Paired Plots Research Articles

Understanding landscape and plot-scale habitat utilisation by Malayan sun bear (Helarctos malayanus) in degraded lowland forest

Malayan sun bear (Helarctos malayanus) is a forest-dependent species globally threatened by loss of suitable habitat and hunting. Understanding how sun bears utilise habitat in more degraded landscapes is increasingly important for the effective conservation of the species. We studied how landscape and plot attributes affect sun bear habitat use along a gradient of logging disturbance in a lowland forest site of Sumatra. We conducted surveys of bear claw marks to indicate sun bear habitat use at plot and landscape scales, and inform forest restoration strategies that benefit the conservation management of the species. We recorded 12 habitat features and the presence/absence of claw marks in 262 plots in four different habitat types. We reduced the number of habitat variables using Principal Components Analysis (PCA), resulting in four derived habitat factors. We used these factors in a Discriminant Analysis to refine habitat classifications of plots, and modelled presence/absence of claw marks using the PCA factors in a binary logistic regression. We inventoried tree species in a subset of randomly selected plots with claw marks alongside paired control plots with no claw marks. We compared tree community compositions in these plots using ANOSIM and SIMPER analyses. Based on claw mark signs, sun bear habitat use appeared to be non-random and was significantly associated with gradients of increasing habitat intactness, from non-forest habitat to least disturbed forest. Two PCA factors explained the probability of bears utilising a given habitat, which increased with tree biomass and decreased with understorey cover. At the plot level, tree family and species compositions were significantly different between plots without and with claw marks. The abundance and use of Olacaceae stems was significantly higher in plots with claw marks. Incorporating forest restoration strategies that enhance or increase more intact forest and the availability of key tree resources should benefit the conservation of sun bears and encourage natural forest regeneration in these degraded landscapes. We also emphasise the conservation value of degraded forest habitats for this species while ensuring bear movement and connectivity within modified landscape matrices.

Invasive shrub removal benefits native plants in an eastern deciduous forest of North America

AbstractIn eastern deciduous forests of North America, invasive shrubs are increasing in richness and abundance at the expense of native species across taxa. Invasive shrubs create an understory that is more dense than both recent and historical preinvasion conditions. Interest in invasive shrub removal to restore native habitat is growing, but our understanding of natural regeneration following treatment of a diverse invasive shrub community is lagging. Using an invasive shrub removal experiment, we provide insight into the effect of repeated removal of a suite of 18 invasive shrub species dominated by border privet (Ligustrum obtusifolium Siebold & Zucc.). In 2009, invasive shrubs were removed from five 20-m-diameter treatment plots, each with a paired control plot. Seven years later, we find an increase in plant diversity, native understory species abundance, and overstory tree species regeneration for individuals under a meter in height. For plants 1 to 4 m in height, the removal treatment has a positive effect on understory woody species, but there has been no change in regenerating overstory trees. A lack of overstory tree regeneration to greater heights is not surprising, given the time frame and the closed-canopy conditions. However, other factors, such as white-tailed deer (Odocoileus virginianus Zimmermann) browse, could be serving as an impediment to taller tree regeneration in the forest understory. An ambient sampling approach in unmanaged, invaded, and uninvaded forest has been used in other studies to estimate the potential impacts of invasive shrub species to native plant communities. However, in this study the ambient sampling approach underestimated the impacts of invasive shrubs compared to their experimental removal. Overall, invasive shrub removal increased plant diversity and allowed passive natural regeneration of native plants that exceeded native cover in the unmanaged, ambient forest under minimal invasive shrub abundance.

Invasive species and carbon flux: the case of invasive beavers (Castor canadensis) in riparian Nothofagus forests of Tierra del Fuego, Chile

Forests are important moderators of global atmospheric CO2 emissions, making them a key focus of terrestrial C-cycling research. The 5th assessment report of the Intergovernmental Panel on Climate Change explicitly calls upon nations to enhance C-stock accounting and mitigate losses of global forest C sinks, which inherently will require more accurate and higher spatial resolution carbon accounting. Monitoring and predicting how disturbances, such as invasive species, influence forest C stocks and the transfer of C from live to dead pools remains a high priority both in the scientific and policy communities. We documented the effects of invasive North American beavers (Castor canadensis) on C-sequestration of riparian Nothofagus forests in Tierra del Fuego, Chile. Our paired plot sampling design quantified significant losses from beaver invasion in total aboveground, live standing, dead standing, and dead and downed C stocks (P < 0.001, paired t tests). We extrapolated stand-level C losses to the entire study area using a Maxent habitat suitability model and estimated that 1.177 (± 0.103) Tg C would be lost if all of the predicted 18,384 ha of invasible habitat (14% of the total forested area) were colonized by beavers. These results document the impacts of invasive mammals on large terrestrial C sinks and highlight the need for understanding the magnitude of such effects across both landscape- and regional-scales.

Efecto de la maleza como cobertera en la fertilidad del suelo y rendimiento de nogal pecanero

El objetivo de este trabajo fue evaluar el efecto de la maleza como cobertera a largo plazo sobre la fertilidad del suelo y rendimiento del nogal pecanero Carya illinoinensis (Wangenh.) K. Koch. El trabajo se desarrolló en el cv Western de 32 años de edad, bajo riego por goteo, en la Costa de Hermosillo, Sonora. Los tratamientos consistieron en cobertera vegetal a base en maleza y el testigo limpio, los cuales se distribuyeron en un diseño de parcelas apareadas con cuatro repeticiones, con unidad experimental de tres árboles por hilera. En contenido de materia orgánica, pH y de la mayoría de nutrientes en el suelo, fue mayor en el tratamiento con cobertera que en el testigo (p&lt;0.05) a los diez años de iniciado el trabajo, mientas que la salinidad del suelo no se modificó. El rendimiento promedio durante el periodo de evaluación fue similar (p&lt;0.05) en ambos tratamientos. Los mayores cambios en el contenido de materia orgánica y concentración de nutrimentos ocurrieron en los primeros 30 cm de profundidad. Se registraron cambios en fertilidad y salinidad en el perfil del suelo, pero fueron independientes de la cobertera. Los resultados muestran que en huertas adultas de nogal pecanero la maleza puede utilizarse como cobertera para mejorar la calidad del suelo sin afectar el rendimiento del nogal pecanero.&#x0D; &#x0D;

Wild boar (Sus scrofa) increases species diversity of semidry grassland: Field experiment with simulated soil disturbances.

BackgroundForaging activities of wild boar (Sus scrofa) create small‐scale soil disturbances in many different vegetation types. Rooting alters species composition by opening niches for less‐competitive plants and, as a recurrent factor, becomes a part of the community disturbance regime. Vegetation responses to wild boar disturbance have mostly been studied in the boar's non‐native range or in native forest, rather than in open habitats in the native range. We investigate the response of open European semidry grassland vegetation dominated by Brachypodium pinnatum to native wild boar pressure in an abandoned agricultural landscape.MethodsTo describe the disturbance regime, we repeatedly mapped rooted patches during a 5‐year period. Additionally, to study the vegetation response, we performed an artificial disturbance experiment by creating 30 pairs of simulated disturbances and undisturbed plots. The vegetation composition of the paired plots was repeatedly sampled five times in eight years of the study.ResultsBased on repeated mapping of disturbances, we predict that if the disturbance regime we observed during the 5‐year period were maintained over the long term, it would yield a stable vegetation ratio consisting of 98.7% of the grassland undisturbed, 0.4% with fresh disturbance, and 0.9% in older successional stages.Vegetation composition in the artificially disturbed plots was continuously converging to that of undisturbed vegetation, but these disturbed plots still differed significantly in composition and had higher species number, even after eight years of succession.SynthesisOur results thus show that wild boar disturbance regime in its native range increases heterogeneity and species diversity of semidry grassland vegetation.

Agricultural Expansion-Induced Infiltration Rate Change in a West African Tropical Catchment

Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity was measured under forty-two (42) pairs of adjacent cropland-fallow plots using a Hood infiltrometer. Ks, Kh, bulk density, and soil texture were further compared using a paired two-tailed Student’s t-test (p=0.05). The results showed that both Ks and Kh are highly variable irrespective of the land use type (coefficient of variation &gt; 100%). The results also showed that Ks was significantly higher (1.16-fold on average) under fallow compared to cropland. As for Kh, the results showed that, from −2 cm to zero tension heads (h), Kh under cropland and fallow is not significantly different; however, as the supplied tension decreases up to the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under cropland and fallow were caused by land use and not preexisting difference in texture. These results suggest an increasing risk of erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.

Importance of tussocks in supporting plant diversity in Carex schmidtii Meinsh. wetlands

Tussocks created by Carex schmidtii in sedge meadows may be able to support biodiversity because of their structural complexity. Concerns about diversity loss and the potential to restore species-rich tussocks led us to investigate how tussocks foster high species richness and affect composition. We investigated vegetation in paired plots on and between tussocks of C. schmidtii, and measured environmental factors on and between tussocks. In all, 79 taxa were found in the sedge meadows. Species richness was higher on rather than between tussocks. During the growing season, the tops of tussocks were above the water level, whereas the area between tussocks was flooded. Soil temperature, organic carbon, soil total P and litter depth were higher on rather than between tussocks. Soil water content and soil total N were lower on than between tussocks. Species richness on tussocks increased with increasing tussock basal area, height and surface area. Based on canonical correspondence analysis, plant composition was mostly related to field water depth, organic carbon and tussock basal area. We conclude that tussocks enhance species richness by increasing surface area, and support a diversity of co-occurring species by creating at least two distinct microhabitats.

Enhancing Data Visualization Capabilities: A Comprehensive Exploration of Seaborn in Python

In the ever-evolving landscape of records technology, the function of powerful information visualization cannot be overstated. As datasets develop in complexity and length, the want for classy gear that could distill meaningful insights from these extensive arrays of records will become more and more important. This studies paper, titled "Enhancing Data Visualization Capabilities: A Comprehensive Exploration of Seaborn in Python," embarks on a adventure to delve deep into the functionalities and programs of Seaborn, a effective and versatile facts visualization library in the Python programming language. The abstract encapsulates the essence of this complete exploration, emphasizing its significance in empowering researchers, analysts, and builders to create visually compelling representations of records. The historical historical past units the stage by using tracing the evolution of data visualization libraries in Python, highlighting the motivations that brought about the emergence of Seaborn. As a foundation, the paper explores the structure and layout standards that underpin Seaborn, presenting readers with a nuanced understanding of its shape and seamless integration with Matplotlib. Building on this foundation, the exploration delves into the world of basic plotting techniques, unraveling how Seaborn facilitates the advent of essential visualizations along with bar plots, histograms, and container plots. A pivotal factor of this studies lies inside the exploration of Seaborn's superior visualization capabilities. This includes an in-intensity examination of complicated strategies like heatmaps, pair plots, and faceting, showcasing how Seaborn stands out in growing informative and visually appealing representations. Furthermore, the paper elucidates Seaborn's integration with Pandas, a cornerstone for efficient records manipulation and analysis. Real-world applications and case research are interwoven all through the narrative, demonstrating how Seaborn transcends theoretical concepts and is carried out in practical eventualities throughout various domains, such as finance, biology, and social sciences. The comparative evaluation gives readers insights into how Seaborn distinguishes itself from different data visualization libraries in Python, emphasizing overall performance, ease of use, and unique use cases in which Seaborn excels. As the exploration maintains, attention is became closer to Seaborn's interactive skills, integration with Jupyter Notebooks, and a plethora of customization options that empower users to craft tailor-made and attractive visualizations. The paper does not turn away from acknowledging demanding situations and obstacles associated with Seaborn, imparting a balanced perspective on its application. The abstract concludes by way of searching toward the destiny, awaiting ongoing tendencies inside the Seaborn library and spotting the collaborative efforts of the network that propels its evolution. In essence, this research paper aspires to be a holistic and enlightening resource, guiding each beginners and seasoned practitioners in harnessing the full capacity of Seaborn for impactful statistics visualization in Python.

To mow or not to mow? Plant functional traits help to understand management impact on rich fen vegetation

AbstractQuestionsFens are important conservation targets in temperate Europe. When hydrologically undisturbed, fens remain open for millennia. However, unaltered fens are scarce, and today their biodiversity largely depends on conservational mowing applied to prevent successional shifts. However, the effects on community structure and conservation values are uncertain, and management might not always be needed where it is a priori applied by managers. Thus, within the presented study, we ask the following questions: (a) How is the species and functional composition of fens influenced by mowing? (b) Does mowing increase the conservation value of fen ecosystems?LocationLowland fens, northern Poland.MethodsThe sample consisted of 27 pairs of mown and unmown plots, located within ten sites. Ordination methods were used to assess the influence of mowing on species composition. Functional traits related to competitiveness, flowering time, mycorrhizal associations and functional groups were used to characterize plant communities and species richness, and the number of specialist and red‐listed species was used to evaluate conservation values. Differences between mown and unmown plots were assessed using linear mixed‐effect models and the effect size approach.ResultsManagement of fens suppresses the growth of trees, shrubs and highly competitive herbaceous species and inhibits the encroachment of Sphagnum mosses. At the same time, it enhances the establishment of species from other ecosystems (grasses, ruderal species, species of drier sites) within fens and alters the microtopography of the fen surface.ConclusionsMowing can enhance species richness and the presence of rich fen specialists in transformed sites, but it can lead to fen ecosystem deterioration towards managed meadow communities within sites sustaining many typical fen species and functional characteristics.

Impacts of feral horses and deer on an endangered woodland of Kosciuszko National Park

SummaryIn recent years, the impacts of rapidly increasing populations of feral horses and deer on the vegetation and stability of soils have become highly visible and widespread in Kosciuszko National Park. We investigated these impacts in the White Cypress Pine (Callitris glaucophylla Joy Thomps. &amp; L.A.S. Johnson) – White Box (Eucalyptus albens Benth) woodlands of the lower Snowy River valley. This woodland is a component of the White Box‐Yellow Box‐Blakely's Red Gum Grassy Woodland and Derived Native Grasslands complex that is nationally listed as a critically endangered ecological community. To investigate the severity of the impacts of feral horse (Equus caballus) and deer (Dama dama and Rusa unicolor) in the valley in 2013 and 2017/18, we surveyed fenced exclosures and paired grazed plots that were first established and surveyed in 1984 and re‐surveyed in 1987. Using LFA and VAST methodologies (not used in 1987), we compared the relative response of environmental variables in plots inside and outside the exclosures in an attempt to ascertain recent herbivore impacts. While there was no evidence of horses or deer from dung surveys in 1987, in 2018, 84% of the dung was from horses, 13% from deer, 1% from rabbits and 2% from macropods. Total herbivore dung density increased fourfold since the 1987 survey. On the understanding that all plots had the same starting condition in 1984 with respect to prior herbivory, we deduce that horses and deer are having significant ecological impacts. There was a far greater cover of understorey plants and the midstorey was denser and taller inside the exclosures. Outside the exclosures, the vegetation cover was far more sparse and soil erosion was active and extensive. The total number of invertebrates captured in small pitfall traps was nearly twice as many within the exclosures compared to the grazed plots. The dense even‐aged regrowth overstorey stands of White Cypress Pine, inside and outside the exclosures, have changed little in 34 years.

Recovery of Pindan vegetation on seismic lines

Exploration for oil and gas resources requiring the clearing of seismic lines has been occurring in central and northern Australia for many years. For example, seismic surveys have been conducted in the West Kimberley region of Western Australia since the 1960s. Despite this being a widespread practice, the recovery of vegetation on seismic lines has not been well studied. To better understand vegetation recovery in the West Kimberley, we conducted vegetation surveys on recovering seismic lines cleared using a raised-blade technique, from ∼two months to 4.9 years post-clearing, and compared them to paired control plots. Generally, the vegetation structure and community composition on seismic lines recovered quickly, with no discernible difference between control and seismic plots that were cleared more than 6 months prior. Some individual vegetation characteristics (e.g. understorey density and overstorey cover) recovered slowly, whereas other characteristics such as the number of individual grasses, recovered quickly. Vegetation recovery was confounded by the time since fire, which accounted for differences in vegetation structure at 1–2 years and 3–4 years since clearing. The fast recovery rate observed suggests that raised-blade clearing may not present a lasting impact on Pindan vegetation in the West Kimberley.

Assessment of losses caused by sesame leaf webber and capsule borer Antigastra catalaunalis (DUPONCHEL)

A study was conducted during kharif seasons of 2016 and 2017 at the Chaudhary Charan Singh Haryana Agricultural University, Hisar to study the quantitative and qualitative losses by the infestation of sesame leaf webber and capsule borer, Antigastra catalaunalis in HT-1 and HT-2 variety of sesame. The experiment was conducted under both protected and unprotected conditions in paired plot design with three replications. Plot size was kept 2.7 x 1.8 m2 and distance between row and plant was maintained at 30 and 10 cm during each season. Pooled data of both years revealed that pod damage in both the varieties varied from 19.72 to 21.62% under unprotected condition while in protected condition it varied from 3.02 to 3.12%. Maximum yield was recorded in HT-2 (921.42 kg/ha) under protected condition while minimum yield was observed in HT-1 (521.48 kg/ha) followed by (555.27 kg/ha) under unprotected condition. Avoidable yield loss due to A. catalaunalis was 35.16 and 39.73% in the varieties HT-1 and HT-2, respectively after three sprays of quinalphos. Total protein and crude fat contents of seeds obtained from damaged pods were significantly lower in both varieties viz., HT-1 and HT-2 as compared to seeds obtained from undamaged pods. This is a big impact on the nutritional quality. However, fibre, ash and moisture contents were not affected to that extent.

Desenvolvimento e validação cruzada de equações preditivas de massa livre de gordura por bioimpedanciometria, para homens brasileiros de 20 a 59 anos de idade

O objetivo do estudo foi desenvolver e validar equação preditiva de massa livre de gordura por bioimpedanciometria para homens da população brasileira. Foram avaliados 203 homens de 20 a 59 anos de idade, divididos aleatoriamente em dois grupos: desenvolvimento (102) e validação cruzada (101). A técnica padrão foi a Abortometria radiológica de dupla energia (DEXA). Teste t pareado, regressão múltipla e plotagem de Bland-Altman foram utilizados para testar a validade do modelo proposto. A equação derivada pelo estudo foi: MLG = 17,57 + 0,348 (Estatura2/Resistência) + 0,513 Massa Corporal – 0,283 Perímetro Abdominal + 0,079 Reatância – 0,038 idade; coeficiente de correlação de concordância – CCC = 0,937; r2= 0,89; erro padrão de estimativa – EPE = 2,55 kg; erro puro – EP = 2,51 kg. Com isso, a nova equação proposta proporciona estimativa válida da massa livre de gordura, sendo recomendada para homens com características semelhantes.&#x0D;

Species turnover in plants does not predict turnover in flower-visiting insects.

Congruence between plant and insect diversity is considered possibly useful in conservation planning, as the better known plants could be surrogates for the lesser known insects. There has been little quantification of congruence across space, especially in biodiversity rich areas. We compare here species richness, and turnover relationships between plants and flower-visiting insects across space (0.5–80 km) in natural areas of a biodiversity hotspot, the Greater Cape Floristic Region, South Africa. A total of 22,352 anthophile individuals in 198 species and 348 plant species were sampled. A comparison between the plants and anthophiles suggest significant concordance between the two assemblages. However, turnover was weaker in plants than in anthophiles. Plant turnover decreased with greater geographical distance between plot pairs. In contrast, insect turnover remained high with increasing geographical distance between plot pairs. These findings suggest that while patterns of plant diversity and distribution shape flower-visiting insect assemblages, they are not reliable surrogates. The conservation significance of these results is that specialist mutualisms are at greatest risk, and that set-asides on farms would help improve the functional connectivity leading to the maintenance of the full range of mutualisms.

The invasive green alga Avrainvillea sp. transforms native epifauna and algal communities on a tropical hard substrate reef

SUMMARYSome introduced species compete directly with native species for resources and their spread can alter communities, while others do not proliferate and remain benign. This study compares community structure and diversity in adjacent areas dominated by the introduced alga Avrainvillea sp. or native algal species on a hard substrate reef. The biomass and species composition of 15 paired plots (30 in total, plot type based on dominance of Avrainvillea sp. or native species) were quantified. Plots dominated by Avrainvillea sp. had a significantly different assemblage of species characterized by lower algal diversity, mostly Dictyota spp. and Laurencia sp., and a higher abundance and diversity of invertebrates, such as small arthropods, polychaetes, and brittlestars. These results suggest that as Avrainvillea sp. becomes more abundant on hard substrate reefs, it will engineer a different community composed of algal epiphytes and an invertebrate assemblage more typically associated with algae in soft sediments.

Impact of troublesome expansive weed Rumex alpinus on species diversity of mountain pastures in Tatra National Park, Poland

Alpine dock (Rumex alpinus) is a native plant species in many European mountain ranges. It comes from moist brushwood and open tall herb communities, though it has invaded mountain pastures. This troublesome weed forms permanent monodominant stands characterised by low nature conservation and agricultural values. However, to the best of our knowledge, there are no studies assessing the impact of R. alpinus on invaded communities. Therefore, in this study we examined the potential effect of an R. alpinus on species richness, diversity and the composition of invaded vegetation in Tatra National Park, Poland. Invaded plots dominated by R. alpinus had, compared to uninvaded control plots, significantly reduced species richness, as well as low Shannon and Simpson diversity and Pielou evenness indices’ values; the species richness decline in the pairs of invaded-uninvaded plots was as much as 37.7%. Analysing changes in diversity from an increase in R. alpinus coverage revealed that Shannon, Simpson and Pielou’s diversity indices’ values did not considerably change up to 30% of R. alpinus coverage, but a further increase in R. alpinus coverage led to a steep decline in diversity. There was exception in a number of species per plot, which decreased steadily along with the increase of R. alpinus coverage. Multivariate analysis indicated a significant shift in the composition of invaded plots in relation to uninvaded plots, resulting from the shared increase of more shadow-tolerant and higher soil base-, nutrient- and moist-demanding species.

Rapid Increase and Long-Term Slow Decrease in Soil C stock Due to Agricultural Development in Hokkaido Tokachi District

Soil properties and functions are dramatically altered by changes in agricultural land use. However, little is known about how ecosystem C stock and its partitioning change with deforestation for agricultural land use, especially in cold humid areas. In this study, we investigated how agricultural development influences temporal changes in soil C pools in upland crop fields using a paired-plot approach. Ten pairs of control forest and agricultural development plots (2 to more than 80 years) were selected with the same crop rotation under humid temperate climate in Northeast Japan. We detected a net gain in soil C during the first 2 years of agricultural land development under the flat field condition. This gain in soil C was caused by an increase in the light fraction soil C, which represents plant residue derived-C due to agricultural development. Agricultural development resulted in the loss of soil C in fields without manure application. There was no difference in the ecosystem C stock among soil types or with the amount of manure applied. Agricultural development resulted in a slow decrease in soil C storage, indicating a slow rate of C decomposition under cool climate conditions.

Extended Water-Level Drawdowns in Dammed Rivers Enhance Fish Habitat: Environmental Pool Management in the Upper Mississippi River.

Environmental Pool Management (EPM) can improve ecosystem function in rivers by restoring aspects of the natural flow regime lost to dam construction. EPM recreates summer baseflow conditions and promotes the growth of terrestrial vegetation which is inundated in the fall, thereby improving habitat heterogeneity for many aquatic taxa. A three-year experiment was conducted wherein terrestrial floodplain areas were dewatered through EPM water-level reductions and the resulting terrestrial vegetation was (1) allowed to remain or (2) removed in paired plots in Mississippi River pool 25. Fish assemblage and abundance were quantified in paired plots after inundation. Abundances of many fish species were greater in vegetated plots, especially for species that utilize vegetation during portions of their life history. Fish assemblages varied more between plot types when the magnitude of EPM water-level drawdowns was greater, which produced greater vegetation growth. Young-of-year individuals, especially from small, early maturing species and/or species reliant on vegetation for refuge, feeding, or life history, utilized vegetated plots more than devegetated plots. Vegetation growth produced under EPM was heavily used by river fishes, including young-of-year individuals, which may ultimately positively influence recruitment. Increased habitat heterogeneity may mitigate some of the negative impacts of dam construction and water-level regulation on river fishes. Annual variability in vegetation responses that occurs under EPM enhances natural environmental variability which could ultimately contribute to increased fish diversity. Low-cost programs like EPM can be implemented as a part of adaptive management plans to help maintain biodiversity and ecosystem health in anthropogenically altered rivers.

Measuring functional dissimilarity among plots: Adapting old methods to new questions

Ecologists routinely use dissimilarity measures between pairs of plots to explore the complex mechanisms that drive community assembly. Traditional dissimilarity measures usually quantify plot-to-plot dissimilarity based either on species presences and absences within plots or on species abundances, thus assuming that all species are equally and maximally distinct from one another. However, the value of dissimilarity measures that incorporate information on functional differences among species is becoming increasingly recognized. Since these ‘functional dissimilarity measures’ have been developed for capturing new aspects of plot-to-plot dissimilarity, they have usually little to do with more traditional measures based solely on species incidence or abundance data. In this paper we introduce a general method for adapting a large family of traditional dissimilarity coefficients to the measurement of functional differences among plots. The behavior of the proposed method, for which we provide a simple R function, was evaluated with published data on plant communities in a coastal marsh plain in Algeria. As shown by the worked example, our proposal produces a coherent framework for summarizing functional dissimilarity among plots. Being based on a generalization of classical dissimilarity measures with well-known properties, this new family of functional dissimilarity indices also has a great potential for future theoretical and applied developments in this field of research.

Slash-and-Burn Practices Decrease Arbuscular Mycorrhizal Fungi Abundance in Soil and the Roots of Didierea madagascariensis in the Dry Tropical Forest of Madagascar

Deforestation and the use of fire to clear land have drastic effects on ecosystem functioning and compromise essential ecosystem services, especially in low-income tropical countries such as Madagascar. We evaluated the effects of local slash-and-burn practices on soil nutrients and arbuscular mycorrhizal (AM) fungi abundance in a southwestern Madagascar forest. Nine sampling plot pairs were established along the border of a reserve within the Fiherenana–Manombo (pk-32) complex, where soil and seedling root samples of the endemic tree Didierea madagascariensis were taken. We analysed soil extractable PO43−, NH4+, and NO3− as well as total soil carbon and nitrogen. We analysed AM fungal abundance in soil and roots through fatty acid marker analysis (NLFA and PLFA 16:1ω5), spore extraction, and root staining. Slash-and-burn caused an increase in pH and doubled the plant available nutrients (from 7.4 to 13.1 µg PO43− g−1 and from 6.9 to 13.2 µg NO3− g−1). Total C and total N increased in deforested soil, from 0.6% to 0.84% and from 0.06% to 0.08%, respectively. There was a significant decline in AM fungi abundance in soil, with a decrease in soil NLFA 16:1ω5 from 0.2 to 0.12 nmol/g. AM fungi abundance in D. madagascariensis roots was also negatively affected and colonization decreased from 27.7% to 16.9% and NLFA 16:1ω5 decreased from 75.7 to 19 nmol/g. Together with hyphal network disruption, increased nutrient availability caused by burning is proposed as an explanation behind AM decline in soil and roots of D. madagascariensis. This is the first study to report the effects of slash-and-burn on AM symbiosis in Madagascar’s dry forests, with likely implications for other tropical and subtropical dryland forests worldwide where slash-and-burn is practiced.