiltration rate was largest for moderate depths of the standing water inside the shaft, ranging between 100 and 130 cm from the bottom of the shaft. The exfiltration rate of the tree boxes was significantly larger for warmer season and significantly smaller for cooler season. The infiltration rate of the underlying soil is a controlling factor of the performance of tree box. PRACTITIONER POINTS: The study determines the exfiltration rates in six tree boxes and analyzes their performance over time. Exfiltration rate in second year decreased significantly by 27%-37% compared to first year. The exfiltration rate of the tree boxes was larger for warmer rain events and smaller for cooler rain events. Tree boxes with lower permeable underlying soil developed higher water level in the shaft.


Asunto(s)
Árboles , Movimientos del Agua , Hidrología , Lluvia , Suelo
11.
Ecotoxicol Environ Saf ; 187: 109750, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31655412

RESUMEN

Drought and nitrogen (N) deposition are important components of global climate and environmental change. In this greenhouse study, we investigated the ecophysiological responses of the seedlings of three subtropical forest plant species (Schima superba, Castanopsis fissa, and Michelia macclurei) to short-term experimental drought stress, N addition, and their interaction. The results showed that drought stress reduced the activities of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] and total antioxidant capacity (T-AOC), but increased the malondialdehyde (MDA), abscisic acid (ABA), and proline (PRO) contents in plants. The PRO content, T-AOC, and antioxidant enzyme activities were increased, and ABA and MDA contents were decreased by N addition alone. Furthermore, N addition under drought stress increased antioxidant enzymes activities, PRO content, and T-AOC. The treatments, however, did not significantly affect the chlorophyll fluorescence parameters of the species. T-AOC was positively correlated with antioxidant enzyme activities in each species, indicating that antioxidant enzymes were important for plant resistance to oxidative stress. MDA content increased with the increase of ABA content, indicating that ABA may help regulate stomatal movement and drought-induced oxidative injury in plants. T-AOC was positively correlated with PRO content, probably because PRO participated in osmotic regulation of cells and increased osmotic stress resistance. These results indicate that N addition can reduce drought stress of subtropical forest plants and will help researchers predict how evergreen broad-leaved forests will respond to global change in the future.


Asunto(s)
Contaminantes Atmosféricos/toxicidad , Antioxidantes/metabolismo , Sequías , Compuestos de Nitrógeno/toxicidad , Estrés Oxidativo/efectos de los fármacos , Árboles/efectos de los fármacos , China , Monitoreo del Ambiente , Fagaceae/efectos de los fármacos , Fagaceae/metabolismo , Bosques , Ósmosis/efectos de los fármacos , Presión Osmótica/efectos de los fármacos , Árboles/metabolismo , Clima Tropical
12.
Chemosphere ; 239: 124777, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31518924

RESUMEN

The effects of a 50% forest thinning intensity on Fukushima-derived 137Cs deposition by litterfall and its discharge by runoff in hillslope coniferous forest were monitored using four litterfall traps and a hillslope erosion plot. The observation was underway during the pre-and post-thinning periods. Results demonstrated that during the pre-thinning period a total 150 ±â€¯13 g m-2 of litterfall deposited about 924 ±â€¯69 Bq m-2 of 137Cs. This accounts for 11% of the local 137Cs fallout recorded for the study site in the aftermath of the accident. After thinning, both litterfall and 137Cs increased by more than six- and two-fold, respectively. This is possibly owing to the slow individual tree recovery rate assisted by the change on the running space provided by canopy openings, which can accelerate even the normal gust wind to gain damaging power on the unshielded mechanically injured parts of the contaminated residual trees. In both cases, litterfall generally transferred about 37% (3 ±â€¯0.2 kBq m-2) of the local 137Cs fallout onto the forest floor over the observation period. The eroded litter-associated 137Cs increased by about a factor of two after thinning, which only accounted for less than 1% of 137Cs deposited by litterfall. This implies that the forest floor retains 137Cs and remains contaminated regardless of the size of the eroded litter material. But this could become a potential secondary contamination source for the downstream resources such as water bodies and villages, especially at the time of flooding, which in turn calls a serious attention in designing decontamination schemes.


Asunto(s)
Radioisótopos de Cesio/análisis , Bosques , Accidente Nuclear de Fukushima , Hojas de la Planta/química , Contaminantes Radiactivos del Suelo/análisis , Japón , Monitoreo de Radiación , Tracheophyta , Árboles
13.
Oecologia ; 192(2): 501-514, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31872269

RESUMEN

Vertical niche partitioning might be one of the main driving forces explaining the high diversity of forest ecosystems. However, the forest's vertical dimension has received limited investigation, especially in temperate forests. Thus, our knowledge about how communities are vertically structured remains limited for temperate forest ecosystems. In this study, we investigated the vertical structuring of an arboreal caterpillar community in a temperate deciduous forest of eastern North America. Within a 0.2-ha forest stand, all deciduous trees ≥ 5 cm diameter at breast height (DBH) were felled and systematically searched for caterpillars. Sampled caterpillars were assigned to a specific stratum (i.e. understory, midstory, or canopy) depending on their vertical position and classified into feeding guild as either exposed feeders or shelter builders (i.e. leaf rollers, leaf tiers, webbers). In total, 3892 caterpillars representing 215 species of butterflies and moths were collected and identified. While stratum had no effect on caterpillar density, feeding guild composition changed significantly with shelter-building caterpillars becoming the dominant guild in the canopy. Species richness and diversity were found to be highest in the understory and midstory and declined strongly in the canopy. Family and species composition changed significantly among the strata; understory and canopy showed the lowest similarity. Food web analyses further revealed an increasing network specialization towards the canopy, caused by an increase in specialization of the caterpillar community. In summary, our study revealed a pronounced stratification of a temperate forest caterpillar community, unveiling a distinctly different assemblage of caterpillars dwelling in the canopy stratum.


Asunto(s)
Biodiversidad , Ecosistema , Animales , Bosques , América del Norte , Árboles
14.
J Environ Manage ; 254: 109544, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31707194

RESUMEN

The present work was conducted to evaluate the carbon storage potential of Moroccan cedar forest and its vulnerability to transformations through deforestation and overgrazing. The present study took place in the Middle Atlas where is the most beautiful of Moroccan cedar forest (Cedrus atlantica). We considered three levels of degradation (Natural cedar, degraded cedar and cleared area). For each land use, we estimated carbon stocks in four reservoirs, i.e., aboveground biomass (trees, shrubs and herbaceous plants), belowground biomass (roots), necromass (litter and deadwood) and the soil. Various physico-biochemical characteristics (structural stability, bulk density, soil organic carbon and carbohydrates (neutral and uronic sugars)) were also evaluated. Carbon stocks were 395.37 Mg ha-1 for the natural cedar and 76.05 Mg ha-1 for the cleared area. Analysis of the ecosystem carbon stock distribution revealed that soil was the largest reservoir. The soil carbon stock varies from 46.4% to 93.5%, that of the biomass (aboveground and belowground) fluctuate between 4.3% and 52.7% and in the necromass it is between 0.8 and 2.2%. The conversion of natural forest into cleared area resulted in a deterioration of the soil physical quality (decrease of the percentage of water-stable aggregate by 36% and increase of bulk density by 57%). Also, natural forests have 25% and 50% more neutral sugars and uronic sugars respectively than the cleared area. The correlations established between carbohydrates and carbon stocks of the different reservoirs considered showed that the increase in neutral sugars is more explained by the aboveground biomass (R2 = 79%, P = 0.0013) and necromass (R2 = 85%, P = 0.0004). Otherwise, the soil carbon stock explained the most increase in uronic sugars (R2 = 99%, P = 0.0001). Neutral sugar can be an indicator of soil physical quality. Neutral sugars were responsible for 85% of the highly significant increase in soil structural stability and over 79% of the highly significant decrease in bulk density. Moreover, uronic sugars appear to be a good indicator of the richness in organic carbon of soils sampled since the increase of these sugars justified more than 90% of the increase in the soil organic carbon content.


Asunto(s)
Carbono , Suelo , Biomasa , Carbohidratos , Ecosistema , Bosques , Árboles
15.
J Environ Manage ; 254: 109792, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31731030

RESUMEN

Windfelled Norway spruce (Picea abies) trees play a crucial role in triggering large-scale outbreaks of the European spruce bark beetle Ips typographus. Outbreak management therefore strives to remove windfelled trees to reduce the risk of outbreaks, a measure referred to as sanitation logging (SL). Although this practice has been traditionally applied, its efficiency in preventing outbreaks remains poorly understood. We used the landscape simulation model iLand to investigate the effects of different spatial configurations and intensities of SL of windfelled trees on the subsequent disturbance by bark beetles. We studied differences between SL applied evenly across the landscape, focused on the vicinity of roads (scenario of limited logging resources) and concentrated in a contiguous block (scenario of spatially diversified management objectives). We focused on a 16 050 ha forest landscape in Central Europe. The removal of >80% of all windfelled trees is required to substantially reduce bark beetle disturbances. Focusing SL on the vicinity of roads created a "fire break effect" on bark beetle spread, and was moderately efficient in reducing landscape-scale bark beetle disturbance. Block treatments substantially reduced outbreaks in treated areas. Leaving parts of the landscape untreated (e.g., conservation areas) had no significant amplifying effect on outbreaks in managed areas. Climate change increased bark beetle disturbances and reduced the effect of SL. Our results suggest that past outbreak management methods will not be sufficient to counteract climate-mediated increases in bark beetle disturbance.


Asunto(s)
Escarabajos , Árboles , Animales , Europa (Continente) , Bosques , Noruega , Corteza de la Planta
16.
J Environ Manage ; 254: 109816, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31743861

RESUMEN

Silvicultural treatments can change the microclimate inside tropical secondary forests and thus enable the artificial regeneration of ecologically and economically important tree species. Increasing levels of canopy tree refinement (diameter at breast height, DBH > 5 cm) were applied and combined with understory slashing to investigate how these silvicultural treatments affect the microclimate of a Central Amazon secondary forest. The refinement treatment was performed in six levels of basal area reduction (0, 20, 40, 60, 80, and 100%) in rectangular plots (2318 m2) and was equally divided in two subplots that did (understory slashed) or did not (control) receive the application of understory slashing. Canopy openness was estimated using hemispherical photography before treatment implementation and periodically over 26 months. Light transmittance, total daily irradiance, air temperature, air humidity and soil moisture were measured during two climatic seasons (Dry and Wet season) of the two years following the application of the treatments. Understory slashing doubled the canopy openness before the refinement and had an effective and persistent effect on canopy openness, light transmittance and total daily irradiance for the 26 months. Refinement increased canopy openness, light transmittance and total daily irradiance; however, after one year of treatment application, the effect was greater in understory slashed than in control subplots. In plots with higher basal area reduction (>60%), the understory slashed subplots total daily irradiance was 19% and 60% higher than control subplots after nine and 26 months, respectively. Refinement increased air temperature and reduced air humidity and soil moisture. The refinement of canopy trees and understory slashing change the microclimate (particularly light availability) in secondary forests and performed best when applied together. Silvicultural implications for sustainable secondary forest management and productive objectives are discussed.


Asunto(s)
Bosques , Microclima , Estaciones del Año , Suelo , Árboles
17.
J Environ Manage ; 254: 109815, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31780267

RESUMEN

Frequent fires were used as a management tool to maintain prairies, savannas, and woodlands in the southern Great Plains of the United States. However, fire exclusion beginning in the mid-1900s allowed for the establishment and growth of fire-intolerant species such as eastern redcedar (Juniperus virginiana: ERC) beyond their naturally occurring habitats. Apart from the reduction in burning, wide soil and climate adaptability, and seed dispersal by birds have facilitated the expansion of ERC in the southern Great Plains. The encroachment of ERC has caused heavy ecological and economic losses to Oklahoma and thus has been a major management concern for the past few decades. This study utilized count data modeling to analyze USDA Forest Service's (USFS) Forest Inventory and Analysis (FIA) data to investigate the relationship between available ecological and economic factors and the abundance of ERC in grassland and forested ecosystems of Oklahoma. The results suggested that low site productivity, high basal area, dense canopy, and silt loam soil texture significantly increase the abundance of ERC on a given site. The results also indicated that the rate of ERC encroachment is 3.3% higher in the softwood and 2.0% higher in the miscellaneous forests, compared to the hardwood forests. However, the economic variables of the study such as ownership type, adoption of active management, and proximity to a metropolitan area did not show a significant relationship to the abundance of ERC.


Asunto(s)
Fuego , Juniperus , Ecología , Ecosistema , Pradera , Oklahoma , Árboles
18.
Ecol Lett ; 23(1): 33-44, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31625281

RESUMEN

Mismatches between species distributions and their optimal habitat are predicted by ecological theory and will affect species responses to changing climate. However, empirical tests lack consensus on the prevalence of such mismatches and their underlying mechanisms. Here we present a conceptual framework to quantify the mismatch between optimal conditions for species occurrence and multiple measures of population and individual performance (density, adult growth and survival, and recruitment) and the associated performance reduction, or cost. We quantified these mismatches for 59 tree species in the western US along a soil water balance gradient and found high variability in mismatches among species and among performance measures, often resulting in high costs. We used functional traits to explore how dispersal limitation, migration lags, and competitive exclusion may cause mismatches. Overall, the large variability in mismatches, their costs and the relationship with functional traits highlight the nuanced relationships between species' performance and their distributions.


Asunto(s)
Ecosistema , Árboles , Clima , Suelo , Especificidad de la Especie
19.
Ecol Lett ; 23(1): 99-106, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31642170

RESUMEN

Understory fires represent an accelerating threat to Amazonian tropical forests and can, during drought, affect larger areas than deforestation itself. These fires kill trees at rates varying from < 10 to c. 90% depending on fire intensity, forest disturbance history and tree functional traits. Here, we examine variation in bark thickness across the Amazon. Bark can protect trees from fires, but it is often assumed to be consistently thin across tropical forests. Here, we show that investment in bark varies, with thicker bark in dry forests and thinner in wetter forests. We also show that thinner bark translated into higher fire-driven tree mortality in wetter forests, with between 0.67 and 5.86 gigatonnes CO2 lost in Amazon understory fires between 2001 and 2010. Trait-enabled global vegetation models that explicitly include variation in bark thickness are likely to improve the predictions of fire effects on carbon cycling in tropical forests.


Asunto(s)
Bosques , Árboles , Ciclo del Carbono , Corteza de la Planta , Sensibilidad y Especificidad
20.
Ecol Lett ; 23(1): 140-148, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31663682

RESUMEN

Ecologists expect species and biomes to shift poleward and upward with climate change, but non-climatic factors complicate these predictions. In mountains, forests are expected to expand upward along climate gradients into subalpine/alpine meadows, while meadows expand upward onto bare ground. However, soils also vary across elevation, with bare soil above the meadows potentially poorer for plant establishment. Poor soil might constrain expansion at meadows' upper edges, while rich meadow soil might facilitate contraction at lower edges by promoting tree establishment. We assessed climate and soil effects on establishment by transplanting soil and seedlings of meadow and tree species across climate gradients on Mount Rainier. There were considerable interspecific differences, but some generalisations emerged. Survival often declined with earlier snow disappearance, with somewhat smaller declines in meadow soil. Size often increased with earlier snow disappearance, with larger increases in meadow soil. Thus, soil patterns may complicate range shifts.


Asunto(s)
Plantones , Suelo , Cambio Climático , Bosques , Nieve , Árboles
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