Ha Of Woodland Research Articles

A generic framework for glacial lake outburst flood investigation: A case study of Zalai Tsho, Southeast Tibet

Glacial lake outburst floods (GLOFs) are one of the most severe natural disasters, resulting in enormous socio-economic losses as well as threatening downstream settlements and infrastructure in the alpine region. Understanding historical GLOFs benefits disaster reduction and landscape conservation, but many GLOF events remain unreported or lack critical attributes. In this study, a novel framework was proposed to detect historical GLOFs and populate related attributes using a combination of Landsat, Sentinel-2 and Planet optical images, Sentinel-1 Synthetic Aperture Radar (SAR) images, field surveys, and documentation. The framework was implemented successfully on the case of Zalai Tsho, which revealed a previously unknown GLOF with critical attributes including the associated lake evolution, the flood process, and the impacts. The Zalai Tsho GLOF event in Bomi County, Southeast Tibet, occurred on July 7, 2018. Zalai Tsho emerged in 1994, and its surface area increased by 178% between 1994 and 2018, followed by a complete disappearance after the dam failure. A total water volume of 2.7 ± 0.2 × 105 m3 was released from Zalai Tsho to generate a peak discharge of 558.4 m3/s estimated by hydrological models, which destroyed a bridge, 23.2 ha of woodland, and 1.7 ha of farmland. The Zalai Tsho GLOF was initiated by intense melting waters, superimposed on water from an upstream supraglacial lake, eventually resulted in serious socio-economic losses and long-term environmental effects. Post-GLOF conservation projects play a positive role in protecting residents against flooding, while soil erosion has been exacerbated in certain areas without artificial countermeasures. This study provided an up-to-date, prototype framework for the identification of historical GLOF events to enrich the GLOF dataset and contributed to the risk assessment of GLOF and landscape conservation.

Frontier metrics for a process-based understanding of deforestation dynamics

Agricultural expansion into tropical and subtropical forests often leads to major social-ecological trade-offs. Yet, despite ever-more detailed information on where deforestation occurs, how agriculture expands into forests remains unclear, which is hampered by a lack of spatially and temporally detailed reconstruction of agricultural expansion. Here, we developed and mapped a novel set of metrics that quantify agricultural frontier processes at unprecedented spatial and temporal detail. Specifically, we first derived consistent annual time series of land-use/cover to, second, describe archetypical patterns of frontier expansion, pertaining to the speed, the diffusion and activity of deforestation, as well as post-deforestation land use. We exemplify this approach for understanding agricultural frontier expansion across the entire South American Chaco (1.1 million km2), a global deforestation hotspot. Our study provides three major insights. First, agricultural expansion has been rampant in the Chaco, with more than 19.3 million ha of woodlands converted between 1985 and 2020, including a surge in deforestation after 2019. Second, land-use trajectories connected to frontier processes have changed in major ways over the 35 year study period we studied, including substantial regional variations. For instance, while ranching expansion drove most of the deforestation in the 1980s and 1990s, cropland expansion dominated during the mid-2000s in Argentina, but not in Paraguay. Similarly, 40% of all areas deforested were initially used for ranching, but later on converted to cropping. Accounting for post-deforestation land-use change is thus needed to properly attribute deforestation and associated environmental impacts, such as carbon emissions or biodiversity loss, to commodities. Finally, we identified major, recurrent frontier types that may be a useful spatial template for land governance to match policies to specific frontier situations. Collectively, our study reveals the diversity of frontier processes and how frontier metrics can capture and structure this diversity to uncover major patterns of human–nature interactions, which can be used to guide spatially-targeted policies.

Future scenarios impact on land use change and habitat quality in Lithuania

Anticipating future land use and land cover (LULC) changes can improve our knowledge of the complexity of human-environment interactions that lead to transformations in the landscape. Therefore, it is key to understand these LULC changes under different scenarios and how they affect habitat quality (HQ) a key indicator for ecosystem services (ES) supply quality. This work aims to study the impacts of LULC changes under different scenarios: business as usual (A0), urbanisation (A1), land abandonment and afforestation (A2) and agriculture intensification (A3) in 2050. To simulate future LULC changes we applied the Cellular Automata (CA) method, and to assess HQ, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used. Spatial autocorrelation was assessed with a Moran's I index and the Getis Ord* hotspot analysis. The result showed that the LULC model calibration and validation were accurate (80%). Between 1990 and 2018 there was an increase in urban areas and forest and woodlands, which was reflected in the A0 scenario in 2050. Under the A1 scenario there was an increase in the urban area (4628 ha) compared to 2018, and in the most important cities (e.g., Vilnius, Kaunas, Klaipeda) in the scenario A2 there was an increase of 375,820 ha of woodland and forest. Finally, under the scenario A3, a large growth in cropland area (884,030 ha) was identified. HQ model had a better validation using three cover density data (r2 = 0.67), than with imperviousness (r2 = 0.26). A2 scenario showed the highest HQ and A3 scenario have the lowest HQ. The land uses of 1990, 2018, and A3 scenario had a clustered distribution while A0, A1 and A2 showed a random pattern. The results can support policy-makers by assessing the impact of future LULC changes in Lithuania.

A Place for Volunteers in Field Sciences

A Place for Volunteers in Field Sciences

Monitoring intra and inter annual dynamics of forest degradation from charcoal production in Southern Africa with Sentinel – 2 imagery

The contribution of forest degradation to changes in forest carbon stocks remains poorly quantified and constitutes a main source of uncertainty in the forest carbon budget. Charcoal production is a major source of forest degradation in sub-Saharan Africa. We used multitemporal Sentinel-2 imagery to monitor and quantify forest degradation extent in the main supplying area of a major urban center of southern Africa over a 4-year period. We implemented an indirect approach combining Sentinel-2 imagery to map kiln and field measurements to estimate AGB removals and carbon losses from charcoal production. This work generated 10 m resolution maps of forest degradation extent from charcoal production in the study area at quarterly intervals from 2016–2019. These maps reveal an intense and rapid forest degradation process and expose the spatial and temporal patterns of forest degradation from charcoal production with high detail. The total area under charcoal production over the study period reached 26,647 ha (SD = 320.8) and the forest degradation front advanced 10.5 km in a 4-year period, with an average of 19.4 ha of woodlands degraded daily. By the end of 2019, charcoal production disturbed most mopane stands in the study area and woodland fragmentation increased in 70.4 % of the mopane woodlands. We estimated that charcoal production was responsible for 2,568,761 Mg (SD = 42,130) of aboveground biomass extracted from the forest and 1,284,381 Mg (SD = 21,075) of carbon loss. The magnitude of these figures underlines the relevance of charcoal production as a main cause of forest cover change and remarks the existing uncertainties in the quantification of forest degradation processes. These results illustrate the potential of multitemporal medium resolution imagery to quantify forest degradation in sub-Saharan Africa and improve REDD + Monitoring, Reporting, and Verification systems in compliance with international reporting commitments.

Cellular automata Markov chain model based deforestation modelling in the pastoral and agro-pastoral areas of southern Ethiopia

Permanent conversion of woodland to large-scale commercial agriculture, pastures or urban areas and temporary or partial removal of indigenous trees for shifting cultivation and selective logging remained major environmental challenges in the tropical region. Cognizant of the environmental changes prevailing in the pastoral and agro-pastoral areas of Southern Ethiopia, we have examined the past conversion of woodland to other land uses through the analysis of Landsat Multi-spectral scanner (MSS) 1973, Thematic Mapper(TM) 1986, Enhanced Thematic Mapper (ETM+) 2003, Operational Land Imagery (OLI) 2017 and then projected the future change in land use/cover (LUC) as well. We have employed Cellular Automata Markov chain model to simulate and predict LUC changes between 2017 and 2060. Four spatial driver variables such as distance to road and settlement, slope and elevation were used to run the simulation. Prior to the prediction, we have simulated the LUC of 2017 using transition potential maps of 2003 and transition matrix between 1973 and 2003. The predictive power of the model was then examined by comparing the reference and simulated LUC maps of 2017and also using the kappa index. A good correlation was obtained between the reference and simulated LUC maps of 2017. In addition, the computed kappa index was above 0.9, which implies that the model is effective in predicting change in LUC. The analysis result revealed that in the entire monitoring period (1973–2017) the area lost 89,875 ha of woodland. The loss is expected to continue during the period 2017–2060, with an estimated loss of 32,423 ha of woodland, if a proper measure is not taken against the continuous loss of woodland. Thus, relentless efforts are needed to rehabilitate the already degraded land and also minimize the potential loss of woodland in the future through the implementation of conservation – livelihood approach, REDD + project, and sustainable land use management strategies.

Impact of managed woodland grazing on forage quantity, quality and livestock performance: the potential for silvopasture in Central Minnesota, USA

Over 177,000 ha of woodlands in Minnesota, USA are grazed. In general, these woodlands are not managed specifically for timber or cattle benefits. This lack of management often leads to decreased timber value and reduced forage yields. Silvopasture is a potential alternative to overcome this lack of land management on Minnesota woodlots. However, very limited information are available about silvopasture use in Minnesota. This three-year study evaluated the potential for silvopasture in Minnesota by comparing the production of unmanaged woodland grazing, silvopastoral, and open pasture systems. Three farmers from Central Minnesota collaborated in this study to assess these grazing systems. Silvopasture paddocks were established when thinning and seeding were performed on woodland areas. We assessed forage production, forage quality, and livestock performance. Forage production was generally greater in silvopastoral systems compared with unmanaged woodland grazing systems, while forage quality was lower in open pasture systems, at least during the first year. Livestock performance was similar between the grazing systems. Results indicate that silvopasture has potential in Minnesota, but more research is required to develop specific management guidelines as well as to monitor silvopasture production systems for longer periods of time.

Zalesianie gruntów rolnych i nieużytków w gminie Szadek w latach 1995–2015

Charakterystyczną cechą przemian współczesnego krajobrazu Polski jest zmniejszanie się powierzchni gruntów rolniczo użytkowanych na rzecz lasów. W pracy przedstawiono dane na temat zalesień słabych gruntów rolnych i tzw. nieużytków zrealizowanych w gminie Szadek w ostatnim dwudziestoleciu. Odnotowano, że w analizowanym okresie powierzchnia lasów tego obszaru zwiększyła się o około 300 ha. Uprawy leśne założono na ponad 170 ha gruntów prywatnych, przy czym w ostatnim dziesięcioleciu zalesiono zaledwie 27 ha. Działalność związana ze zmianą formy użytkowania gruntu prywatnego z rolnego na leśny jest od 2004 r. (po wstąpieniu Polski do Unii Europejskiej) wspierana finansowo ze środków Europejskiego Funduszu Rolnego na rzecz Rozwoju Obszarów Wiejskich w ramach Wspólnej Polityki Rolnej UE. Według danych Agencji Restrukturyzacji i Modernizacji Rolnictwa w Gminie Szadek na zalesienie 23,75 ha gruntów przeznaczono ponad 800 tys. zł (w ramach Programu Rozwoju Obszarów Wiejskich). Stwierdzono, że rozmiar realizowanych zalesień był warunkowany m.in. brakiem długoterminowej stabilności zasad udzielania wsparcia finansowego, ale też znaczącym wzrostem wartości rynkowej gruntów rolnych. Brak stabilizacji gospodarczej czy politycznej oraz zmiany regulacji prawnych związanych z użytkowaniem gruntów rolnych i leśnych w krajach Unii Europejskiej, w tym w Polsce, hamują – uzasadniony względami ekonomicznymi (zalesianie gruntów nieodpowiednich do prowadzenia gospodarki rolnej) i ekologicznymi (odtworzenie ekosystemów leśnych w krajobrazie zdominowanym przez pola uprawne) – proces zalesiania słabych gruntów rolnych i nieużytków.

Current status and recent trend of the Eurasian Woodcock Scolopax rusticola as a breeding bird in Britain

Capsule The breeding Woodcock population in Britain in 2013 was estimated at 55 241 males (95% CL: 41 806–69 004), suggesting a large-scale decline that is supported by 2 additional sources of data.Aims To provide an updated estimate of the size of Britain's breeding Woodcock population, measure recent trends and identify spatial patterns of change.Methods Displaying male Woodcock were surveyed at a stratified sample of 834 randomly selected sites. Population estimates were compared with a baseline survey conducted in 2003 and the trend with data from annual Woodcock counts (2003–13) and Bird Atlas 2007–11.Results Woodcock were estimated to be present at 22% of 1 × 1 km squares containing ≥10 ha of woodland, compared to 35% in 2003. The British population estimate fell by 29% between 2003 and 2013. The Atlas suggests that presence at the 10 × 10 km scale has declined by 56% between 1970 and 2010. Both data sources suggest regional variation in the rate of decline, with losses greatest in the West and South.Conclusion The Woodcock's population size and breeding range appear to be declining severely across Britain. Regional variation in the rate of decline might be explained by the distribution of large continuous woodlands.

Landscape pattern changes at a catchment scale: a case study in the upper Jinjing river catchment in subtropical central China from 1933 to 2005

Land use and cover changes have been reported to have a great association with the alteration of regional ecological functions, and, thus, pose significant changes to the environmental quality. The analysis of landscape pattern changes is regarded as one of the most important prerequisites to quantify such land use and cover changes. Four-year land use maps (1933, 1955, 1990, and 2005) of the upper Jinjing river catchment in Hunan Province in subtropical central China, consisting of an area of 13,500 ha and containing three administrative districts (ADs) (Jinjing, Guanjia, and Tuojia), were used for analyzing the landscape pattern changes. Our results showed that a major landscape pattern has been established since 1933. A moderate changing trend, the decrease of woodland resulting from the increase of paddy field, was also observed. From 1933 to 2005, 1,270 ha of woodland were converted to paddy field, accounting for 13 % of the woodland present in 1933. An analysis of landscape indices demonstrated that the catchment landscape became more heterogeneous from 1933 to 1990, and that the patch fragmenting trend has remained fairly stable since 1990. Compared to the other two ADs, Jinjing showed a contrasting trajectory in the temporal trend of the largest patch index, indicating a distinct urbanization in that AD since 1990. Guanjia showed a different temporal trend in the perimeter-area fractal dimension, suggesting that this district was experiencing disordered development, and, thus, a comprehensive planning should be a concern. The predominant driving forces for the land use changes were found to be the terrain and the governmental policies. Climate change and anthropogenic activities (e.g., rapid population growth and migration) may also be important factors that have impacted the landscape changes of the studied catchment.

Phosphorus dynamics in an ephemeral wetland ecosystem after re-flooding

To test whether large amounts of phosphorus (P) are accumulated in the floodplain during dry antecedent conditions, and whether they would be released as the predominant source of P in the overlaying floodwater, in accord with the Flood Pulse Concept, we calculated the mass balance of P in an intermittent floodplain wetland after environmental water application. The P mass balance was calculated by combining a wetland water balance model and P releasing dynamics that were estimated from glasshouse sediment inundation experiments. Upon receiving environmental water, which inundated 412 ha of swamps and river red gum (Eucalyptus camaldulensis) woodlands, our results showed that 394.5 kg of P was mobilised in the system (342.0 kg from 368.4 ha of woodland and 52.5 kg from 43.6 ha of swamp and channels). In addition, the mass of P in incoming water was 74.0 kg, giving a peak in situ mass of 468.5 kg P in the water column. The estimation was verified using the water column P calculated from field samples. Our results indicated that the majority of P (84.2%) was internal loading, and the floodplain may be a source of P enrichment for adjacent water bodies or groundwater if floodwater is discharged rapidly. However, our modelling results also suggested that the high concentration of P in the water column was not sustained most probably because soils re-adsorbed the dissolved P. Approximately 110 days for the woodland and 39 days for the swamp were needed to reduce the P levels to 20% of their peak values respectively. Environmental water managers must decide how to manage P-enriched floodwater; retaining floodwater in the floodplain for a long time could reduce the risk of P enrichment downstream receiving water bodies; or, keeping internal P loading in the wetland could cause eutrophication in the system that was initially targeted for restoration. Best management practices, such as staged flooding and flooding timing are discussed.

Drought and Heat Triggers Sudden and Severe Dieback in a Dominant Mediterranean-Type Woodland Species

th , 2012; revised July 10 th , 2012; accepted July 25 th , 2012 Ecosystems in Mediterranean climate regions are projected to undergo considerable changes as a result of shifting climate, including from extreme drought and heat events. A severe and sudden dieback event, occurring in regionally significant Eucalyptus gomphocephala woodland in Western Australia, coincided with extreme drought and heat conditions in early 2011. Using a combination of remote sensing and fieldbased approaches, we characterized the extent and severity of canopy dieback following the event, as well as highlighted potential predisposing site factors. An estimated 500 ha of woodland was severely affected between February and March 2011. Tree foliage rapidly discolored and died over this period. In the affected portion of the woodland, approximately 90% of trees greater than 20 cm DBH were impacted, while in the adjacent unaffected woodland 6% showed signs of damage. Tree density in the unaffected area had approximately 4.5 times more trees than the affected woodland. Precipitation drainage patterns are thought to explain the difference between affected and unaffected woodland. Dropping groundwater levels, a relatively shallow soil profile, and extreme drought and heat in 2010-2011 are thought to predispose water-shedding sites to drought-triggered canopy dieback during extended periods of dryness. Tracking forest health changes in response to severe disturbance is an important key to deciphering past and future vegetation change.

Phytophthora ramorum and Phytophthora kernoviae: the woodland perspective

Phytophthora ramorum and P. kernoviae were first identified in Great Britain (GB) in 2002 and 2003 respectively, although both are believed to have been present for perhaps 10–20 years. Public gardens have been badly affected by these pathogens, but British woodlands are also considered at risk as a number of tree species have been found to be susceptible to the pathogens. The principal host of both Phytophthoras in GB is Rhododendron ponticum, which is arguably our most invasive weed species. It is found extensively in GB, especially along the west coast which has ideal climatic conditions for its growth and spread. In 2004 the Forestry Commission surveyed 1479 woodlands where R. ponticum was present, and in 2008 both infected and non‐infected R. ponticum were cleared from approximately 1200 ha of woodlands in England and Wales where P. ramorum had been found. No clearance to date has taken place in Scotland. In the case of a positive finding in a garden or woodland, all woodlands with rhododendron within a 3 km radius of such a finding are to be surveyed. As both pathogens are notifiable any positives must be eradicated or contained through the serving of an official phytosanitary notice. Ministerial approval has now been given to a joint Defra and Forestry Commission initiative to undertake inter alia the removal of host plants (primarily rhododendrons) infected with these sporulating pathogens in woodlands and the wider environment in England and Wales. A similar programme will be effected in Scotland where the Forestry Commission is working with the Scottish Government’s Rural Payments and Inspections Directorate.

Densities and population estimates of breeding Eurasian Woodcock Scolopax rusticola in Britain in 2003

Capsule The breeding Eurasian Woodcock population in Britain was estimated at 78 346 males (95% CL 61 717–96 493), with substantial differences in densities between regions and woodland type. Aim To estimate the breeding population size of Woodcock in Britain using a dedicated survey method, to enable assessment of current status and the creation of a baseline for future monitoring. Methods Passes of roding male Woodcock were recorded on three evening visits to 807 randomly selected sites, stratified by region and woodland size, by volunteer observers during May–June 2003. Results Roding Woodcock were present in 35% of 1‐km squares containing at least 10 ha of woodland and the mean density of males in occupied squares was 2.76 ± 0.29 birds/km2 (± se). There was significant regional variation in the occurrence and density of roding Woodcock. Woodcock presence differed between woodland types at the 1‐km2 level and the stand level, but densities within occupied woods were similar across woodland types. Conclusion Previous estimates of the size of the British breeding Woodcock population are far too low and the species shows much spatial variation in breeding density.

Slow recolonization of burned oak–juniper woodlands by Ashe juniper ( Juniperus ashei): Ten years of succession after crown fire

Fire is an important control on the distribution of plant communities on the Edwards Plateau in central Texas. Although the effects of fire in grasslands have been well studied, little is known about the recovery of mature oak–Ashe juniper ( Quercus spp.– Juniperus ashei) woodlands after crown fire. These woodlands are the only nesting habitat of the endangered golden-cheeked warbler ( Dendroica chrysoparia). In February 1996, crown fires burned more than 4000 ha of woodland on Fort Hood Military Reservation. Permanent transects were installed in moderately to severely burned areas on three soils types in 1996 and data were collected annually from 1996 to 2002 and again in 2005. We also sampled 36 transects in unburned areas on the same soil types in 2001 and 2005. Overall stem density (all species combined) in the burned areas recovered rapidly, at least in the smaller size classes (<1.8 m tall), and, by 2005, sapling stem density (>1.8 m tall, <5 cm dbh) was higher in burned areas than in unburned areas for all soil types (ANOVA, p < 0.02). Tree density (>5 cm dbh) in burned areas remained low until 2005 (2001: 20 ± 36 stems/ha; 2005: 326 ± 260 stems/ha). The dominant oak species recovered rapidly due to vigorous resprouting. Ashe juniper, a fire-sensitive species, recovered much more slowly. Only six Ashe juniper saplings (and no trees) were found in burned transects in 2005, compared to 646–871 trees/ha in unburned areas. Although Ashe juniper was largely absent from the burned areas, post-fire species composition was otherwise similar to unburned communities and became more similar with time (Sorenson similarity index in 1996: 0.70–0.83; 2005: 0.86–0.88). NMS ordination separated burned communities on different soils more than unburned communities, because all unburned areas were dominated by Ashe juniper. Due to the slow recovery of Ashe juniper, it will likely be decades before the burned areas are again suitable as breeding habitat for golden-cheeked warblers.

Using Radio-tracking and Direct Observation to Estimate Roe Deer Capreolus Capreolus Density in a Fragmented Landscape: A Pilot Study

In this pilot study, we estimate roe deer Capreolus capreolus density in a fragmented landscape, using radio-tracking and direct observation in a Petersen-Lincoln framework with the joint hypergeometric maximum likelihood estimator. We used radio-tracking to obtain a direct count of the number of marked animals potentially observable in a given sample area, thus avoiding edge effects. We then carried out a coordinated observation survey, including drive beating, to ascertain the proportion of marked roe deer in the population sampled and thus generate a population estimate. Surveys were repeated three times in four sample blocks within the fragmented landscape, and estimates were compared to a sample block of a central forest in the same area. In general, roe deer are difficult to observe and census, but our experimental set-up in the fragmented landscape enabled us to observe on average 75% of marked animals present in a given survey (compared to 21.5% in the central forest). The variability in capture probability between individuals was low as three quarters of all marked individuals were observed in all, or all but one, of the surveys. Density estimates were largely similar across the sample blocks of the fragmented landscape (4.0-7.9 deer/100 ha), but lower than in the central forest (34.3 deer/100 ha). The variability of daily population estimates was quite low and similar in the fragmented landscape (CV of 25.9%) and the central forest (CV of 25.3%). Taking availability of woodland into account, the density in the fragmented landscape was as high, or higher, than in the central forest, reaching an exceptional 145.3 deer/100 ha of woodland in one survey area.

A comparison of terrestrial snail faunas between strip-mined land and relatively undisturbed land in Ohio, USA – an evaluation of recovery potential and changing faunal assemblages

Terrestrial snail surveys were conducted at 1693 ha of reclaimed strip-mined land at The Wilds and at 3344 ha of woodland at the Shawnee Wilderness Area, both in Ohio, USA. These areas shared the same original physiography, vegetative cover, and soils prior to mining and are believed to have had the same land snail assemblages. The Wilds consisted of 37% woods and 63% open fields, both the result of reclamation activities. The Shawnee site was 3% fields and 97% woods. Fifty species were recorded from Shawnee and 60 from The Wilds. The older areas of woodlands and marginal new growth stands in The Wilds had recovered up to 55% of the presumed original woodland fauna based on shared assemblages with Shawnee. The fields at The Wilds were dominated by species that were rare at Shawnee. We hypothesize that these species were adapted to specialized but sparse microhabitats at Shawnee and were able to successfully colonize the disturbed areas (fields) at The Wilds when given the opportunity. As the fields at The Wilds yield to new growth woods these “field” species should return to their lower densities in the woodlands. The ranges of the original woodland species at The Wilds, now confined to the older growth woods, will expand as succession continues. If the woodlands are left to expand, then we expect the majority of the original land snail fauna will eventually return to The Wilds. However, the conversion of original woodlands at The Wilds to open fields during reclamation has complicated and slowed this recovery process. Fifty years after restoration began, The Wilds has not regained its original snail fauna.

Conceptual ecological models for the Long Island pitch pine barrens: implications for managing rare plant communities

Fire dependent pitch pine ( Pinus rigida Mill.) and scrub oak ( Quercus ilicifolia Wang.) barrens are found on coarse-textured, droughty soils in the northeastern United States. These communities are globablly rare and, in many areas, dependent on active management to sustain them. We used historic and recent aerial photographs of the Central Pine Barrens in New York to develop transition matrices and trajectories of vegetation change. A vegetation map for 1990 provided pre-burn cover type information for a 1,200 ha area burned by an extremely severe wildfire in August 1995. Geographic information system analyses, a fire-history study, post-wildfire research and existing literature provided additional information for development of three conceptual models that describe our understanding of vegetation change in response to fire and land clearing. A simulation model was then used to predict the amount of each cover type in 2046. The reasonableness of the prediction was assessed based on our understanding of pine barrens vegetation dynamics. In 1938, following a period of frequent, intense wildfires of the region, 90% of vegetation in the study area was open canopy barrens (including dwarf pine plains, pitch pine–scrub oak woodland, heath, pine–heath woodland, and scrub oak shrubland). Between 1938 and 1994, wildfires decreased in size, the average area burned per year generally declined, and there were no fires in 70% of the study area. As a result, barrens decreased to ∼45% of study area vegetation. In August 1995, an unusually severe summer wildfire converted 810 ha of woodland and forest into scrub oak shrubland, and increased barrens to 60% of study area vegetation. Most areas of heath and pine–heath, which comprised 24% of barrens vegetation in 1996, are successional types that developed on formerly cleared land. In the absence of extensive burning, we expect barrens vegetation to be converted to closed-canopy forest as coppice trees and new seedlings mature. Recent changes in fire regimes are likely to result in a loss of barrens vegetation that exceeds predictions of the simulation model. Careful use of prescribed fire and/or mechanical treatments to simulate the effects of fire are recommended for future restoration and maintenance of pitch pine barrens, and for protection of human life and property.

Planning a red squirrel conservation area: using a spatially explicit population dynamics model to predict the impact of felling and forest design plans

Summary This paper describes the use of a spatially explicit population model (SEPM) to investigate the effects of different forest management strategies on a red squirrel conservation area. The study was based in woodland managed by Forest Enterprise, which manages 75 000 ha of woodlands in Northumberland, Co. Durham, Tyne and Wear, and east Cumbria. The forests contain the largest remaining red squirrel populations in northern England and the area of the study, Kidland Forest, is one of five key areas or refuges where red squirrel conservation is a priority. The SEPM integrates expert knowledge on red and grey squirrels, based on 10 years of fieldwork in the area and information from the scientific literature. We investigated the current tree species composition, distribution and proposed felling plans as well as the future restocking for Kidland Forest, an area of 2050 ha of predominantly conifer species. The assessment also included a proposed planting of 15 ha of oak and its likely consequences on grey squirrel population viability. These results were then applied to develop a forest design plan to ensure red squirrel persistence over the next rotation. Results indicated that red squirrels were at risk of extinction due to a drastic reduction in the availability of suitable habitats through clear-felling. Furthermore the proposed planting of 15 ha of oak could lead to a substantial grey squirrel population at Kidland once the trees matured and assuming that grey squirrels colonize the area. The felling profile was therefore revised, allocating a proportion of the tree crop on more wind-firm sites to long-term retentions. The approach adopted at Kidland illustrates how geographical information systems, expert knowledge on the threatened species and spatially explicit models can be integrated to assist forest managers in assessing the suitability of a site for red squirrel conservation.

Population ecology of the red squirrel (Sciurus vulgaris) in a fragmented woodland ecosystem on the Island of Jersey, Channel Islands

AbstractThe Channel Island of Jersey is 116 km2 but has only 540 ha of woodland distributed in 237 wooded fragments with mean size of 2.5 ha. Despite this, the island supports 300 to 600 red squirrels Sciurus vulgaris, a species that is under threat in mainland Britain from habitat fragmentation, disease and the spread of the alien grey squirrel S. carolinensis. Grey squirrels are not present on Jersey. Between 1994 and 1997, using trapping and tracking techniques, we studied how red squirrels survive on Jersey by focusing on three local populations in sites B, C and S with contrasting food availability. The primary squirrel foods at site B were autumn tree seeds, at site C autumn tree seeds and summer conifer cones, and at site S autumn tree seeds and ad libitum, year‐round supplementary food provided by local people. The densities of squirrels in site C (mean over 3 years 0.97 ha−1) and site S (1.21 ha−1) were more than one and a half times that of site B (0.68 ha−1), which relied on autumn seeds. Body mass and condition, and early breeding (spring litters) were not affected by food availability although conception occurred as early as November, earlier than in mainland Britain. Less than 50% of females produced summer litters, and 88% of non‐breeders did not receive supplementary food. Turnover rates were lowest and most stable in site B. Annual residency was not influenced by the size of the natural tree seed crop. Cat and road kills caused two out of three reported deaths. This island population seems to remain viable as a result of an extended breeding season and increased population densities in sites with summer or supplementary food. The results emphasize the beneficial effects of extra food provided by local people. This provides a buffering effect against variations in natural food availability, and seems to be important for their long‐term survival.