Hierarchical Patch Dynamics Research Articles

Decades of eelgrass meadow dynamics across the northeast Pacific support seascape-scale conservation

Abstract Eelgrass meadows provide vital nearshore habitats and ecosystem services, but they have declined from human stressors and conservation efforts are now widespread. Dynamic ecosystems like eelgrass meadows naturally rearrange as disturbance and recruitment unfold across seascapes. However, some decisions that protect eelgrass only consider extant meadows, thus ignoring the potential for change. Here, we report decades of eelgrass dynamics observed across the northeast Pacific. Our observations support conservation expanded to the seascape scale, which includes potentially inhabitable areas along with extant meadows. We found that total seascape meadow area changed over time, and changes within seascapes were often asynchronous. Some meadows rearranged across seascapes over multiple kilometres and decades. Also, some seascapes compartmentalized meadow collapse, which enabled later recovery, or supported local recruitment that substantially increased total meadow area. These observations were consistent with hierarchical patch dynamics, which promote ecosystem persistence over larger space and time scales. Thus, to enable the dynamics that underpin eelgrass persistence, it is necessary to keep many eelgrass habitat options open across seascapes, rather than protect only extant meadows. Given that dynamic, hierarchical ecosystems are common along marine shorelines, this approach may be effective for both nearshore ecosystems in general and for eelgrass in particular.

Protected area tourism and management as a social-ecological complex adaptive system

This article presents a mini review of systems and resilience approaches to tourism analysis and to protected area management, and of how the Social-Ecological Complex Adaptive Systems (SECAS) framework can help link them together. SECAS is a unique framework that integrates social theories (structuration) and ecological theories (hierarchical patch dynamics) and examines inputs, outputs, and feedback across a variety of hierarchically nested social and ecological systems. After an introduction to the need for continued theoretical development, this article continues with a review of the origins and previous applications of the SECAS framework. I subsequently highlight how complex adaptive systems and resilience have been presented in the literature as a way to separately study (1) protected area management, (2) protected area tourism/ecotourism, and (3) land-use change in adjacent forest and agricultural landscapes. The purpose of this article is to build on the frameworks described in this literature and link them through the SECAS framework. I populate the SECAS framework with components identified in the literature on protected area management, ecotourism, and land-use change to present an example of a full systems perspective. Each component also represents a hierarchically nested system, such as a governance system, health system, or transportation system. I conclude with a three-step (5-part) multi-scale and temporal method for SECAS research derived from hierarchy and structuration theories.

Seeing the locust in the swarm: accounting for spatiotemporal hierarchy improves ecological models of insect populations

Ecological phenomena operate at different spatial scales and are not uniform across landscapes or through time. One ecological theory that attempts to account for scaling and spatiotemporal variances is hierarchical patch dynamics. It introduces a hierarchical patch network with smaller spatiotemporal scales being nested within larger scales. However, few studies have modeled its presence within animal population dynamics. Locusts are an excellent model for investigating the spatiotemporal hierarchy of animal population dynamics, due to their high migratory capacity, large geographic ranges that extend across widely differing environments, and available long‐term data on distributions. Here, we investigated the influence of preceding vegetation growth on desert locust Schistocerca gregaria and Australian plague locust Chortoicetes terminifera outbreaks on three spatial levels (species range > geographic region > land unit) and between seasons. Both species are dryland herbivores with population dynamics linked to habitat productivity pulses after rain. We used NDVI data (MODIS imagery) as a measure of vegetation growth in hierarchical generalized additive models at different scales. Locust outbreaks were either preceded by vegetation growth between 78 and 32 days (Australian plague locusts) or 32 and 20 days before (desert locust) the observation. Although prior vegetation growth characterized outbreaks of both species, the temporal pattern of NDVI differed between spatiotemporal levels. All model selection criteria selected for a similar spatial hierarchy for both species: geographic region > land unit which supports the hierarchical patch dynamics paradigm. Further, it illuminates important timing differences between geographic regions and land units for preceding vegetation growth and locust outbreaks which can help locust managers identify when and where outbreaks occur. By acknowledging the spatiotemporal patterning of locust abundance, we account for heterogeneity of population dynamics throughout species ranges. Our findings demonstrate the importance of incorporating spatiotemporal variation in population models of insects and other animals.

Scale associated coupling between channel morphology and riparian vegetation in a bedrock-controlled stream

Most fluvial systems exhibit systematic, continuous upstream to downstream variations in channel morphology and related ecological and hydrological parameters (emphasized by conceptual frameworks such as downstream hydraulic geometry and the river continuum concept), and discontinuous, shorter range variations (emphasized by hierarchical patch dynamics). This study investigates the relative importance of broader-scale upstream to downstream variation and local variation at the hydraulic unit scale in a bedrock-controlled stream in central Kentucky, USA. A nested ANOVA analytical approach was used to determine the relative importance of three nested spatial scales in explaining variations in channel morphology and riparian trees. Results show that channel morphology is largely controlled by local-scale variation explaining about 92% of slope, 46% of bankfull width, 99% of average depth, 54% of width-depth ratio, 86% of channel cross-sectional area, and 100% of the hydraulic radius of the channel. Different categories of substrate characteristics, however, represent anomalies with respect to variance explained at different levels. Furthermore, local-scale controls explain 60% of variations in species richness, 59% of variations in the total number of individual trees, 68% of variation in the proportion of Platanus occidentalis basal area and 43% of variation in the total number of biogeomorphic impacts. These results are consistent with the idea of tight coupling between channel morphology and riparian vegetation, although they do not, by themselves, prove such interactions. The morphological variation of the channel at the local scale is primarily attributable to the geological controls (e.g., faults, bedding planes, joints and fractures) and incision status associated with the study area. The local scale variation in vegetation pattern can be explained by the highly local edaphic differences along the riparian corridor, which is likely to be related to the local scale fluvial process-form variations, and biogeomorphic impacts and feedbacks. These patterns may therefore be common in bedrock rivers strongly influenced by geological controls.

Recreation as a Social-Ecological Complex Adaptive System

The environment and society are both the context for and product of human actions and interactions. Outdoor recreation is the primary interaction many people have with the environment and it is an interaction that greatly contributes to human well-being. To sustainably manage the social and ecological components of outdoor recreation, an integrative and dynamic systems perspective is needed. Analyses that link recreation management and recreational experiences to both social and ecological outcomes across multiple sales and over time are not developed. This article will outline how a number of fragmented recreation management frameworks such as the recreation experience model, beneficial outcomes, the recreation opportunity spectrum, limits of acceptable change, and constraints theory can be organized within a larger social-ecological framework. The outdoor recreation meta-framework presented here links structuration theory from the social sciences with theories of complex adaptive systems and hierarchical patch dynamics from ecology to understand the human and ecological drivers for and responses to outdoor recreation.

Hierarchical Patch Dynamics Perspective in Farming System Design

Farming systems are complex and include a variety of interacting biophysical and technical components. This complexity must be taken into account when designing farming systems to improve sustainability, but more methods are needed to be able to do so. This article seeks to apply the Hierarchical Patch Dynamics theory (HPD) to farming systems to understand farming system complexity and be better able to support farming system re-design. A six-step framework is proposed to adapt the HPD theory to farming system analysis by taking into account (i) spatial and temporal interactions and (ii) field and management diversity. This framework was applied to a vineyard case study. The result was a hierarchical formalization of the farming system. The HPD framework improved understanding and enabled the formalization of (i) the hierarchical structure of the farming system, (ii) the interactions between structure and processes and (iii) scaling up and down from field to farm scale. HPD theory proved to be successful in analyzing farming system complexity at the farm scale. The framework can help with specific aspects of farming system design, such as how to change the scale of study or determining which scale should be used when choosing indicators for crop management and integrating multi-scale constraints and processes.

What drives urban growth in China? A multi-scale comparative analysis

Driving forces of urban growth differ across spatial scales, but most previous studies have been done for single cities of different sizes. Multi-scale analysis of urbanization drivers is still lacking. In this study, we investigated the drivers of urban growth in the central Yangtze River Delta, China from 1990 to 2008, using a hierarchical patch dynamics (HPD) approach that consisted of three spatial scales or hierarchical administrative levels of county, prefecture, and the region. Logistic regression, partial least square regression, and Pearson correlations were used to identify specific drivers. Our results show that the main drivers of urban growth differed between hierarchical levels and over time. First, urban growth occurred frequently next to existing urban land for most cities at all the hierarchical levels, while accessibility to railways, waters and prefectural cities became unimportant to urban expansion over time. Second, GDP, non-agricultural population proportion, gross industrial output and foreign investment in actual use were the top four important socioeconomic factors influencing urban growth for the majority of cities at both the prefectural and county levels, but the relative importance of the key influencing factors of urban growth differed across different hierarchical levels. Third, economic policies and institutional shifts by the central and local governments also played an important role in urban growth especially for cities of Wuxi and Changzhou. These multiscale relations of urban growth to potential drivers, revealed via the HPD approach, are useful for strategic planning to curb excessive urban expansion in the study region. Although the geographical and socioeconomic variables could independently explain more than 75% of variations of urban growth across spatial and temporal scales, the impacts of their interactions on urban growth need further studies in the future.

Hierarchical modeling of a groundwater remediation capture system

Summary In this paper, we present a real-world demonstration of a generalized hierarchical approach for modeling complex groundwater systems, the hierarchical patch dynamics paradigm (HPDP). In particular, we illustrate how the HPDP approach enables flexible and efficient simulation of a complex contaminant capture system at one of the largest groundwater pump-and-treat remediation operations in Michigan. The groundwater flow system at the site exhibits a multi-scale pattern that is difficult to simulate using standard modeling tools because of the complex interaction between ambient hydrologic stresses and on-site remediation operations. The hierarchical modeling system was calibrated to water level measurements collected from 208 monitoring wells located both on-site and in its immediate proximity and flux measurements from 6 trenches on-site. Systematic hierarchical simulations, including forward and reverse particle tracking as well as integrated water budget analyses, were performed to study the on-going remediation. The hierarchical modeling results show that some contamination leaked off-site because of small-scale inefficiencies in the design of the remediation system. Thus, the HPDP approach provides an opportunity to analyze complex hydrological field environments in a pragmatic, time-efficient manner.

Longitudinal Distribution of the Functional Feeding Groups of Aquatic Insects in Streams of the Brazilian Cerrado Savanna.

We demonstrate that the distribution of the functional feeding groups of aquatic insects is related to hierarchical patch dynamics. Patches are sites with unique environmental and functional characteristics that are discontinuously distributed in time and space within a lotic system. This distribution predicts that the occurrence of species will be based predominantly on their environmental requirements. We sampled three streams within the same drainage basin in the Brazilian Cerrado savanna, focusing on waterfalls and associated habitats (upstream, downstream), representing different functional zones. We collected 2,636 specimens representing six functional feeding groups (FFGs): brushers, collector-gatherers, collector-filterers, shredders, predators, and scrapers. The frequency of occurrence of these groups varied significantly among environments. This variation appeared to be related to the distinct characteristics of the different habitat patches, which led us to infer that the hierarchical patch dynamics model can best explain the distribution of functional feeding groups in minor lotic environments, such as waterfalls.

Quantifying the speed, growth modes, and landscape pattern changes of urbanization: a hierarchical patch dynamics approach

Urbanization transforms landscape structure and profoundly affects biodiversity and ecological processes. To understand and solve these ecological problems, at least three aspects of spatiotemporal patterns of urbanization need to be quantified: the speed, urban growth modes, and resultant changes in landscape pattern. In this study, we quantified these spatiotemporal patterns of urbanization in the central Yangtze River Delta region, China from 1979 to 2008, based on a hierarchical patch dynamics framework that guided the research design and the analysis with landscape metrics. Our results show that the urbanized area in the study region increased exponentially during the 30 years at the county, prefectural, and regional levels, with increasing speed down the urban hierarchy. Three growth modes—infilling, edge-expanding, and leapfrogging—operated concurrently and their relative dominance shifted over time. As urbanization progressed, patch density and edge density generally increased, and the connectivity of urban patches in terms of the average nearest neighbor distance also increased. While landscape-level structural complexity also tended to increase, the shape of individual patches became increasingly regular. Our results suggest that whether urban landscapes are becoming more homogenous or heterogeneous may be dependent on scale in time and space as well as landscape metrics used. The speed, growth modes, and landscape pattern are related to each other in complicated fashions. This complex relationship can be better understood by conceptualizing urbanization not simply as a dichotomous diffusion-coalescence switching process, but as a spiraling process of shifting dominance among multiple growth modes: the wax and wane of infilling, edge-expansion, and leapfrog across the landscape.

The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters

Billions of dollars are being spent in the United States to restore rivers to a desired, yet often unknown, reference condition. In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse. Geological and ecological processes, however, create patchy and discontinuous fluvial systems. One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America. Under modern conditions, beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments. One beaver impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally alter biogeochemical cycles and ecological structures. In this article, we use hierarchical patch dynamics to investigate beaver-mediated discontinuity across spatial and temporal scales. We then use this conceptual model to generate testable hypotheses addressing channel geomorphology, n...

Landscape Pattern Dynamics and Mechanisms during Vegetation Restoration: A Multiscale, Hierarchical Patch Dynamics Approach

The spatial pattern of vegetation changes during ecological restoration, and these changes are affected by the process of restoration. The objective of this study was to integrate the pattern and mechanism of forest restoration in the Dinghushan Nature Reserve (DNR), Guangdong, China, based on data from remote sensing and long‐term field observations. We studied the pattern dynamics of three main forest types and their underlying mechanisms during restoration following a multiscale, hierarchical patch dynamics framework that integrates population, community, and landscape processes. Remote sensing data were used to determine the changes in landscape pattern during different periods of forest restoration from 1978 to 2006. At the landscape scale, the number, area, and perimeter of the needle/broad‐leaved mixed forest (MF) and the evergreen broad‐leaved forest (BF) increased, whereas those of the tropical needle‐leaved forest (NF) decreased during succession. Our analysis based on long‐term field observations indicated that the change rate of NF was lower than that of MF during 1981–1996, but became much higher during 1996–2007. The rate of change in landscape pattern and the progression of succession stages were consistent with each other. Our results also showed that species regeneration and community succession are the biological basis of forest landscape dynamics during vegetation restoration. Landscape pattern analysis allowed us to show “what” happened during vegetation restoration and “where,” and population and community analysis indicated “why” and “how” it happened.

Across-scale patterning of plant-soil–water interactions surrounding tree islands in Southern Everglades landscapes

The freshwater Everglades is a complex system containing thousands of tree islands embedded within a marsh-grassland matrix. The tree island-marsh mosaic is shaped and maintained by hydrologic, edaphic and biological mechanisms that interact across multiple scales. Preserving tree islands requires a more integrated understanding of how scale-dependent phenomena interact in the larger freshwater system. The hierarchical patch dynamics paradigm provides a conceptual framework for exploring multi-scale interactions within complex systems. We used a three-tiered approach to examine the spatial variability and patterning of nutrients in relation to site parameters within and between two hydrologically defined Everglades landscapes: the freshwater Marl Prairie and the Ridge and Slough. Results were scale-dependent and complexly interrelated. Total carbon and nitrogen patterning were correlated with organic matter accumulation, driven by hydrologic conditions at the system scale. Total and bioavailable phosphorus were most strongly related to woody plant patterning within landscapes, and were found to be 3 to 11 times more concentrated in tree island soils compared to surrounding marshes. Below canopy resource islands in the slough were elongated in a downstream direction, indicating soil resource directional drift. Combined multi-scale results suggest that hydrology plays a significant role in landscape patterning and also the development and maintenance of tree islands. Once developed, tree islands appear to exert influence over the spatial distribution of nutrients, which can reciprocally affect other ecological processes.

Hierarchical Patch Dynamics Modeling of Near-Well Dynamics in Complex Regional Groundwater Systems

One of the challenges in groundwater modeling is the prediction of hydraulic head in close proximity to a pumping well using a regional-scale model. Typical applications of numerical models to field-scale problems generally require large grids that can seldom accommodate cells as small as the actual well diameter. In this paper, we apply a dynamically integrated “hierarchical patch dynamics paradigm (HPDP)” to model detailed near-well dynamics and interactions. The HPDP enables converting a large, complex problem into a network of hierarchically nested and dynamically coupled patch models that can be easily solved. The performance of the HPDP is verified against the analytical solution for a single well, against a superposition of analytical solutions for a wellfield, and against a numerical solution in a three-dimensional heterogeneous system. The results show that the HPDP is capable of providing an accurate and efficient representation of head in a wellfield in large-scale hydrogeologic systems.

Hierarchical patch dynamics and animal movement pattern

In hierarchical patch systems, small-scale patches of high density are nested within large-scale patches of low density. The organization of multiple-scale hierarchical systems makes non-random strategies for dispersal and movement particularly important. Here, we apply a new method based on first-passage time on the pathway of a foraging seabird, the Antarctic petrel (Thalassoica antarctica), to quantify its foraging pattern and the spatial dynamics of its foraging areas. Our results suggest that Antarctic petrels used a nested search strategy to track a highly dynamic hierarchical patch system where small-scale patches were congregated within patches at larger scales. The birds searched for large-scale patches by traveling fast and over long distances. Once within a large-scale patch, the birds concentrated their search to find smaller scale patches. By comparing the pathway of different birds we were able to quantify the spatial scale and turnover of their foraging areas. On the largest scale we found foraging areas with a characteristic scale of about 400 km. Nested within these areas we found foraging areas with a characteristic scale of about 100 km. The large-scale areas disappeared or moved within a time frame of weeks while the nested small-scale areas disappeared or moved within days. Antarctic krill (Euphausia superba) is the dominant food item of Antarctic petrels and we suggest that our findings reflect the spatial dynamics of krill in the area.

The riverine ecosystem synthesis: biocomplexity in river networks across space and time

AbstractWe propose an integrated, heuristic model of lotic biocomplexity across spatiotemporal scales from headwaters to large rivers. This riverine ecosystem synthesis (RES) provides a framework for understanding both broad, often discontinuous patterns along longitudinal and lateral dimensions of river networks and local ecological patterns across various temporal and smaller spatial scales. Rather than posing a completely new model, we arrange a conceptual marriage of eco‐geomorphology (ecological aspects of fluvial geomorphology) with a terrestrial landscape model describing hierarchical patch dynamics. We modify five components of this terrestrial model for lotic ecosystems: (1) nested, discontinuous hierarchies of patch mosaics; (2) ecosystem dynamics as a composite of intra‐ and inter‐patch dynamics; (3) linked patterns and processes; (4) dominance of non‐equilibrial and stochastic processes; and (5) formation of a quasi‐equilibrial, metastable state. Our conceptual model blends our perspectives on biocomplexity with aspects of aquatic models proposed from 1980–2004.Contrasting with a common view of rivers as continuous, longitudinal gradients in physical conditions, the RES portrays rivers as downstream arrays of large hydrogeomorphic patches (e.g. constricted, braided and floodplain channel areas) formed by catchment geomorphology and climate. The longitudinal distribution of these patches, which are identifiable using standard geomorphic techniques, varies amongst rivers and is difficult to forecast above ecoregional scales. Some types of hydrogeomorphic patches may reoccur along this downstream passage. Unique ecological ‘functional process zones’ are formed by individual types of hydrogeomorphic patches because of physiochemical habitat differences which affect ecosystem structure and function.The RES currently includes 14 tenets predicting how patterns of individual species distributions, community regulation, lotic ecosystem processes, and floodplain interactions will vary over spatiotemporal scales, especially as they relate to the functional process zones formed by hydrogeomorphic differences in the river network. Copyright © 2006 John Wiley & Sons, Ltd.

An object-oriented hierarchical patch dynamics paradigm (HPDP) for modeling complex groundwater systems across multiple-scales

In this paper, we present an object-oriented hierarchical patch dynamics paradigm (HPDP) for modeling complex groundwater systems across multiple-scales – one that has the potential to significantly alleviate the infamous “curse-of-dimensionality” and the associated computational bottlenecks. The HPDP takes advantage of hierarchy theory, divides and conquers complexities, and decouples scale-dependent dynamics hierarchically. The object-oriented HPDP represents a generalization of the “telescopic-mesh-refinement” (TMR) techniques, providing dynamic model coupling, visual interactive steering, and freeing the modelers from the impractical task of having to interact offline and iteratively with potentially large numbers of modeling patches. The HPDP provides a valuable tool for understanding scale-dependent processes and for practical groundwater investigations. We illustrate the effectiveness of the HPDP and its potential for multi-scale groundwater modeling using an example.

Evidence of Hierarchical Patch Dynamics in an East African savanna?

Evidence of Hierarchical Patch Dynamics in an East African savanna?

Evidence of Hierarchical Patch Dynamics in an East African Savanna?

The Hierarchical Patch Dynamics Paradigm provides a conceptual framework for linking pattern, process and scale in ecosystems, but there have been few attempts to test this theory because most ecological studies focus on only one spatial scale, or are limited in their temporal scope. Here I use palaeoecological techniques (analysis of fossil pollen and stable carbon isotopes) to compare vegetation heterogeneity in an east African savanna at three spatial scales, over hundreds of years. The data show that patterns of vegetation change are different at the three spatial scales of observation, and suggest that different ecological processes dominate tree abundance at micro, local and landscape scales. Interactions between plants, disturbance (e.g., by fire and herbivores), climate and soil type may influence tree density at differing spatial and temporal scales. This hierarchical explanation of savanna vegetation dynamics could inform future biodiversity conservation and management in savannas.

A multi-scale segmentation/object relationship modelling methodology for landscape analysis

Natural complexity can best be explored using spatial analysis tools based on concepts of landscape as process continuums that can be partially decomposed into objects or patches. We introduce a five-step methodology based on multi-scale segmentation and object relationship modelling. Hierarchical patch dynamics (HPD) is adopted as the theoretical framework to address issues of heterogeneity, scale, connectivity and quasi-equilibriums in landscapes. Remote sensing has emerged as the most useful data source for characterizing land use/land cover but a vast majority of applications rely on basic image processing concepts developed in the 1970s: one spatial scale, per-pixel classification of a multi-scale spectral feature space. We argue that this methodology does not make sufficient use of spatial concepts of neighbourhood, proximity or homogeneity. In contrast, the authors demonstrate in this article the utility of the HPD framework as a theoretical basis for landscape analysis in two different projects using alternative image processing methodologies, which try to overcome the ‘pixel-centred’ view. The first project focuses on habitat mapping using a high dimension multi-scale GIS database. Focal patches are derived through aggregating automatically generated landscape segments using sub-patch information including dominant tree crown densities and species. The second project uses fractal-based segmentation to produce multiple candidate segmented agricultural scenes, and then develops a decision framework to choose the combination of segmentation levels best suited to identifying shrub encroachment. The challenge and flexibility of the multi-scale segmentation/object relationship modelling approach lies in the defining of the semantic rules which relate the lower level landscape units or holons to higher levels of organization. We seek to embrace the challenges of scale and hierarchy in landscapes and have tested two different ways to decompose complex natural environments into focal units utilising topological relations to model between the smallest units of differentiation and the focal level. We believe the use of a HPD theoretical framework will help development of better tools for characterizing the patterns and processes, acting through a range of scales, which make up landscapes.