SOIL MOISTURE VARIABILITY: IMPLICATIONS FOR THE HYDROLOGY, EROSION AND MANAGEMENT OF GULLIED CATCHMENTS IN CENTRAL SPAIN

In semi-arid environments, the combination of a non-uniform distribution of vegetation, an often highly irregular terrain and complex geological, pedological and management histories have frequently given rise to considerable spatial variability in the physical and hydrological properties of soils. Heterogeneity within the soil's physical and hydrological properties can result in pronounced differences in infiltration and soil moisture. The hydrological response of semi-arid landscapes to rainfall events may therefore be spatially non-uniform. Quantifying the spatial pattern of hydrological response is important for identifying those areas within the landscape which arc vulnerable to runoff and erosion. Since soil moisture is considered to be a key factor in determining hydrological response and its spatial distribution is a function of the soil's physical and hydrological properties, the spatial and temporal measurement of soil moisture may be used to identify contrasting areas of hydrological response. In a badlands environment located approximately 70 km north of Madrid, central Spain, an experiment was established to describe the temporal and spatial variability in soil moisture at three scales, with the primary aim of furthering the understanding of the hydrological and geomorphological processes operating in semi-arid landscapes. At each measurement scale, the macroscale (25m sampling interval), the mesoscale (gully catchments, 5m sampling interval) and the microscale (1 m sampling interval), two distinct groups of soil moisture conditions emerged related to dry and wet weather conditions. At each measurement scale the maximum variability in soil moisture is similar (>20% volumetric content difference between immediately adjacent sampling points). At the meso and microscale the spatial pattern of soil moisture could be described as a mosaic pattern which during the dry period was more fragmented and variable than during the wet period. The spatial pattern of soil moisture during wet conditions is more uniform due to the development of extensive wet areas within the catchments. During these conditions the range of spatial correlation in soil moisture may double (to greater than 30m) compared to dry conditions, indicating an increase in the spatial continuity of soil moisture. The spatial variability in soil moisture therefore displays a temporal dependency; the mosaic soil moisture pattern is more fragmented and spatially discontinuous during dry than wet conditions. A striking characteristic of the study area is the near horizontal interbedding of sediment horizons which may strongly contrast in their textural composition over relatively short distances. This variability in soil texture and the associated changes in pore size characteristics, were the principal controlling factors in determining the spatial patterns of soil moisture and overrides the known influence of vegetation and topography on soil moisture. During dry conditions the non-uniform uptake of soil moisture by vegetation may partly explain the greater variability in soil moisture observed during this period. The mosaic patterns of soil moisture represent areas of contrasting hydrological response. During dry periods when the mosaic pattern is more fragmented, source areas of overland flow are spatially isolated and surrounded by 'sink' areas capable of re-absorbing runoff and sediment deposition. Hydrological pathways are therefore discontinuous resulting in minimal runoff reaching the catchments channels. Since soil moisture values during this period are below saturation, any runoff which does occur is generated as infiltration excess overland flow. In semi-arid areas spatial variability in soil properties or vegetation patterns may therefore be beneficial for runoff and erosion control by creating a self-regulating system in which runoff producing areas are surrounded by buffer zones capable of re-absorbing the runoff. During wet periods extensive areas of the catchments may be saturated. source areas are no longer spatially isolated and continuous hydrological pathways may develop rapidly during this period. During the wet period when conditions arc above a critical saturation threshold value widespread runoff will occur regardless of the spatial variability in the soil's physical and hydrological properties. The creation of a mosaic pattern in which buffer zones are adjacent to potential runoff producing areas, as identified from spatial soil moisture patterns, may provide the most effective management strategy in runoff and erosion control for degraded semi-arid environments. The creation of a mosaic pattern is most applicable at the watershed scale allowing several land uses, including those which are potentially degrading, to co-exist. Increasing the critical threshold value above which widespread runoff occurs should also.be included as part of this management strategy

BAAD: a Biomass And Allometry Database for woody plants

CABI:20153174020Understanding how plants are constructed - i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals - is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259634 measurements collected in 176 different studies, from 21084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01-100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub-sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross-section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation

On the Measurement of Ecological Novelty: Scale-Eating Pupfish Are Separated by 168 my from Other Scale-Eating Fishes

The colonization of new adaptive zones is widely recognized as one of the hallmarks of adaptive radiation. However, the adoption of novel resources during this process is rarely distinguished from phenotypic change because morphology is a common proxy for ecology. How can we quantify ecological novelty independent of phenotype? Our study is split into two parts: we first document a remarkable example of ecological novelty, scale-eating (lepidophagy), within a rapidly-evolving adaptive radiation of Cyprinodon pupfishes on San Salvador Island, Bahamas. This specialized predatory niche is known in several other fish groups, but is not found elsewhere among the 1,500 species of atherinomorphs. Second, we quantify this ecological novelty by measuring the time-calibrated phylogenetic distance in years to the most closely-related species with convergent ecology. We find that scale-eating pupfish are separated by 168 million years of evolution from the nearest scale-eating fish. We apply this approach to a variety of examples and highlight the frequent decoupling of ecological novelty from phenotypic divergence. We observe that novel ecology is not always tightly correlated with rates of phenotypic or species diversification, particularly within recent adaptive radiations, necessitating the use of additional measures of ecological novelty independent of phenotype

Multiple continental radiations and correlates of diversification in Lupinus (Leguminosae): testing for key innovation with incomplete taxon sampling

Replicate radiations provide powerful comparative systems to address questions about the interplay between opportunity and innovation in driving episodes of diversification and the factors limiting their subsequent progression. However, such systems have been rarely documented at intercontinental scales. Here, we evaluate the hypothesis of multiple radiations in the genus Lupinus (Leguminosae), which exhibits some of the highest known rates of net diversification in plants. Given that incomplete taxon sampling, background extinction, and lineage-specific variation in diversification rates can confound macroevolutionary inferences regarding the timing and mechanisms of cladogenesis, we used Bayesian relaxed clock phylogenetic analyses as well as MEDUSA and BiSSE birth–death likelihood models of diversification, to evaluate the evolutionary patterns of lineage accumulation in Lupinus. We identified 3 significant shifts to increased rates of net diversification (r) relative to background levels in the genus (r = 0.18–0.48 lineages/myr). The primary shift occurred approximately 4.6 Ma (r = 0.48–1.76) in the montane regions of western North America, followed by a secondary shift approximately 2.7 Ma (r = 0.89–3.33) associated with range expansion and diversification of allopatrically distributed sister clades in the Mexican highlands and Andes. We also recovered evidence for a third independent shift approximately 6.5 Ma at the base of a lower elevation eastern South American grassland and campo rupestre clade (r = 0.36–1.33). Bayesian ancestral state reconstructions and BiSSE likelihood analyses of correlated diversification indicated that increased rates of speciation are strongly associated with the derived evolution of perennial life history and invasion of montane ecosystems. Although we currently lack hard evidence for “replicate adaptive radiations” in the sense of convergent morphological and ecological trajectories among species in different clades, these results are consistent with the hypothesis that iteroparity functioned as an adaptive key innovation, providing a mechanism for range expansion and rapid divergence in upper elevation regions across much of the New World

BAAD: a biomass and allometry database for woody plants\ud \ud \ud

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01–100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub-sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross-section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation

BAAD: a Biomass And Allometry Database for woody plants

Understanding how plants are constructed i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01-100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub‐sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross‐section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation

Letter abstract - Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer's Disease

We undertook a two-stage genome-wide association study (GWAS) of Alzheimer's disease (AD) involving over 16,000 individuals, the most powerful AD GWAS to date. In stage 1 (3,941 cases and 7,848 controls), we replicated the established association with the apolipoprotein E (APOE) locus (most significant SNP, rs2075650, P = 1.8 10-157) and observed genome-wide significant association with SNPs at two loci not previously associated with the disease: at the CLU (also known as APOJ) gene (rs11136000, P = 1.4 10-9) and 5' to the PICALM gene (rs3851179, P = 1.9 10-8). These associations were replicated in stage 2 (2,023 cases and 2,340 controls), producing compelling evidence for association with Alzheimer's disease in the combined dataset (rs11136000, P = 8.5 10-10, odds ratio = 0.86; rs3851179, P = 1.3 10-9, odds ratio = 0.86).<br/