TIMBER HARVEST IMPACTS ON SMALL HEADWATER STREAM CHANNELS IN THE COAST RANGES OF WASHINGTON1

ABSTRACT: We evaluated changes in channel habitat distributions, particle‐size distributions of bed material, and stream temperatures in a total of 15 first‐or second‐order streams within and nearby four planned commercial timber harvest units prior to and following timber harvest. Four of the 15 stream basins were not harvested, and these streams served as references. Three streams were cut with unthinned riparian buffers; one was cut with a partial buffer; one was cut with a buffer of non‐merchantable trees; and the remaining six basins were clearcut to the channel edge. In the clearcut streams, logging debris covered or buried 98 percent of the channel length to an average depth of 0.94 meters. The slash trapped fine sediment in the channel by inhibiting fluvial transport, and the average percentage of fines increased from 12 percent to 44 percent. The trees along buffered streams served as a fence to keep out logging debris during the first summer following timber harvest. Particle size distributions and habitat distributions in the buffered and reference streams were largely unchanged from the pre‐harvest to post‐harvest surveys. The debris that buried the clearcut streams effectively shaded most of these streams and protected them from temperature increases. These surveys have documented immediate channel changes due to timber harvest, but channel conditions will evolve over time as the slash decays and becomes redistributed and as new vegetation develops on the channel margins.     

A novel two-dimensional model for colloid transport in physically and geochemically heterogeneous porous media

A two-dimensional model for colloid transport in geochemically and physically heterogeneous porous media is presented. The model considers patchwise geochemical heterogeneity, which is suitable to describe the chemical variability of many surficial aquifers with ferric oxyhydroxide-coated porous matrix, as well as spatial variability of hydraulic conductivity, which results in heterogeneous flow field. The model is comprised of a transient fluid flow equation, a transient colloid transport equation, and an equation for the dynamics of colloid deposition and release. Numerical simulations were carried out with the model to investigate the colloid transport behavior in layered and randomly heterogeneous porous media. Results demonstrate that physical and geochemical heterogeneities markedly affect the colloid transport behavior. Layered physical or geochemical heterogeneity can result in distinct preferential flow paths of colloidal particles. Furthermore, the combined effect of layered physical and geochemical heterogeneity may result in enhanced or reduced preferential flow of colloids. Random distribution of physical heterogeneity (hydraulic conductivity) results in a random flow field and an irregularly distributed colloid concentration profile in the porous medium. Contrary to random physical heterogeneity, the effect of random patchwise geochemical heterogeneity on colloid transport behavior is not significant. It is mostly the mean value of geochemical heterogeneity rather than its distribution that governs the colloid transport behavior.     

Use of data on avian demographics and site persistence during overwintering to assess quality of restored riparian habitat

Monitoring responses by birds to restoration of riparian vegetation is relatively cost-effective, but in most assessments species-specific abundances, not demography, are monitored. Data on birds collected during the nonbreeding season are particularly lacking. We captured birds in mist nets and resighted banded birds to estimate species richness and diversity, abundance, demographic indexes, and site-level persistence of permanent-resident and overwintering migrants in remnant and restored riparian sites in California. Species richness in riparian remnants was significantly higher than in restored sites because abundances of uncommon permanent residents were greater in remnants. Species richness of overwintering migrants did not differ between remnants and restored sites. Responses among overwintering migrants (but not permanent residents) to remnant and restored riparian sites differed. Capture rates were higher in remnant or restored riparian sites for 7 of 10 overwintering migratory species. For Lincoln's Sparrows (Melospiza lincolnii) and White-crowned Sparrows (Zonotrichia leucophrys) proportions of older birds were significantly higher in remnants, even though capture rates of these species were higher in restored sites. Overwinter persistence of 4 migrant species was significantly higher in remnant than in restored sites. A higher proportion of Hermit Thrushes (Catharus guttatus, 56.3%), older Fox Sparrows (Passerella iliaca, 57.1%), Lincoln's Sparrows (59.7%), and White-crowned Sparrows (67.8%) persisted in remnants than restored sites. Our results suggest restored riparian sites provide habitat for a wide variety of species in comparable abundances and diversity as occurs in remnant riparian sites. Our demographic and persistence data showed that remnants supported some species and age classes to a greater extent than restored sites.     

ANADROMOUS SALMONID RECOVERY IN THE UMATILLA RWER BASIN,OREGON: A CASE STUDY1

ABSTRACT: The Umatilla River Basin Fisheries Restoration Plan was initiated in the early 1980s to mitigate salmonid losses caused by hydroelectric development and habitat degradation. The objectives are to enhance the abundance of endemic steelhead and reintroduce extirpated chinook and coho salmon. The project prompted collaborative effort among federal, state, and tribal agencies, and local water users. It has incorporated habitat restoration, flow enhancement, fish passage improvements, and population supplementation through artificial production. Water exchanges have successfully increased minimum flows during spring and fall migration. While flows remain depressed compared to historic conditions, there is potential for improved habitat, passage, and homing. The mean adult‐to‐adult return rate of hatchery‐reared steelhead exceeded replacement and that of the naturally‐spawning population. Although the smolt‐to‐adult survival rates of hatchery‐reared fish fluctuate, salmonid escapement has increased in recent years, permitting steelhead and spring chinook harvest. Enumeration of potential spawners and observed redds reveals an increase in natural production of all supplemented species. Comparison of hatchery‐reared and naturally‐spawning steelhead populations revealed differences in life history characteristics (in age composition and sex ratios) though run timing and genetic stock compositions of the two components of the populations have not differed. Sustained monitoring is needed to determine benefits of integrating habitat restoration and artificial production in restoring salmonid populations.     

The influence of field-scale heterogeneity on the infiltration and entrapment of dense nonaqueous phase liquids in saturated formations

Numerical simulations are used for the systematic exploration of the migration and entrapment of dense nonaqueous phase liquids (DNAPLs) in heterogeneous formations. Ensembles of realizations of random, spatially correlated permeability fields are generated and employed in model simulations of a spill event. Statistical techniques are then used to quantify the sensitivity of model predictions to input parameters, thereby identifying the parameters or processes that may be of primary importance in the determination of organic liquid distributions in heterogeneous systems. Results of the study indicate that the most critical factors in modeling organic entrapment include the spill release rate, reliable estimates of the mean, variance, and vertical correlation scale of the formation permeability, and an accurate representation of the correlation between the capillary pressure–saturation function and the permeability. In contrast, the hydraulic gradient and cross-correlation of residual saturations with permeabilities are found to have only minor influence on organic liquid distributions in such heterogeneous formations.     

Description of hydrogeologic heterogeneity and evaluation of radionuclide transport at an underground nuclear test

Realistic models of contaminant transport in groundwater demand detailed characterization of the spatial distribution of subsurface hydraulic properties, while at the same time programmatic constraints may limit collection of pertinent hydraulic data. Fortunately, alternate forms of data can be used to improve characterization of spatial variability. We utilize a methodology that augments sparse hydraulic information (hard data) with more widely available hydrogeologic information to generate equiprobable maps of hydrogeologic properties that incorporate patterns of connected permeable zones. Geophysical and lithologic logs are used to identify hydrogeologic categories and to condition stochastic simulations using Sequential Indicator Simulation (SIS). The resulting maps are populated with hydraulic conductivity values using field data and Sequential Gaussian Simulation (SGS). Maps of subsurface hydrogeologic heterogeneity are generated for the purpose of examining groundwater flow and transport processes at the Faultless underground nuclear test, Central Nevada Test Area (CNTA), through large-scale, three-dimensional numerical modeling. The maps provide the basis for simulation of groundwater flow, while transport of radionuclides from the nuclear cavity is modeled using particle tracking methods. Sensitivity analyses focus on model parameters that are most likely to reduce the long travel times observed in the base case. The methods employed in this study have improved our understanding of the spatial distribution of preferential flowpaths at this site and provided the critical foundation on which to build models of groundwater flow and transport. The results emphasize that the impacts of uncertainty in hydraulic and chemical parameters are dependent on the radioactive decay of specific species, with rapid decay magnifying the effects of parameters that change travel time.     

Spatial optimization of protected area placement incorporating ecological, social and economical criteria

We describe two approaches for spatial optimization of protected area placement, both based on maximizing an objective function that incorporates ecological, social, and economical criteria. Of these, a seed cell selection procedure works by evaluating potential cells for protection one by one, picking the one that maximizes the objective function, adding seed cells. This continues to full protection of the project area. The other is a Monte Carlo approach, which uses a likelihood sampling procedure based on weighted importance layers of conservation interest to evaluate alternative protected area sizing and placement. This is similar to the objective function of Marxan, a priority-selection decision-support tool based on optimization algorithms using geographic information system data. The two approaches are alternative options in a common spatial optimization module, which uses the time- and spatial-dynamic Ecospace model for the evaluations. The optimizations are implemented as components of the Ecopath with Ecosim approach and software. In a case study, we find that there can be protected area zoning that will accommodate economical and social factors, without causing ecological deterioration. We also find a tradeoff between including cells of special conservation interest, and the economic and social interests. While this does not need to be a general feature, it emphasizes the need to use modeling techniques to evaluate the tradeoff.     

Predicting the Deleterious Effects of Mutation Load in Fragmented Populations

Abstract:  Human-induced habitat fragmentation constitutes a major threat to biodiversity. Both genetic and demographic factors combine to drive small and isolated populations into extinction vortices. Nevertheless, the deleterious effects of inbreeding and drift load may depend on population structure, migration patterns, and mating systems and are difficult to predict in the absence of crossing experiments. We performed stochastic individual-based simulations aimed at predicting the effects of deleterious mutations on population fitness (offspring viability and median time to extinction) under a variety of settings (landscape configurations, migration models, and mating systems) on the basis of easy-to-collect demographic and genetic information. Pooling all simulations, a large part (70%) of variance in offspring viability was explained by a combination of genetic structure ( F_ST ) and within-deme heterozygosity ( H_S ). A similar part of variance in median time to extinction was explained by a combination of local population size ( N ) and heterozygosity ( H_S ). In both cases the predictive power increased above 80% when information on mating systems was available. These results provide robust predictive models to evaluate the viability prospects of fragmented populations.     

Pyric Herbivory: Rewilding Landscapes through the Recoupling of Fire and Grazing

Abstract:  Our understanding of fire and grazing is largely based on small-scale experimental studies in which treatments are uniformly applied to experimental units that are considered homogenous. Any discussion of an interaction between fire and grazing is usually based on a statistical approach that ignores the spatial and temporal interactions on complex landscapes. We propose a new focus on the ecological interaction of fire and grazing in which each disturbance is spatially and temporally dependent on the other and results in a landscape where disturbance is best described as a shifting mosaic (a landscape with patches that vary with time since disturbance) that is critical to ecological structure and function of many ecosystems. We call this spatiotemporal interaction pyric herbivory (literal interpretation means grazing driven by fire). Pyric herbivory is the spatial and temporal interaction of fire and grazing, where positive and negative feedbacks promote a shifting pattern of disturbance across the landscape. We present data we collected from the Tallgrass Prairie Preserve in the southern Great Plains of North America that demonstrates that the interaction between free-roaming bison ( Bison bison ) and random fires promotes heterogeneity and provides the foundation for biological diversity and ecosystem function of North American and African grasslands. This study is different from other studies of fire and grazing because the fires we examined were random and grazing animals were free to roam and select from burned and unburned patches. For ecosystems across the globe with a long history of fire and grazing, pyric herbivory with any grazing herbivore is likely more effective at restoring evolutionary disturbance patterns than a focus on restoring any large vertebrate while ignoring the interaction with fire and other disturbances .     

广东连州田心自然保护区香果树种群及其生境特征

香果树是中国特有的茜草科的单种属植物,1993年被列入国家重点保护植物名录（Ⅱ级）。论文首次报道了广东境内的香果树Emmenopterys henryi最大种群及其群落的基本情况,以期为深入了解该保护植物的生态适应性、种群的生存和发展提供基础资料。2013年采用美国Onset公司产HOBO-U23-002温度-湿度记录仪对广东连州田心梅树冲的香果树种群所处生境进行了为期1年的监测;测定了土壤的理化特性、叶面和旷地的光照强度、香果树群落的物种组成、香果树种群的基径径级结构与高度结构,以及叶片的某些生理生态特性。结果表明,连州田心梅树冲是香果树的适宜生长地,生境的年均气温17.315℃,年均大气相对湿度84.316%;土壤pH5.64,有机质含量1.95%（大于林外旷地的0.50%）;叶面光照强度小于旷地的12%。香果树叶片SPAD值约为40,净光合速率为2.16-12.92μmol·m-2·s-1（以CO2计）,蒸腾速率0.29-0.62 mmol·m-2·s-1（以H2O计）。群落中有维管植物33种,其中乔木层17种,以壳斗科的4种为最多,樟科3种次之;除香果树外,群落优势种为灯台树Bothrocaryum controversum、西川朴Celtis vandervoetiana、野黄桂Cinnamomum jensenianum和金叶含笑Michelia foveolata等。连州田心梅树冲的香果树种群共有97个个体,其中Ⅰ级幼苗11株（占11.34%）,Ⅱ级幼苗76株（占78.35%）,小树9株（占9.28%）,中树0株,大树1株（1.03%）;高度为0.20-2.03 m的个体数77株,占总数的79.38%。径级结构和高度结构均表明,种群目前虽暂时处于增长阶段,但因受2008年南岭地区的冰灾影响,能产生果实的大树严重受损,缺失中树阶段的个体,且Ⅰ级幼苗数量少于Ⅱ级幼苗,该种群将在一定时期后因无法更新而进入衰退阶段,为此应加强香果树的就地和迁地保护、科学研究和宣传教育。