Spatial Scales For Management Research Articles

Forest stand dynamics of a short‐stature tree species: Ecological knowledge for sustainable forest management

Abstract Worldwide, the implementation of forest management guidelines has tried to mimic natural forest dynamics. The Oliver forest stand dynamics model has been successful in bridging natural forest dynamics associated with the disturbances of various spatial scales and silviculture also related to various spatial scales of management. However, the application of this model (and others) is restricted to tall forests. We claim here that the general research and commercial interest bias towards tall tree species has permeated silviculture and forest management, and that both the stand dynamics of short‐stature tree species and their treatment have remained largely unexplored and unknown. Using one short‐stature tree species, Nothofagus antarctica, as a model system, we show that this species indeed follows a stand dynamic different from other tall Nothofagus‐dominated forests in southern South America. This species forms short, mature, even‐aged stands without large canopy gaps that promote tree regeneration. With this in mind, we propose a conceptual ecology‐based silvicultural guideline focusing on the creation of strip cuts or gaps along with topsoil scarification to ensure regeneration and forest reorganization after disturbances. Policy implications. The acknowledgement that short‐stature tree species follow a stand dynamic different from tall tree species necessarily implies that they must be managed differently. This recognition, along with the implementation of ecology‐based silvicultural recommendations, represents strong arguments to make modifications to forest legislation that, together, must be aimed at conservation and sustainable forest management.

Range-wide contrast in management outcomes for transboundary Northeast Pacific sablefish

Sablefish (Anoplopoma fimbria) of the Northeast Pacific support a highly mobile, valuable fishery resource currently managed as three separate populations. Recent work has shown sablefish to be genetically mixed; have high movement rates; and have synchronous biomass trends, including recent declines. A management strategy evaluation was developed with stakeholders and scientists from three regions to investigate whether spatially-structured management paradigms might result in better conservation and economic outcomes. The management strategy evaluation includes a transboundary operating model to represent spatial population dynamics including movement and a delay-difference estimation method with varying spatial complexities and potential stratifications, and harvest control rules. Mismatches in the spatial scale of management and the underlying biological units pose a crucial risk of localized depletion in the southern U.S. West Coast. This study presents one of the first transboundary, spatially-explicit management strategy evaluations conditioned to actual data. These results underscore the importance of spatial management strategy evaluation tools and implications when regional management is conducted in isolation. Future work should incorporate additional spatial hypotheses and investigate the drivers of recruitment patterns range-wide.

Adding Nuance to Our Understanding of Dog-Wildlife Interactions and the Need for Management.

The interactions of dogs and wildlife are receiving increasing attention across the globe. Evidence suggests that dogs can negatively affect wildlife in a variety of ways, including through the risk of predation, by hybridizing with other Canis species, by acting as a reservoir or vector of pathogens, and by competing with wildlife for resources. A multitude of observations and case studies for each of these interactions has led to calls to prioritize increased management of dogs, for instance, through population reduction, vaccination, movement restrictions, and enhanced care of the dogs themselves. Here, I argue that while the risks that dogs present to wildlife are real, they vary in their importance across the globe. Furthermore, often the approaches used to address these risks are championed without a full understanding of the likelihood of success given the necessary spatial scale of management, the availability of alternative management approaches, and the role dogs play in societies. For instance, culling, vaccination, and animal husbandry approaches in reducing the impacts of dogs on wildlife sometimes fail to recognize that local human populations actively recruit replacement dogs, that vaccination often fails to reach levels necessary for herd immunity, and that enhanced dog husbandry may have indirect impacts on wildlife by requiring environmentally impactful activities. I suggest there is a need for attention not only to identify the impacts of dogs but also to determine where and when such interactions with wildlife are problematic and the likelihood of success for any proposed management approach. The impacts of dogs should be mediated in a context-specific manner that accounts for factors such as the local density of dogs, the susceptibility of local wildlife populations to the risks that dog populations may represent, and the local societal norms that underpin how dogs might be managed.

Spatial variation in exploited metapopulations obscures risk of collapse.

Unanticipated declines among exploited species have commonly occurred despite harvests that appeared sustainable prior to collapse. This is particularly true in the oceans where spatial scales of management are often mismatched with spatially complex metapopulations. We explore causes, consequences, and potential solutions for spatial mismatches in harvested metapopulations in three ways. First, we generate novel theory illustrating when and how harvesting metapopulations increases spatial variability and in turn masks local-scale volatility. Second, we illustrate why spatial variability in harvested metapopulations leads to negative consequences using an empirical example of a Pacific herring metapopulation. Finally, we construct a numerical management strategy evaluation model to identify and highlight potential solutions for mismatches in spatial scale and spatial variability. Our results highlight that spatial complexity can promote stability at large scales, however, ignoring spatial complexity produces cryptic and negative consequences for people and animals that interact with resources at small scales. Harvesting metapopulations magnifies spatial variability, which creates discrepancies between regional and local trends while increasing risk of local population collapses. Such effects asymmetrically impact locally constrained fishers and predators, which are more exposed to risks of localized collapses. Importantly, we show that dynamically optimizing harvest can minimize local risk without sacrificing yield. Thus, multiple nested scales of management may be necessary to avoid cryptic collapses in metapopulations and the ensuing ecological, social, and economic consequences.

Seeking sustainability: Employing Ostrom's SESF to explore spatial fit in Maine’s sea urchin fishery

Achieving resource sustainability in complex social-ecological systems requires employing place-based management mechanisms congruent with the underlying temporal, spatial, and functional dynamics of the system in question. However, matching management to system dynamics can prove extremely challenging, as has been illustrated in Maine’s sea urchin fishery where fishery managers have struggled to resolve management spatial scale mismatch for over two decades. In Maine, the spatial scale of management far exceeds the relevant spatial dynamics of the urchin resource and leaves fine-scale urchin aggregations in a de facto open access state. These conditions facilitated the serial overharvest of urchin aggregations and resulted in the substantial loss of viable urchin habitat as overharvested areas transitioned to kelp-dominated ecosystem states that inhibit urchin recruitment. Although fishery actors contemplated adopting a number of fine-scale management alternatives to enhance social-ecological fit in the fishery, to date, no such alternatives have been employed. We adopted an ethnographic research approach and conducted semi-structured key informant interviews, document analysis of archived meeting minutes, and participant observation at co-management meetings and restoration events to explore these dynamics from the fishery’s incipience to the present. Following data analysis, we employed Ostrom’s social-ecological systems framework as a diagnostic tool to identify the factors that have influenced management spatial fit in the urchin fishery. Research findings suggest that a number of interacting variables, including harvesters’ heterogeneity and conflicting mental models of the SES, low levels of trust and social capital, and changes in the resource system following collapse impeded collective action necessary to support fine-scale management. However, changing leadership characteristics and increasing horizontal collaboration between harvesters and scientists have positively influenced governance outcomes in recent years and provide a window of opportunity to transition towards a more adaptive and collaborative governance arrangement conducive to addressing problems of fit in the urchin fishery.

After the gold rush: population structure of spiny lobsters in Hawaii following a fishery closure and the implications for contemporary spatial management

We compared mitochondrial genetic data for two spiny lobsters in Hawaii with different geographic ranges and histories of fishing pressure. Panulirus marginatus (Quoy and Gaimard, 1825) is endemic to Hawaii, and experienced a short, intense fishery in the Northwestern Hawaiian Islands (NWHI) and long-term, less intense exploitation in the Main Hawaiian Islands (MHI). Populations show significant overall structure (F ST = 0.0037, P = 0.007; D est_Chao = 0.137), with regional differentiation (F CT = 0.002, P = 0.047) between the MHI and the NWHI. Haplotype diversity did not differ significantly between regions (F2, 8 = 3.740, P = 0.071); however, nucleotide diversity is significantly higher at the primary NWHI fishery banks (0.030) than in the MHI (0.026, Tukey's P = 0.013). In contrast, Panulirus penicillatus (Olivier, 1791), found across the tropical Indo-West Pacific region, was not targeted by the NWHI fishery, but has experienced long-term exploitation in the MHI. Panulirus penicillatus has no significant overall population structure in Hawaii (F ST = 0.0083, P = 0.063; D est_Chao = 0.278), although regional differentiation (F CT = 0.0076, P = 0.0083) between the MHI and the NHWI is significant. Neither haplotype nor nucleotide diversity differed significantly between regions for P. penicillatus While neither species has suffered a loss of genetic diversity from fishing, our results highlight that only by incorporating knowledge of fishing history with genetic connectivity data can we understand the most beneficial management strategy for each species. Neither exemplar species nor specific suites of traits are reliable predictors of the spatial scales of management.

Distribution of Wild Mammal Assemblages along an Urban–Rural–Forest Landscape Gradient in Warm-Temperate East Asia

Urbanization may alter mammal assemblages via habitat loss, food subsidies, and other factors related to human activities. The general distribution patterns of wild mammal assemblages along urban–rural–forest landscape gradients have not been studied, although many studies have focused on a single species or taxon, such as rodents. We quantitatively evaluated the effects of the urban–rural–forest gradient and spatial scale on the distributions of large and mid-sized mammals in the world's largest metropolitan area in warm-temperate Asia using nonspecific camera-trapping along two linear transects spanning from the urban zone in the Tokyo metropolitan area to surrounding rural and forest landscapes. Many large and mid-sized species generally decreased from forest landscapes to urban cores, although some species preferred anthropogenic landscapes. Sika deer (Cervus nippon), Reeves' muntjac (Muntiacus reevesi), Japanese macaque (Macaca fuscata), Japanese squirrel (Sciurus lis), Japanese marten (Martes melampus), Japanese badger (Meles anakuma), and wild boar (Sus scrofa) generally dominated the mammal assemblage of the forest landscape. Raccoon (Procyon lotor), raccoon dog (Nyctereutes procyonoides), and Japanese hare (Lepus brachyurus) dominated the mammal assemblage in the intermediate zone (i.e., rural and suburban landscape). Cats (feral and free-roaming housecats; Felis catus) were common in the urban assemblage. The key spatial scales for forest species were more than 4000-m radius, indicating that conservation and management plans for these mammal assemblages should be considered on large spatial scales. However, small green spaces will also be important for mammal conservation in the urban landscape, because an indigenous omnivore (raccoon dog) had a smaller key spatial scale (500-m radius) than those of forest mammals. Urbanization was generally the most important factor in the distributions of mammals, and it is necessary to consider the spatial scale of management according to the degree of urbanization.

Discrete spatial dynamics in a marine broadcast spawner: Re-evaluating scales of connectivity and habitat associations in Atlantic cod ( Gadus morhua L.) in coastal Newfoundland

We examined the spatial dynamics of Atlantic cod, Gadus morhua, through its life history on the northeast and southeast coasts of Newfoundland in order to delineate dispersal and critical habitat requirements as potential determinants of appropriate spatial scales for management. Hydroacoustic surveys across the northeast Newfoundland shelf in 1990, 1995, and 2000 showed the distribution of the remaining large aggregations of cod to be concentrated in inshore embayments, which is contrary to historic patterns. Inshore surveys on the south coast identified local spawning aggregations at specific geographic locations, to which adults homed in subsequent years. Dispersal of eggs and larvae to the offshore occurred during spring, but was localized (within bay) in the warm summer months. Abundance of age-0 cod increased with proximity to spawning location inshore, suggesting self-recruitment within local embayments. Age-2–3 juveniles actively selected structurally complex habitat at scales of less than tens of kilometers, with home ranges typically less than 10 ha. Juveniles were associated with specific habitat types, especially at age 0, in both lab and field experiments. Our results suggest that self-recruitment and critical life-history events (e.g., spawning, settlement, and maturity) may occur within local embayments, which currently assume much greater importance to overall cod stock dynamics than in the past. Given evidence for limited dispersal, and the inshore presence of critical habitat for early life-history stages, spatial management tools that consider local dynamics may provide a greater degree of protection for coastal Newfoundland cod than previously thought.

Rivers as resources, rivers as borders: community and transboundary management of fisheries in the Upper Zambezi River floodplains

This article examines the recent convergence of community‐based and transboundary natural resource management in Africa. We suggest that both approaches have potential application to common‐pool resources such as floodplain fisheries. However, a merging of transboundary and community‐based management may reinforce oversimplifications about heterogeneity in resources, users, and institutions. A scalar mismatch between the ecosystem of concern in transboundary management and local resources of concern in community‐based management, as well as different colonial and post‐colonial histories contribute to this heterogeneity. We describe a fishery shared by Namibia and Zambia in terms of hybrid fisheries management. We examine settlement patterns, fishermen characteristics, sources of conflict, and perceptions regarding present and potential forms of fisheries management in the area. We also consider the implications that initiatives to manage resources on the local and ecosystem scale have for these fishing livelihoods. Our findings indicate that important social factors, such as the unequal distribution of population and fishing effort, as well as mixed opinions regarding present and future responsibility for fisheries management will complicate attempts to implement a hybrid community‐transboundary management initiative.