Response of an aridland ecosystem to interannual climate variability and prolonged drought

Water is a key driver of ecosystem processes in aridland ecosystems. Thus, changes in climate could have significant impacts on ecosystem structure and function. In the southwestern US, interactions among regional climate drivers (e.g., El Niño Southern Oscillation) and topographically controlled convective storms create a spatially and temporally variable precipitation regime that governs the rate and magnitude of ecosystem processes. We quantified the spatial and temporal distribution of reduced grassland greenness in response to seasonal and annual variation in precipitation at two scales at the Sevilleta Long Term Ecological Research site in central New Mexico, using Normalized Difference Vegetation Index (NDVI) values from bi-weekly AVHRR data and seasonal ETM data from 1989 to 2005. We used spatially explicit NDVI Z-scores to identify times and places of significantly reduced greenness and related those to interactions between plant functional type, seasonal climate variation, and topography. Seasonal greenness was bimodal with a small peak in spring and a stronger peak following the summer monsoon. Greenness was generally spatially homogeneous in spring and more spatially variable in summer. From 2001 through spring 2002, drought effects were evidenced by a 4-fold increase in the number of pixels showing significantly low greenness. Spatial distribution of low greenness was initially modulated by topographic position, but as the drought intensified spread throughout the study area. Vegetation green up occurred rapidly when drought conditions ceased. We conclude that drought effects vary spatially over time, pervasive drought reduces broad-scale spatial heterogeneity, and greenness patterns recover rapidly when drought conditions end.     

Impact of land-use change on biodiversity and ecosystem services in the Chilean temperate forests

Context

Land-use change impacts biodiversity and ecosystem services, which are intrinsically related. There is a serious lack of knowledge concerning on how land-use change affects this relationship at landscape level, where the greatest impacts have been reported. A proper knowledge of that relationship would provide crucial information for planning conservation strategies. The forest landscape of southern Chile, which includes Valdivian Temperate Forest, has been designated as a hotspot for biodiversity conservation. However, this landscape has been transformed by land-use change.

Objective

We evaluated the impact of land-use change on the spatial patterns of the diversity of native forest habitat and the influence of these impacts on the provision of the ecosystem services water supply, erosion control, and organic matter accumulation from 1986 to 2011.

Methods

The evaluation, at the landscape level, was carried out using satellite images, landscape metrics, spatially explicit models and generalized linear models. Results: We found that the area loss of native forest habitat was 12%, the number patches of native forest habitat increased more than 150% and the Shannon diversity index decreased by 0.20. The largest decrease in the provision of services was recorded for erosion control (346%), and the smallest for water supply (11%).

Conclusions

The loss of provision of the ecosystem services can be explained by the interaction between the area loss, increase in the number patches and diversity loss. We recommend that the conservation planning strategies should consider the current landscape configuration, complemented with land-use planning.

     

Bird response to future climate and forest management focused on mitigating climate change

Context

Global temperatures are projected to increase and affect forests and wildlife populations. Forest management can potentially mitigate climate-induced changes through promoting carbon sequestration, forest resilience, and facilitated change.

Objectives

We modeled direct and indirect effects of climate change on avian abundance through changes in forest landscapes and assessed impacts on bird abundances of forest management strategies designed to mitigate climate change effects.

Methods

We coupled a Bayesian hierarchical model with a spatially explicit landscape simulation model (LANDIS PRO) to predict avian relative abundance. We considered multiple climate scenarios and forest management scenarios focused on carbon sequestration, forest resilience, and facilitated change over 100 years.

Results

Management had a greater impact on avian abundance (almost 50% change under some scenarios) than climate (<3% change) and only early successional and coniferous forest showed significant change in percent cover across time. The northern bobwhite was the only species that changed in abundance due to climate-induced changes in vegetation. Northern bobwhite, prairie warbler, and blue-winged warbler generally increased in response to warming temperatures but prairie warbler exhibited a non-linear response and began to decline as summer maximum temperatures exceeded 36 °C at the end of the century.

Conclusion

Linking empirical models with process-based landscape change models can be an effective way to predict climate change and management impacts on wildlife, but time frames greater than 100 years may be required to see climate related effects. We suggest that future research carefully consider species-specific effects and interactions between management and climate.

     

Changes in land-use/land-cover patterns in Italy and their implications for biodiversity conservation

Land-use/land-cover change is the most important factor in causing biodiversity loss. The Mediterranean region has been affected by antropic disturbance for thousands of years, and is, nowadays, one of the most significantly altered hotspots in the world. However, in the last years a significant increase in forest cover has been measured. These new patterns are independent from planned conservation strategies and appear to have a substantial impact on landscapes and biodiversity. We used three land-use/land-cover maps (from 1960 to 2000) covering the Italian peninsula to analyze the pattern of land-use/land-cover change. We measured an increase in forests, especially in mountains, an increase in artificial areas, especially in coastal zones, and a decrease in pastures. Intensively cultivated areas showed a limited decrease while extensively cultivated ones showed a marked decrease. In the same period mammal and bird species followed a similar pattern, with forest birds, ungulates and carnivores increasing, and typically Mediterranean species decreasing. We suggest that our results may provide important information, which could be useful for conservation planning in the entire Mediterranean hotspot. We suggest that an increasing conservation effort should be made to protect the Mediterranean-type forests and scrublands, as well as traditional agricultural practices. Moreover, future conservation efforts should consider the broad socio-political and ecological processes that are most likely to occur across the whole hotspot, especially along coastal areas, and the network of protected areas should be functionally integrated in a conservation strategy that includes the human-dominated landscape.     

Sensitivity and future exposure of ecosystem services to climate change on the Tibetan Plateau of China

Context

Climate change has imposed tremendous impacts on ecosystem services. Recent attempts to quantify such impacts mainly focused on a basin or larger scale, or used limited time periods that largely ignore observations of long-term trends at a fine resolution, thereby affecting the recognition of climate change’s effect on ecosystem services.

Objectives

This study conducts a detailed and spatially explicit recognition of climate change’s effect on ecosystem services and provides an intuitive map for decision-making and climate change adaptation planning.

Methods

We used long-term time series of ecosystem service assessments and various future climate scenarios to quantify the sensitivity and future exposure of ecosystem services to climate change on the Tibetan Plateau.

Results

Carbon sequestration (CS) and habitat quality experience significant growth, while water retention did not show any trend. Sensitivity patterns of these ecosystem services vary largely. For CS, more than half of the pixels showed a positive sensitivity to climate change, even though the degree of sensitivity is not high. There is substantial spatial heterogeneity in the exposure of ecosystem services to future climate changes, and high levels of future climate change increase the intensity of exposure.

Conclusions

This study illustrates the complex spatial association between ecosystem services and climatic drivers, and these findings can help optimize local response strategies in the context of global warming. For example, the existing protected areas have notable conservation gaps for disturbance of future climate change on ecosystem services, especially in the southeastern part of the study area.

     

Wildfire and exotic grass invasion alter plant productivity in response to climate variability in the Mojave Desert

Context

Annual grass invasions often increase the frequency and extent of wildfire. Climate variability and fire history may have modifying effects on invasion success and its link to changing fire regimes.

Objective

Characterize the role of climate variability and fire history in vegetation shifts of an invaded desert landscape.

Method

Pre- and post-fire landscape vegetation greenness were assessed on multiple, independent wildfires in Mojave Desert shrublands using a 34 year record of normalized difference vegetation index (NDVI) derived from 1685 Landsat images and matched with a record of precipitation using linear regression.

Results

Annual maximum NDVI, and its annual variance of monthly maximum values, were significantly higher on post-fire than pre-fire landscapes. Additionally, post-fire landscapes showed greater sensitivity to antecedent precipitation received the previous 4 months than pre-fire and unburned landscapes. Ground surveys of vegetation indicate that post-fire landscapes show little indication of recovery of native shrub cover and density but instead are dominated by the exotic grass red brome (Bromus rubens L.). Increased NDVI sensitivity to precipitation is likely related to the growth of red brome, which dominates burned landscapes. Record precipitation in the fall of 2004 contributed to the record NDVI values in 2005 likely driven by high density of red brome.

Conclusions

The heightened response of post-fire vegetation to extreme and more variable precipitation events appears to be contributing to the emergence of an invasive grass-fire cycle that constrains the re-establishment of fire sensitive native shrubs while reinforcing the dominance of exotic grasses.

     

Impact of data integration technique on historical land-use/land-cover change: Comparing historical maps with remote sensing data in the Belgian Ardennes

Historical reconstructions of land-use/cover change often require comparing maps derived from different sources. The objective of this study was to measure land-use/cover changes over the last 225 years at the scale of a Belgian landscape, Lierneux in Ardennes, on the basis of a heterogeneous time series of land cover data. The comparability between the land-cover maps was increased following a method of data integration by map generalisation. Two types of time series were built by integrating the maps either by reference to the initial map of the time series or by pair of successive maps. Land-cover change detection was performed on the initial time series without data integration and on the two types of integrated time series. Results reveal that land cover and landscape structure have been subject to profound changes in Lierneux since 1775, with an annual rate of change at the landscape level of up to 1.40%. The major land-cover change processes observed are expansion of grasslands-croplands and reforestation with coniferous species, leading to amore fragmented landscape structure. The annual rates of land-cover change estimated from integrated data are significantly different from the annual rates of change estimated without a prior integration of the data. There is a trade-off between going as far back in time as possibleversus performing change detection as accurately as possible. This revised version was published online in July 2006 with corrections to the Cover Date.     

Developing a multi-scale visualisation framework for use in climate change response

Climate change is predicted to impact countries, regions and localities differently. However, common to the predicted impacts is a global trend toward increased levels of carbon dioxide and rising sea levels. Governments and communities need to take into account the likely impacts of climate on the landscape, both built and natural. There is a growing and significant body of climate change research. Much of this information produced by domain experts for a range of disciplines is complex and difficult for planners, decision makers and communities to act upon. The need to communicate often complex scientific information which can be used to assist in the planning cycle is a key challenge. This paper draws from a range of international examples of the use of visualisation in the context of landscape planning to communicate climate change impact and adaptation options within the context of the planning cycle. Missing from the literature, however, is a multi-scalar approach which allows decision makers, planners and communities to seamlessly explore scenarios at their special level of interest, as well as to collectively understand what is driving these at a larger scale, and what the implications are at ever more local levels. Visualisation tools such as digital globes provide one way to bring together multi-scaled spatial–temporal datasets. We present an initial development with this goal in mind. Future research is required to determine the best tools for communicating particular complex scientific data and also to better understand how visualisation can be used to improve the landscape planning process.     

Revision and application of the LINKAGES model to simulate forest growth in central hardwood landscapes in response to climate change

Context

Global climate change impacts forest growth and methods of modeling those impacts at the landscape scale are needed to forecast future forest species composition change and abundance. Changes in forest landscapes will affect ecosystem processes and services such as succession and disturbance, wildlife habitat, and production of forest products at regional, landscape and global scales.

Objectives

LINKAGES 2.2 was revised to create LINKAGES 3.0 and used it to evaluate tree species growth potential and total biomass production under alternative climate scenarios. This information is needed to understand species potential under future climate and to parameterize forest landscape models (FLMs) used to evaluate forest succession under climate change.

Methods

We simulated total tree biomass and responses of individual tree species in each of the 74 ecological subsections across the central hardwood region of the United States under current climate and projected climate at the end of the century from two general circulation models and two representative greenhouse gas concentration pathways.

Results

Forest composition and abundance varied by ecological subsection with more dramatic changes occurring with greater changes in temperature and precipitation and on soils with lower water holding capacity. Biomass production across the region followed patterns of soil quality.

Conclusions

Linkages 3.0 predicted realistic responses to soil and climate gradients and its application was a useful approach for considering growth potential and maximum growing space under future climates. We suggest Linkages 3.0 can also can used to inform parameter estimates in FLMs such as species establishment and maximum growing space.

     

The future demographic niche of a declining grassland bird fails to shift poleward in response to climate change

Context

Temperate grasslands and their dependent species are exposed to high variability in weather and climate due to the lack of natural buffers such as forests. Grassland birds are particularly vulnerable to this variability, yet have failed to shift poleward in response to recent climate change like other bird species in North America. However, there have been few studies examining the effect of weather on grassland bird demography and consequent influence of climate change on population persistence and distributional shifts.

Objectives

The goal of this study was to estimate the vulnerability of Henslow’s Sparrow (Ammodramus henslowii), an obligate grassland bird that has been declining throughout much of its range, to past and future climatic variability.

Methods

We conducted a demographic meta-analysis from published studies and quantified the relationship between nest success rates and variability in breeding season climate. We projected the climate-demography relationships spatially, throughout the breeding range, and temporally, from 1981 to 2050. These projections were used to evaluate population dynamics by implementing a spatially explicit population model.

Results

We uncovered a climate-demography linkage for Henslow’s Sparrow with summer precipitation, and to a lesser degree, temperature positively affecting nest success. We found that future climatic conditions—primarily changes in precipitation—will likely contribute to reduced population persistence and a southwestward range contraction.

Conclusions

Future distributional shifts in response to climate change may not always be poleward and assessing projected changes in precipitation is critical for grassland bird conservation and climate change adaptation.

     

Assessing source-sink stability in the context of management and land-use change

Context

Management actions and land-use change can disrupt interdependent population processes, re-define population networks, and change source-sink dynamics. Yet we know little about the types of changes that can de-stabilize source-sink dynamics and how such changes could affect management decisions.

Objectives

We examined the degree to which source-sink status and strength could change under a range of management actions and land-use change scenarios including different patterns and extents of habitat loss, restoration, demographic improvements from parasitism control, and increased frequencies inter-population movement.

Methods

We developed an empirically-rich, spatially explicit, individual-based model for the formerly endangered Black-capped vireo in Texas. We simulated the network-wide consequences of different kinds of changes and compared the resulting source-sink strength, status, and regional abundance across scenarios. We gauged source-sink stability by the degree to which system changes caused the reversal of source or sink status.

Results

The stability of source-sink characterizations differed with the type of change. Source-sink dynamics were less responsive to small changes to population structure and changes that minimally affected demographic conditions. Source-sink status was most responsive to changes that affected habitat patterns and quality.

Conclusions

Accurately classifying sources and sinks is challenging, particularly in variable and directionally changing systems. The stability of source-sink classifications depends on the type of management or land-use change. Management actions may need to weigh interventions that improve regional abundance against those that alter regional source-sink dynamics as abundance and source-sink states can be sensitive to different kinds of change.

     

Scale dependence in quantification of land-cover and biomass change over Siberian boreal forest landscapes

We investigated the influence of remote sensing spatial resolution on estimates of characteristic land-cover change (LCC) and LCC-related above-ground biomass change (Δbiomass) in three study sites representative of the East Siberian boreal forest. Data included LCC estimated using an existing Landsat-derived land-cover dataset for 1990 and 2000, and above-ground standing biomass stocks simulated by the FAREAST forest succession model and applied on a pixel basis. At the base 60 m resolution, several landscape pattern metrics were derived to describe the characteristic LCC types. LCC data were progressively degraded to 240, 480, and 960 m. LCC proportions and Δbiomass were derived at each of the coarser resolutions and scale dependences of LCC and Δbiomass were analyzed. Compared to the base 60 m resolution, the Logged LCC type was highly scale dependent and was consistently underestimated at coarser resolutions. The Burned type was under- or over-estimated depending strongly on its patch size. Estimated at the base 60 m resolution, modeled biomass increased in two sites (i.e., 3.0 and 6.4 Mg C ha⁻¹ for the Tomsk and Krasnoyarsk sites, respectively) and declined slightly in one site (i.e., −0.5 Mg C ha⁻¹ for the Irkutsk site) between the two dates. At the degraded resolutions, the estimated Δbiomass increased to 3.3 and 7.0 Mg C ha⁻¹ for the Tomsk and Krasnoyarsk sites, while it declined to −0.8 Mg C ha⁻¹ for the Irkutsk site. Results indicate that LCC and Δbiomass values may be progressively amplified in either direction as resolution is degraded, depending on the mean patch size (MPS) of disturbances, and that the error of LCC and Δbiomass estimates also increases at coarser resolutions.     

Synergistic effects of climate and land cover: grassland birds are more vulnerable to climate change

Context

Climate change is not occurring over a homogeneous landscape and the quantity and quality of available land cover will likely affect the way species respond to climate change. The influence of land cover on species’ responses to climate change, however, is likely to differ depending on habitat type and composition.

Objectives

Our goal was to investigate responses of forest and grassland breeding birds to over 20 years of climate change across varying gradients of forest and grassland habitat. Specifically, we investigated whether (i) increasing amounts of available land cover modify responses of forest and grassland-dependent birds to changing climate and (ii) the effect of increasing land cover amount differs for forest and grassland birds.

Methods

We used Bayesian spatially-varying intercept models to evaluate species- and community-level responses of 30 forest and 10 grassland birds to climate change across varying amounts of their associated land cover types.

Results

Responses of forest birds to climate change were weak and constant across a gradient of forest cover. Conversely, grassland birds responded strongly to changing climatic conditions. Specifically, increasing temperatures led to higher probabilities of localized extinctions for grassland birds, and this effect was intensified in regions with low amounts of grassland cover.

Conclusions

Within the context of northeastern forests and grasslands, we conclude that forests serve as a possible buffer to the impacts of climate change on birds. Conversely, species occupying open, fragmented grassland areas might be particularly at risk of a changing climate due to the diminished buffering capacity of these ecosystems.

     

Recovery dynamics and climate change effects to future New England forests

Context

Forests throughout eastern North America continue to recover from broad-scale intensive land use that peaked in the nineteenth century. These forests provide essential goods and services at local to global scales. It is uncertain how recovery dynamics, the processes by which forests respond to past forest land use, will continue to influence future forest conditions. Climate change compounds this uncertainty.

Objectives

We explored how continued forest recovery dynamics affect forest biomass and species composition and how climate change may alter this trajectory.

Methods

Using a spatially explicit landscape simulation model incorporating an ecophysiological model, we simulated forest processes in New England from 2010 to 2110. We compared forest biomass and composition from simulations that used a continuation of the current climate to those from four separate global circulation models forced by a high emission scenario (RCP 8.5).

Results

Simulated forest change in New England was driven by continued recovery dynamics; without the influence of climate change forests accumulated 34 % more biomass and succeed to more shade tolerant species; Climate change resulted in 82 % more biomass but just nominal shifts in community composition. Most tree species increased AGB under climate change.

Conclusions

Continued recovery dynamics will have larger impacts than climate change on forest composition in New England. The large increases in biomass simulated under all climate scenarios suggest that climate regulation provided by the eastern forest carbon sink has potential to continue for at least a century.

     

Multiscale effects of habitat and surrounding matrices on waterbird diversity in the Yangtze River Floodplain

Context

With the expansion in urbanization, understanding how biodiversity responds to the altered landscape becomes a major concern. Most studies focus on habitat effects on biodiversity, yet much less attention has been paid to surrounding landscape matrices and their joint effects.

Objective

We investigated how habitat and landscape matrices affect waterbird diversity across scales in the Yangtze River Floodplain, a typical area with high biodiversity and severe human-wildlife conflict.

Methods

The compositional and structural features of the landscape were calculated at fine and coarse scales. The ordinary least squares regression model was adopted, following a test showing no significant spatial autocorrelation in the spatial lag and spatial error models, to estimate the relationship between landscape metrics and waterbird diversity.

Results

Well-connected grassland and shrub surrounded by isolated and regular-shaped developed area maintained higher waterbird diversity at fine scales. Regular-shaped developed area and cropland, irregular-shaped forest, and aggregated distribution of wetland and shrub positively affected waterbird diversity at coarse scales.

Conclusions

Habitat and landscape matrices jointly affected waterbird diversity. Regular-shaped developed area facilitated higher waterbird diversity and showed the most pronounced effect at coarse scales. The conservation efforts should not only focus on habitat quality and capacity, but also habitat connectivity and complexity when formulating development plans. We suggest planners minimize the expansion of the developed area into critical habitats and leave buffers to maintain habitat connectivity and shape complexity to reduce the disturbance to birds. Our findings provide important insights and practical measures to protect biodiversity in human-dominated landscapes.

     

Assessing and comparing risk to climate changes among forested locations: implications for ecosystem services

Forests provide key ecosystem services (ES) and the extent to which the ES are realized varies spatially, with forest composition and cultural context, and in breadth, depending on the dominant tree species inhabiting an area. We address the question of how climate change may impact ES within the temperate and diverse forests of the eastern United States. We quantify the vulnerability to changes in forest habitat by 2100, based on the overall pressures of community change from an aggregation of current and potential future habitats for 134 tree species at each of 149 US Department of Defense installations. To do so, we derive an index, Forest-Related Index of Climate Vulnerability, composed of several indicators of vulnerability for each site. Further, a risk matrix (likelihood × consequences) provides a visual cue to compare vulnerabilities among species (example from Pennsylvania) or among sites [example for Acer saccharum (sugar maple) in Vermont vs. Kentucky]. Potential changes in specific ES can then be qualitatively examined. For example in Pennsylvania, the loss of the provisioning services (wood products) of Prunus serotina (black cherry) and Fraxinus americana (white ash) habitat projected for the future will not likely be compensated for by concomitant increases in Juniperus virginiana (redcedar) and Pinus echinata (shortleaf pine) habitat. Taken together, this approach provides a conceptual framework that allows for consideration of how potential changes in tree species habitats, as impacted by climate change, can be combined to explore relative changes in important ES that forests provide.