Diversity Of Oak Species Research Articles

Canopy arthropod diversity associated with Quercus laurina: importance of an oak species diversity gradient on abundance, species richness and guild composition

Canopy arthropod diversity associated with Quercus laurina: importance of an oak species diversity gradient on abundance, species richness and guild composition

Combining Satellite Remote Sensing and Climate Data in Species Distribution Models to Improve the Conservation of Iberian White Oaks (Quercus L.)

The Iberian Peninsula hosts a high diversity of oak species, being a hot-spot for the conservation of European White Oaks (Quercus) due to their environmental heterogeneity and its critical role as a phylogeographic refugium. Identifying and ranking the drivers that shape the distribution of White Oaks in Iberia requires that environmental variables operating at distinct scales are considered. These include climate, but also ecosystem functioning attributes (EFAs) related to energy–matter exchanges that characterize land cover types under various environmental settings, at finer scales. Here, we used satellite-based EFAs and climate variables in species distribution models (SDMs) to assess how variables related to ecosystem functioning improve our understanding of current distributions and the identification of suitable areas for White Oak species in Iberia. We developed consensus ensemble SDMs targeting a set of thirteen oaks, including both narrow endemic and widespread taxa. Models combining EFAs and climate variables obtained a higher performance and predictive ability (true-skill statistic (TSS): 0.88, sensitivity: 99.6, specificity: 96.3), in comparison to the climate-only models (TSS: 0.86, sens.: 96.1, spec.: 90.3) and EFA-only models (TSS: 0.73, sens.: 91.2, spec.: 82.1). Overall, narrow endemic species obtained higher predictive performance using combined models (TSS: 0.96, sens.: 99.6, spec.: 96.3) in comparison to widespread oaks (TSS: 0.80, sens.: 92.6, spec.: 87.7). The Iberian White Oaks show a high dependence on precipitation and the inter-quartile range of Normalized Difference Water Index (NDWI) (i.e., seasonal water availability) which appears to be the most important EFA variable. Spatial projections of climate–EFA combined models contribute to identify the major diversity hotspots for White Oaks in Iberia, holding higher values of cumulative habitat suitability and species richness. We discuss the implications of these findings for guiding the long-term conservation of Iberian White Oaks and provide spatially explicit geospatial information about each oak species (or set of species) relevant for developing biogeographic conservation frameworks.

Distribution and diversity of Fagaceae in Hidalgo, Mexico

Background: The family Fagaceae is one of the most important in temperate regions of the Northern hemisphere. Fagus and Quercus are distributed in Mexico, the former in Northeastern Mexico, while the latter reaches a high diversity in the Sierra Madre Oriental, Mexico. In Hidalgo state, located mainly in the Sierra Madre Oriental, knowledge of the Fagaceae diversity is still uncertain.
 Questions and/or hypothesis: We carried out a taxonomic revision of the genus and species of Fagaceae in Hidalgo state. We determined how many and which species are distributed in Hidalgo. We also present a morphological description and ecological characters of each one.
 Studied species: The species of the family Fagaceae
 Study site: Hidalgo state, Mexico.
 Method: We collected herbarium specimens, made field observations and reviewed herbarium data of Fagaceae specimens at FCME, INEGI, MEXU, ENCB, SLPM, HUMO, XAL and partly BH herbaria. In addition, we checked taxonomic literature and protologues of each species.
 Results: We found one species of Fagus and 43 of Quercus , 22 of which belong to the section Quercus (white oaks) and 21 to section Lobatae (red oaks). Morphological descriptions, altitudinal and geographical distribution, vegetation types of each species and a dichotomous key for species identification are presented. Illustrations and photographs of the species are also included.
 Conclusions: A high diversity of Fagaceae species is present in Hidalgo state. In Mexico, Hidalgo ranks in fifth place for oak species diversity, just behind Oaxaca (50 species), Puebla (50), San Luis Potosí (45), and Jalisco (45).

Stand Structure, Productivity and Carbon Sequestration Potential of Oak Dominated Forests in Kumaun Himalaya

Present study deals with stand structure, biomass, productivity and carbon sequestration in oak dominated forests mixed with other broad leaved tree species. The sites of studied forests were located in Nainital region between 29058’ N lat. and 79028’ E long at 1500-2150 m elevation. Tree density of forests ranged from 980-1100 ind.ha-1. Of this, oak trees shared 69-97%. The basal area of trees was 31.81 to 63.93 m2 ha-1. R. arboreum and Q. floribunda shared maximum basal area 16.45 and 16.32 m2 ha-1, respectively in forest site-1 and 2 while Quercus leucotrichophora shared maximum (35.69 m2 ha-1) in site-3. The biomass and primary productivity of tree species ranged from 481-569 t ha-1 and 16.9-20.9 t ha-1yr-1, respectively. Of this, biomass and primary productivity of oak tree species accounted for 81 to 95 and 78 to 98%, respectively. Carbon stock and carbon sequestration ranged from 228 to 270 t ha-1 and 8.0 to 9.9 t ha-1yr-1, respectively. The share of oak tree species ranged from 81 to 94.7 and 79 to 97%, respectively. The diversity of tree species ranged from 0.03 to 0.16 in forest sites-1, 2 and 3. The diversity of oak species was 0.08-0.16 in all the forest sites. Thus it is concluded that among the oak tree species, Quercus floribunda and Quercus leucotrichophora were highly dominated in the studied forests. The climax form of oak dominated trees in the studied forest sites depicted slightly lower richness and diversity of tree species compared to the forests in the region and elsewhere. As far as dry matter and carbon of forests is concerned, these estimates are close to the earlier reports of forests in the region. Therefore, studied forests have the potential to increase the diversity, productivity and carbon sequestration of forest tree species by providing the adequate scientific conservation and management inputs.

Structure and diversity of oak forests in the El Tepozteco National Park (Morelos, Mexico)

Quercus (oak) is among the most speciose and widespread genera occurring in Mexico; paradoxically, the ecological knowledge about Mexican oak forests is meager. Here we describe the floristic composition, diversity, and structure of the terrestrial component of the oak forests of the El Tepozteco National Park (TNP), Central Mexico, and relate their floristic and structural heterogeneity to the geomorphological complexity of the park. We randomly distributed sixty 100-m2 plots among six geomorphological units: the lava fields of the Chichinautzin, Suchiooc, Otates (upper and lower) and Oclayuca volcanoes, and the El Tepozteco Range. Vegetation structure and diversity were described by geomorphological unit and for the oak forest as a whole for canopy (DBH ? 2.5 cm) and understory plants. We report 324 vascular plant species recorded in the plots, plus 17 species collected outside the plots (a total of 341 species, 208 genera and 88 families). The family with more species was Asteraceae (57) and the most speciose genus was Salvia (0). Geomorphological units differed in mean species richness per plot (2.0-33.5 species), absolute richness (60-149 species), and species’ structural contributions. Structural differences were also observed, but they were not always significant. Quercus rugosa was dominant in Chichinautzin, Suchiooc, and upper Otates; Styrax ramirezii in lower Otates and Oclayuca, and Quercus castanea and Q. obtusata shared dominance in El Tepozteco Range (the unit with the largest overall richness and oak species diversity). The structure and composition of TNP oak forests are highly variable, apparently due to the region’s complex geological past. This heterogeneity should guide the conservation and restoration of these forests.

How Are Oaks Distributed in the Neotropics? A Perspective from Species Turnover, Areas of Endemism, and Climatic Niches

Premise of research. The most important diversity hot spot of genus Quercus (Fagaceae) in America is situated in southern Mexico. From this area down to the Colombian Andes, oak species diversity decreases considerably, but the pattern of species distribution and turnover has not been analyzed. This study aimed at determining geographical patterns of species turnover, species distribution, and endemism for Neotropical Quercus species.Methodology. Occurrence records for 58 oak species belonging to the Quercus and Lobatae sections were obtained. Patterns of species turnover were determined by comparing species composition among latitudinal/longitudinal units. Areas of endemism were determined using weighted networks. The potential distribution of oak species was determined using ecological niche models. Finally, a principal component analysis was used to identify changes in the oak species’ ecological niche across areas.Pivotal results. The species composition analysis indicated that the Tehuantepec Isthmus...

Ecological value of retaining pyrophytic oaks in longleaf pine ecosystems

Species intolerant to fire, defined as lacking adaptations needed to establish dominance in a frequently burned landscape, are found within fire-prone ecosystems globally. Such species are frequently targeted for reduction or eradication to further conservation or restoration of biological diversity because the dominant paradigm in restoration of fire-dependent communities is to reduce the dominance or eliminate fire-intolerant invaders. To explore this paradigm, we examined the role of oaks (Quercus spp.) within fire-dependent upland and sandhill longleaf pine (Pinus palustris) ecosystems of the southeastern United States. These pine-oak ecosystems have among the highest levels of biodiversity in the temperate zone. This diversity is inextricably linked to a frequent fire regime and includes many species readily top-killed by fire, particularly oaks, which were common in the early settlement landscape. In examining the diversity of oak species found within longleaf pine ecosystems, we identify a group of pyrophytic oaks and show that these oaks are critical components of sandhill and other longleaf pine ecosystems, and their occurrence should be considered as part of conservation and restoration goals. Providing a better understanding of the ecological role of such species will benefit conservation management and strategic planning in fire-prone southeastern ecosystems and more broadly where fire is used as a management tool. © 2014 The Wildlife Society.

Estimating the potential effects of sudden oak death on oak-dependent birds

Sudden oak death (SOD), a disease induced by the fungus-like pathogen Phytophthora ramorum, threatens to seriously reduce or eliminate several oak species endemic to the west coast of North America. We investigated how the disappearance of one of these species, coast live oak ( Quercus agrifolia), may affect populations of five resident oak-affiliated California birds – acorn woodpecker ( Melanerpes formicivorus), Nuttall’s woodpecker ( Picoides nuttallii), Hutton’s vireo ( Vireo huttoni), western scrub-jay ( Aphelocoma californica), and oak titmouse ( Baeolophus inornatus) – using geocoded data from Audubon Christmas Bird Counts, North American Breeding Bird Surveys, and the California Gap Analysis. Capitalizing on observed relationships between the focal bird species and both oak species diversity and areal extent, we modeled relative bird abundance while assuming complete loss of Q. agrifolia and complete, partial, or no loss of oak habitat following a disease sweep. Post-SOD projections of bird populations occurring within the range of coast live oak were on average 25–68% smaller and 13–49% more variable relative to pre-SOD estimates. SOD effects were greatest for habitats with low initial oak species diversity. Climatic SOD models predicted that the disease stands to negatively impact populations of all five focal bird species throughout 20% of California’s coast live oak habitats. This study provides the first spatially explicit insights into the potential effects of SOD on avian distribution and abundance. Results may be used to help prioritize conservation plans aimed at minimizing overall community level disturbances resulting from the disease.

MULTIPLE TRAIT ASSOCIATIONS IN RELATION TO HABITAT DIFFERENTIATION AMONG 17 FLORIDIAN OAK SPECIES

Differentiation of species distributions along environmental gradients and phenotypic specialization help explain the co‐presence of 17 oak species that might otherwise be expected to competitively exclude one another. In an effort to understand the role of niche differentiation in the co‐presence of these congeneric species in north‐central Florida, we examined the community structure of oak‐dominated forests in this region in relation to environmental variables and a suite of life history and physiological traits. Landscape distribution patterns of oaks and other woody species were determined from randomly established plots in three state parks. Soil moisture, nutrient availability, and fire regime were found to be critical factors influencing community structure, and the distribution of oak species was strongly correlated with these gradients. Detrended correspondence analysis of species' distributions supported the grouping of oak species into three major community types: (1) hammock, (2) sandhill, and (3) scrub. Principal components of multiple traits also supported differentiation of oak species into these three groups.There is clear evidence for ecological sorting among the oaks in these forests as species partition environmental gradients more than expected by chance, and most functional traits of species correspond to species distributions as predicted based on a priori understanding of trait function. Across phylogenetic lineages, species showed evolutionary convergence in function and habitat preference. In contrast, leaf‐level traits were conserved within phylogenetic lineages and were not well correlated with local habitat factors, but rather with the broader geographic distributions and northern range limits of species. The cumulative results reported here provide strong evidence that oak species specialize for particular niches via trade‐offs in functional traits, and such niche partitioning contributes to the high diversity of oak species at the landscape level. At smaller spatial scales, phylogenetic diversity among the oaks is likely to be important in promoting their coexistence through other mechanisms.

Estimating Effects of Limiting Factors with Regression Quantiles

In a recent Concepts paper in Ecology, Thomson et al. emphasized that assumptions of conventional correlation and regression analyses fundamentally conflict with the ecological concept of limiting factors, and they called for new statistical procedures to address this problem. The analytical issue is that unmeasured factors may be the active limiting constraint and may induce a pattern of unequal variation in the biological response variable through an interaction with the measured factors. Consequently, changes near the maxima, rather than at the center of response distributions, are better estimates of the effects expected when the observed factor is the active limiting constraint. Regression quantiles provide estimates for linear models fit to any part of a response distribution, including near the upper bounds, and require minimal assumptions about the form of the error distribution. Regression quantiles extend the concept of one-sample quantiles to the linear model by solving an optimization problem of minimizing an asymmetric function of absolute errors. Rank-score tests for regression quantiles provide tests of hypotheses and confidence intervals for parameters in linear models with heteroscedastic errors, conditions likely to occur in models of limiting ecological relations. We used selected regression quantiles (e.g., 5th, 10th, . . . , 95th) and confidence intervals to test hypotheses that parameters equal zero for estimated changes in average annual acorn biomass due to forest canopy cover of oak (Quercus spp.) and oak species diversity. Regression quantiles also were used to estimate changes in glacier lily (Erythronium grandiflorum) seedling numbers as a function of lily flower numbers, rockiness, and pocket gopher (Thomomys talpoides fossor) activity, data that motivated the query by Thomson et al. for new statistical procedures. Both example applications showed that effects of limiting factors estimated by changes in some upper regression quantile (e.g., 90–95th) were greater than if effects were estimated by changes in the means from standard linear model procedures. Estimating a range of regression quantiles (e.g., 5–95th) provides a comprehensive description of biological response patterns for exploratory and inferential analyses in observational studies of limiting factors, especially when sampling large spatial and temporal scales.

ESTIMATING EFFECTS OF LIMITING FACTORS WITH REGRESSION QUANTILES

In a recent Concepts paper in Ecology, Thomson et al. emphasized that assumptions of conventional correlation and regression analyses fundamentally conflict with the ecological concept of limiting factors, and they called for new statistical procedures to address this problem. The analytical issue is that unmeasured factors may be the active limiting constraint and may induce a pattern of unequal variation in the biological response variable through an interaction with the measured factors. Consequently, changes near the maxima, rather than at the center of response distributions, are better estimates of the effects expected when the observed factor is the active limiting constraint. Regression quantiles provide estimates for linear models fit to any part of a response distribution, including near the upper bounds, and require minimal assumptions about the form of the error distribution. Regression quantiles extend the concept of one-sample quantiles to the linear model by solving an optimization problem of minimizing an asymmetric function of absolute errors. Rank-score tests for regression quantiles provide tests of hypotheses and confidence intervals for parameters in linear models with heteroscedastic errors, conditions likely to occur in models of limiting ecological relations. We used selected regression quantiles (e.g., 5th, 10th, . . . , 95th) and confidence intervals to test hypotheses that parameters equal zero for estimated changes in average annual acorn biomass due to forest canopy cover of oak (Quercus spp.) and oak species diversity. Regression quantiles also were used to estimate changes in glacier lily (Erythronium grandiflorum) seedling numbers as a function of lily flower numbers, rockiness, and pocket gopher (Thomomys talpoides fossor) activity, data that motivated the query by Thomson et al. for new statistical procedures. Both example applications showed that effects of limiting factors estimated by changes in some upper regression quantile (e.g., 90–95th) were greater than if effects were estimated by changes in the means from standard linear model procedures. Estimating a range of regression quantiles (e.g., 5–95th) provides a comprehensive description of biological response patterns for exploratory and inferential analyses in observational studies of limiting factors, especially when sampling large spatial and temporal scales.