Reduced Canopy Cover Research Articles

Have we been successful? Monitoring horizontal forest complexity for forest restoration projects

Forest management today often seeks to restore ecological integrity and enhance human well‐being by increasing forest complexity, resilience, and functionality. However, effective and financially expedient monitoring of forest complexity is challenging. In this study, we developed a practical and inexpensive technique to measure horizontal forest complexity. This monitoring method uses intuitively understandable data (imagery) and facilitates stakeholder participation in the adaptive management process within collaborative projects. We used this technique to determine if current restoration projects are successfully achieving their spatial restoration goals. We focused on the Colorado Front Range Landscape Restoration Initiative (CFRLRI) as a representative of the typical collaborative restoration projects underway in formerly fire‐dependent dry conifer forests. The developed monitoring method is practical and cost‐effective by using free aerial imagery to map, quantify, and analyze the distribution of canopy cover pre‐ and post‐treatment. We found the CFRLRI has successfully reduced canopy cover (from 44 to 26% on average) and increased some aspects of horizontal forest complexity. The application of these monitoring techniques has allowed the CFRLRI collaborative group to objectively quantify changes to horizontal forest complexity, and has facilitated stakeholder communication about forest spatial patterns. These methods could be adapted for use by other similar forest restoration projects around the world by utilizing increasingly available satellite or aerial imagery.

The effects of riparian restoration following saltcedar (Tamarix spp.) biocontrol on habitat and herpetofauna along a desert stream

Amphibians and reptiles (herpetofauna) have been linked to specific microhabitat characteristics, microclimates, and water resources in riparian forests. Our objective was to relate variation in herpetofauna abundance to changes in habitat caused by a beetle used for Tamarix biocontrol (Diorhabda carinulata; Coleoptera: Chrysomelidae) and riparian restoration. During 2013 and 2014, we measured vegetation and monitored herpetofauna via trapping and visual encounter surveys (VES) at locations affected by biocontrol along the Virgin River in the Mojave Desert of the southwestern United States. Twenty‐one sites were divided into four riparian stand types based on density and percent cover of dominant trees (Tamarix, Prosopis, Populus, and Salix) and presence or absence of restoration. Restoration activities consisted of mechanically removing non‐native trees, transplanting native trees, and restoring hydrologic flows. Restored sites had three times more total lizard and eight times more yellow‐backed spiny lizard (Sceloporus uniformis) captures than other stand types. Woodhouse's toad (Anaxyrus woodhousii) captures were greatest in unrestored and restored Tam‐Pop/Sal sites. Results from VES indicated that herpetofauna abundance was greatest in the restored Tam‐Pop/Sal site compared with the adjacent unrestored Tam‐Pop/Sal site. Tam sites were characterized by having high Tamarix cover, percent canopy cover, and shade. Restored Tam‐Pop/Sal sites were most similar in habitat to Tam‐Pop/Sal sites. Two species of herpetofauna (spiny lizard and toad) were found to prefer habitat components characteristic of restored Tam‐Pop/Sal sites. Restored sites likely supported higher abundances of these species because restoration activities reduced canopy cover, increased native tree density, and restored surface water.

Global forest area disturbance from fire, insect pests, diseases and severe weather events

Reliable global data on forest degradation and disturbances due to fire, insect pests, diseases and severe weather are important to understand ecosystem health and condition, safeguard production of goods and services and avoid negative impacts on human livelihoods. This paper presents a global analysis of forest area affected by fire, significant insect pest outbreaks, diseases and severe weather reported by countries as part of the Global Forest Resources Assessment 2015. Between 2003 and 2012, approximately 67million hectares (1.7%) of forest land burned annually, mostly in tropical South America and Africa. In a similar reporting period, in total 142million hectares of forest land were affected by other disturbances than fire. Insect pests affected more than 85million hectares of forest, of which a major part was in temperate North America. Severe weather disturbed over 38million hectares, mostly in Asia. About 12.5million hectares were reported to be disturbed by diseases, mostly in Asia and Europe. There were strong correlations between burned forest area and the area of partial canopy cover reduction, as well as between burned forest area and net forest loss. Partial canopy cover reduction is used as a proxy for forest degradation, although it also includes land under management that is not degraded. A decreasing trend in burned forest area was found, largely accounted for by decreased area burned within the last ten years in tropical South America. However, an increasing trend in burned forest area was found in the boreal climatic domain. The data on other disturbances was not suitable for determining any year on year correlations and should be improved in future data collection exercises.

The Susceptibility of Southeastern Amazon Forests to Fire: Insights from a Large-Scale Burn Experiment

The interaction between droughts and land-use fires threaten the carbon stocks, climate regulatory functions, and biodiversity of Amazon forests, particularly in the southeast, where deforestation and land-use ignitions are high. Repeated, severe, or combined fires and droughts result in tropical forest degradation via nonlinear dynamics and may lead to an alternate vegetation state. Here, we discuss the major insights from the longest (more than 10 years) and largest (150-hectare) experimental burn in Amazon forests. Despite initial forest resistance to low-intensity fires, repeated fire during drought killed the majority of trees, reduced canopy cover by half, and favored invasive grasses—but the persistence of this novel vegetation state is unknown. Forest edges, where drying, fire intensity and grass invasion are greatest, were most vulnerable. Crucial to advancing fire ecology in tropical forests, we need to scale these results to understand how flammability and resilience postfire varies across Amazon forest types.

Natural disturbance reduces disease risk in endangered rainforest frog populations.

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11–28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.

Differences in the impacts of formal and informal recreational trails on urban forest loss and tree structure

Recreational trails are one of the most common types of infrastructure used for nature-based activities such as hiking and mountain biking worldwide. Depending on their design, location, construction, maintenance and use, these trails differ in their environmental impacts. There are few studies, however, comparing the impacts of different trail types including between formal management-created trails and informal visitor-created trails. Although both types of trails can be found in remote natural areas, dense networks of them often occur in forests close to cities where they experience intense visitor use. To assess the relative impacts of different recreational trails in urban forests, we compared the condition of the trail surface, loss of forest strata and changes in tree structure caused by seven types of trails (total network 46.1 km) traversing 17 remnants of an endangered urban forest in Australia. After mapping and classifying all trails, we assessed their impact on the forest condition at 125 sites (15 sites per trail type, plus 15 control sites within undisturbed forest). On the trail sites, the condition of the trail surface, distance from the trail edge to four forest strata (litter, understory, midstorey and tree cover) and structure of the tree-line were assessed. Informal trails generally had poorer surface conditions and were poorly-designed and located. Per site, formal and informal trails resulted in similar loss of forest strata, with wider trails resulting in greater loss of forest. Because there were more informal trails, however, they accounted for the greatest cumulative forest loss. Structural impacts varied, with the widest informal trails and all formal hardened trails resulting in similar reductions in canopy cover and tree density but an increase in saplings. These structural impacts are likely a function of the unregulated and intense use of large informal trails, and disturbance from the construction and maintenance of formal trails. The results demonstrate that different types of recreational trails vary in the type and range of impacts they cause to forests. They highlight the importance of careful consideration towards management options when dealing with trail networks especially in areas of high conservation value.

Level of UV-B radiation influences the effects of glyphosate-based herbicide on the spotted salamander.

Glyphosate-based herbicides are the number one pesticide in the United States and are used commonly around the world. Understanding the affects of glyphosate-based herbicides on non-target wildlife, for example amphibians, is critical for evaluation of regulations pertaining to the use of such herbicides. Additionally, it is important to understand how variation in biotic and abiotic environmental conditions, such as UV-B light regime, could potentially affect how glyphosate-based herbicides interact with non-target species. This study used artificial pond mesocosms to identify the effects of generic glyphosate-based herbicide (GLY-4 Plus) on mortality, cellular immune response, body size, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect moderate (UV(M)) and low (UV(L)) UV-B light regimes. Survival within a given UV-B level was unaffected by herbicide presence or absence. However, when herbicide was present, survival varied between UV-B levels with higher survival in UV(M) conditions. Herbicide presence in the UV(M) treatments also decreased body size and reduced cellular immune response. In the UV(L) treatments, the presence of herbicide increased body size and affected tail morphology. Finally, in the absence of herbicide, body size and cellular immune response were higher in UV(M) treatments compared to UV(L) treatments. Thus, the effects of herbicide on salamander fitness were dependent on UV-B level. As anthropogenic habitat modifications continue to alter landscapes that contain amphibian breeding ponds, salamanders may increasingly find themselves in locations with reduced canopy cover and increased levels of UV light. Our findings suggest that the probability of surviving exposure to the glyphosate-based herbicide used in this study may be elevated in more open canopy ponds, but the effects on other components of fitness may be varied and unexpected.

Thinning of kelp canopy modifies understory assemblages: the importance of canopy density

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 514:57-70 (2014) - DOI: https://doi.org/10.3354/meps10964 Thinning of kelp canopy modifies understory assemblages: the importance of canopy density E. B. Flukes1,*, C. R. Johnson1, J. T. Wright2 1Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia 2National Centre for Marine Conservation and Resource Sustainability, Australian Maritime College, University of Tasmania, PO Box 986, Launceston, Tasmania 7250, Australia *Corresponding author: eflukes@utas.edu.au ABSTRACT: Kelp forests in southeastern Australia form canopies that support complex understory assemblages. Predicted levels of climate change in this region are likely to impact the health and distribution of these forests, potentially resulting in large-scale reductions in canopy cover. This study determined the impacts of a permanent reduction in canopy cover of the dominant kelp in this region, Ecklonia radiata, on the structure of understory algal and sessile invertebrate community assemblages. Changes in assemblages were determined over 12 mo in 3 treatments: unmanipulated, 33% canopy reduction and 66% canopy reduction. Clearance treatments were maintained to simulate the predicted effects of long-term climate-driven canopy reduction. Thinning of E. radiata canopy (especially 66% loss) caused a shift towards a foliose algal-dominated understory, with an associated loss of sponges, bryozoans, and encrusting algae. Canopy loss homogenised existing patchiness in understory assemblages, and high recruitment of E. radiata occurred at both levels of thinning. A 66% reduction in kelp canopy increased understory community diversity, but did not affect species richness. Thus, changes to understory assemblages occurred in a density-dependent manner, with 66% canopy loss required to alter the structure of assemblages at the community scale. Changes at this scale were subtle but important (with stability attributed to a combination of biogeography and resistance to perturbation driven by high diversity), and indicate that partial loss of kelp canopy under future climate change scenarios will shift understory communities towards a foliose algal-dominated state, which has important implications for sessile invertebrates and potentially future recruitment of kelp. KEY WORDS: Ecklonia radiate · Canopy disturbance · Understory assemblages · Kelp bed · Community ecology · Canopy density · Seaweeds · Community structure Full text in pdf format PreviousNextCite this article as: Flukes EB, Johnson CR, Wright JT (2014) Thinning of kelp canopy modifies understory assemblages: the importance of canopy density. Mar Ecol Prog Ser 514:57-70. https://doi.org/10.3354/meps10964 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 514. Online publication date: November 06, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

A grass-fire cycle eliminates an obligate-seeding tree in a tropical savanna.

A grass–fire cycle in Australian tropical savannas has been postulated as driving the regional decline of the obligate-seeding conifer Callitris intratropica and other fire-sensitive components of the regional flora and fauna, due to proliferation of flammable native grasses. We tested the hypothesis that a high-biomass invasive savanna grass drives a positive feedback process where intense fires destroy fire-sensitive trees, and the reduction in canopy cover facilitates further invasion by grass. We undertook an observational and experimental study using, as a model system, a plantation of C. intratropica that has been invaded by an African grass, gamba (Andropogon gayanus) in the Northern Territory, Australia. We found that high grass biomass was associated with reduced canopy cover and restriction of foliage to the upper canopy of surviving stems, and mortality of adult trees was very high (>50%) even in areas with low fuel loads (1 t·ha−1). Experimental fires, with fuel loads >10 t·ha−1, typical of the grass-invasion front, caused significant mortality due to complete crown scorch. Lower fuel loads cause reduced canopy cover through defoliation of the lower canopy. These results help explain how increases in grass biomass are coupled with the decline of C. intratropica throughout northern Australia by causing a switch from litter and sparse perennial grass fuels, and hence low-intensity surface fires, to heavy annual grass fuel loads that sustain fires that burn into the midstorey. This study demonstrates that changes in fuel type can alter fire regimes with substantial knock-on effects on the biota.

Pinyon Pine Mortality Alters Communities of Ground-Dwelling Arthropods

We documented the effect of drought-induced mortality of pinyon pine (Pinus edulis Engelm.) on communities of ground-dwelling arthropods. Tree mortality alters microhabitats utilized by ground-dwelling arthropods by increasing solar radiation, dead woody debris, and understory vegetation. Our major objectives were to determine (1) whether there were changes in community composition, species richness, and abundance of ground-dwelling arthropods associated with pinyon mortality and (2) whether specific habitat characteristics and microhabitats accounted for these changes. We predicted shifts in community composition and increases in arthropod diversity and abundance due to the presumed increased complexity of microhabitats from both standing dead and fallen dead trees. We found significant differences in arthropod community composition between high and low pinyon mortality environments, despite no differences in arthropod abundance or richness. Overall, 22% (51 taxa) of the arthropod community were identified as being indicators of either high or low mortality. Our study corroborates other research indicating that arthropods are responsive to even moderate disturbance events leading to changes in the environment. These arthropod responses can be explained in part due to the increase in woody debris and reduced canopy cover created by tree mortality.

English

This study examined the interplay between anthropogenic habitat degradation, forest protection level and density of Turner’s Eremomela (TE) (Eremomela turneri), a globally endangered bird in Kenya’s Kakamega forest. Sampling was conducted from May-June 2012 in two contiguous and one isolated forest blocks. Logging intensity, canopy height and cover, plant species richness and other key anthropogenic disturbance were used to characterize habitat quality. Density, encounter rates and TE spatial occurrence were determined using distance sampling. Combined TE density was 0.43 SE 0.09 ha-1(N = 7, p = 0.03) and was higher in the most protected north block. Estimated overall population in closed canopy forest was 4,282 (CI = 3,417 to 5,147). High canopy cover boosted TE density (R2 = 0.786, N = 7). Logging intensity was the key driver of forest disturbance (R = 0.742; p = 0.052) leading to reduced canopy cover (R = -0.658, p = 0.050) and reduced plant species richness (R = 0.771, p = 0.042). However, TE presence in the Kisere fragment suggests resilience to some level of isolation or forest disturbance provided sizeable near-primary forest is maintained. An effective medium term conservation strategy should include stricter forest protection and reforesting logged areas to reduce the impact of logging.     Key words: Eremomela turneri, human impact, habitat quality, forest protection.

Effects of a forest pathogen on habitat selection and quality for the endangered golden‐cheeked warbler

ABSTRACTOak wilt is a fatal forest disease caused by the fungus Ceratocystis fagacearum. Loss or degradation of habitat caused by oak wilt may negatively affect forest songbirds, including the federally endangered golden‐cheeked warbler (Setophaga chrysoparia), a species that breeds exclusively in the Ashe juniper–oak woodlands (Juniperus ashei–Quercus spp.) of central Texas, USA. During 2010 and 2011, we investigated the influence of oak wilt on golden‐cheeked warbler habitat selection and quality at 25 study sites that each contained forest affected by oak wilt and unaffected forest. We assessed habitat selection in terms of use versus availability at 2 scales: within the patch and within the territory. We also assessed post‐breeding use of affected forest by comparing detection densities in affected and unaffected forest. To assess the influence of oak wilt on habitat quality, we compared the reproductive outcome of territories in unaffected and affected areas. We assessed within‐patch habitat selection for 67 territories and found that golden‐cheeked warblers used affected forest significantly less than its availability. We found use of affected forest to be variable within the 14 territories that contained affected forest in >10% of their area. Post‐breeding use of affected forest was also variable. Pairing success was 27% lower for males whose territories contained >10% affected forest but fledging success was not affected. Our results suggest that the presence of oak wilt negatively influences habitat selection and quality for golden‐cheeked warblers, likely due to reduced canopy cover in susceptible oak species. © 2013 The Wildlife Society.

Impact of Prescribed Fire, Timber Removal, and the Seed Bank on Understory Plant Diversity and Canopy Cover in an Oak-Pine Barrens, Central Wisconsin, USA

Oak-pine barrens are globally imperiled and support many endangered and threatened species. In central Wisconsin, these ecosystems have been designated as high priority for restoration by the Wisconsin Department of Natural Resources, but information regarding site potential for restoration and the most effective management approaches is lacking. In 1994, after seven decades of fire suppression, management was initiated at Quincy Bluff, a 1900-ha area with extensive oak-pine barrens. In the summer of 2010, we inventoried the area to assess the impact of prescribed fire, timber removal, and the seed bank on understory plant diversity and canopy cover. Species richness and ground layer cover in 2010 were lowest in management units treated with prescribed fire alone and were 50–150% greater in units with substantial reduction in canopy cover and basal area, secondary to timber removal and a tornado event. The cover of species designated as barrens indicator species declined in all units. Seed bank analysis demonstrated low species richness and produced few germinants of restoration value, including barrens indicator species. Despite 16 years of management, further degradation of the herbaceous understory and seed bank has occurred. These results suggest that within seven decades the resiliency of this system has been exceeded, and future management will need to address low propagule availability in order to recover understory diversity consistent with historical accounts of barrens communities.

Water balance changes in the tropical rainforest with intensive forest management system

Understanding the water balance changes in the forested area is important for managing the sustainability of water resources and anticipating potential disturbance caused by the implementation of a particular forest management system. This study was conducted in a natural tropical rainforest of Central Kalimantan, Indonesia. The objective of this study is to determine the water balance changes in the tropical rainforest under Intensive Forest Management System (IFMS) using a Thornthwaite Mather Water Balance (TMWB) model. The TMWB model calculates the water balance based on long-term average monthly precipitation, potential evapotranspiration, and combined latitudes, soil properties, and vegetation characteristics. The results found a good agreement between the predicted and observed monthly streamflows both in the natural forest and treated forest. In the natural forest found the runoff coefficient is 0.5. It is assumed that 50% of the surplus water is actually available as streamflow in any given month, and the rest become detention water to supply soil moisture and ground water. It is also assumed that 50% of detention water is available as streamflow in the next month. 1-year after IFMS treatment, the runoff coefficient increased to 0.6. Canopy cover reduction in the treated forest has reduced the annual evapotranspiration approximately in 45.3%, while the annual runoff has increased approximately in 33.7% from natural forest. The overall results of calculations using the the TMWB method indicated that the water balance status and runoff are not experiencing the problems leading to water deficit under natural tropical forest conditions. These results suggest that in the forested area, a strong relationship exists among rainfall, evapotranspiration, and runoff production. Surface disturbances, land-use changes, and reductions in canopy cover potentially impact the water balance—in particular, they influence evapotranspiration and infiltration processes that reduce evapotranspiration and increase runoff.

Stand structure and breeding birds: Implications for restoring ponderosa pine forests

Fire-adapted forests in the western United States have dramatically departed from the natural or evolutionary environment over the past century because of fire suppression, logging, grazing, and other management practices. In particular, most southwestern ponderosa pine (Pinus ponderosa) forests are characterized by dense stands of small-diameter trees that are susceptible to stand-replacing crown fires and ensuing damage to watersheds, wildlife habitat, and communities at the wildland-urban interface. Restoration treatments using mechanical thinning and prescribed fire have become the dominant management paradigm in this forest type, with landscape-scale projects being implemented over the next 20 years. Although many studies have examined wildlife responses to restoration treatments, single-species information is difficult for managers to synthesize and incorporate into management decisions made at large scales. Our goal was to investigate responses of breeding birds in ponderosa pine forests to forest stand characteristics modified by restoration treatments. We sampled birds in 23 stands for 3 years in northern Arizona, and used multi-season and multi-species occupancy models to determine relationships between avian occupancy and stand attributes affected by treatment. Increasing occupancy rates and species richness were associated with decreasing canopy cover, increasing density of mature trees, and increasing density of snags. Occupancy rates and species richness were negatively associated with quadratic mean diameter, medium-sized trees, and downed woody material. Associations of the avian community and individual species with herbaceous cover and tree clumping were less consistent. Our results support the implementation of forest restoration treatments for restoring avian community occupancy in ponderosa pine forests, and emulating the evolutionary environment is likely the best approach. We recommend reducing canopy cover via thinning, and retaining trees >45.7 cm diameter at breast height and snags. A commonly-proposed diameter cap for retaining large trees after thinning (40.6 cm dbh) seems unlikely to benefit nesting passerines, as resulting tree densities would remain too large. We recommend occupancy modeling as an efficient method for assessing wildlife-habitat relationships at large scales. © 2013 The Wildlife Society.

Are silvopastoral systems compatible with forest regeneration? An integrative approach in southern Patagonia

We used an integrated approach to analyze the influence of silvopastoral management on the biotic and abiotic factors influencing on the natural recruitment of native forests in Tierra del Fuego (Argentina). The probabilities of transition from flowers to seeds to seedlings were estimated in forests with silvopastoral management (i.e., stands that had been both grazed and thinned), secondary growth stands, and unmanaged old-growth areas. Pre-dispersal losses were caused by microclimate and insect predation acting on flowers and immature fruits. Post-dispersal losses resulted from the impact of reduced litterfall and microclimate. But the most critical stage of the overall cycle was seedling establishment. Silvopastoral practices and stand age modified the main drivers of regeneration. While flowering was unaffected by management, fruiting and seed production were more successful in unmanaged forests. Seedling establishment and survival were favored by canopy cover reduction in silvopastoral stands. The increase of solar radiation and soil moisture in managed forests positively influenced the seedling establishment and survival, while in second-growth forests it was limited by suitable micro-site availability. Thinning practices aimed at increasing the understory heterogeneity in mature forests and restoring canopy complexity of second-growth stands could be suitable for sustainable management of these temperate forests.

Wildfire Impacts on Red Imported Fire Ant Captures Around Forest Ponds in the Lost Pines Ecoregion of Texas

Abstract The impacts of high-intensity wildfires on red imported fire ant Solenopsis invicta abundances in forest systems are currently unknown. The purpose of this study was to evaluate the effects of a high-intensity wildfire around pond edges on red imported fire ant captures in the Lost Pines ecoregion of Texas, which provides habitat for most of the remaining endangered Houston toads Bufo houstonensis. The red imported fire ant is a known predator of Houston toads, and thus there is interest in understanding the potential and realized impacts of this species on Houston toad survivorship. Our results suggest the wildfire did not directly impact captures-per-unit-effort, but it had indirect positive impacts through reductions in canopy cover due to overstory tree mortality. The results of this study indicate that both area occupied by red imported fire ants and site-specific red imported fire ant densities could increase dramatically in the Lost Pines as a result of the wildfire and subsequent human-based recovery efforts.

Nonlinear variation of stream–forest linkage along a stream‐size gradient: an assessment using biogeochemical proxies of in‐stream fine particulate organic matter

Summary Spatial scale of processes is necessary information to design appropriate ecosystem research and management. In‐stream ecological processes are tightly linked with their adjacent terrestrial environment and impacted by modifications of riparian environments, particularly in small, forested streams. Quantitative understanding of how the dynamic coupling of these adjacent ecosystems varies along stream continua is necessary to enhance stream research and management. In temperate, forest‐dominated watersheds of British Columbia, Canada, we examined the stream–forest linkage along a stream‐size gradient based on biogeochemical analysis of fine particulate organic matter retained in streambed sediment (FPOMS). We analysed FPOMS at 48 stations in 14 cobble‐bed streams from 2·2 to 39 m bankfull widths during summer low‐flow conditions and tested their relationships with local, forest‐related, environmental factors (light penetration, benthic coarse POM biomass, riparian‐soil properties) along the stream‐size gradient. Carbon/nitrogen ratio of FPOMS (FPOMS‐C/N) was distinctly lower in stream bankfull widths larger than an estimated threshold around 7·6 m and corresponded with decrease in N/chlorophyll a of FPOMS and inorganic nitrogen concentration. We found significant linkages of FPOMS‐C/N with local streamside environments in streams narrower than the threshold (but not in widths <~3 m). For wider streams, reduced canopy cover was likely to enhance in‐stream nitrogen cycling by algae and consistently lowered FPOMS‐C/N regardless of streamside environment. These indicate a nonlinear attenuation of the strength of linkage between in‐stream biogeochemical processes and forest‐related environments along the stream‐size gradient. Synthesis and applications. The relationship of biogeochemical proxies of in‐stream fine particulate organic matter with local environments can be a practical tool for measuring the strength of stream‐forest linkage. Furthermore, regional‐ and stream‐specific threshold stream widths dividing in‐stream biogeochemical regimes can be an important landmark for ecologists and managers to refine designs for stream research and management at appropriate spatial scales. For stream widths narrower than a threshold, reach‐scale linkages between stream and terrestrial environments can be a major focus, and riparian conditions need to be carefully managed to protect stream habitats. For stream widths wider than a threshold, catchment impacts on streams at larger spatial scales would be a more important focus.

Evaluating Methods to Restore Amphibian Habitat in Fire-Suppressed Pine Flatwoods Wetlands

Although fire is recognized as an important disturbance in longleaf pine uplands of the southeastern US, less is known about the importance of fire or other disturbances in the wetlands embedded within this ecosystem. The reticulated flatwoods salamander (Ambystoma bishopi), a federally endangered species, and other rare and declining amphibians, are less likely to breed in low-quality wetlands with high canopy cover and low herbaceous groundcover that typically occur from fire exclusion. Fire rarely carries through these wetlands during winter because of the presence of standing water at this time of year. Our objective was to evaluate whether mechanical removal of the woody midstory could serve as a surrogate for fire, and create high-quality wetlands with moderate canopy cover and high herbaceous groundcover. We chose a series of high-quality (n = 4) and low-quality (n = 21) ephemeral wetlands for study. A subset of the low-quality wetlands were then treated mechanically and with herbicide (n = 8), burned (n = 4), or retained in a low-quality state (n = 7). Mechanical treatments reduced canopy cover (from 55.7% to 41.4%) to similar levels as high-quality sites (36.7%); however, herbaceous groundcover did not increase (17.2% post-treatment compared to 37.3% at high-quality sites). Fire reduced the canopy cover (from 41.3% to 33.0%), and herbaceous groundcover was similar (33.2% post treatment) to high-quality sites as of four months post burn. More time will be required to assess the response of herbaceous groundcover and whether mechanical methods can be used as a surrogate for fire to restore amphibian breeding habitat. Identifying surrogates for fire could add an important technique to our management toolbox.

Influence of climate, fire severity and forest mortality on predictions of long term streamflow: Potential effect of the 2009 wildfire on Melbourne’s water supply catchments

Summary In February 2009, wildfire affected nine catchments, or approximately 28% of forested catchment area that supplies water to the city of Melbourne, Australia. This has potential to significantly affect the long term water use of these Eucalyptus forests and the consequential water yield because of the ecohydrologic response of some eucalypt species. Approximately 11% of the catchment area was severely burnt by intense fire, where vegetation mortality is higher. Catchment scale models using a physically-based approach were developed for the fire-affected water supply catchments. Different inputs of climate and forest mortality after fire were used to examine the relative contributions of rainfall, fire severity, forest type and forest age on post-fire streamflow. Simulations show the effect of fire on long term streamflow is likely to depend on a number of factors, the relative influence of which changes as rainfall becomes more limiting. Under average rainfall conditions, total reduction in post-fire streamflow after 100 years estimated to be between 1.4% (∼12 GL year −1 ) and 2.8% (∼24 GL year −1 ) are an order of magnitude lower than reductions in total catchment inflow during the period of low rainfall between 1997 and 2009, in which reservoir inflow was reduced by nearly 37%. The main reasons for the lower than expected changes in water yield are that a lower proportion of the catchments were affected by severe fire, and so mortality within the fire area was relatively low, and that the average age of the forest canopy (93 years) is younger than what is generally considered old growth forest. This means that the baseline (no-fire) streamflow used for reference is lower than would be expected with older, mature forest. The greatest post-fire affect on total water yield was predicted for the O’Shannassy catchment. This is due to the average forest age, which is the oldest of any of the catchments, that it has the highest average rainfall (1680 mm year −1 ), and that it contains the largest proportion of ash-type forest severely burnt (38.7%). Under wetter than average conditions, change in post-fire water yield is largely explained by changes in average age of the forest. The rates of ET are largely determined by the conductance and interception of the forest canopy. Under lower than average rainfall conditions, when water becomes limiting, annual rainfall is the best predictor of post-fire change in water yield. Under conditions of low rainfall and low soil water content that are conducive to larger wildfires, any initial increase in post-fire streamflow due to reduced canopy cover may not occur or be detected because a substantial soil water deficit must first be removed before appreciable changes in streamflow will occur. This partly explains the lack of increase in initial post-fire streamflow reported after wildfire compared to an increase in streamflow following forest harvesting experiments during wetter periods.