Shrub Areas Research Articles

A test of desert shrub facilitation via radiotelemetric monitoring of a diurnal lizard.

Preservation of desert ecosystems is a worldwide conservation priority. Shrubs can play a key role in the structure of desert communities and can function as foundation species. Understanding desert shrub ecology is therefore an important task in desert conservation. A useful model for the function of shrubs in deserts is ecological facilitation, which explores benefits that shrubs confer on their community. Facilitation has been well developed in the context of shrub–plant interactions but less well studied for plant–animal interactions. We used radiotelemetry to test the hypothesis that a dominant desert shrub facilitates one species of diurnal lizard. We hypothesized that the blunt‐nosed leopard lizard Gambelia sila would spend some part of its daily activity cycle associated with California jointfir Ephedra californica, and that lizard association with shrubs would increase during the afternoon peak temperature period. We relocated lizards three times daily for 24 days and scored whether lizards were within 0.5 m of a shrub, which we used as an indicator of shrub association. For each relocation, we also scored lizard association with a set of predefined microhabitat features. We also scored lizard behavior according to a set of predefined behavioral traits. We constructed home ranges following the minimum convex polygon method and generated estimates of shrub density and relative shrub area within each home range polygon. We obtained 1,190 datapoints from a sample of 27 lizards. We found that lizards were associated with open sites significantly more often than with shrubs but were associated with shrubs more than predicted by percent shrub area within their home ranges. Lizards were associated significantly more often under shrubs during the afternoon peak temperature period, and lizards were observed cooling under shrubs significantly more often. The frequency of association of individual lizards with shrubs was not correlated with the density of shrubs within their home range. Synthesis and Applications. Shrubs can be considered as a component of high‐quality habitat for ectothermic desert vertebrates for the purposes of restoration and management. Furthermore, radiotelemetry provides a novel methodological approach for assessing shrub–animal facilitative interactions within desert communities.

Multiple readings of the mining landscape in Lavreotiki (SE Attica, Greece)

From the widespread mineral exploitation of the past to the protected territory of the Sounion National Park in the present, the region of Lavreotiki has diachronically been at the centre of human activities and experiences. Nowadays, the landscape of the region, as defined by hills, valleys and the coastline at the SE of Attica, includes a variety of land uses, such as settlements (with prevailing traditional or contemporary styles), isolated properties (legal or illegal, inland or by the coast), agricultural lands (mainly vineyards and olive groves), uninhabited areas, roads, pathways and other transport routes, industrial units, tourist complexes, geological formations, archaeological and historical sites and landmarks, protected forest and shrub areas. However, the connecting element between them all has always been the large multi-metallic ore deposits found underground - their exploitation has shaped the landscape diachronically in a multitude of ways. This paper aims to explore the multiple facets of the landscape, interpret its characteristics as part of the diachronic heritage of the region and discuss its potential as an ‘off the beaten track’ place to visit.

The Impacts of Climate Variability and Land Use Change on Streamflow in the Hailiutu River Basin

The Hailiutu River basin is a typical semi-arid wind sandy grass shoal watershed in northwest China. Climate and land use have changed significantly during the period 1970–2014. These changes are expected to impact hydrological processes in the basin. The Mann–Kendall (MK) test and sequential t-test analysis of the regime shift method were used to detect the trend and shifts of the hydrometeorological time series. Based on the analyzed results, seven scenarios were developed by combining different land use and/or climate situations. The Soil Water Assessment Tool (SWAT) model was applied to analyze the impacts of climate variability and land use change on the values of the hydrological components. The China Meteorological Assimilation Driving Datasets for the SWAT model (CMADS) was applied to enhance the spatial expressiveness of precipitation data in the study area during the period 2008–2014. Rather than solely using observed precipitation or CMADS precipitation, the precipitation values of CMADS and the observed precipitation values were combined to drive the SWAT model for better simulation results. From the trend analysis, the annual streamflow and wind speed showed a significant downward trend. No significant trend was found for the annual precipitation series; however, the temperature series showed upward trends. With the change point analysis, the whole study period was divided into three sub-periods (1970–1985, 1986–2000, and 2001–2014). The annual precipitation, mean wind speed, and average temperature values were 316 mm, 2.62 m/s, and 7.9 °C, respectively, for the sub-period 1970–1985, 272 mm, 2.58 m/s, and 8.4 °C, respectively, for the sub-period 1986–2000, and 391 mm, 2.2 m/s, and 9.35 °C, respectively, for the sub-period 2001–2014. The simulated mean annual streamflow was 35.09 mm/year during the period 1970–1985. Considering the impact of the climate variability, the simulated mean annual streamflow values were 32.94 mm/year (1986–2000) and 36.78 mm/year (2001–2014). Compared to the period 1970–1985, the simulated mean annual streamflow reduced by 2.15 mm/year for the period 1986–2000 and increased by 1.69 mm/year for the period 2001–2014. The main variations of land use from 1970 to 2014 were the increased area of shrub and grass land and decreased area of sandy land. In the simulation it was shown that these changes caused the mean annual streamflow to decrease by 0.23 mm/year and 0.68 mm/year during the periods 1986–2000 and 2001–2014, respectively. Thus, the impact of climate variability on the streamflow was more profound than that of land use change. Under the impact of coupled climate variability and land use change, the mean annual streamflow decreased by 2.45 mm/year during the period 1986–2000, and the contribution of this variation to the decrease in observed streamflow was 27.8%. For the period 2001–2014, the combined climate variability and land use change resulted in an increase of 0.84 mm/year in annual streamflow. The results obtained in this study could provide guidance for water resource management and planning in the Erdos plateau.

High soil acidity under native shrub encroachment in the Cobar Pediplain, south-eastern Australia

This study investigated the chemical characteristics of shallow (0–30 cm) soil profiles under shrubs in areas of dense encroachment and compared them with shallow soil profiles under nearby large trees. Consistent patterns of high soil acidity were found under shrubs, as well as lower litter alkalinity, lower relative concentrations of calcium (Ca2+), lower effective cation exchange capacity, and higher aluminium (Al3+) and sodium (Na+) in the soil profile compared with under trees. Soil pH (CaCl2) was strongly correlated with the Ca content of surface litter. These findings suggest that shrubs (which at most sites included the shrub form of tree species) cycle alkalinity differently from large and mature trees, resulting in high acidity in the shallow soil profile acidity, and possible loss of alkalinity via surface movement of material from areas of dense encroachment.

Browse by White-tailed Deer Decreases Cover and Growth of the Invasive Shrub, Lonicera maackii

Abstract While arthropod herbivory on invasive plant species is generally low, herbivory by generalist mammals is often high. We tested whether exclusion of white-tailed deer, Odocoileus virginianus, increased the cover and growth of Lonicera maackii, an invasive shrub, in forested natural areas in Ohio, U.S.A. We found leaf frequency of L. maackii in two height ranges, 0.5–1 m and 1–1.5 m, was significantly greater where deer had been excluded for 4 y. Furthermore, the basal area growth of these shrubs over 5 y tended to be higher, and the final basal area of small shrubs was significantly higher, in exclosures. These findings, along with direct evidence of deer browse from the literature, indicate deer browse on this invasive shrub is sufficient to affect its architecture and growth, and potentially mitigate its negative effect on native plants.

Greenhouse gas emissions in restored secondary tropical peat swamp forests

Restoration of deforested and drained tropical peat swamp forests is globally relevant in the context of reducing emissions from deforestation and forest degradation. The seasonal flux of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in a restoration concession in Central Kalimantan, Indonesia, was measured in the two contrasting land covers: shrubs and secondary forests growing on peatlands. We found that land covers had high, but insignificantly different, soil carbon stocks of 949 + 56 and 1126 + 147 Mg ha−1, respectively. The mean annual CO2 flux from the soil of shrub areas was 52.4 ± 4.1 Mg ha−1 year−1, and from secondary peat swamp forests was 42.9 ± 3.6 Mg ha−1 year−1. The significant difference in mean soil temperature in the shrubs (31.2 °C) and secondary peat swamp forests (26.3 °C) was responsible for the difference in total CO2 fluxes of these sites. We also found the mean annual total soil respiration was almost equally partitioned between heterotrophic respiration (20.8 + 1.3 Mg ha−1 year−1) and autotrophic respiration (22.6 + 1.5 Mg ha−1 year−1). Lowered ground water level up to − 40 cm in both land covers caused the increase of CO2 fluxes to 40–75%. These numbers contribute to the provision of emission factors for rewetted organic soils required in the national reporting using the 2013 Supplement of the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for wetlands as part of the obligation under the United Nations Framework Convention on Climate Change (UNFCCC).

Assessing Lightning and Wildfire Hazard by Land Properties and Cloud to Ground Lightning Data with Association Rule Mining in Alberta, Canada.

Hotspot analysis was implemented to find regions in the province of Alberta (Canada) with high frequency Cloud to Ground (CG) lightning strikes clustered together. Generally, hotspot regions are located in the central, central east, and south central regions of the study region. About 94% of annual lightning occurred during warm months (June to August) and the daily lightning frequency was influenced by the diurnal heating cycle. The association rule mining technique was used to investigate frequent CG lightning patterns, which were verified by similarity measurement to check the patterns’ consistency. The similarity coefficient values indicated that there were high correlations throughout the entire study period. Most wildfires (about 93%) in Alberta occurred in forests, wetland forests, and wetland shrub areas. It was also found that lightning and wildfires occur in two distinct areas: frequent wildfire regions with a high frequency of lightning, and frequent wild-fire regions with a low frequency of lightning. Further, the preference index (PI) revealed locations where the wildfires occurred more frequently than in other class regions. The wildfire hazard area was estimated with the CG lightning hazard map and specific land use types.

Vegetation ecology and carbon sequestration potential of shrubs in tropics of Chhattisgarh, India.

Tropical forests are well known to have great species diversity and contribute substantial share in terrestrial carbon (C) stocks worldwide. Shrubs are long-neglected life form in the forest ecosystem, playing many roles in the forest and human life. Shrub has great impact on vegetation attributes which in turn modify the C storage and capture. In the present investigation, an attempt has been made to explore the dynamics of shrub species in four fire regimes, viz. high, medium, low, and no fire zones of Bhoramdeo Wildlife Sanctuary of Kawardha forest division (Chhattisgarh), India. The variations in structure, diversity, biomass, productivity, and C sequestration potential in all the sites were quantified. The density and basal area of shrub varied from 1250 to 3750 individuals ha-1 and 2.79 to 4.92m2ha-1, respectively. The diversity indices showed that the value of Shannon index was highest in medium fire zone (3.77) followed by high, low, and no fire zones as 3.25, 3.12, and 2.32, respectively. The value of Simpson's index or concentration of dominance (Cd) ranged from 0.08 to 0.20, species richness from 0.56 to 1.58, equitability from 1.41 to 1.44, and beta diversity from 1.50 to 4.20, respectively. The total biomass and C storage ranged from 6.82 to 15.71 and from 2.93 to 6.76t ha-1, respectively. The shrub density, importance value index (IVI), and abundance to frequency ratio (A/F) significantly correlated between high fire and medium fire zone. The basal area was found to be significantly positively correlated between high fire and medium fire, and low and no fire zones, respectively. Two-way cluster analysis reflected various patterns of clustering due to influence of the forest fire which showed that some species have distant clustering while some have smaller cluster. Principal component analysis (PCA) reflects variable scenario with respect to shrub layer. Ventilago calyculata and Zizyphus rotundifolia showed higher correlation between themselves in terms of basal area (BA). The total shrub production was 1.59-3.53tha-1year-1 while the C sequestration potential of 0.71-1.57tha-1year-1 under different fire regimes. Shrub community in the medium fire zone reflected higher productivity and higher C sequestration in comparison to other fire zone. Among the different plant parts, the biomass accumulation ratio was highest in the root of shrub community among various fire regimes. Screening of species for restoration and different land-use pattern on the basis of biomass accumulation and carbon sequestering potential would be an effective strategy for decision-making in sustainable forest management.

Monitoring and Modeling of Spatiotemporal Urban Expansion and Land-Use/Land-Cover Change Using Integrated Markov Chain Cellular Automata Model

Spatial–temporal analysis of land-use/land-cover (LULC) change as well as the monitoring and modeling of urban expansion are essential for the planning and management of urban environments. Such environments reflect the economic conditions and quality of life of the individual country. Urbanization is generally influenced by national laws, plans and policies and by power, politics and poor governance in many less-developed countries. Remote sensing tools play a vital role in monitoring LULC change and measuring the rate of urbanization at both the local and global levels. The current study evaluated the LULC changes and urban expansion of Jhapa district of Nepal. The spatial–temporal dynamics of LULC were identified using six time-series atmospherically-corrected surface reflectance Landsat images from 1989 to 2016. A hybrid cellular automata Markov chain (CA–Markov) model was used to simulate future urbanization by 2026 and 2036. The analysis shows that the urban area has increased markedly and is expected to continue to grow rapidly in the future, whereas the area for agriculture has decreased. Meanwhile, forest and shrub areas have remained almost constant. Seasonal rainfall and flooding routinely cause predictable transformation of sand, water bodies and cultivated land from one type to another. The results suggest that the use of Landsat time-series archive images and the CA–Markov model are the best options for long-term spatiotemporal analysis and achieving an acceptable level of prediction accuracy. Furthermore, understanding the relationship between the spatiotemporal dynamics of urbanization and LULC change and simulating future landscape change is essential, as they are closely interlinked. These scientific findings of past, present and future land-cover scenarios of the study area will assist planners/decision-makers to formulate sustainable urban development and environmental protection plans and will remain a scientific asset for future generations.

Green alder encroachment in the European Alps: The need for analyzing the spread of a native-invasive species across spatial data

Forest regrowth is an ongoing process in the European Alps. In the Unteralptal, a valley in central Switzerland, landscape characteristics show considerable change toward the encroachment of green alder (Alnus viridis (Chaix) DC. = Alnus alnobetula (Ehrh.) K. Koch). Initially, green alder was described to grow on moist, north-facing and steep slopes of high geomorphic activity. However, the recent spreading of green alder described in several studies over the alpine arc questions the ecological habitat described in historic literature. Thus, a time series of aerial photographs and a digital elevation model (DEM) with a resolution of 2m were used to find proxies for green alder encroachment. The cover of “new shrub areas” was analyzed based on relief parameter values and geomorphic landforms. The results show that green alder is spreading on more gentle slopes and well-drained areas, as well as on areas with lower geomorphic activity than anticipated. Thus, the habitat spectrum of green alder is much wider than assumed and encroachment has potentially greater consequences for landscape ecology than expected.

Vegetation change during 40 years of repeated managed wildfires in the Sierra Nevada, California

Fire suppression has been reported to homogenize landscapes in regions that historically experienced frequent wildfire. The Illilouette Creek Basin in Yosemite National Park experienced nearly 100years of fire suppression, but after a change in management strategy it is now one of the few areas in the United States that has experienced a frequent fire regime for the past half-century. This study quantifies changing landscape properties in the Basin from its fire-suppressed state to the present. These landscape properties range from the relative dominance of different vegetation types to the spatial distribution of vegetation patches. This is the first detailed study of watershed-scale changes in overstory vegetation within a landscape transitioning from a fire suppressed condition to frequent, mixed severity wildfires.We mapped major vegetation types over time within Illilouette Creek Basin using high resolution aerial images from four different decades, starting with the final years of a fire-suppressed period and capturing multiple snapshots during forty years of repeated fires. We quantify landscape heterogeneity and vegetation patch shape properties using landscape metrics. From 1969 to 2012, conifer cover decreased by 24% while shrub area increased by 35%, sparse meadow area increased by 199% and dense meadows by 155%. The Shannon’s Evenness Index based on these four vegetation types increased from 0.4 to 0.7, indicating increased landscape heterogeneity. This study demonstrates that wildfires can return diversity to a fire-suppressed landscape, even after protracted fire suppression. Management of forests to restore fire regimes has the potential to maintain healthy, resilient landscapes in frequent fire-adapted ecosystems.

Regional sensitivities of seasonal snowpack to elevation, aspect, and vegetation cover in western North America

AbstractIn mountains with seasonal snow cover, the effects of climate change on snowpack will be constrained by landscape‐vegetation interactions with the atmosphere. Airborne lidar surveys used to estimate snow depth, topography, and vegetation were coupled with reanalysis climate products to quantify these interactions and to highlight potential snowpack sensitivities to climate and vegetation change across the western U.S. at Rocky Mountain (RM), Northern Basin and Range (NBR), and Sierra Nevada (SNV) sites. In forest and shrub areas, elevation captured the greatest amount of variability in snow depth (16–79%) but aspect explained more variability (11–40%) in alpine areas. Aspect was most important at RM sites where incoming shortwave to incoming net radiation (SW:NetR↓) was highest (∼0.5), capturing 17–37% of snow depth variability in forests and 32–37% in shrub areas. Forest vegetation height exhibited negative relationships with snow depth and explained 3–6% of its variability at sites with greater longwave inputs (NBR and SNV). Variability in the importance of physiography suggests differential sensitivities of snowpack to climate and vegetation change. The high SW:NetR↓ and importance of aspect suggests RM sites may be more responsive to decreases in SW:NetR↓ driven by warming or increases in humidity or cloud cover. Reduced canopy‐cover could increase snow depths at SNV sites, and NBR and SNV sites are currently more sensitive to shifts from snow to rain. The consistent importance of aspect and elevation indicates that changes in SW:NetR↓ and the elevation of the rain/snow transition zone could have widespread and varied effects on western U.S. snowpacks.

Estimation of shrub biomass availability along two geographical transects in the Iberian Peninsula for energy purposes

In this paper we estimate the availability of shrub biomass along two different geographical transects in the Iberian Peninsula, i) North transect: NE-NW and ii) an Atlantic-Mediterranean transect: NW-S. To determine the available shrub area, the legal, technical, economic and environmental restrictions pertinent to the study areas were identified and their relative thresholds were established. Additionally, the amount of available shrub biomass (tonnes dry matter per hectare) along both geographical transects was calculated using equations specifically created for Spanish shrub formations. The NE-NW transect gave shrub biomass accumulations ranging from 11 to 16 t ha−1, while the NW-S transect displayed much lower values, from 3 to 16 t ha−1. Furthermore, the stored energy potential (gigajoules per hectare) for each shrub formation was calculated at each location. This paper provides realistic information, by shrub formation, on shrub biomass availability in the Mediterranean basin, highlighting the suitability of scrublands as potential sources of biomass, as well as the strengths and weaknesses of harvesting such biomass using machinery specifically designed for shrubs.

Analysis and Identification of Landuse on the Coastal Environment of South Sumatra using GIS

Analysis and identification of land use in coastal areas to study the coastal environment Sembilang National Park in South Sumatra using remote sensing system (Geographical Information System) has been conducted from June until November 2014. The objective to study the changes that occur in the coastal environment as well as to identify and estimate the area use change existing mangrove areas in Region I of the Section of Sembilang National Park Management, South Sumatra. Methods for the analysis and identification based on Landsat image data 8 in 2013 using ENVI 4.3 and Arc GIS 9.3 software as well as the conversion of ground check. The results showed the use of land in the mangrove areas in the region I of the Section of Sembilang National Park Management classified into 5 classes, namely mangrove, water area, mangrove shrubs, mainland mud, and ponds areas. The area of each class were observed in sequence as follows 8921.19 ha (41.69%) as mangrove area; 3934.3 ha (23.28%) as water areas; 3.608,52 ha (17.41%) as area of mangrove shrubs; 1.649,11 ha (9.05%) as mainland mud and settlement area; and 1.561,04 ha (8.57%) as the ponds area. The percentage of the class obtained as a result of the conversion of ground check, and it is based on the land use map data over the total area observed.

Seasonal characterization and discrimination of savannah physiognomies in Brazil using hyperspectral metrics from Hyperion/EO-1

ABSTRACTThe seasonal characterization and discrimination of savannahs in Brazil are still challenging due to the high spatial variability of the vegetation cover and the spectral similarity between some physiognomies. As a preparatory study for future hyperspectral missions that will operate with large swath width and better signal-to-noise ratio than the current orbital sensors, we evaluated six Hyperion images acquired over the Estação Ecológica de Águas Emendadas, a protected area in central Brazil. We studied the seasonal variations in spectral response of the savannah physiognomies and tested their discrimination in the rainy and dry seasons using distinct sets of hyperspectral metrics. Floristic and structural attributes were inventoried in the field. We considered three sets of metrics in the data analysis: the reflectance of 146 Hyperion bands, 22 narrowband vegetation indices (VIs), and 24 absorption band parameters. The VIs were selected to represent vegetation structure, biochemistry, and physiology. The depth, area, width, and asymmetry of the major absorption bands centred at 680 nm (chlorophyll), 980, and 1200 nm (leaf water) and 1700, 2100, and 2300 nm (lignin-cellulose) were calculated on a per-pixel basis using the continuum removal method. Using feature selection and multiple discriminant analysis (MDA), we tested the discriminatory capability of these metrics and of their combined use for vegetation discrimination in the rainy and dry seasons. The results showed that the spectral modifications with seasonality were stronger with the savannah woodland-grassland gradient represented by decreasing tree height, basal area, tree density and biomass and by increasing canopy openness. We observed a reflectance increase in the red, red edge, and shortwave (SWIR) intervals towards the dry season. In the near-infrared, the reflectance differences between the physiognomies were smaller in the dry season than in the rainy season. From the 22 VIs, the visible atmospherically resistant index (VARI), visible green index (VIg), and normalized difference infrared index (NDII) were the most sensitive indices to water stress and vegetation cover, presenting the largest rates of changes between the rainy (March) and dry (August) seasons in shrub and grassland areas. Absorption band parameters associated with the lignin-cellulose spectral features in the SWIR increased towards the dry season with great amounts of non-photosynthetic vegetation (NPV) in the herbaceous stratum. The opposite was observed for the 680 nm chlorophyll absorption band and the 980 and 1200 nm leaf water features. In general, the number of selected metrics necessary for vegetation discrimination was lower in the dry season than in the rainy season. The best MDA-classification accuracy was obtained in the dry season using nine VIs (79.5%). The combination of different hyperspectral metrics increased the classification accuracy to 81.4% in the rainy season and to 84.2% in the dry season. This combination added a gain higher than 10% for the classification of shrub savannah, open woodland savannah and wooded savannah.

Land altitude, slope, and coverage as risk factors for Porcine Reproductive and Respiratory Syndrome (PRRS) outbreaks in the United States.

Porcine reproductive and respiratory syndrome (PRRS) is, arguably, the most impactful disease on the North American swine industry. The Swine Health Monitoring Project (SHMP) is a national volunteer initiative aimed at monitoring incidence and, ultimately, supporting swine disease control, including PRRS. Data collected through the SHMP currently represents approximately 42% of the sow population of the United States. The objective of the study here was to investigate the association between geographical factors (including land elevation, and land coverage) and PRRS incidence as recorded in the SHMP. Weekly PRRS status data from sites participating in the SHMP from 2009 to 2016 (n = 706) was assessed. Number of PRRS outbreaks, years of participation in the SHMP, and site location were collected from the SHMP database. Environmental features hypothesized to influence PRRS risk included land coverage (cultivated areas, shrubs and trees), land altitude (in meters above sea level) and land slope (in degrees compared to surrounding areas). Other risk factors considered included region, production system to which the site belonged, herd size, and swine density in the area in which the site was located. Land-related variables and pig density were captured in raster format from a number of sources and extracted to points (farm locations). A mixed-effects Poisson regression model was built; and dependence among sites that belonged to a given production system was accounted for using a random effect at the system level. The annual mean and median number of outbreaks per farm was 1.38 (SD: 1.6), and 1 (IQR: 2.0), respectively. The maximum annual number of outbreaks per farm was 9, and approximately 40% of the farms did not report any outbreak. Results from the final multivariable model suggested that increments of swine density and herd size increased the risk for PRRS outbreaks (P < 0.01). Even though altitude (meters above sea level) was not significant in the final model, farms located in terrains with a slope of 9% or higher had lower rates of PRRS outbreaks compared to farms located in terrains with slopes lower than 2% (P < 0.01). Finally, being located in an area of shrubs/ herbaceous cover and trees lowered the incidence rate of PRRS outbreaks compared to being located in cultivated/ managed areas (P < 0.05). In conclusion, highly inclined terrains were associated with fewer PRRS outbreaks in US sow farms, as was the presence of shrubs and trees when compared to cultivated/ managed areas. Influence of terrain characteristics on spread of airborne diseases, such as PRRS, may help to predicting disease risk, and effective planning of measures intended to mitigate and prevent risk of infection.

Shrub Communities, Spatial Patterns, and Shrub-Mediated Tree Mortality following Reintroduced Fire in Yosemite National Park, California, USA

Shrubs contribute to the forest fuel load; their distribution is important to tree mortality and regeneration, and vertebrate occupancy. We used a method new to fire ecology—extensive continuous mapping of trees and shrub patches within a single large (25.6 ha) study site—to identify changes in shrub area, biomass, and spatial pattern due to fire reintroduction by a backfire following a century of fire exclusion in lower montane forests of the Sierra Nevada, California, USA. We examined whether trees in close proximity to shrubs prior to fire experienced higher mortality rates than trees in areas without shrubs. We calculated shrub biomass using demography subplots and existing allometric equations, and we developed new equations for beaked hazel (Corylus cornuta ssp. californica [A. de Candolle] E. Murray) from full dissection of 50 stems. Fire decreased shrub patch area from 15.1 % to 0.9 %, reduced live shrub biomass from 3.49 Mg ha−1 to 0.27 Mg ha−1, and consumed 4.41 Mg ha−1 of living and dead shrubs. Distinct (non-overlapping) shrub patches decreased from 47 ha−1 to 6 ha−1. The mean distance between shrub patches increased 135 %. Distances between montane chaparral patches increased 285 %, compared to a 54 % increase in distances between riparian shrub patches and an increase of 267 % between generalist shrub patches. Fire-related tree mortality within shrub patches was marginally lower (67.6 % versus 71.8 %), showing a contrasting effect of shrubs on tree mortality between this forest ecosystem and chaparral-dominated ecosystems in which most trees are killed by fire.

Straight from the caribou’s (Rangifer tarandus) mouth: detailed observations of tame caribou reveal new insights into summer–autumn diets

High-quality habitats for caribou (Rangifer tarandus (L., 1758)) are associated primarily with lichens, but lichens alone fail to satisfy summer nutritional requirements. To evaluate the summer forage value of plant communities across northeastern British Columbia (BC), where populations of northern and boreal ecotypes of caribou are declining, we observed foraging by tame, female caribou. We compared diet composition with forage abundance to determine forage selection and to quantify forage availability. Deciduous shrubs, not lichens, largely dominated summer diets. Caribou were highly selective foragers, with 28 species comprising 78% of diets. Caribou avoided ≥50% of understory vegetation in all communities, especially conifers, evergreen shrubs, mosses, and two genera of terrestrial lichens. Availability of accepted forage (species not avoided) was strongly heterogeneous across landscapes. Alpine shrub areas and mid-elevation spruce–fir stands in the mountains, as well as treed rich fens and white spruce communities in the boreal forests, provided the greatest quantities of accepted forage for caribou. Dry alpine sites and unproductive black spruce communities provided the least accepted forage. Our work has direct implications to caribou conservation by contributing to a greater understanding of the forage value of summer habitats, with implications to habitat selection, seasonal movements, and distribution ecology.

Identifying separate impacts of climate and land use/cover change on hydrological processes in upper stream of Heihe River, Northwest China

AbstractClimate change and land use/cover change (LUCC) are two factors that produce major impacts on hydrological processes. Understanding and quantifying their respective influence is of great importance for water resources management and socioeconomic activities as well as policy and planning for sustainable development. In this study, the Soil and Water Assessment Tool (SWAT) was calibrated and validated in upper stream of the Heihe River in Northwest China. The reliability of the SWAT model was corroborated in terms of the Nash–Sutcliffe efficiency (NSE), the correlation coefficient (R), and the relative bias error (BIAS). The findings proposed a new method employing statistical separation procedures using a physically based modeling system for identifying the individual impacts of climate change and LUCC on hydrology processes, in particular on the aspects of runoff and evapotranspiration (ET).The results confirmed that SWAT was a powerful and accurate model for diagnosis of a key challenge facing the Heihe River Basin. The model assessment metrics, NSE, R, and BIAS, in the data were 0.91%, 0.95%, and 1.14%, respectively, for the calibration period and 0.90%, 0.96%, and −0.15%, respectively, for the validation period. An assessment of climate change possibility showed that precipitation, runoff, and air temperature exhibited upward trends with a rate of 15.7 mm, 6.1 mm, and 0.38 °C per decade for the 1980 to 2010 period, respectively. Evaluation of LUCC showed that the changes in growth of vegetation, including forestland, grassland, and the shrub area have increased gradually while the barren area has decreased. The integrated effects of LUCC and climate change increased runoff and ET values by 3.2% and 6.6% of the total runoff and ET, respectively. Climate change outweighed the impact of LUCC, thus showing respective increases in runoff and ET of about 107.3% and 81.2% of the total changes. The LUCC influence appeared to be modest by comparison and showed about −7.3% and 18.8% changes relative to the totals, respectively. The increase in runoff caused by climate change factors is more than the offsetting decreases resulting from LUCC. The outcomes of this study show that the climate factors accounted for the notable effects more significantly than LUCC on hydrological processes in the upper stream of the Heihe River.

Landscape changes of the Ejin Delta in the Heihe River Basin in Northwest China from 1930 to 2010

ABSTRACTThe Heihe River Basin is located in the arid and semi-arid region of Northwest China; during the past 80 years, this basin has experienced water resource competition between irrigation agriculture and ecological demand in its middle and lower reaches, respectively. The land cover of the Ejin Delta in the lower reaches of the Heihe River Basin was interpreted and analysed for four different periods using a map created by Dr Sven Hedin in the 1930s, Corona satellite images taken in 1961, and Landsat Thematic Mapper (TM) images taken in 2000 and 2010. Overall, the results show that (1) the coarse resolution of the 1930s map increased the uncertainty of analysis in the study area and (2) the river area in the Ejin Delta decreased by 91.0% from the 1930s to 2000. In addition, two major terminal lakes, Gaxun Nuur Lake and Sogo Nuur Lake, dried up in 1961 and 1992, respectively, and the area of Populus euphratica decreased by 76.1% from the 1930s to 2000. Most reeds were overtaken by shrubs between the 1930s and 1961, which caused the area of reeds to decrease from 3481 to 1332 km2 and the area of shrubs to increase from 805 to 2795 km2. From the 1930s to 2000, the desert and alkaline land areas increased by 42.2% and 52.4%, respectively. (3) After the water transfer project was implemented in 2000, the area of Sogo Nuur Lake recovered to 40.58 km2 by 2010. The areas of Populus euphratica, shrubland, and reedland showed a recovering trend, with increases of 4.5%, 6.5%, and 43.5%, respectively, by 2010. The desert and alkaline land areas decreased by 4.2% and 15.2%, respectively, by 2010. The area of cultivated land increased from 25 km2 in 1961 to 85 km2 in 2000 and rapidly approached 160 km2 in 2010. These changes over time indicated that the ecological habitat in the Ejin Delta deteriorated between the 1930s and 2000. However, the water transfer project effectively changed the degradation trend.