The National Resources Inventory: a long-term multi-resource monitoring programme

Interest in natural resources and the environment has led to the development of new federal monitoring efforts, the expansion of existing federal inventory programmes, and discussions of inter-agency collaboration for natural resource assessment data collection. As federal programmes evolve, knowledge gained from existing long-term survey programmes can provide valuable contributions to statistical and operational aspects of survey efforts. This paper describes the National Resources Inventory (NRI), which has been conducted by the US Department of Agriculture's Natural Resources Conservation Service in cooperation with the Iowa State University Statistical Laboratory for several decades. The current NRI is a longitudinal survey of soil, water, and related environmental resources designed to assess conditions and trends every five years on non-federal US lands. An historical overview is provided highlighting the development of the survey programme. Sample design, data collection, and estimation procedures used in the 1992 NRI are described, and statistical issues related to long-term monitoring are discussed.     

Combining a generic process-based productivity model and a statistical classification method to predict the presence and absence of tree species in the Pacific Northwest,U.S.A.

Although long-lived tree species experience considerable environmental variation over their life spans, their geographical distributions reflect sensitivity mainly to mean monthly climatic conditions. We introduce an approach that incorporates a physiologically based growth model to illustrate how a half-dozen tree species differ in their responses to monthly variation in four climatic-related variables: water availability, deviations from an optimum temperature, atmospheric humidity deficits, and the frequency of frost. Rather than use climatic data directly to correlate with a species’ distribution, we assess the relative constraints of each of the four variables as they affect predicted monthly photosynthesis for Douglas-fir, the most widely distributed species in the region. We apply an automated regression-tree analysis to create a suite of rules, which differentially rank the relative importance of the four climatic modifiers for each species, and provide a basis for predicting a species’ presence or absence on 3737 uniformly distributed U.S. Forest Services’ Forest Inventory and Analysis (FIA) field survey plots. Results of this generalized rule-based approach were encouraging, with weighted accuracy, which combines the correct prediction of both presence and absence on FIA survey plots, averaging 87%. A wider sampling of climatic conditions throughout the full range of a species’ distribution should improve the basis for creating rules and the possibility of predicting future shifts in the geographic distribution of species.     

Using forest inventory data to assess fisher resting habitat suitability in California.

The fisher (Martes pennanti) is a forest-dwelling carnivore whose current distribution and association with late-seral forest conditions make it vulnerable to stand-altering human activities or natural disturbances. Fishers select a variety of structures for daily resting bouts. These habitat elements, together with foraging and reproductive (denning) habitat, constitute the habitat requirements of fishers. We develop a model capable of predicting the suitability of fisher resting habitat using standard forest vegetation inventory data. The inventory data were derived from Forest Inventory and Analysis (FIA), a nationwide probability-based sample used to estimate forest characteristics. We developed the model by comparing vegetation and topographic data at 75 randomly selected fisher resting structures in the southern Sierra Nevada with 232 forest inventory plots. We collected vegetation data at fisher resting locations using the FIA vegetation sampling protocol and centering the 1-ha FIA plot on the resting structure. To distinguish used and available inventory plots, we used nonparametric logistic regression to evaluate a set of a priori biological models. The top model represented a dominant portion of the Akaike weights (0.87), explained 31.5% of the deviance, and included the following variables: average canopy closure, basal area of trees <51 cm diameter breast height (dbh), average hardwood dbh, maximum tree dbh, percentage slope, and the dbh of the largest conifer snag. Our use of routinely collected forest inventory data allows the assessment and monitoring of change in fisher resting habitat suitability over large regions with no additional sampling effort. Although models were constrained to include only variables available from the list of those measured using the FIA protocol, we did not find this to be a shortcoming. The model makes it possible to compare average resting habitat suitability values before and after forest management treatments, among administrative units, across regions and over time. Considering hundreds of plot estimates as a sample of habitat conditions over large spatial scales can bring a broad perspective, at high resolution, and efficiency to the assessment and monitoring of wildlife habitat.     

Implementing Ecosystem Management in Public Agencies: Lessons from the U.S. Bureau of Land Management and the Forest Service

Abstract:  Ecosystem management was formally adopted over a decade ago by many U.S. natural resource agencies, including the Forest Service and the Bureau of Land Management. This approach calls for management based on stakeholder collaboration; interagency cooperation; integration of scientific, social, and economic information; preservation of ecological processes; and adaptive management. Results of previous studies indicate differences in the extent to which particular components of ecosystem management would be implemented within the U.S. Forest Service and the Bureau of Land Management and suggest a number of barriers thought to impede implementation. Drawing on survey and interview data from agency personnel and stakeholders, we compared levels of ecosystem-management implementation in the Forest Service and Bureau of Land Management and identified the most important barriers to implementation. Agency personnel perceived similarly high levels of implementation on many ecosystem-management components, whereas stakeholders perceived lower levels. Agencies were most challenged by implementation of preservation of ecological processes, adaptive management, and integration of social and economic information, whereas the most significant barriers to implementation were political, cultural, and legal.     

Resource use conflicts in Usangu Plains,Mbarali District,Tanzania

Conflicts over natural resources such as land, water, and forests are ubiquitous. People everywhere have competed for natural resources to enhance their livelihoods. However, the dimensions, level and intensity of conflict vary greatly from one place to another. This study was conducted in Usangu plains, Mbarali district, Tanzania, to investigate resource use conflicts and their underlying causes. Participatory Rural Appraisal (PRA) and household survey using a structured questionnaire were the major tools for data collection. Participant observation and secondary data sources were also used to supplement information. The study revealed the existence of resource use conflicts in the area. About 50% of respondents argued that relationships between the various ethnic groups in Usangu plains were bad. Conflicts were centred on competition for water and land. Crop damage was ranked highest (25% of respondents) as a cause behind many conflicts in the area. The study recommends that the government should redefine land tenure and land rights, enhance crop-livestock linkages and carry out a stakeholder analysis in the Usangu plains.     

A resource-based approach to modelling the dynamics of interacting populations

The procedure for modelling the growth of single-species populations [Sakanoue, S., 2007. Extended logistic model for growth of single-species populations. Ecol. Model. 205, 159–168] is improved to be applicable to the study of the dynamics of interacting populations. The improved procedure is based on three assumptions: resource availability changes with population size as a variable, resource supply to populations and population demand for resources are defined as functions of resource availability and population size, and the variables of resource availability and population size shift in the supply function attracted to the demand function. These assumptions are organized into three equations. The equations can generate the dynamics models of plant, herbivore, and detritivore populations, and their own resources. The models can be used to describe prey–predator dynamics. They naturally contain nonlinear terms for the predator’s numerical and functional responses. Depending on the terms, the fluctuations in resource availability and population size stabilize. The three equations can also generate the dynamics models of different populations consuming the same resources. The analysis of zero isoclines of the models shows that a superior population can be simply defined as one with a higher intrinsic rate of natural increase, that a stable coexistence may be realized with the intraspecific interference or the interspecific facilitation of superiors, and that the interspecific interference or the intraspecific facilitation of inferiors may make the coexistence unstable and the inferiors winners depending on their initial population size.     

A power-efficiency trade-off in resource use alters epidemiological relationships

Trade-offs play pivotal roles in the ecology and evolution of natural populations. However, trade-offs are probably not static, invariant relationships. Instead, ecological factors can shift, alter, or reverse the relationships underlying trade-offs and create critical genotype x environment (G x E) interactions. But which ecological factors alter trade-offs or create G x E interactions, and why (mechanistically) do they do this? We tackle these questions using resource quality as the central ecological factor and a case study of disease in the plankton. We show that clonal genotypes of a zooplankton host (Daphnia dentifera) exhibit a "power-efficiency" trade-off in resource use, where powerful (fast-feeding) host clones perform well on richer algal resources, but more efficient (slow-feeding) clones perform relatively well on poorer resources. This resource-based trade-off then influences epidemiological relationships due to fundamental connections between resources and fecundity, transmission rate (an index of resistance), and replication of a virulent fungal parasite (Metschnikowia bicuspidata) within hosts. For instance, using experiments and dynamic energy budget models, we show that the power-efficiency trade-off overturned a previously detected trade-off between fecundity and transmission risk of hosts to this parasite. When poorer resources were eaten, transmission risk and fecundity were negatively, not positively, correlated. Additionally, poor resource quality changed positive relationships between yield of infectious stages (spores) and host fecundity: those fecundity-spore relationships with poor food became negative or nonsignificant. Finally, the power-efficiency trade-off set up an interaction between host clone and resource quality for yield of fungal spores: powerful clones yielded relatively more spores on the better resource, while efficient clones yielded relatively more on the poorer resource. Thus, the physiological ecology of resource use can offer potent, mechanistic insight linking environmental factors to epidemiological relationships.     

Primate Conservation along the Tana River, Kenya: An Examination of the Forest Habitat

The Tana River National Primate Reserve, Kenya, was established in 1976 to preserve the endemic and endangered Tana River red colobus ( Colobus badius rufomitratus ) and crested mangabey ( Cercocebus galeritus galeritus ). Between 1975 and 1985 their populations declined by 80% and 45%, respectively. A study addressing primate-to-habitat relationships was conducted in 12 forest areas to determine what attributes appear most important to the in situ preservation of both endangered primates. Correlations among the abundances of primate groups, their group sizes, and the structural, resource, disturbance, and spatial attributes of the forest were used to distinguish the quality of forest patches. Intraforest habitat quality was examined, using canonical variate analysis to discriminate primate ranging patterns based on canopy and subcanopy tree composition. The colobus and mangabey show positive relationships to interior-forest habitat and appear susceptible to forest disturbances that reduce forest area or that increase forest edge and intraforest disturbance. Forest loss, fragmentation, and consequent reduction in the area-to-perimeter ratio of the remaining forests measured from 1960 to 1975 provide a partial explanation for the decline in primate populations. The results suggest that a combination of primary food items and seasonal food resources in large, high-stature, closed-canopy forests is the best predictor of high-quality habitat for these monkeys. Stewardship should be directed at the preservation of these areas or the restoration of forests toward this habitat model     

Halton iterative partitioning: spatially balanced sampling via partitioning

A new spatially balanced sampling design for environmental surveys is introduced, called Halton iterative partitioning (HIP). The design draws sample locations that are well spread over the study area. Spatially balanced designs are known to be efficient when surveying natural resources because nearby locations tend to be similar. The HIP design uses structural properties of the Halton sequence to partition a resource into nested boxes. Sample locations are then drawn from specific boxes in the partition to ensure spatial diversity. The method is conceptually simple and computationally efficient, draws spatially balanced samples in two or more dimensions and uses standard design-based estimators. Furthermore, HIP samples have an implicit ordering that can be used to define spatially balanced over-samples. This feature is particularly useful when sampling natural resources because we can dynamically add spatially balanced units from the over-sample to the sample as non-target or inaccessible units are discovered. We use several populations to show that HIP sampling draws spatially balanced samples and gives precise estimates of population totals.     

Major shifts in Amazon wildlife populations from recent intensification of floods and drought

In the western Amazon Basin, recent intensification of river‐level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high‐water seasons, and a drought occurred during the 2010 low‐water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km²) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish.     

Comparing resource pulses in aquatic and terrestrial ecosystems

Resource pulses affect productivity and dynamics in a diversity of ecosystems, including islands, forests, streams, and lakes. Terrestrial and aquatic systems differ in food web structure and biogeochemistry; thus they may also differ in their responses to resource pulses. However, there has been a limited attempt to compare responses across ecosystem types. Here, we identify similarities and differences in the causes and consequences of resource pulses in terrestrial and aquatic systems. We propose that different patterns of food web and ecosystem structure in terrestrial and aquatic systems lead to different responses to resource pulses. Two predictions emerge from a comparison of resource pulses in the literature: (1) the bottom-up effects of resource pulses should transmit through aquatic food webs faster because of differences in the growth rates, life history, and stoichiometry of organisms in aquatic vs. terrestrial systems, and (2) the impacts of resource pulses should also persist longer in terrestrial systems because of longer generation times, the long-lived nature of many terrestrial resource pulses, and reduced top-down effects of consumers in terrestrial systems compared to aquatic systems. To examine these predictions, we use a case study of a resource pulse that affects both terrestrial and aquatic systems: the synchronous emergence of periodical cicadas (Magicicada spp.) in eastern North American forests. In general, studies that have examined the effects of periodical cicadas on terrestrial and aquatic systems support the prediction that resource pulses transmit more rapidly in aquatic systems; however, support for the prediction that resource pulse effects persist longer in terrestrial systems is equivocal. We conclude that there is a need to elucidate the indirect effects and long-term implications of resource pulses in both terrestrial and aquatic ecosystems.     

Positives and pathologies of natural resource management on private land‐conservation areas

In managed natural resource systems, such as fisheries and rangelands, there is a recognized trade‐off between managing for short‐term benefits and managing for longer term resilience. Management actions that stabilize ecological attributes or processes can improve productivity in the supply of ecosystem goods and services in the short term but erode system resilience at longer time scales. For example, fire suppression in rangelands can increase grass biomass initially but ultimately result in an undesirable, shrub‐dominated system. Analyses of this phenomenon have focused largely on how management actions influence slow‐changing biophysical system attributes (such as vegetation composition). Data on the frequency of management actions that reduce natural ecological variation on 66 private land‐conservation areas (PLCAs) in South Africa were used to investigate how management actions are influenced by manager decision‐making approaches, a largely ignored part of the problem. The pathology of natural resource management was evident on some PLCAs: increased focus on revenue‐generation in decision making resulted in an increased frequency of actions to stabilize short‐term variation in large mammal populations, which led to increased revenues from ecotourism or hunting. On many PLCAs, these management actions corresponded with a reduced focus on ecological monitoring and an increase in overstocking of game (i.e., ungulate species) and stocking of extralimitals (i.e., game species outside their historical range). Positives in natural resource management also existed. Some managers monitored slower changing ecological attributes, which resulted in less‐intensive management, fewer extralimital species, and lower stocking rates. Our unique, empirical investigation of monitoring‐management relationships illustrates that management decisions informed by revenue monitoring versus ecological monitoring can have opposing consequences for natural resource productivity and sustainability. Promoting management actions that maintain resilience in natural resource systems therefore requires cognizance of why managers act the way they do and how these actions can gradually shift managers toward unsustainable strategies.     

Protected-Area Monitoring Dilemmas: a New Tool to Assess Success

Abstract:  Understanding factors that influence the success of protected areas in curbing unsustainable resource consumption is essential for determining best management strategies and allocating limited resources to those projects most likely to succeed. I used a law-enforcement and monitoring game-theory model from the political science literature to identify three key variables useful in predicting the success of a protected area: costs of monitoring for rule breakers, benefits of catching a rule breaker, and probability of catching a rule breaker if monitoring. Although assigning exact values for each of these variables was difficult, the variables had a strong predictive capacity even when coded as coarse ordinal values. A model in which such values were used correctly predicted the outcome of 88 of 116 protected areas sampled from the peer-reviewed literature. The model identified a critical zone of common mismatch between protected-area circumstances and management policies. In situations where the costs of monitoring were greater than the product of the probability of catching a rule breaker and the benefit of doing so, conservation was unlikely to succeed. Control of illegal use of protected resources was reported in only 8% of such cases, regardless of strategies to motivate potential users to cooperate with conservation. My model does not prescribe a best management policy for conserving natural resources; rather, it can be used as a tool to help predict whether a proposed management policy will likely succeed in a given situation.     

森林碳汇的估算方法及其发展趋势

森林生态系统是地球陆地生物圈的主体,也是陆地表面最大的碳库,在全球碳循环研究中扮演着重要角色,它通过同化作用吸收固定大气中的CO_2,抑制其浓度上升的功能对于应对气候变化问题具有积极的现实意义.准确地估算森林生态系统的碳汇储量,不仅有利于解释全球碳收支不平衡的问题,也有利于促进林业碳汇交易的快速发展.但是目前的估算方法在具有一定适用性的同时也都存在着各自的不足.评述了目前国内外应用最为广泛的样地清查法、涡度相关法及应用遥感技术的模型模拟法三种森林碳汇估算方法的发展历史和应用现状,并分析了各方法的优点与局限性.最后指出:应根据实际情况选择适合的单一方法或几种方法的结合来估算森林碳汇,以便提高估算精度;应加强森林生态系统内部联系及数据时空转换、插补的研究,并充分发挥各方法的优势,采取多种方法相结合的方式完善连续观测系统和区域监测网络的建设,降低估算方法中的不确定性,为大尺度估算提供合理的参数和数据分析基础.     

The Complex Links between Governance and Biodiversity

Abstract:  We argue that two problems weaken the claims of those who link corruption and the exploitation of natural resources. The first is conceptual and the second is methodological. Studies that use national-level indicators of corruption fail to note that corruption comes in many forms, at multiple levels, that may affect resource use quite differently: negatively, positively, or not at all. Without a clear causal model of the mechanism by which corruption affects resources, one should treat with caution any estimated relationship between corruption and the state of natural resources. Simple, atheoretical models linking corruption measures and natural resource use typically do not account for other important control variables pivotal to the relationship between humans and natural resources. By way of illustration of these two general concerns, we used statistical methods to demonstrate that the findings of a recent, well-known study that posits a link between corruption and decreases in forests and elephants are not robust to simple conceptual and methodological refinements. In particular, once we controlled for a few plausible anthropogenic and biophysical conditioning factors, estimated the effects in changes rather than levels so as not to confound cross-sectional and longitudinal variation, and incorporated additional observations from the same data sources, corruption levels no longer had any explanatory power.     

It takes more than a village: the challenges of co-management in Uganda's fishery and forestry sectors

Decentralisation policies in least developed countries have emerged in response to failed centralised natural resource governance programmes because high-value natural resources are distributed unequally, with central governments often reaping more than local-level users. Current natural resource governance institutions have been created to remedy the problems that central governments formerly posed. Here, we argue that Uganda's forestry and fishery resources are biologically diverse and thus amenable to current decentralised management programmes, provided that there is compromise between market values and local cultural and subsistence values and uses. We observe, however, Uganda's current institutional arrangement favours the former over the latter and determine that successful natural resource decentralisation requires strengthening local-level natural resource institutions with increased fiscal flow, enforcement, monitoring and judicial powers. A strong and reliable partnership between local-level resource users and the central government is necessary for this to occur.     

Potentials and limitations of using large-scale forest inventory data for evaluating forest succession models

Forest gap models have been applied widely to examine forest development under natural conditions and to investigate the effect of climate change on forest succession. Due to the complexity and parameter requirements of such models a rigorous evaluation is required to build confidence in the simulation results. However, appropriate data for model assessment are scarce at the large spatial and temporal scales of successional dynamics. In this study, we explore a data source for the evaluation of forest gap models that has been used only little in the past, i.e., large-scale National Forest Inventory data. The key objectives of this study were (a) to examine the potentials and limitations of using large-scale forest inventory data for evaluating the performance of forest gap models and (b) to test two particular models as case studies to derive recommendations for their future improvement.     

Estimation of Core Terrestrial Habitat for Stream-Breeding Salamanders and Delineation of Riparian Buffers for Protection of Biodiversity

Abstract:  Many species of wildlife depend on riparian habitats for various life-history functions (e.g., breeding, foraging, overwintering). Although this unique habitat is critical for many species, delineations of riparian zones and buffers for various taxa are lacking. Typically when buffer zones are determined to mitigate edge effects, they are based on criteria that protect aquatic resources alone and do not consider impacts to wildlife and other terrestrial resources. Using two different survey methods (area-constrained daytime searches and nighttime visual encounter searches), we estimated core terrestrial habitat and buffer widths for stream-breeding salamanders in southern Appalachian streams from May to August 2004. A core terrestrial habitat of 27.0 m encompassed 95% of the salamander assemblage (four species of stream plethodontids), and an additional 50 m (to buffer edge effects) yielded a total buffer of 77.0 m. When each species of the assemblage was analyzed separately, the maximum core terrestrial habitat needed for the Blue Ridge two-lined salamander ( Eurycea wilderae ), a dominant member and the farthest-ranging species from the stream, was 42.6 m. Thus, we recommend an overall buffer width of 92.6 m in southern Appalachian streams. To protect stream amphibians and other wildlife dependent on riparian areas, land managers and policy makers must consider conserving more than aquatic resources alone. Developing core terrestrial habitat estimates and buffer zone widths for wildlife populations is a critical first step in the conservation of many semiaquatic organisms and protecting biodiversity.     

The influence of resource subsidies on cave invertebrates: results from an ecosystem-level manipulation experiment

Spatial resource subsidies can greatly affect the composition and dynamics of recipient communities. Caves are especially tractable for studying spatial subsidies because primary productivity is absent. Here, we performed an ecosystem-level manipulation experiment to test the direct influence of detrital subsidies on community structure in terrestrial cave ecosystems. After performing baseline censuses of invertebrates, we removed all organic material from 12 caves and constructed exclusion boxes to prevent natural resource inputs. Next, we stocked each cave with standardized quantities of two major natural subsidies to caves: leaves (leaf packs) and carcasses (commercially supplied rodents), and measured the invertebrate colonization and utilization of these resources for 23 months. Over the course of the experiment, 102 morphospecies were observed. Diplopods and collembolans were most abundant on leaf packs, and dipteran larvae and collembolans were most abundant on the rats. On average, caves receiving either treatment did not differ in species richness, but abundance was significantly higher in rat caves over both the duration of the experiment and the temporal "life" of the individual resources, which were restocked upon exhaustion. Post-manipulation invertebrate communities differed predictably depending on the type of subsidy introduced. Over the course of the experiment, caves that received the same subsidy clustered together based on community composition. In addition, the invertebrate community utilizing the resource changed over the duration of the two-year experiment, and evidence of succession (i.e., directional change) was observed. Results from this study demonstrate how allochthonous resources can drive the community dynamics of terrestrial invertebrates in cave ecosystems and highlight the need for consideration of the surface environment when managing and protecting these unique habitats.     

Resource users as land-sea links in coastal and marine socioecological systems

Coastal zones, which connect terrestrial and aquatic ecosystems, are among the most resource-rich regions globally and home to nearly 40% of the global human population. Because human land-based activities can alter natural processes in ways that affect adjacent aquatic ecosystems, land-sea interactions are increasingly recognized as critical to coastal conservation planning and governance. However, the complex socioeconomic dynamics inherent in coastal and marine socioecological systems (SESs) have received little consideration. Drawing on knowledge generalized from long-term studies in Caribbean Nicaragua, we devised a conceptual framework that clarifies the multiple ways socioeconomically driven behavior can link the land and sea. In addition to other ecosystem effects, the framework illustrates how feedbacks resulting from changes to aquatic resources can influence terrestrial resource management decisions and land uses. We assessed the framework by applying it to empirical studies from a variety of coastal SESs. The results suggest its broad applicability and highlighted the paucity of research that explicitly investigates the effects of human behavior on coastal SES dynamics. We encourage researchers and policy makers to consider direct, indirect, and bidirectional cross-ecosystem links that move beyond traditionally recognized land-to-sea processes.