Eucalyptus Sites Research Articles

Land-use patterns and fungal bioaerosols in the Brazilian Atlantic Forest biome

Whilst the importance of fungal primary biological aerosol particles (PBAPs) has been recognised, few studies have empirically assessed how land-use patterns influence them. Here, we show the impacts of different land-use patterns on fungal PBAPs within the Brazilian Atlantic Forest biodiversity hotspot. Spanning a distance of ca. 600 km within this biome, we collected fungal bioaerosols in the following land-use patterns: a 25-year-old coffee plantation, a 2.5-year-old Eucalyptus plantation, a 3-months-old maize crop, a 2-year-old and another 7-year-old native forest reforestation area, and a native forest fragment. Using the portable Burkard air sampler, a total of 14 morphotype-species were found. Cladosporium sp. comprised as much as about 95% of all fungal spores collected, being present in all samples (frequency of 100%). Forest systems had as much as 5-to-19-fold more fungal spores in the air than maize crops. Sampling height and time (morning vs. afternoon) did not influence fungal concentration and number of species. In addition, using data derived from an eddy covariance tower in the Eucalyptus site, we estimated the emission rate to be 6649 spores m−2 s−1. Our study confirms that land-use patterns affect fungal PBAPs, and that replacing large areas of native Atlantic Forest by monospecific stands, a homogenisation of airborne fungi is occurring, with unknown consequences for climate regulation.

Land Use Change from Natural Tropical Forests to Managed Ecosystems Reduces Gross Nitrogen Production Rates and Increases the Soil Microbial Nitrogen Limitation.

Understanding the underlying mechanisms of soil microbial nitrogen (N) utilization under land use change is critical to evaluating soil N availability or limitation and its environmental consequences. A combination of soil gross N production and ecoenzymatic stoichiometry provides a promising avenue for nutrient limitation assessment in soil microbial metabolism. Gross N production via 15N tracing and ecoenzymatic stoichiometry through the vector and threshold element ratio (Vector-TER) model were quantified to evaluate the soil microbial N limitation in response to land use changes. We used tropical soil samples from a natural forest ecosystem and three managed ecosystems (paddy, rubber, and eucalyptus sites). Soil extracellular enzyme activities were significantly lower in managed ecosystems than in a natural forest. The Vector-TER model results indicated microbial carbon (C) and N limitations in the natural forest soil, and land use change from the natural forest to managed ecosystems increased the soil microbial N limitation. The soil microbial N limitation was positively related to gross N mineralization (GNM) and nitrification (GN) rates. The decrease in microbial biomass C and N as well as hydrolyzable ammonium N in managed ecosystems led to the decrease in N-acquiring enzymes, inhibiting GNM and GN rates and ultimately increasing the microbial N limitation. Soil GNM was also positively correlated with leucine aminopeptidase and β-N-acetylglucosaminidase. The results highlight that converting tropical natural forests to managed ecosystems can increase the soil microbial N limitation through reducing the soil microbial biomass and gross N production.

Eucalyptus productive matrix influences the soil seed bank in southern Brazil

<i>Eucalyptus </i>species are cultivated for various purposes around the world, mainly because they adapt well and grow quickly. These productive matrices of planted forests are common in Brazil, added to which, areas of native vegetation are requirements of environmental legislation. Although eucalyptus plantations are widely distributed in Brazil, little is known about the soil seed bank (SSB) in the eucalyptus productive matrix (EPM). We aim to understand how the EPM made up of eucalyptus plantations and native forest remnants affect the SSB in the Brazilian Pampa. Samples of the SSB of EPM were collected and monitored for six months in a shade house. We evaluated seedling emergence, richness, composition, ecological characteristics of the species, diversity, and floristic similarity. We recorded a high rate of seedling emergence, species richness, and different life forms and native species in all EPM treatments, however the similarity between native remnants and eucalyptus plantations was low. The size and level of conservation of native remnants and the position and management of eucalyptus sites in the EPM influenced the diversity and composition of species. Eucalyptus plantations contain SSBs with potential for natural regeneration when they are in a landscape that maintains conserved native forest remnants. These results expand the knowledge of the SSB in EPM and can support actions in ecological restoration projects.

Influência de plantações de eucalipto na comunidade de macroinvertebrados bentônicos em nascentes neotropicais

Abstract Aim The high sensitivity of springs to anthropic impacts is largely due to the high existing aquatic-terrestrial connectivity. The degradation of these ecosystems can be caused by land use, such as eucalyptus monoculture. The aim of this study was to test the influence of Eucalyptus urograndis plantations on the richness and diversity of the benthic macroinvertebrate community and on the environmental variables measured in springs in the Atlantic Forest domains. Methods Ten springs (5 in native forest areas and 5 in eucalyptus area) were sampled in the dry period of 2017. The organisms were screened and identified at the family level. For each spring, dissolved oxygen, temperature, pH, turbidity, electrical conductivity, total dissolved solids, total nitrogen, nitrite, nitrate, ammonia, total phosphorus, vegetation cover, granulometric characterization and organic matter were also measured. Results: The t-test showed that some environmental variables differed, with the eucalyptus areas having higher values of total dissolved solids and electrical conductivity, and lower values of coarse sand. In the present study, the richness and diversity of the benthic fauna of springs were significantly lower in eucalyptus sites than in native sites. Nonetheless, the composition of the communities did not differ. The Indicator Species Analysis (IndVal) associated Acari, Hydropsychidae, Leptoceridae, Nematoda, Psychodidae, and Tipulidae with areas of native forest. Conclusions Our results show that Brazilian springs are affected by eucalyptus monocultures reducing the richness and diversity of benthic macroinvertebrates and also changing water environmental properties. Thus, we verified that previous studies elsewhere in the world also apply to neotropical areas where eucalyptus is not native.

Natural Areas of Cerrado Foster Wasp (Hymenoptera) Diversity in Human Modified Landscapes.

Land use changes from native vegetation to agriculture, livestock grazing, and urban development are among the main problems related to biodiversity loss worldwide. In this paper we evaluate how land use changes (eucalypt plantation and pasture) affect the richness and assemblage of wasps (Braconidae, Ichneumonidae, Pompilidae, and Vespidae), in comparison with nearby areas with native vegetation in the Cerrado. Specimens were collected at six points, with two Malaise traps at each location. The collections were performed monthly for 10 d, for 12 mo. A total of 773 hymenopterans of the selected groups were collected, representing 253 species or morphospecies. Richness of the families Ichneumonidae and Pompilidae between the areas did not present significant differences. For the families Braconidae and Vespidae, the richness was greater in the eucalypt plantation and pasture areas compared to the native area. Species composition in the native habitat was different from either of the managed habitats in the studied environment. Furthermore, the composition of wasps in native areas varied less throughout the sampling campaigns when compared with the pasture and eucalyptus sites. In native areas, 85 exclusive morphospecies were found. Thus, changes in land use may cause changes in the composition of wasp species, since areas with native vegetation presented more heterogeneous and stable environments than the other land uses. The maintenance of native areas, even if close to planted forest and/or pasture areas, could be the best way to combine forest productivity with biodiversity conservation.

Exotic pastureland is better than Eucalyptus monoculture: β-diversity responses of flower chafer beetles to Brazilian Atlantic Forest conversion

Human activities, such as conversion and degradation of habitats, are modifying the natural ecosystems, causing biodiversity declines globally. However, the responses of many understudied biological groups are less clear. Here, we explore how spatial components of β-diversity (incidence- and abundance-based) of flower chafer beetles are influenced by land use changes. We sampled the insects using aerial fruit-baited traps weekly from September to December 2012, in five sites of Brazilian Atlantic Forest, Eucalyptus plantations and pasturelands (Urochloa spp.). We find that compositional changes of beetle assemblages are completely represented by nestedness patterns, either among or within habitats. When accounting for abundance, except for Eucalyptus sites, there are a similar contribution of change and loss of individuals among and within habitats. Within Eucalyptus sites, assemblages are completely nested in terms of species and individuals. Eucalyptus sites are a poor-homogenized subset of some disturbance-tolerant flower chafer beetle species also found in forest and open habitats (such as pastures). When resources are available, these beetles can inhabit both forest and open habitats and appear to be ‘guests’ in Eucalyptus sites, using them only when moving through space. Finally, conversion of Atlantic Forest sites into Eucalyptus causes poor-homogenized assemblages of flower chafer beetles.

Consequences of removal of exotic species (eucalyptus) on carbon and nitrogen cycles in the soil-plant system in a secondary tropical Atlantic forest in Brazil with a dual-isotope approach.

The impact of exotic species on heterogeneous native tropical forest requires the understanding on which temporal and spatial scales these processes take place. Functional tracers such as carbon (δ13C) and nitrogen (δ15N) isotopic composition in the soil-plant system might help track the alterations induced by the exotic species. Thus, we assess the effects from the removal of the exotic species eucalyptus (Corymbia cytriodora) in an Atlantic forest Reserve, and eucalyptus removal on the alteration of the nutrient dynamics (carbon and nitrogen). The hypotheses were: (1) the eucalyptus permanence time altered δ13C and δ15N in leaves, soils and litter fractions (leaves, wood, flowers + fruits, and rest); and (2) eucalyptus removal furthered decomposition process of the soil organic matter. Hence, we determined the soil granulometry, the δ13C and δ15N in leaves, in the superficial soil layer, and litter in three sites: a secondary forest in the Atlantic forest, and other two sites where eucalyptus had been removed in different times: 12 and 3 months ago (M12 and M3, respectively). Litter samples presented intermediate δ13C and δ15N values in comparison with leaves and soil. In the M3, the greater δ13C values in both litter rest fraction and soil indicate the presence, cycling and soil incorporation of C, coming from the C4 photosynthesis of grassy species (Poaceae). In the secondary forest, the soil δ15N values were twice higher, compared with the eucalyptus removal sites, revealing the negative influence from these exotic species upon the ecosystem N dynamics. In the M12, the leaves presented higher δ13C mean value and lower δ15N values, compared with those from the other sites. The difference of δ13C values in the litter fractions regarding the soil led to a greater fractioning of 13C in all sites, except the flower + fruit fractions in the secondary forest, and the rest fraction in the M3 site. We conclude that the permanence of this exotic species and the eucalyptus removal have altered the C and N isotopic and elemental compositions in the soil-plant system. Our results suggest there was organic matter decomposition in all litter fractions and in all sites. However, a greater organic matter decomposition process was observed in the M3 soil, possibly because of a more intense recent input of vegetal material, as well as the presence of grassy, easily-decomposing herbaceous species, only in this site. Therefore, the dual-isotope approach generated a more integrated picture of the impact on the ecosystem after removing eucalyptus in this secondary Atlantic forest, and could be regarded as an option for future eucalyptus removal studies.

Shifting States, Altered Fates: Divergent Fuel Moisture Responses after High Frequency Wildfire in an Obligate Seeder Eucalypt Forest

High frequency wildfires can shift the structure and composition of obligate seeder forests and initiate replacement with alternative vegetation states. In some forests, the alternative stable state is drier and more easily burned by subsequent fires, driving a positive feedback that promotes further wildfire and perpetuates alternative stable states. Mountain Ash (Eucalyptus regnans (F.Muell.)) forests are highly valued for their biodiversity, water, timber and carbon. Fires are a natural part of the lifecycle of these forests, but too frequent fires can eliminate Mountain Ash and trigger a transition to lower stature, non-eucalypt forests which are dominated by understorey species. This study sought to better understand the fuel moisture dynamics of alternative stable states resulting from high frequency wildfires. A vegetation mosaic in the Central Highlands, Victoria created a unique opportunity to measure fuel moisture in adjacent forest stands that differed in overstorey species composition and time since fire. Specifically, we measured fuel moisture and microclimate at two eucalypt sites (9 and 79 years old) and three non-eucalypt sites (two 9 year old and one 79 year old). Fuel availability, defined here as the number of days surface fuels were below 16% and dry enough to ignite and sustain fire, was calculated to estimate flammability. Fuel availability differed between sites, particularly as a function of time since fire, with recently burnt sites available to burn more often (4–17 versus 0–3 days). There were differences in fuel availability between non-eucalypt sites of the same age, suggesting that high frequency fire does not always lead to the same vegetation condition or outcome for fuel availability. This indicates there is potential for both positive and negative flammability feedbacks following state transition depending on the composition of the non-eucalypt state. This is the first study to provide empirical insight into the fuel moisture dynamics of alternative stable states in Mountain Ash forests.

Land use change alters the radiocarbon age and composition of soil and water-soluble organic matter in the Brazilian Cerrado

The Brazilian Cerrado has undergone extensive land-use change in the past century with large areas converted to agriculture and silviculture. Eucalyptus is the dominant planted tree species in Brazil, but the short rotations (6–7 years) and the associated soil disturbances can reduce soil organic matter (SOM), particularly in subsurface soil over long timeframes. SOM is critical to the continued productivity of forests and may be particularly important in Oxisol soils, which underlie much of Brazil. These soils are low in cation exchange sites and rely upon SOM for nutrient and water retention. However, the mechanisms that drive SOM loss under Eucalyptus remain unclear. This study examines both bulk soil and water-soluble organic matter chemistry deep into the soil profile (1.3 m) in paired Eucalyptus and Cerrado forest stands to identify changes in biodegradability, radiocarbon age, and functional group composition that may explain long-term declines in SOM stocks. We hypothesize that changes in litter quality associated with the conversion of Cerrado forest to Eucalyptus plantations increases the content of aliphatic functional groups in water soluble organic matter (WSOM) more quickly than bulk SOM, which drives subsoil accumulation of aliphatic organic moieties through hydrophobic interactions with soil minerals. By utilizing a suite of spectroscopic techniques (1H nuclear magnetic resonance and Fourier transform infrared spectroscopy) alongside isotopic and incubation techniques, this study found substantial shifts toward aliphatic functional group composition in WSOM in both Eucalyptus stands and deeper soil horizons. The radiocarbon age of WSOM was younger than bulk SOM at every depth but still substantially diverged from modern in B horizons. This observation is consistent with the theory that WSOM is in dynamic equilibrium with mineral adsorbed SOM, and that old organic matter replaced on mineral surfaces by fresh inputs may be leached or further degraded by microbes. Radiocarbon age of bulk SOM was younger under Eucalyptus compared to Cerrado forest and the difference between WSOM and bulk SOM radiocarbon age was much smaller in Eucalyptus soils, which together indicate that microbes may be preferentially consuming older SOM after land-use change. The presence of Cerrado understory in Eucalyptus may be important to maintaining SOM cycling; WSOM biodegradability and microbial biomass was greatly reduced in the Eucalyptus site without any understory. Ecotones with Cerrado understory provide diversity in litter types and rooting strategies, while monoculture Eucalyptus, which is commonly found in stand interiors, may reduce the ability for microbes to maintain active nutrient recycling of organic residues.

Evidences of soil geochemistry and mineralogy changes caused by eucalyptus rhizosphere

Eucalyptus trees grow in a variety of environmental conditions and cause contrasting effects on soils. Changes in soil geochemistry and mineralogy due to eucalyptus have not been clearly established to date. The objective of this study was to identify evidences of the effects of eucalyptus root system on geochemistry and clay mineralogy of a Ferralsol. Soil samples were collected in different positions of an old eucalyptus site (R1: rhizosphere of small roots; R2: coarse roots, and R3: bulk soil). The soil pH was very acid (3.8) and Al3+ (4.7 cmolc kg−1) and H+ + Al3+ (40.2 cmolc kg−1) were higher in R1 compared to R3. Additionally, reduction of clay fraction content and an increase in the proportion of Al-interlayered clay minerals were also observed in the eucalyptus rhizosphere. This suggests the occlusion of Al3+ in the interlayer space of 2:1 clay minerals and explains the tendency of a low cation exchange capacity of the clay fraction. Then, the acidification due to eucalyptus did not alter the composition of the mineral assemblage (mineral species) but the trend was a decrease of the proportion of the fine clay fraction (<0.1 μm) as well as an increase of the proportion of 2:1 Al-interlayered clay mineral in the clay fraction. The results suggest that when alien tree species are introduced into natural lands worldwide, a comprehensive geochemical-mineralogical approach must be applied in order to provide the extension of constituent changes.

Urochloa decumbens grown with different Eucalyptus clones in an integrated crop-livestock-forest system

The objective of this study is to evaluate the forage mass, chemical composition, mineral content, and mineral absorption in signal grass (Urochloa decumbens) grown with different eucalypt clones in an integrated crop-livestock-forest (iCLF) system. The split-split-plot scheme included three replicates arranged in a completely randomized block design. The eucalyptus clones GG 100 and I 144 (Eucalyptus grandis × Eucalyptus urophylla) and VM 58 (Eucalyptus grandis × Eucalyptus camaldulensis) were distributed in the plots. The split plots corresponded to the growth ages of signal grass (10, 17, 24, 31, 38, 45, and 52 days after corn harvest for silage). The split-split plots corresponded to two sampling sites: center of the inter-row and soil under the Eucalyptus canopy. The Eucalyptus clones did not affect the forage mass of the grass. Forage mass was increased linearly as the grass matured and was more readily available in the center of the inter-row than under the tree canopy. The grass grown with clone I 144 presented better chemical composition, with higher levels of crude protein and phosphorus and lower levels of neutral detergent fiber. The Eucalyptus clones did not significantly affect mineral absorption. However, the Eucalyptus clones, grass age, and sampling sites significantly changed potassium absorption. It is concluded that the forage mass of signal grass is suitable for use in grazing at 38 to 52 days after corn harvest in the iCLF system in the autumn season in the Midwest region of Minas Gerais, without compromising the chemical composition of the grass.

Influence of native or exotic trees on soil fertility in decades of silvopastoral system at the Brazilian savannah biome

Silvopastoral systems (SPSs) are considered a conservationist system by combining forestry species cultivation with domesticated grazing animals, intercropping trees, and pasture in the same area. SPSs are noun for its contribution to improve soil chemical and physical properties, enhance grass nutritional status, provide healthier animal environment, and increase farmers’ options to maximize the use of land. In soil degraded areas, such as those found in Brazilian savannah biome (BSB), the SPSs constitute an alternative to soil recuperation in these areas. Therefore, our aim was to assess soil fertility attributes at different depths on a BSB grown with Brachiaria brizantha cv. Marandu grass, the influence of SPS with native tree zeyheria (Zeyheria tuberculosa) settled in 1984, or with the exotic eucalyptus (Eucalyptus grandis) settled in 1994. The soil water pH, P, Ca, Mg, and K contents, as well as soil base sum and saturation, were found superior mostly at the top layer (0–2 cm) of the eucalyptus site, than for the ipe-felpudo site. This response was correlated to greater soil organic matter and carbon at the eucalyptus site, which demonstrated to have high nutrient cycling rates. Around 50 % of the CEC in both SPSs was occupied by bases, demonstrating that the areas have large potential to absorb applied nutrients. The SPSs have no significant impact on S-SO4 2− or micronutrient availability. The litter composition in eucalyptus site was accountable for the superior results of this SPS, which has shown as a promising choice for land use and conservation in the BSB.

Annual runoff and erosion in a recently burn Mediterranean forest – The effects of plowing and time-since-fire

The impacts of forest fires on runoff and soil erosion have been assessed by many studies, so the effects of fires on the hydrological and geomorphological processes of burnt forest areas, globally and in the Mediterranean region, are well established. Few studies, however, have assessed post-fire runoff and erosion on large time scales. In addition, a limited number of studies are available that consider the effect of pre-fire land management practices on post-fire runoff and erosion.This study evaluated annual runoff and sediment losses, at micro plot scale, for 4years after a wildfire in three eucalypt plantations with different pre-fire land management practices (i.e., plowed and unplowed). During the four years following the fire, runoff amounts and coefficients at the downslope plowed (1257mm, 26%) and contour plowed eucalypt sites (1915mm, 40%) were higher than at the unplowed site (865mm, 14%). Sediment losses over the 4years of study were also consistently higher at the two plowed sites (respectively, 0.47 and 0.83Mgha−1y−1 at the downslope and contour plowed eucalypt site) than at the unplowed site (0.11Mgha−1y−1). Aside from pre-fire land management, time-since-fire also seemed to significantly affect post-fire annual runoff and erosion. In general, annual runoff amounts and erosion rates followed the rainfall pattern. Runoff amounts presented a peak during the third year of monitoring while erosion rates reached their maximum one year earlier, in the second year. Runoff coefficients increased over the 4years of monitoring, in disagreement to the window of disturbance post-fire recovery model, but sediment concentrations decreased over the study period.When compared with other long-term post-fire studies and with studies evaluating the effects of pre- and post-fire management practices, the results of the present work suggest that an ecosystem's recovery after fire is highly dependent on the background of disturbances of each site, as runoff and erosion values were higher at the plowed sites than at the unplowed site.

Short-time phosphorus losses by overland flow in burnt pine and eucalypt plantations in north-central Portugal: A study at micro-plot scale

Over the past decades, wildfires have affected vast areas of Mediterranean ecosystems leading to a variety of negative on- and off-site environmental impacts. Research on fire-affected areas has given more attention to sediment losses by fire-enhanced overland flow than to nutrient exports, especially in the Mediterranean region. To address this knowledge gap for post-fire losses of phosphorus (P) by overland flow, a recently burnt forest area in north-central Portugal was selected and instrumented immediately after a wildfire. Three slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Micro-plots were monitored over a period of six months, i.e. till the construction of terraces for reforestation obliged to the removal of the plots. During this 6-month period, overland flow samples were collected at 1- to 2-weekly intervals, depending on rainfall. Total P and PO4-P losses differed markedly between the two types of forests on schist, being lower at the pine site than at the eucalypt site, probably due to the presence of a protective layer of pine needle cast. Parent material did not play an important role in PO4-P losses by overland flow but it did in TP losses, with significantly lower values at the eucalypt site on granite than that on schist. These differences in TP losses can be attributed to the coarser texture of granite soils, typically promoting infiltration and decreasing runoff. The present findings provided further insights into the spatial and temporal patterns of post-fire soil nutrient losses in fire-prone forest types during the initial stages of the window-of-disturbance, which can be useful for defining post-fire emergency measures to reduce the risk of soil fertility losses.

Surface runoff and soil erosion under eucalyptus and oak canopy

AbstractTo assess potential differences in stormwater runoff and sediment yield between plots of blue gum eucalyptus (Eucalyptus globulus) and coast live oak (Quercus agrifolia), we measured runoff, sediment yield, water repellency and soil moisture at eight paired sites. Eucalyptus has been associated in many studies worldwide with elevated soil water repellency and increased runoff, a likely contributor to soil erosion. To better understand these connections and their relationship to land cover, there is a need for studies employing either rainfall simulators or natural rainfall. Our research employs the latter, and was subject to contrasting hydrologic conditions in the two years of the study. Fieldwork was conducted from October 2006 to February 2008 in the San Francisco Bay Area of central California. During the 2006–2007 winter wet season, runoff was significantly higher under eucalypts than at paired oak sites, and in the early phases of the season was connected with elevated water repellency. However, sediment yield at all sites during the 2006–2007 hydrologic year was below the detection limit of the Gerlach sediment collection traps, possibly due to a limited wet season, and only appeared as suspended sediment captured in overflow buckets. Intensive rainfall events in January 2008 however created substantial runoff of sediment and litter with significantly greater yield at oak sites compared to paired eucalyptus sites. Water repellency likely had little effect on runoff during these events, and the primary cause of greater erosion under oaks is the thinner cover of leaf litter in comparison to eucalyptus. Our study is limited to undisturbed sites with intact litter cover that have not experienced recent wildfires; if disturbed, we would expect a different picture given the propensity for crown fires of eucalypts, enhancement of rainsplash erosion, and the likely greater potential for stream‐connected sediment yield from post‐disturbance soil erosion events.

Short-term nitrogen losses by overland flow in a recently burnt forest area in north-central Portugal: A study at micro-plot scale

Over the past decades, wildfires have affected extensive areas of the Mediterranean region with negative impacts on the environment. Most of the studies on fire-affected areas have focused on sediment losses by overland flow, whereas few have addressed post-fire nutrient export. The present study aimed to address this research gap by assessing nitrogen (nitrate and total nitrogen) losses by overland flow in a recently burnt area in north-central Portugal. To this end, three burnt slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Overland flow samples were collected during the first six months after the wildfire on a 1- to 2-weekly basis, after which this study had to be cancelled due to bench terracing of some of the sites. A peak in total nitrogen concentrations was observed in burnt areas immediately after the first post-fire rainfall event as a response to the erosion of the N-enriched ash layer. After this initial peak, smaller peaks were observed throughout the study period, mainly as a response to overland flow and/or erosion events. Nitrogen export differed strikingly between the two types of forests on schist, being higher at the eucalypt than at the pine site, due to the lack of a protective soil layer. Parent material did not play an important role on nitrogen export by overland flow since no significant differences were found between the eucalypt sites on granite and schist. The present study provides some insight into the differences in post-fire soil fertility losses between forest types and parent materials in the Mediterranean region, which is crucial information for defining post-fire land management measures to reduce soil degradation.

Coleópteros necrócolos (Scarabaeidae: Scarabaeinae, Silphidae y Trogidae) del Bosque Los Colomos, Guadalajara, Jalisco, México

A survey of the necrocolous beetle assemblage was done in the Bosque Los Colomos, a Protected Natural Area from Guadalajara County, Jalisco, Mexico. The study area contains elements of pine, casuarina and eucalyptus. This area is dedicated to public activities, mainly devoted to sports. Based in the anthropic activity as a qualitative criterion of environmental perturbation, carrion beetle assemblage was evaluated. Fieldwork was done from July 2011 to July 2012 using carrion traps baited with squid. A total of 362 specimens belonging to 8 species of the families Trogidae, Silphidae and Scarabaeidae (Scarabaeinae) were collected. Trox spinulosus dentibius Robinson, 1940, and Oxelytrum discicolle (Brullé, 1840) were the most abundant species. Lower abundance and specific richness in this area is explained as an effect of the landscape changes due to an increase of anthropic activities. Seasonal abundance is closely related to temperature and precipitation values: highest abundance was from June to November in eucalyptus sites. Trox spinulosus dentibius was the dominant species. We do not have detailed information to explain this high abundance, although it could be due to the change in the assemblage structure in these environments.

Abiotic features of a river from the Upper Tietê River Basin (SP, Brazil) along an environmental gradient

Aim: This study aimed to assess the spatial and seasonal variation of the water quality and physical habitat characteristics along the upper-middle stretch of the Paraitinga River, a tributary of Tietê River, considering the potential influence of different riparian conditions along the stretch studied.MethodsSixteen sites with different riparian vegetation, including native forest, secondary forest, pasture, and eucalyptus were sampled during the dry and rainy seasons of 2004/2005, before the damming of the Paraitinga Reservoir. Several physicochemical and habitat parameters were determined and data analyzed in relation to spatial distribution and potential influence of riparian conditions.ResultsWater quality parameters were in general within the limits established by CONAMA for Class 2 waters, except for turbidity and total phosphorus. There were seasonal and spatial differences in the limnological parameters along the stretch studied and apparently they were related to point specific influences associated with land use and canopy cover. Habitat characteristics were markedly different between the upper and middle river stretches, especially in relation to depth, width, substrate and canopy cover.ConclusionsAlthough a direct influence on the observed variables could not be attributed solely to the riparian vegetation, vegetation cover seemed to affect particular stream characteristics. Open pasture and eucalyptus sites were subject to point specific effects that caused phosphorus inputs and higher turbidity and temperature, and showed different morphological features, suggesting that land use at the sub-watershed scale was an important factor affecting stream conditions.

English

The soil-surface dwelling invertebrate assemblage of four sites (habitat patches) in Luchaba Nature Reserve was assessed using pitfall traps. A total of 335 specimens in three phyla (Arthropoda, Annelida and Mollusca) were sampled. Of the nine arthropod orders recorded, four were identified to seven families and ten species while five orders and two phyla (Annelida and Mollusca) were separated into 15 morphospecies. The eucalypt site supported fewer taxa compared to indigenous acacia and grassland patches while the mixed alien patch attracted the highest numbers of invertebrate families, species and individuals. Although species composition across sites was not significantly different (P>0.05), specimen counts showed significant differences (P<0.05). The implications of these preliminary results suggest that habitat-patch level management for conserving action in the short term should consider eradicating the species-poor eucalypt stands from the reserve while replacing all alien plants in the reserve area with native flora in the medium to long term. Furthermore, widespread/abundant species that occurred in all four sites e.g. Crematogaster sp, Pardosa crassipalpis and Pheidole sp. and habitat-restricted taxa can be used as potential bio-indicators for assessing the conservation value of habitat patches in Luchaba Nature Reserve and other protected areas of the King Sabata Dalindyebo Municipality. Key words: Soil-surface dwelling invertebrates, nature reserve, indigenous plants, alien invasive plants.

Runoff and inter-rill erosion in a Maritime Pine and a Eucalypt plantation following wildfire and terracing in north-central Portugal

Abstract The purpose of this study was to assess how terracing affected overland flow and associated sediment losses, at the micro-plot scale (0.25 m2), in recently burnt stands of the two principal forest types in north-central Portugal, i.e. mono-specific stands of Maritime Pine and Eucalypt. Terracing is an increasingly common practice of slope engineering in the study region but its impacts on runoff and erosion are poorly studied. Non-terraced plots at the Eucalypt and the Pine site revealed similar median runoff coefficients (rc: 20-30%) as well as comparable median sediment losses (15-25 g m-2) during the first seven months following wildfire. During the ensuing, slightly wetter 18-month period, however, non-terraced plots at the Pine site lost noticeably more sediments (in median, 90 vs. 18 g m-2), in spite the runoff response had remained basically the same (median rc: 33 vs. 28%). By contrast, terraced plots at the same Pine site lost hugely more sediments (in median, 1,200 g m-2) during this 18-month period. Terraced plots at the Eucalypt site even lost three times more sediments (in median, 3,600 g m-2). Ground cover and resistance to shear stress seemed to be key factors in the observed/inferred impacts of terracing.