Bryan A. Endress

The socio-cultural importance of Mauritia flexuosa palm swamps (aguajales) and implications for multi-use management in two Maijuna communities of the Peruvian Amazon

BackgroundFruit from the palm Mauritia flexuosa (aguaje) is harvested throughout the Peruvian Amazon for subsistence and commercial purposes. Recent estimates suggest that residents of Iquitos, the largest city in the region, consume approximately 148.8 metric tons of aguaje fruit per month, the vast majority of which is harvested by felling and killing adult female trees. In this study, we sought to better understand and document the importance of M. flexuosa palm swamps (aguajales) in two Maijuna indigenous communities to inform the sustainable management of this habitat and species.MethodsSemi-structured interviews, focus groups, and household surveys were carried out to assess the significance of aguajales and their associated plant and animal resources as well as to determine how the relationship that the Maijuna have with aguajales has changed over time.ResultsAguajales and their associated resources are culturally significant and useful to the Maijuna in a wide variety of ways. In addition to M. flexuosa, the Maijuna use over 60 different species of plants from aguajales. When M. flexuosa is in fruit, aguajales are important hunting areas with a total of 20 different animal species hunted. The Maijuna also have traditional beliefs about aguajales, believing that malevolent supernatural beings reside in them. Notably, the relationship that the Maijuna have with aguajales has changed considerably over the years as aguaje fruit went from a subsistence item collected opportunistically from the ground to a market good destructively harvested beginning in the early 1990s. The Maijuna are concerned not only about how this has affected the future commercial harvest of aguaje but also about its effects on game animals given the importance of hunting to Maijuna cultural identity, subsistence, and income generation.ConclusionsIn order to meet the multiple socio-cultural and economic needs of the Maijuna, sustainable management efforts must be expanded to not only focus on the commercial harvest of aguaje but also other facets of their relationship with this habitat. Our study suggests that the research and development of multi-use forest management plans must not be restricted to commercial forest products and ecosystem services given that many communities rely on tropical forests for a wide range of non-market cultural, economic, and subsistence goods and services.ResumenAntecedentesLa fruta de la palma Mauritia flexuosa (aguaje) se cosecha en toda la Amazonía peruana con fines de subsistencia y comerciales. Recientes estimados sugieren que los habitantes de Iquitos, la ciudad más grande en la región, consumen aproximadamente 148.8 toneladas métricas de fruta mensualmente, la gran mayoría de las cuales se cosecha mediante la tala de palmas adultas de genero femenino. En este estudio, hemos tratado de comprender y documentar la importancia de los pantanos de las palmeras M. flexuosa (aguajales) en dos de las comunidades indígenas Maijuna y de esta manera informar el manejo sostenible de este hábitat y esta especie.MétodosEntrevistas semiestructuradas, grupos focales y encuestas a hogares se llevaron a cabo para evaluar la importancia de aguajales y los recursos de plantas y animales asociados a estos. Así como también para determinar cómo la relación que tienen los Maijuna con los aguajales ha cambiado a través del tiempo.ResultadosLos aguajales y los recursos asociados con estos son culturalmente significativos y útiles para los Maijuna en una amplia variedad de formas. Adicionalmente a M. flexuosa, los Maijuna utilizan más de 60 diferentes especies de plantas en los aguajales. Cuando la cosecha de fruta de M. flexuosa ocurre, los aguajales son importantes áreas de caza ya que un total de 20 especies diferentes de animales pueden ser casados. Los Maijuna también tienen creencias tradicionales relacionadas a los aguajales, existe una creencia que seres sobrenaturales malévolos residen en allí. Es de destacar que la relación que tienen los Maijuna con los aguajales ha cambiado considerablemente a través del tiempo, ya que el fruto de aguaje pasó de ser un elemento de subsistencia recolectado de manera oportunista de la tierra, a un bien de mercado cosechado de manera destructiva desde principios de los 1990. Los Maijuna están preocupados no sólo sobre cómo esta practica ha afectado el futuro de la cosecha comercial del aguaje, sino también sobre sus efectos en los animales de caza, dada la importancia que tienen la caza en su identidad cultural y su subsistencia y generación de ingresos.ConclusionesCon el fin de satisfacer las múltiples necesidades socio-culturales y económicas de los Maijuna, los esfuerzos de manejo sostenible deben expandirse a enfocar no sólo a la cosecha comercial de aguaje, sino también tener en cuenta otras facetas de su relación con este hábitat. Dado que muchas comunidades dependen de los bosques tropicales en una amplia gama de aspectos culturales, económicos y de subsistencia que no están relacionados al mercado, nuestro estudio sugiere que la investigación y el desarrollo de los planes de usos múltiples para el manejo forestal no deben limitarse únicamente a los productos forestales comerciales y a los servicios de los ecosistemas.

Age structure and age-related performance of sulfur cinquefoil (Potentilla recta)

Abstract Age distributions of sulfur cinquefoil populations were determined on sites that were historically grazed, cultivated, and mechanically disturbed. From 12 sites, a total of 279 reproductively active plants were collected and aged by using herbchronology (counting rings in the secondary root xylem of the root crown) to (1) estimate the age structure of the populations, (2) relate plant size and flower production to plant age, and (3) examine the relation of population age structure to environmental variables and disturbance history. Results indicated that the mean age for all sampled plants was 3.5 (± 1.74 SD) yr and ranged from 1 to 10 yr. Age was not related to number of flowers, plant size (number of stems per plant or plant height), or site disturbance type but was positively correlated with site elevation (P < 0.001). The pooled age distribution from all 12 sites was right-skewed with fewer old plants than young plants. We conclude that sulfur cinquefoil plants sampled in northeast Oregon are able to colonize, establish, and reproduce at disturbed sites rapidly. We suggest that herbchronology may be a useful technique to improve understanding of invasion biology and ecology for invasive plant species that form annual rings. Nomenclature: Sulfur cinquefoil, Potentilla recta L. PTLRC.

Source-sink dynamics within a plant population: the impact of substrate and herbivory on palm demography

Site factors have frequently been shown to affect survival, growth, and reproduction in plant populations. The source-sink concept proposed by Pulliam is one way of integrating this spatial demographic variation into population models. Source-sink models describe a population where propagules from “source” habitats sustain less productive “sink” areas. We adapted this concept to model the population dynamics of the understory palm Chamaedorea radicalis on two substrates, rock outcrops and forest floor. In our model, sources and sinks correspond to fine-scale demographic structure within the population, rather than spatially discrete subpopulations as described in the Pulliam model. We constructed a stage-structured population matrix model that integrates the site-specific demography of individuals across two habitats types that are linked by migration. We then parameterized this model with field data from C. radicalis. To address whether observed differences in palm demography between rock outcrops and the forest floor were due to natural variation between microsites or due to differences in browsing intensity from free range livestock, we parameterized separate models based on the substrate-specific demography of protected, non-browsed palms and of palms exposed to burro browse. Results showed that herbivory reduced survival and fecundity on the forest floor, which in the absence of seed migration resulted in a projected decline of forest floor palms (sinks). However with seed dispersal, palms persisted and total population growth (both substrates) was projected to be positive, indicating that seed dispersal from non-browsed palms on rock outcrops (sources) was sufficient to sustain C. radicalis on the forest floor.

Multiscale Detection of Sulfur Cinquefoil Using Aerial Photography

Abstract We evaluated the effectiveness of natural color aerial photography as a tool to improve detection, monitoring, and mapping of sulfur cinquefoil (Potentilla recta L.) infestations. Sulfur cinquefoil is an exotic perennial plant invading interior Pacific Northwest rangelands. Because sulfur cinquefoil produces distinctive pale yellow flowers, we timed aerial photography for early July, when the plant was at peak bloom. Photography was collected at 3 spatial scales (1:3 000, 1:6 000, and 1:12 000). A grid with 250-m spacing was superimposed over photographs of the entire study area using geographic information systems. At each grid intersection point (n = 80), we visually analyzed the photographs within a 404.7-m2 (0.1 acre) circular plot, recorded sulfur cinquefoil presence, and estimated sulfur cinquefoil percent cover. Sample points on the grid were then located in the field using a global positioning system. Field data collected at each point included sulfur cinquefoil presence, percent cover, and stem density; and total vegetation composition and percent cover by life form. Results indicate that the accuracy of detecting sulfur cinquefoil increased from small to large scale. At the 1:3 000 scale, sulfur cinquefoil presence was correctly identified in 76.9% of the sites, whereas at the 1:6 000 and 1:12 000 scales, infestations were identified in 67.9% and 59.1% of the sites, respectively. Low-density infestations (< 1% cover) were detected at all scales. Accuracy of percent cover estimates ranged from 33.8% to 38.0% across scales. Although tree canopy hindered detection, our results indicate that aerial photography can be used to detect sulfur cinquefoil infestations in open forests and rangelands in the Intermountain West.

Landscape Factors Influencing the Abundance and Dominance of the Invasive Plant Potentilla Recta

Abstract Little is known about the relative importance of environmental, biotic, historical, and spatial factors that influence invasive plant abundance, dominance, and distribution across landscapes. We identified factors that influence the abundance and dominance of Potentilla recta L. (sulfur cinquefoil) in bunchgrass grasslands of northeastern Oregon to better understand the conditions under which it becomes a major component of plant communities. We estimated P. recta stem density and dominance from field measurements across the landscape and used classification and regression tree analyses to assess the importance of environmental, biotic, spatial, and historical factors in explaining P. recta presence, stem density, and dominance. Plots were sampled within a systematic grid with 250-m spacing within our 6.5-km2 study landscape. At each sample point we recorded P. recta presence, stem density, and dominance as well as 11 biological, environmental, spatial, and historical variables. P. recta was widely distributed, with stem densities in occupied plots averaging 5.8 stems • m−2 and dominance values ranging from 1% to 52%. Percent cover of bare ground was the most important variable to predict the presence of P. recta, though the model fit was poor, likely because the entire study area is suitable for P. recta establishment. A strong relationship between P. recta dominance and habitat type (r2  =  67.5%) was found, with dominance greatest in old fields on relatively flat slopes (mean dominance of 34.1%). Dominance estimates were ≤ 1% in plots located in forest, shrub, and grassland habitats. Factors that make old fields susceptible to dominance remain unknown, though microsite conditions that increase P. recta seedling survival rates and limited native propagule availability due to previous cultivation may be involved. Since old fields are found throughout the region, are highly susceptible to P. recta invasion, and represent a source of seeds, containment and restoration activities should focus on these areas.

Herbicide and Native Grass Seeding Effects on Sulfur Cinquefoil (Potentilla Recta)-Infested Grasslands

Abstract Sulfur cinquefoil is an exotic, perennial forb that invades a wide range of ecosystems in western North America. It forms dense populations and often threatens native plant species and communities. In this study, we address the following questions: (1) what herbicides, rates, and application times are most effective at reducing sulfur cinquefoil abundance while having the least impact on native plants; and (2) does postherbicide seeding with native grass species increase native plant abundance? In 2002, we experimentally examined the effects of five herbicides (dicamba + 2,4-D; metsulfuron-methyl; triclopyr; glyphosate; and picloram) at two rates of application (low and high), three application times (early summer, fall, and a combined early summer–fall treatment), and two postherbicide seed addition treatments (seeded or not seeded) on sulfur cinquefoil abundance, plant community composition, and species richness. Experimental plots were monitored through 2005. Picloram was the most effective herbicide at reducing sulfur cinquefoil density, the proportion of remaining adult plants, and seed production. The effects of picloram continued to be evident after 3 yr, with 80% reduction of sulfur cinquefoil in 2005. In addition, seeding of native grass seeds alone (no herbicide application) reduced the proportion of sulfur cinquefoil plants that were reproductively active. Despite reductions in sulfur cinquefoil abundance, all treatments remained dominated by exotic species because treated areas transitioned from exotic forb- to exotic grass-dominated communities. However, a one-time herbicide application controlled sulfur cinquefoil for at least 3 yr, and therefore might provide a foundation to begin ecological restoration. Herbicide applications alone likely are to be insufficient for long-term sulfur cinquefoil control without further modification of sites through native grass or forb seeding. Integrating herbicides with native plant seeding to promote the development of plant communities that are resistant to sulfur cinquefoil invasion is a promising management approach to ecological restoration. Nomenclature: Dicamba; 3,6-dichloro-2-methoxybenzoic acid; Glyphosate; N-(phosphonomethyl)glycine; Metsulfuron-methyl; 2-[[[[94-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoic acid, Picloram; 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid; Triclopyr; [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid; Sulfur cinquefoil, Potentilla recta L

Ungulate Browsing Maintains Shrub Diversity in the Absence of Episodic Disturbance in Seasonally-Arid Conifer Forest

Ungulates exert a strong influence on the composition and diversity of vegetation communities. However, little is known about how ungulate browsing pressure interacts with episodic disturbances such as fire and stand thinning. We assessed shrub responses to variable browsing pressure by cattle and elk in fuels treated (mechanical removal of fuels followed by prescribed burning) and non-fuels treated forest sites in northeastern Oregon, US. Seven treatment paddocks were established at each site; three with cattle exclusion and low, moderate and high elk browsing pressure, three with elk exclusion and low, moderate and high cattle browsing pressure, and one with both cattle and elk exclusion. The height, cover and number of stems of each shrub species were recorded at multiple plots within each paddock at the time of establishment and six years later. Changes in shrub species composition over the six year period were explored using multivariate analyses. Generalized Linear Mixed Models were used to determine the effect of browsing pressure on the change in shrub diversity and evenness. Vegetation composition in un-browsed paddocks changed more strongly and in different trajectories than in browsed paddocks at sites that were not fuels treated. In fuels treated sites, changes in composition were minimal for un-browsed paddocks. Shrub diversity and evenness decreased strongly in un-browsed paddocks relative to paddocks with low, moderate and high browsing pressure at non-fuels treated sites, but not at fuels treated sites. These results suggest that in the combined absence of fire, mechanical thinning and ungulate browsing, shrub diversity is reduced due to increased dominance by certain shrub species which are otherwise suppressed by ungulates and/or fuels removal. Accordingly, ungulate browsing, even at low intensities, can be used to suppress dominant shrub species and maintain diversity in the absence of episodic disturbance events.

Grassland Response to Herbicides and Seeding of Native Grasses 6 Years Posttreatment

Abstract Herbicides are the primary method used to control exotic, invasive plants. This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments. Of the five herbicides we evaluated, picloram continued to provide the best control of sulfur cinquefoil over 6 yr. We found the timing of picloram applications to be important to the native forb community. Plots with picloram applied in the fall had greater native forb cover. However, without the addition of native perennial grass seeds, the sites became dominated by exotic grasses. Seeding resulted in a 20% decrease in exotic grass cover. Successful establishment of native perennial grasses was not apparent until 6 yr after seeding. Our study found integrating herbicide application and the addition of native grass seed to be an effective grassland restoration strategy, at least in the case where livestock are excluded. Nomenclature: Picloram, sulfur cinquefoil, Potentilla recta L. Management Implications: If the objective is simply to reduce abundance of an invasive plant for temporary control, one application of the proper herbicide may suffice. This study found that a one-time application of picloram effectively reduced sulfur cinquefoil for 6 yr. Although herbicide applications were successful at reducing sulfur cinquefoil abundance, they were was not successful at reducing overall exotic plant cover, as other exotics species, primarily annual grasses generally replaced sulfur cinquefoil. Simply seeding native perennial grasses into plots was effective at reducing sulfur cinquefoil abundance, and herbicide application combined with native grasses seeding provided best control of sulfur cinquefoil while at the same time increasing native species abundance. Seeding success appeared poor in the first 1 to 3 yr because of the slow growth and small size of native perennial grass species in the years immediately following seeding. Therefore, longer-term monitoring is needed to evaluate success of seeding efforts.

Cattle, Deer, and Elk Grazing of the Invasive Plant Sulfur Cinquefoil

Abstract The role of ungulates as contributors to establishment and spread of non-native invasive plants in natural areas is not well known. The objectives of this study were to document whether or not sulfur cinquefoil (Potentilla recta L.) is grazed by ungulates and to quantify the effects of ungulate herbivory on the density and demography of sulfur cinquefoil. Despite reports suggesting sulfur cinquefoil is minimally grazed, our results indicate that substantial grazing of sulfur cinquefoil occurs in a northeastern Oregon natural area. The number of sulfur cinquefoil flowers and seed heads differed significantly (P < 0.0001) among all grazing treatments at all sampling periods. Cattle (Bos Taurus) grazed sulfur cinquefoil throughout early summer, resulting in smaller plants with few flowers and subsequent seed heads. Sulfur cinquefoil was grazed by deer (Odocoileus heminous and O. virginianus) and elk (Cervus elaphus) primarily in the fall and winter by specifically removing just the seed heads. As sulfur cinquefoil reproduces only by seed and seeds typically fall within 3 m of a parent plant, grazing by ungulates and subsequent deposition of the seeds by endozoochory may explain the establishment of satellite infestations across susceptible natural areas.

Rapid Assessment of Sustainable Harvesting of Leaves from the Understory Palm, Chamaedorea radicalis

Abstract We explored a rapid-assessment protocol for Chamaedorea radicalis, an understory palm from which leaves are harvested for use in the cut-greens industry. We developed a multiple-regression model relating the finite rate of population growth to vegetative and reproductive variables from a 4-year demographic study across leaf-harvesting treatments in Reserva de la Biosfera El Cielo, Tamaulipas, Mexico. The resulting model, including total fecundity of adults and mean number of leaflets, was applied to 21 populations of C. radicalis using measurements collected from a single season. Predicted estimates of population-growth rate were 0.94–1.27, but 20 of the 21 populations had predictions bracketing the net-replacement rate = 1 for population growth. We then implemented a fixed-design, life-table-response experiment to explore whether measurements of annual transition probabilities provided a superior assessment; however, addition of transition probabilities only marginally increased predictive power of the model. Therefore, implementation of this protocol is limited by imprecision of estimates of population-growth rate. Resumen Hemos explorado un método de evaluación rápida para Chamaedorea radicalis, una palma del sotobosque en el que las hojas se cosechan para su uso en la industria de follaje verde. Hemos desarrollado un modelo de regresión múltiple que relaciona la tasa finita de crecimiento de las poblaciones a las variables vegetativas y reproductivas de un estudio demográfico de 4 años a través de tratamientos de cosecha de hojas en la Reserva de la Biosfera El Cielo, México. El modelo resultante, incluyendo la fecundidad total de adultos y el número medio de foliolos, se aplicó a 21 poblaciones de C. radicalis utilizando medidas tomadas en una sola temporada. Las estimaciones previstas de la tasa de crecimiento de las poblaciones varió desde 0.94 hasta 1.27, pero en 20 de las 21 poblaciones hubo intérvalos de predicción incluyendo la tasa de sustitución neta = 1 de la tasa de crecimiento de las poblaciones. Por consiguiente implementamos un experimento de respuesta de tablas de vida de diseño-fijo para explorar si las medidas de las tasas anuales de transición proporcionan una evaluación superior; sin embargo, la adición de las tasas de transición sólo ligeramente aumentó la capacidad predictiva del modelo. Por lo tanto, la aplicación de este método es limitada por la imprecisión de las estimaciones de la tasa de crecimiento de las poblaciones.