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1.
Environ Monit Assess ; 193(1): 28, 2021 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-33392829

RESUMEN

In contrast to the expectations of an increase in annual fire activity and the severity of fire season due to climate change and large fires, which have been occurring in recent years, a downtrend has been identified in fire activity in many studies conducted for the whole of Europe in recent years. Similarly, in Turkey, according to the General Directorate of Forestry statistics, while there is an increase in the number of annual fires, the burnt area has a downtrend pattern. In this study, fire activity and climate data statistics for Turkey were examined along with the fire season length and severity. The results obtained conform with the studies conducted in places from Spain at the westernmost part of Mediterranean Europe to Israel at the easternmost part of the Mediterranean. Considering the changes in temperatures, temperature rise of 2 to 3 °C was detected at all stations in the study area. No decrease was observed in the average temperatures at any of the stations within the study period between 1940 and 2018. On the other hand, the precipitation trend varied according to the stations. Although there have been increases in precipitation in Fethiye, Isparta, and Marmaris since 1960, the decrease in precipitation by 132 mm in Afyon since 1970 and the decrease in precipitation by 137 mm in Bodrum since 1940 are attention-grabbing. These stations are followed by Izmir station with 66 mm and Cesme station with 37 mm of decrease, despite being smaller decreases. In the study, the long-term (1940-2018) data of the meteorological stations discussed within the study, the Canadian Fire Weather Index (FWI) and the Fine Fuel Moisture Code (FFMC) values were calculated. According to the FWI results used in determining the severity and length of fire season on the coastline of Turkey from the northern Aegean to Antalya, the likelihood of large fires decreased by about 52% in 2018 compared to 1970. This decrease in FWI value indicates that the fire severity is reduced. The specified decrease in fire severity also explains the reason of the decrease in the burnt area that occurred over the years in Turkey. No significant change was observed in the FFMC values indicating the possibility of human-induced fires between 1970 and 2018.


Asunto(s)
Fuego , Incendios Forestales , Canadá , Monitoreo del Ambiente , Europa (Continente) , Humanos , Israel , Estaciones del Año , España , Árboles , Turquia
2.
Plant Dis ; 105(1): 183-192, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33170770

RESUMEN

Copper is the most efficient pesticide for the control of citrus canker (Xanthomonas citri subsp. citri). To mitigate the environmental impacts and costs, the copper sprays in citrus orchards are being optimized based on the tree row volume (TRV). A previous investigation allowed for significant reductions of the spray volume and copper rates. Nevertheless, the results also indicated the need for additional studies. The aim of this work was to assess whether both the spray volume and the metallic copper rate based on the TRV may be further reduced. A field trial was carried out during two seasons in a 3-year-old commercial orchard of Pera sweet orange located in the municipality of Paranavaí, Paraná, Brazil. The volumes of 20 and 40 ml of spray mixture per m3 of the tree canopy were assessed in combination with the metallic copper rates of 10.5, 21.0, 36.8, or 52.5 mg/m3. Disease was measured as the temporal progress of canker incidence on leaves, cumulative dropped fruit with canker, and incidence of diseased fruit at harvest. The quality of sprays was assessed by measuring the copper deposition and leaf coverage. The treatment with the highest citrus canker control for the lowest use of water and copper was the combination of 40 ml and 36.8 mg/m3. Regression analyses indicated that the minimum threshold deposition of copper was ∼1.5 µg Cu2+/cm2 leaf area. In addition, the lowest spray volume and copper rate necessary to achieve this deposition are 35 ml/m3 and 30 mg/m3. The use of 20 ml/m3 did not efficiently control the disease due to the deficient coverage of treated surfaces. This study demonstrated that it is possible to use even lower amounts of copper and water without interfering with the efficiency of control of citrus canker.


Asunto(s)
Citrus , Brasil , Cobre/farmacología , Enfermedades de las Plantas/prevención & control , Árboles , Xanthomonas
3.
Sci Total Environ ; 758: 143619, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33221014

RESUMEN

Litterfall helps maintaining primary production and nutrient cycling in forest ecosystems. However, few studies have investigated long-term characteristics of litterfall in tropical karst and non-karst forests co-occurring in the same region. A 10-year comparative study was conducted to estimate the biomass, litter accumulation, turnover rate, nutrient return and nutrient use efficiency associated with litterfall in a karst forest (KF) and a nearby non-karst forest (NKF) in northern tropical China. Significant spatial-temporal variation was observed in monthly and annual litterfall biomass in the two forests. Annual mean litterfall biomass in KF (9.75 Mg ha-1 year-1) was obviously lower than that in NKF (10.49 Mg ha-1 year-1). The litterfall biomass in NKF was significantly correlated with maximum air temperature, wind speed and total solar radiation, whereas that in KF was significantly correlated with relative humidity, wind speed and low temperature. Average stand litter in KF (2.92 Mg ha-1 year-1) was significantly higher than that in NKF (2.38 Mg ha-1 year-1). Stand litter mostly occurred during the cool and dry season, which coincided with litterfall input and exhibited bimodal pattern. Turnover rate was 1.3 time higher in NKF than in KF, suggesting that litter decomposed slowly in karst habitats. Distinct temporal dynamic and significant differences were observed in chemical composition of litterfall between KF and NKF. Total amounts of C, P, K and total nutrients returned to the topsoil in KF were significantly lower than those in NKF. The KF exhibited relatively high P and K use efficiency because of their low availability in karst soils. Compared with the non-karst habitat, the tropical karst habitats are more likely to develop a plant community with certain nutrient concentrations of litterfall and with a nutrient cycling mechanism that is well-adapted to harsh and heterogeneous condition.


Asunto(s)
Ecosistema , Árboles , Biomasa , China , Bosques , Nutrientes , Suelo
4.
Sci Total Environ ; 758: 143711, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33223162

RESUMEN

The fungal community plays an important role in forest ecosystems via the provision of resources to plant nutrition and productivity. However, the ecology of the fungal network and its relationship with phosphorus (P) dynamics remain poorly understood in mixed forest plantations. Here, we analyzed the fungal community using the amplicon sequencing in plantations of pure Eucalyptus grandis, with (E + N) and without N fertilization (E), besides pure Acacia mangium (A), and in a consortium of E. grandis and A. mangium (E + A), at 27 and 39 months after planting. We analyzed chemical, physical and biochemical soil and litter attributes related to P cycling, and the fungal community structure to find out if mixed plantations can increase fungal connections and to identify their role in the P dynamics in the soil-litter system. Soil organic fraction (OF), phosphorus in OF, total-P and acid phosphatase activity were significantly higher in E + A and A treatments regardless of the sampling period. Total N and P, richness, and Shannon diversity of the fungi in the litter was significantly higher in the treatments E + A and A. The fungal community structure in litter differed between treatments and sampling periods, and E + A showed an intermediate structure between the two pure treatments (E) and (A). E + A correlated highly with P dynamics when evaluated by both Pearson and redundancy analyses, particularly in the litter layer. Co-occurrence networks of fungal taxa became simpler in pure E. grandis plantations, whereas mixed system (E + A) showed a more connected and complex network. Our findings provide novel evidence that mixed forest plantations promote positive responses in the fungal community connections, which are closely related to P availability in the system, prominently in the litter layer. This indicates that the litter layer represents a specific niche to improve nutrient cycling by fungi in mixed forest ecosystems.


Asunto(s)
Micobioma , Árboles , Ecosistema , Bosques , Nitrógeno , Fósforo , Suelo , Microbiología del Suelo
5.
Ecotoxicol Environ Saf ; 208: 111457, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33120255

RESUMEN

The chemical composition in the precipitation is constantly changing, thus acid rain type is gradually changing from sulfuric type to mixed type and then nitric type. The influence of the changing acid rain type on the rhizosphere soil of tree species remains unclear. A pot experiment was performed with two-year-old Pinus massoniana, Cunninghamia lanceolate, Cyclobalanpsis glauca and Phyllostachys edulis seedlings with similar growth condition. Simulated acid rain consists of sulfuric(S/N = 5), mixed(S/N = 1) and nitric(S/N = 0.2) acid rain, and each type acid rain diluted to three acid rain intensity: pH = 2.5, 3.5, 4.5. Soil pH, soil organic matter, cation exchange capacity, the exchangeable Na+, K+, Ca2+, Mg2+ and enzyme activity were inhibited by acid rain intensity, while exchangeable Al3+ and H+ were promoted. Mg2+ was most relevant index to the tolerance to acid rain and the correlation degree of soil chemical index was higher than that of enzyme activity. Response of soil chemical properties differed in tree species under different acid rain types. Soil enzyme activity of Pinus massoniana, Cunninghamia lanceolate, and Phyllostachys edulis reached lowest under nitric acid rain, and that of Cyclobalanpsis glauca reached highest. Rhizosphere soil of Cunninghamia lanceolate is tolerant to sulfuric and nitric acid rain, and that of Cyclobalanpsis glauca is tolerant to mixed acid rain.


Asunto(s)
Monitoreo del Ambiente , Microbiología del Suelo , Lluvia Ácida , China , Cunninghamia/crecimiento & desarrollo , Ácido Nítrico , Pinus , Poaceae , Rizosfera , Plantones/crecimiento & desarrollo , Suelo/química , Árboles
6.
Mycorrhiza ; 31(1): 43-53, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33140217

RESUMEN

The first life stages of a tree are subject to strong environmental stresses and competition, limiting their chances of survival. Establishing a mutualistic relationship with mycorrhizal fungi during early life stages may increase growth and survival rates of trees, but how mycorrhizal communities assemble during these stages remains unclear. Here, we studied variation in the ectomycorrhizal (EcM) fungal communities in the soil and roots of Fagus sylvatica seedlings and saplings. Fungal DNA was extracted from the soil and seedling and sapling roots collected in 156 plots across the beech-dominated Sonian forest (Belgium) and community composition was determined through metabarcoding. EcM fungal community composition significantly differed between soil, seedlings and saplings. Russula, Amanita and Inocybe were most abundant in soil, while Lactarius and Scleroderma were more abundant in seedling and sapling roots and Xerocomellus and Laccaria were most abundant in sapling roots. Our results provide evidence of partner turnover in EcM fungal community composition with increasing age in the early life stages of F. sylvatica.


Asunto(s)
Fagus , Micobioma , Micorrizas , Bosques , Raíces de Plantas , Árboles
7.
Sci Total Environ ; 757: 143724, 2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33221010

RESUMEN

High species diversity is generally thought to be a requirement for sustaining forest multifunctionality. However, the degree to which the relationship between species-, structural-, and trait-diversity of forests and multifunctionality depend on the context (such as stand age or abiotic conditions) is not well studied. Here, we hypothesized that context-dependency of tree species diversity, functional trait composition and stand structural attributes promote temperate forest multifunctionality including above- and below-ground multiple and single functions. To do so, we used repeated forest inventory data, from temperate mixed forests of northeast China, to quantify two above-ground (i.e. coarse woody productivity and wild edible plant biomass), five below-ground (i.e. soil organic carbon, total soil nitrogen, potassium, phosphorus and sulfur) functions, tree species diversity, individual tree size variation (CVDBH) and functional trait composition of specific leaf area (CWMSLA) as well as stand age and abiotic conditions. We found that tree species diversity increased forest multifunctionality and most of the single functions. Below-ground single and multifunctionality were better explained by tree species diversity. In contrast, above-ground single and multifunctionality were better explained by CVDBH. However, CWMSLA was also an additional important driver for maintaining above- and below-ground forest multifunctionality through opposing plant functional strategies. Stand age markedly reduced forest multifunctionality, tree species diversity and CWMSLA but substantially increased CVDBH. Below-ground forest multifunctionality and tree species diversity decreased while above-ground forest multifunctionality increased on steep slopes. These results highlight that context-dependency of forest diversity attributes might regulate forest multifunctionality but may not have a consistent effect on above-ground and below-ground forest multifunctionality due to the fact that those functions were driven by varied functional strategies of different plant species. We argue that maximizing forest complexity could act as a viable strategy to maximizing forest multifunctionality, while also promoting biodiversity conservation to mitigate climate change effects.


Asunto(s)
Carbono , Árboles , Biodiversidad , Biomasa , China , Bosques , Suelo
8.
Sci Total Environ ; 757: 143903, 2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33316528

RESUMEN

Spring phenology influences terrestrial ecosystem carbon, water and energy exchanges between the biosphere and atmosphere. Accurate prediction of spring phenology is therefore a prerequisite to foresee the impacts of climate warming on terrestrial ecosystems. In the present study, we studied the model performance of four widely used process-based models of spring leaf unfolding, including both a one-phase model (not considering a chilling phase: the Thermal Time model) and three two-phase models (all accounting for a required chilling period: the Parallel model, the Sequential model, the Unified model). Models were tested on five deciduous tree species occurring across Europe. We specifically investigated the divergence of their phenology predictions under future climate warming scenarios and studied the differences in the chilling periods. We found that, in general, the two-phase models performed slightly better than the one-phase model when fitting to the observed data, with all two-phase models performing similarly. However, leaf unfolding projections diverged substantially among the two-phase models over the period 2070-2100. Furthermore, we found that the modeled end dates of the chilling periods in these models also diverged, with advances for both the Sequential and Parallel models during the period 2070-2100 (compared to the period 1980-2010), and delays in the Unified model. These findings thus highlight large uncertainty in the two-phase phenology models and confirm that the mechanism underlying the leaf unfolding process is not yet understood. We therefore urgently need an improved understanding of the leaf unfolding process in order to improve the representation of phenology in terrestrial ecosystem models.


Asunto(s)
Ecosistema , Árboles , Cambio Climático , Europa (Continente) , Hojas de la Planta , Estaciones del Año , Temperatura , Incertidumbre
9.
Sci Total Environ ; 757: 143847, 2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33316534

RESUMEN

The rapid increases in atmospheric nitrogen (N) deposition have greatly affected the carbon (C) cycles of terrestrial ecosystems. Most studies concerning on the effects of N deposition have simulated N deposition by directly applying N to the understory and have therefore not accounted for the possibility of N absorption, retention, and transformation by the canopy. In this study, we compared the effects of understory addition of N (UN), canopy addition of N (CN) at 25 and 50 kg N ha-1 yr-1, and ambient addition of N (CK) on soil carbon-related processes in a subtropical forest. After seven years of addition, the contribution of new C from litter (Fnew) was more than 2× greater with UN treatments than with CN treatments. UN treatments significantly increased the activity of ß-1,4-glucosidase (BG) but reduced the activities of ß-1,4-N-acetylglucosaminidase (NAG), polyphenol oxidase (PPO), and peroxidase (PER). CN treatments, in contrast, did not alter the activities of extracellular enzyme. Compared to CN, UN treatments significantly enhanced soil organic carbon (SOC) and mean weight diameter (MWD, represents soil aggregate stability). Differences in the responses of SOC and MWD to CN and UN treatments were positively correlated with Fnew but negatively correlated with the activities of PPO and PER. The results imply that forest canopy mitigates the effects of atmospheric N inputs on SOC, and that conventional understory N addition might overestimate the positive effects of N deposition on forest soil C-related processes. We suggest that CN rather than UN should be used to simulate the effects of atmospheric N deposition on soil C dynamics in subtropical forests.


Asunto(s)
Nitrógeno , Suelo , Carbono , Ecosistema , Bosques , Nitrógeno/análisis , Microbiología del Suelo , Árboles
10.
Environ Pollut ; 269: 116104, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33339707

RESUMEN

Global urban planning has promoted green infrastructure (GI) such as street trees, shrubs or other greenspace in order to mitigate air pollution. Although considerable attention has been paid to understanding particulate matter (PM) deposition on GI, there has been little focus on identifying which leaf traits might maximise airborne PM removal. This paper examines existing literature to synthesize the state of knowledge on leaf traits most relevant to PM removal. We systematically reviewed measurement studies that evaluated particulate matter accumulated on leaves on street trees, shrubs green roofs, and green walls, for a variety of leaf traits. Our final selection included 62 papers, most from field studies and a handful from wind tunnel studies. The following were variously promoted as useful traits: coniferous needle leaves; small, rough and textured broadleaves; lanceolate and ovate shapes; waxy coatings, and high-density trichomes. Consideration of these leaf traits, many of which are also associated with drought tolerance, may help to maximise PM capture. Although effective leaf traits were identified, there is no strong or consistent evidence to identify which is the most influential leaf trait in capturing PM. The diversity in sampling methods, wide comparison groups and lack of background PM concentration measures in many studies limited our ability to synthesize results. We found that several ancillary factors contribute to variations in the accumulation of PM on leaves, thus cannot recommend that selection of urban planting species be based primarily on leaf traits. Further research into the vegetation structural features and standardization of the method to measure PM on leaves is needed.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Material Particulado/análisis , Hojas de la Planta/química , Árboles
11.
Ecol Lett ; 24(2): 186-195, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33103837

RESUMEN

How are rainforest birds faring in the Anthropocene? We use bird captures spanning > 35 years from 55 sites within a vast area of intact Amazonian rainforest to reveal reduced abundance of terrestrial and near-ground insectivores in the absence of deforestation, edge effects or other direct anthropogenic landscape change. Because undisturbed forest includes far fewer terrestrial and near-ground insectivores than it did historically, today's fragments and second growth are more impoverished than shown by comparisons with modern 'control' sites. Any goals for bird community recovery in Amazonian second growth should recognise that a modern bird community will inevitably differ from a baseline from > 35 years ago. Abundance patterns driven by landscape change may be the most conspicuous manifestation of human activity, but biodiversity declines in undisturbed forest represent hidden losses, possibly driven by climate change, that may be pervasive in intact Amazonian forests and other systems considered to be undisturbed.


Asunto(s)
Conservación de los Recursos Naturales , Bosque Lluvioso , Animales , Biodiversidad , Aves , Bosques , Humanos , Árboles
12.
J Environ Manage ; 280: 111646, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33213989

RESUMEN

Artificial creation of dead wood in managed forests can be used to mitigate the negative effects of forestry on biodiversity. For this to be successful, it is essential to understand the conservation value that the created dead wood has in comparison to naturally occurring dead wood, and, furthermore, where in the landscape addition of dead wood is most beneficial, i.e. how landscape composition influences species occurrence on dead wood. We examined these questions by surveying epixylic lichens on artificially created high stumps of Scots pine (Pinus sylvestris) in 3-17 years old clear-cuts. We compared lichen assemblages on high stumps to those on other types of pine dead wood in mature forests, and examined how stump age, the amount of dead wood at the clear-cuts, and landscape composition at 500 m - 2.5 km scale influenced the assemblages. In comparison to other dead wood types, high stumps hosted lower lichen richness and less variable assemblages containing mainly common generalist species. Species richness increased with stump age, whereas dead wood amount and landscape composition were not important; only the total amount of forests in the landscape had a minor positive effect. We conclude that at the studied timescale high stumps of Scots pine are not particularly valuable for epixylic lichens and provide a poor substitute for naturally occurring dead wood in mature forests, although their value may increase with age. Furthermore, directing dead wood creation to specific stands or landscapes does not appear beneficial for lichen biodiversity, given the minor effect of landscape composition found at scales below 2.5 km.


Asunto(s)
Líquenes , Biodiversidad , Agricultura Forestal , Bosques , Árboles , Madera
13.
J Environ Manage ; 279: 111630, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33213995

RESUMEN

Many terrestrial ecosystems have undergone profound transformation under the pressure of multiple human stressors. This may have oriented altered ecosystems toward transient or new states. Understanding how these cumulative impacts influence ecosystem functions, services and ecological trajectories is therefore essential to defining effective restoration strategies. This is particularly the case in riverine ecosystems, where the profound alteration of natural disturbance regimes can make the effectiveness of restoration operations questionable. Using the case study of legacy dike fields, i.e., area delimited by longitudinal and lateral dikes, along the regulated Rhône River, we studied the impacts of long-term channelization and flow regulation on environmental conditions and riparian forests attributes along a 200 km climatic gradient. We characterized the imprint of human stressors on these forests by comparing the dike field stands to more natural stands in both young and mature vegetation stages. Across four reaches of the river between Lyon and the Mediterranean Sea, we found that channelization consistently promoted high rate of overbank sedimentation and rapid disconnection of dike field surfaces from the channel. The rapid terrestrialisation of dike field surfaces, i.e., the process by which former aquatic areas transition to a terrestrial ecosystem as a result of dewatering or sedimentation, fostered a pulse of riparian forest regeneration in these resource-rich environments that differs from more natural sites in structure and composition. Within the dike fields, older pre-dam stands are dominated by post-pioneer and exotic species, and post-dam stands support large, aging pioneer trees with a largely exotic understory regeneration layer. These patterns were associated with differences in the relative surface elevation among dike fields, whereas species shifts generally followed the river's longitudinal climate gradient. To enhance the functionality of these human-made ecosystems, restoration strategies should target the reconnection of dike fields to the river by dismantling part of the dikes to promote lateral erosion, forest initiation and community succession, as well as increasing minimum flows in channels to improve connection with groundwater. However, since a river-wide return to a pre-disturbance state is very unlikely, a pragmatic approach should be favoured, focusing on local actions that can improve abiotic and biotic function, and ultimately enhancing ecosystem services such biodiversity, habitat, and recreation opportunities.


Asunto(s)
Ecosistema , Ríos , Bosques , Humanos , Mar Mediterráneo , Árboles
14.
J Environ Manage ; 280: 111671, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33218834

RESUMEN

Globally, while experts debated whether planted forests (PF) restore biodiversity or create biological deserts, their potential role in mitigating climate change is mostly overlooked. In this study, we investigated the long-term impact of PF on the species composition, plant diversity, biomass stock, and carbon (C) storage potential in the Brahmaputra flood plain of North-East India. The phytosociological study was conducted using a modified Gentry plot method and species-specific allometric models were used to estimate biomass stock in the 39-year old PF and equivalent age of natural forest (NF). We identified 57 trees, 22 shrubs, and 23 herb species in the PF, and 54 trees, 17 shrubs, and 8 herb species in the NF. Species richness and biodiversity indices showed greater values in PF whereas species dominance and evenness were higher in NF. After 39-year of plantation, total biomass C was estimated at 165 Mg C ha-1 in PF and 197 Mg C ha-1 in equivalent age of NF. Bombax ceiba, Dalbergia sissoo, Samanea saman, Tetrameles nodiflora, and Gmelina arborea were the dominant tree species that contribute 56% of the total biomass C in the PF. The ecosystem carbon pool (plant biomass + deadwood + litter + SOC) was 17% higher in NF and showed the greater potential of carbon dioxide sequestration (959 Mg CO2 ha-1) compared to the PF (818 Mg CO2 ha-1). Our study suggested PF in flood plain degraded lands can act as a major C sink and stored a substantial amount of carbon dioxide after 39-year of the plantation. It is concluded that PF can be a preferable ecosystem management tool to fulfill the objectives of biodiversity conservation and provisioning climate services like C sequestration.


Asunto(s)
Secuestro de Carbono , Ecosistema , Biodiversidad , Biomasa , Inundaciones , Bosques , Árboles
15.
J Environ Manage ; 280: 111647, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33243623

RESUMEN

Soil organisms play essential roles in maintaining multiple ecosystem processes, but our understanding of the dynamics of these communities during forest succession remains limited. In this study, the dynamics of soil organism communities were measured along a 3-step succession sequence of subtropical forests (i.e., a conifer forest, CF; a mixed conifer and broad-leaved forest, MF; and a monsoon evergreen broad-leaved forest, BF). The eco-exergy evaluation method was used as a complement to the classic community structure index system to reveal the holistic dynamics of the bio-thermodynamic health of soil organism communities in a forest succession series. Association between the self-organization of soil organisms, soil properties, and plant factors were explored through redundancy analyses (RDA). The results indicated that the biomass of soil microbes progressively increased in the dry season, from 0.75 g m-2 in CF to 1.75 g m-2 in BF. Microbial eco-exergy showed a similar pattern, while the community structure and the specific eco-exergy remained constant. Different trends for the seasons were observed for the soil fauna community, where the community biomass increased from 0.72 g m-2 to over 1.97 g m-2 in the dry season, but decreased from 3.94 g m-2 to 2.36 g m-2 in the wet season. Faunal eco-exergies followed a similar pattern. Consequently, the average annual biomass of the soil faunal community remained constant (2.17-2.39 g m-2) along the forest succession sequence, while the significant seasonal differences in both faunal biomass and eco-exergy observed at the early successional stage (CF) were insignificant in the middle and late forest successional stages (MF and BF). Both the dynamics of soil microbes and soil fauna were tightly correlated with tree biomass and with soil physicochemical properties, especially soil pH, moisture, total nitrogen, nitrate nitrogen, and organic matter content.


Asunto(s)
Ecosistema , Suelo , Biomasa , China , Bosques , Microbiología del Suelo , Termodinámica , Árboles
16.
J Environ Manage ; 280: 111711, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33267977

RESUMEN

The establishment of protected areas has been considered a tool to battle deforestation in densely populated countries like Bangladesh. Since 2000, Bangladesh's Forest Department has declared about 41 protected areas. However, before more land is designated as a protected area, it is important to know how effective existing protected areas are in achieving conservation goals. Unfortunately, the determination of the conservation effectiveness of protected areas, such as their capacity to reduce deforestation and forest fragmentation over a considerable period at high temporal frequency (e.g., yearly), is still unavailable despite some known methods being available, for example, the System for the Integrated Assessment of Protected Areas. In this study, we processed and analyzed the Hansen dataset from 2000 to 2018 to produce yearly forest/non-forest maps of four protected areas in Bangladesh and used these maps, with a matching method, to estimate the effectiveness of protected area in reducing deforestation after controlling for potential hidden bias. We also analyzed the forest fragmentation scenario over the same time frame. The forest cover change results from 2010 to 2018 revealed a large-scale deforestation pattern in areas adjacent to the protected area boundary of Chunati Wildlife Sanctuary (CWS) and Baroiyadhala National Park-Hazarikhil Wildlife Sanctuary (together B-HWS). Using a propensity score matching (PSM) approach with a caliper of 0.25, we found that B-HWS was the best performing of the studied protected areas, and that 37% of forest pixels in B-HWS would have been deforested in 2018 if they had not been brought under protection in 2010. Similarly, the estimated avoided deforestation rates were approximately 21% and 4% for CWS and Dudpukuria-Dhopachari Wildlife Sanctuary, respectively. Despite an improvement in deforestation scenarios, during the period 2010-2018, for all protected areas, the forest fragmentation scenarios were exacerbated both inside their boundaries and in adjacent unprotected areas. Therefore, it remains questionable whether protected areas can ultimately maintain the integrity of conservation.


Asunto(s)
Conservación de los Recursos Naturales , Agricultura Forestal , Bangladesh , Bosques , Parques Recreativos , Árboles
17.
J Environ Manage ; 280: 111759, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33298397

RESUMEN

Tropical montane grasslands (TMG) support biodiverse and endemic taxa and provide vital ecosystem services to downstream communities. Nevertheless, invasive alien tree species across the world have threatened tropical grasslands and grassland endemic species. In India, TMG in the Shola Sky Islands of the Western Ghats have been reduced due to exotic tree invasions (Acacias, Pines, and Eucalyptus species). The loss of grassland habitat has, in turn, reduced the range sizes of species endemic to grasslands (plants, birds, amphibians, and mammals), driving some populations to local extinction. Grassland conversion to exotic trees has also impacted ecosystem services in the Western Ghats. Conserving existing grassland and restoring invaded habitat is critical to reverse these losses. This research focused on identifying grassland restoration sites using satellite images with a high spatial resolution (RapidEye). We used an object-oriented Random Forest classification to map the area for grassland restoration. We identified an area of 254 sq. km. as suitable for grassland restoration and an area of 362 sq. km. for grassland conservation and preventing invasion by exotic tree species. For restoration, we recommend careful removal of young and isolated exotic trees at the invasion front and restoring grasslands, instead of removing dense stands of mature exotic trees. Although our limited data indicate that areas with low fire frequency tend to be invaded, and areas invaded by exotic trees tend to burn at higher intensities, we recommend a broader investigation of these patterns to critically examine a potential role for the use of fire in invasive species management. We assume that removing exotic tree species in the identified restoration sites and restoring the grassland will help recover lost habitat and ensure the viability of indigenous and endemic species and increase streamflow.


Asunto(s)
Especies Introducidas , Árboles , Animales , Biodiversidad , Ecosistema , Pradera , India , Islas , Tecnología de Sensores Remotos
18.
J Environ Manage ; 279: 111805, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33316643

RESUMEN

Tropical secondary forests play a prominent role in conserving biodiversity and providing ecosystem services, but their recovery can be slow and their succession trajectory is distinct from old-growth forests. Thinning is an essential silvicultural approach to enhance the recovery rate and timber production of forests. However, the selection of trees to thin has been mainly based on size class rather than on species identity. There is little empirical or experimental evidence of species-focused thinning with the goal of altering species composition. We examined the effects of thinning on community structure, demographic rates, species richness and functional diversity of woody plants in a detailed investigation of 60-year-old secondary tropical lowland rain forest on Hainan Island, South China. The density and basal area of trees ≥5 cm DBH (diameter at breast height) increased significantly after five years' recovery with no significant change for saplings (DBH < 5 cm). Species composition after thinning changed significantly and mid-to late-successional species of both saplings and trees were more abundant after five years' recovery. The relative growth rates (RGR) and recruitment rates were significantly higher in thinning plots for both saplings and trees, and RGRs increased by 127% and 48%, respectively. The mortality rate decreased by 13% for trees and increased by 47% for saplings in thinning plots compared to the control. The community weighted mean (CWM) of the specific leaf area (SLA) of saplings showed a significantly decreasing trend while CWMs of wood density (WD) and mean maximum height (Hmax) of saplings increased after thinning. By contrast, CWMs of SLA and Hmax of trees were significantly higher, but WD was significantly lower- in thinning plots than the control. RGR and recruitment rate of saplings and trees increased significantly as thinning intensity increased. However, the thinning intensity had a weak or nil effect on the mortality rate. Our results support the selective removal and girdling of pioneer and mid-successional species in a way that could accelerate recovery and improve the growth and recruitment of late-successional species in tropical secondary forests. Thinning at a relatively low intensity can maintain species diversity and alter species functional composition. This outcome shows promise for improved future management of tropical forests in human-modified tropical forest landscapes.


Asunto(s)
Ecosistema , Clima Tropical , Biodiversidad , China , Demografía , Bosques , Humanos , Persona de Mediana Edad , Bosque Lluvioso , Árboles
19.
Sci Total Environ ; 754: 142202, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33254844

RESUMEN

Biological nitrogen fixation (BNF) is a fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with 15N2, to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level. We found that bryophytes and leaves situated in the canopy in particular displayed high mass-based rates of free-living BNF. Additionally, we calculated that nearly 2 kg of nitrogen enters the forest ecosystem through free-living BNF every year, 40% of which was fixed by the various canopy components. Our results reveal that in the studied tropical lowland forest a large part of the nitrogen input through free-living BNF stems from the canopy, but also that the total nitrogen inputs by free-living BNF are lower than previously thought and comparable to the inputs of reactive nitrogen by atmospheric deposition.


Asunto(s)
Fijación del Nitrógeno , Suelo , Ecosistema , Bosques , Nitrógeno , Árboles , Clima Tropical
20.
Sci Total Environ ; 756: 143795, 2021 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-33302079

RESUMEN

Tropospheric ozone (O3) levels are still elevated in many regions of the world including Northern Hemisphere forests areas, and are predicted to increase further due to anthropogenic activities and climate change. Oaks are major woody angiosperms in the Northern Hemisphere in terms of biodiversity, ecological dominance, and economic values. This meta-analysis shows overwhelming evidence of the O3 effects on 51 growth, anatomical, biomass, physiological and biochemical parameters of 14 deciduous or evergreen oak species distributed all around the Northern Hemisphere. Although no large impacts were observed on biomass, suggesting an O3 tolerance by oaks, some impairments were found at physiological level that might negatively affect carbon sequestration and water vapour transfer to the atmosphere. This outcome suggests the need to incorporate this phenomenon into future projection studies dealing with how atmospheric change and forest biomes will interact in effecting climatic change. Among the antioxidants used by oaks to respond to O3, phenols seem to have a crucial role. Deciduous species resulted more affected by O3 than evergreen ones, as well as oaks native to Eurasia, in comparison with those from North-America. Experiments performed in less controlled environments showed more O3 deleterious effects, especially under higher AOT40 levels, but negative impacts were also reported for acute O3 exposures. Most of the reviewed studies with additional treatments to O3 exposure investigated the interaction(s) between O3 and drought, but the negative effects induced by drought seemed not to be exacerbated by the pollutant. However, more combined experiments on the impact of O3 and co-occurring stressors on woody species are necessary. Another major issue is the lack of experiments on adult trees. To better understand O3 impacts, and to reinforce the strength of O3 impact predictions, O3 controlled experiments on young individuals should be combined with long-term experiments on mature trees grown in open-air conditions.


Asunto(s)
Ozono , Quercus , Bosques , Humanos , América del Norte , Ozono/toxicidad , Hojas de la Planta , Árboles
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