Land-use Legacies Research Articles

Forest expansion in mountain protected areas: Trends and consequences for the landscape

Mountain regions in Western Europe have gone through a massive rural–urban migration and the collapse of their traditional socioeconomic system. As a result, forest has occupied many old pastures and croplands. In protected areas – such as National Parks – changes in the landscape can affect biodiversity and other services, including the values that motivated their declaration. Any policy decision in these areas requires quantifying the extent and impact of land-cover changes and their consequences on landscape structure and functioning. In this study we analyze the patterns of change in forest cover during six decades in three mountain National Parks in Spain. Our aim is to quantify those patterns, their effects on the landscape, and discuss the potential consequences for the main natural values and services. We assessed changes in forest cover through reclassification of aerial ortophotographs taken in 1956–57 (past images) and 2016–17 (recent images). The three Parks show a relatively low change in total forest area (+5–10%), and a much larger increase in dense forest (+20–30%), with an important effect of land-use legacies, and similar patterns of landscape homogenization. There were fewer but larger forest patches in 2016 than in 1956, and most of the gain in dense forest occurred in core areas (+20%), while transition areas such as edges, bridges or loops decreased between 30 and 55%. Given their potential consequences on biodiversity and other services, these patterns of land-cover change and landscape configuration should be explicitly considered when designing the sustainable management of abandoned landscapes in protected areas.

Elevated uranium in drinking water sources in basement aquifers of southern India

Groundwater resources in the crystalline basement complex of India are crucial for supplying drinking water in both rural and urban settings. Groundwater depletion is recognised as a challenge across parts of India due to over-abstraction, but groundwater quality constraints are perhaps even more widespread and often overlooked at the local scale. Uranium contamination in basement aquifers has been reported in many parts of India, locally exceeding WHO drinking water guideline values of 30 μg/L and posing a potential health risk. In this study 130 water samples were collected across three crystalline basement catchments to assess hydrochemical, geological and anthropogenic controls on uranium mobility and occurrence in drinking water sources. Groundwaters with uranium concentrations exceeding 30 μg/L were found in all three study catchments (30% of samples overall), with concentrations up to 589 μg/L detected. There appears to be a geological control on the occurrence of uranium in groundwater with the granitic gneiss of the Halli and Bengaluru study areas having higher mean uranium concentrations (51 and 68 μg/L respectively) compared to the sheared gneiss of the Berambadi catchment (6.4 μg/L). Uranium – nitrate relationships indicate that fertiliser sources are not a major control on uranium occurrence in these case studies which include two catchments with a long legacy of intense agricultural land use. Geochemical modelling confirmed uranium speciation was dominated by uranyl carbonate species, particularly ternary complexes with calcium, consistent with uranium mobility being affected by redox controls and the presence of carbonates. Urban leakage in Bengaluru led to low pH and low bicarbonate groundwater hydrochemistry, reducing uranium mobility and altering uranium speciation. Since the majority of inhabitants in Karnataka depend on groundwater abstraction from basement aquifers for drinking water and domestic use, exposure to elevated uranium is a public health concern. Improved monitoring, understanding and treatment of high uranium drinking water sources in this region is essential to safeguard public health.

Remote Sensing Reveals Lasting Legacies of Land-Use by Small-Scale Foraging Communities in the Southwestern Indian Ocean

Archaeologists interested in the evolution of anthropogenic landscapes have productively adopted Niche Construction Theory (NCT), in order to assess long-term legacies of human-environment interactions. Applications of NCT have especially been used to elucidate co-evolutionary dynamics in agricultural and pastoral systems. Meanwhile, foraging and/or highly mobile small-scale communities, often thought of as less intensive in terms of land-use than agropastoral economies, have received less theoretical and analytical attention from a landscape perspective. Here we address this lacuna by contributing a novel remote sensing approach for investigating legacies of human-environment interaction on landscapes that have a long history of co-evolution with highly mobile foraging communities. Our study is centered on coastal southwest Madagascar, a region inhabited by foraging and fishing communities for close to two millennia. Despite significant environmental changes in southwest Madagascar’s environment following human settlement, including a wave of faunal extinctions, little is known about the scale, pace and nature of anthropogenic landscape modification. Archaeological deposits in this area generally bear ephemeral traces of past human activity and do not exhibit readily visible signatures of intensive land-use and landscape modification (e.g., agricultural modifications, monumental architecture, etc.). In this paper we use high-resolution satellite imagery and vegetative indices to reveal a legacy of human-landscape co-evolution by comparing the characteristics – vegetative productivity and geochemical properties – of archaeological sites to those of locations with no documented archaeological materials. Then, we use a random forest (RF) algorithm and spatial statistics to quantify the extent of archaeological activity and use this analysis to contextualize modern-day human-environment dynamics. Our results demonstrate that coastal foraging communities in southwest Madagascar over the past 1,000 years have extensively altered the landscape. Our study thus expands the temporal and spatial scales at which we can evaluate human-environment dynamics on Madagascar, providing new opportunities to study early periods of the island’s human history when mobile foraging communities were the dominant drivers of landscape change.

Does Pastoral Land-Use Legacy Influence Topsoil Carbon and Nitrogen Accrual Rates in Tallgrass Prairie Restorations?

Restoration can recover degraded ecosystems and ecosystem services. However, effects of restoration on soil nutrient accrual are difficult to predict, partly because prior land use affects rates of soil nutrient recovery. In tallgrass prairie restorations, land-use legacy effects have not yet been quantified. We investigated topsoil carbon and nitrogen accrual within seven land-use histories: (1) row crop agriculture, (2) pasture, (3) pasture converted from row crops, (4) prairie restored from row crop, (5) prairie restored from old pasture, (6) bison prairie restored from pasture and row crops, and (7) remnant prairie. Soil samples were collected in 2008 and again in 2018 at Midewin National Tallgrass Prairie in Will County, IL. Soil samples were analyzed for bulk density, root chemistry, macro- and micronutrients, and carbon. Restored prairies contained similar soil bulk densities and rates of topsoil carbon accrual compared to each other in 2018. However, restorations from row cropping accrued nitrogen more slowly than restorations from pastures. Additionally, pastures converted from crop fields exhibited fewer legacy effects than restorations converted from crop fields. This research illustrates land-use legacy effects on soil and nutrients during grassland restorations, with implications for potential restoration trajectories and their role in carbon sequestration and ecosystem functioning.

Land‐use history alters the diversity, community composition and interaction networks of ectomycorrhizal fungi in beech forests

Abstract Forests have expanded across Europe over the last centuries as a consequence of farmland (agricultural and pasture) abandonment. Agricultural practices usually increase soil fertility and reduce the diversity and abundance of ectomycorrhizal (ECM) fungi, essential mutualists of many woody species in temperate and Mediterranean forests. The recovery of this biotic interaction after the cessation of human activities is, thus, crucial for the re‐establishment of functional forest ecosystems. Here we addressed the legacies of past land use and the recovery of the mutualism between ECM fungi and Fagus sylvatica trees in recent beech forests (<50 years) in Northeast Spain. Soil and root samples were collected in six long‐established and eight recent beech forests to analyse soil abiotic properties and the ECM fungi associated with beech roots (Illumina DNA metabarcoding of ECM tips). Up to 609 amplicon sequence variants (ASVs) of ECM fungi were identified, with 220 ASVs found in both forest types. Recent forests had a significantly lower soil organic matter and phosphorus content, which had a significant effect on the community structure of ECM fungi in beech roots. Moreover, beech trees in recent forests interacted with less fungal taxa but had a higher relative abundance of Ascomycota. Tarzetta spp. (Ascomycota, Pezizales) and Lactarius blennius (Basidiomycota, Russulales) emerge as the particular taxa associated with recent and long‐established forests respectively. More specialized mutualistic networks with a lower species normalized degree were found in recent forests, which might result in a lower quality and resilience of the ECM mutualism. Synthesis. Land‐use history modulated the mycorrhizal symbiosis in regenerating beech forests through changes in soil organic matter and nitrogen, which were the main drivers of the differences in fungal community composition and functional types associated with beech trees in recent forests.

A canonical metacommunity structure over 3 decades: ecologically consistent but spatially dynamic patterns in a hurricane-prone montane forest.

The Anthropocene is a time of rapid change induced by human activities, including pulse and press disturbances that affect the species composition of local communities and connectivity among them, giving rise to spatiotemporal dynamics at multiple scales. We evaluate effects of global warming and repeated intense hurricanes on gastropod metacommunities in montane tropical rainforests of Puerto Rico for each of 28 consecutive years. Specifically, we quantified metacommunity structure each year; assessed effects of global warming, hurricane-induced disturbance, and secondary succession on interannual variation in metacommunity structure; and evaluated legacies of previous land use on metacommunity structure. Gastropods were sampled annually during a 28-year period characterized by disturbance and succession associated with 3 major hurricanes (Hurricanes Hugo, Georges, and Maria). For each year, we evaluated coherence (the extent to which the environmental distributions of species are uninterrupted along a common latent environmental gradient), species range turnover, and species range boundary clumping; and conducted co-occurrence analyses for each pair of species. We used generalized linear mixed-effects model to evaluate long-term responses of the metacommunity to aspects of global warming and disturbance. Metacommunity structure was remarkably stable, with consistent patterns of species co-occurrence. Disturbance, warming, and successional stage had little effect on metacommunity structure. Despite great temporal variation in environmental conditions, groups of species tracked their niche through space and time to maintain the same general structure. Consequently, metacommunity structure was highly resistant and resilient to multiple disturbances, even those that greatly altered forest structure.

Large ecosystem-scale effects of restoration fail to mitigate impacts of land-use legacies in longleaf pine savannas.

Ecological restoration is a global priority, with potential to reverse biodiversity declines and promote ecosystem functioning. Yet, successful restoration is challenged by lingering legacies of past land-use activities, which are pervasive on lands available for restoration. Although legacies can persist for centuries following cessation of human land uses such as agriculture, we currently lack understanding of how land-use legacies affect entire ecosystems, how they influence restoration outcomes, or whether restoration can mitigate legacy effects. Using a large-scale experiment, we evaluated how restoration by tree thinning and land-use legacies from prior cultivation and subsequent conversion to pine plantations affect fire-suppressed longleaf pine savannas. We evaluated 45 ecological properties across four categories: 1) abiotic attributes, 2) organism abundances, 3) species diversity, and 4) species interactions. The effects of restoration and land-use legacies were pervasive, shaping all categories of properties, with restoration effects roughly twice the magnitude of legacy effects. Restoration effects were of comparable magnitude in savannas with and without a history of intensive human land use; however, restoration did not mitigate numerous legacy effects present prior to restoration. As a result, savannas with a history of intensive human land use supported altered properties, especially related to soils, even after restoration. The signature of past human land-use activities can be remarkably persistent in the face of intensive restoration, influencing the outcome of restoration across diverse ecological properties. Understanding and mitigating land-use legacies will maximize the potential to restore degraded ecosystems.

Legacies of Indigenous land use shaped past wildfire regimes in the Basin-Plateau Region, USA

Climatic conditions exert an important influence on wildfire activity in the western United States; however, Indigenous farming activity may have also shaped the local fire regimes for millennia. The Fish Lake Plateau is located on the Great Basin–Colorado Plateau boundary, the only region in western North America where maize farming was adopted then suddenly abandoned. Here we integrate sedimentary archives, tree rings, and archeological data to reconstruct the past 1200 years of fire, climate, and human activity. We identify a period of high fire activity during the apex of prehistoric farming between 900 and 1400 CE, and suggest that farming likely obscured the role of climate on the fire regime through the use of frequent low-severity burning. Climatic conditions again became the dominant driver of wildfire when prehistoric populations abandoned farming around 1400 CE. We conclude that Indigenous populations shaped high-elevation mixed-conifer fire regimes on the Fish Lake Plateau through land-use practices.

Land‐use legacies influence tree water‐use efficiency and nitrogen availability in recently established European forests

Abstract Forest regrowth following farmland (agriculture and pasture) abandonment has been positively associated with a number of processes including the regulation of hydrological cycling, the enhancement of soil functioning and an increase in forest productivity and carbon (C) sequestration. Although these changes in ecosystem functioning post‐farmland abandonment have been observed in multiple locations and studies, the ecophysiological basis underpinning these patterns remains unclear. Here, we examine whether increased forest expansion following pastureland abandonment is associated with greater water‐use efficiency (WUE) and legacies from previous land use in terms of nitrogen (N) availability. We thus explored differences in leaf traits and N availability between recently established (post‐1950) beech Fagus sylvatica (L.) forests on former pastureland and long‐established beech forests (pre‐1950). The investigated leaf traits were SLA, leaf N concentration (%N) and intrinsic WUE (iWUE, i.e. the ratio between photosynthesis and stomatal conductance); as well, leaf and soil stable N isotope composition (δ15N) and total %N were used to assess changes in N availability. Finally, we compared the correlation strength between the above‐mentioned parameters and those associated with tree productivity (wood density and basal area increment, BAI) and the richness of ectomycorrhizal fungi (ECM) in these two forest types. Recent forests had greater iWUE than long‐established forests, which was associated more with lower SLA than leaf %N. Leaf and soil δ15N were more robust proxies than %N for detecting differences in N availability. Less negative leaf and soil δ15N values in recent versus long‐established forests suggest, on the one hand, greater N availability, probably due to higher historical N input originating from animal excreta on these former pasturelands, and, on the other hand, an increase in N loss pathways. Our results point to greater correlations between leaf δ15N, tree iWUE and productivity in recent forests than in long‐established forests, thereby suggesting a close link between C and N cycles. Our findings also highlight different N dynamics between the two forest types, with recent forests showing ‘leaky’ N cycling wherever lower N retention by trees and associated ECM fungi occurs as a legacy of previous land use. A free Plain Language Summary can be found within the Supporting Information of this article.

Long-term variability of root production in bioenergy crops from ingrowth core measurements

Abstract Aims Long-term determination of root biomass production upon land-use conversion to biofuel crops is rare. To assess land-use legacy influences on belowground biomass accumulation, we converted 22-year-old Conservation Reserve Program (CRP) grasslands and 50+-year-old agricultural (AGR) lands to corn (C), switchgrass (Sw) and restored prairie (Pr) biofuel crops. We maintained one CRP grassland as a reference (Ref). We hypothesized that land-use history and crop type have significant effects on root density, with perennial crops on CRP grasslands having a higher root biomass productivity, while corn grown on former agricultural lands produce the lowest root biomass. Methods The ingrowth core method was used to determine in situ ingrowth root biomass, alongside measurements of aboveground net primary productivity (ANPP). Ancillary measurements, including air temperature, growing season length and precipitation were used to examine their influences on root biomass production. Important Findings Root biomass productivity was the highest in unconverted CRP grassland (1716 g m−2 yr−1) and lowest in corn fields (526 g m−2 yr−1). All perennial sites converted from CRP and AGR lands had lower root biomass and ANPP in the first year of planting but peaked in 2011 for switchgrass and a year later for restored prairies. Ecosystem stability was higher in restored prairies (AGR-Pr: 4.3 ± 0.11; CRP-Pr: 4.1 ± 0.10), with all monocultures exhibiting a lower stability. Root biomass production was positively related to ANPP (R2 = 0.40). Overall, attention should be given to root biomass accumulation in large-scale biofuel production as it is a major source of carbon sequestration.

Low forest productivity associated with increasing drought-tolerant species is compensated by an increase in drought-tolerance richness.

Many temperate forests are changing in composition due to a combination of changes in land-use, management and climate-related disturbances. Previous research has shown that in some regions these changes frequently favour drought-tolerant tree species. However, the effects of these changes in composition on forest functioning (e.g. productivity) are unclear. We studied 25years of change in individual tree biomass growth, ingrowth and mortality, and community composition and total plot biomass across 2663 permanent forest plots in Catalonia (NE Spain) comprising 85,220 trees of 59 species. We focused on the relationship between community-level forest productivity and drought tolerance (DT), which was estimated using hydraulic traits as well as biogeographic indicators. We found that there was a small increase (1.6%-3.2% on average) in community-mean DT (DTcwm) during the study period, concurrent with a strong increase (12.4%-19.4% on average) in DT richness (DTric; i.e. trait range). Most importantly, we found that the mean DT was negatively related to forest productivity, which was explained because drought-tolerant tree species have lower tree-level growth. In contrast, DT richness was strongly and positively related to forest productivity, probably because it allowed for a more stable production along wet and dry periods. These results suggest a negative impact of ongoing climate change on forest productivity mediated by functional composition shifts (i.e. selection of drought-tolerant species), and a positive effect of increased DT richness as a consequence of land-use legacies. Such a trend towards functional diversification, although temporary, would increase forests' capacity to resist drought and place them in a better position to face the expected change in climate.

Forest land use discontinuity and northern red oak Quercus rubra introduction change biomass allocation and life strategy of lingonberry Vaccinium vitis-idaea

BackgroundMulti-purpose use of forests in a sustainable way forces a recognition of how introduction of alien woody species in forests with different land use histories affect native plants other than trees. Lingonberry Vaccinium vitis-idaea is an important understory component of temperate and boreal forests and provider of valuable non-wood forest products. Here we studied effects of land use changes and introduction of Northern red oak Quercus rubra on lingonberry in mesic Scots pine forests (in central Poland). We measured lingonberry cover, height of shoots, biomass of stems and leaves, and fruit productivity. Shoots were collected within 200 research plots located in recent and ancient Scots pine forests, with and without Q. rubra.ResultsWe found that V. vitis-idaea reached lower cover, aboveground biomass and fruit production in recent than ancient forests and in forests with than without Q. rubra. The fruit production in recent pine forest was only 2% of that reported in ancient pine forest, and V. vitis-idaea did not reproduce generatively in forests with Q. rubra. Biomass and carbon sequestration of V. vitis-idaea in forests with alien (invasive) trees decreased by 75% compared to ancient pine forest. Effects were also clear at the individual shoot level – in less suitable conditions we found taller heights and higher biomass allocation into stems than foliage. Biomass allocation in fruiting and non-fruiting shoots in pine forests was also different – less of the dry biomass of fruiting shoots was allocated to leaves than to stems.ConclusionsIn the age of high interest in ecosystem services and discussions about usage of alien tree species as alternatives in forest management, our results clearly indicate disruption of ecosystem services provided by V. vitis-idaea in the presence of Q. rubra. Lingonberry benefited from the continuity of forest land use, however, regardless of land-use legacy, alien tree introduction led to decline in abundance of species crucial for ecosystem functioning. Therefore, to maintain valuable native species and for conservation of ecosystem services delivery, we suggest limiting the introduction of Q. rubra in areas with abundant V. vitis-idaea, especially in forests with continuous forest land-use history.

Bird Occupancy of a Neotropical Forest Fragment Is Mostly Stable over 17 Years but Influenced by Forest Age

The effects of forest degradation, fragmentation, and climate change occur over long time periods, yet relatively few data are available to evaluate the long-term effects of these disturbances on tropical species occurrence. Here, we quantified changes in occupancy of 50 bird species over 17 years on Barro Colorado Island (BCI), Panama, a model system for the long-term effects of habitat fragmentation. The historical data set (2002–2005) was based on point counts, whereas the contemporary data set (2018) was based on acoustic monitoring. For most species, there was no significant change in occupancy; however, the occupancy of four species (Tinamus major, Polioptila plumbea, Myiarchus tuberculifer, and Ceratopipra mentalis) increased significantly, and the occupancy of three species (Saltator grossus, Melanerpes pucherani, and Cyanoloxia cyanoides) decreased significantly. Forest age explained the majority of occupancy variation and affected the occupancy of more bird species than survey period or elevation. Approximately 50% of the species seem to favor old-growth forest, and 15 species (30%) had a significantly higher occupancy in old-growth forest sites. Elevation had no significant impact on the occupancy of the majority of bird species. Although BCI has been a protected reserve for approximately 100 years, land-use legacies (i.e., forest age) continue to influence bird distribution.

The impact of land-use legacies and recent management on natural disturbance susceptibility in mountain forests

Mountain forests provide a wide range of ecosystem services, including carbon sequestration and protection from natural hazards. Forest cover in the European Alps has increased over the last century, but in recent years, these forests have experienced an increasing rate of natural disturbances by agents such as windthrow, bark beetle outbreaks, and forest fires. These disturbances pose a challenge for forest management, making it important to understand how site and stand characteristics, land use legacies and recent management influence disturbance probability. We combined a dataset of forest disturbances detected from space with in-situ forest management records, allowing us to differentiate between different types of disturbances for the Canton of Graubünden, Switzerland, in the years 2005–2018. The resulting dataset of over 28′000 attributed disturbance patches (corresponding to a disturbed forest area of ca. 23′600 ha) was combined with information on topography, forest structure, and historical forest cover. A machine-learning approach was used to investigate the non-linear and interacting relationships between potential drivers and disturbance occurrence. Natural disturbances (especially windthrow and bark beetle outbreaks) were most common at lower elevations, on shallow and south-facing slopes, and in even-aged, spruce-dominated stands with a closed canopy. Forests established in the 20th century were significantly more susceptible to natural disturbances than forests that were already present before 1880, which may be due to the uniform age and vertical structure of secondary forests, as well as legacy effects of former agricultural use. On the other hand, forest management more often took place in forests present before 1880. Management interventions (such as thinning) in turn increased the susceptibility to natural disturbances in the short term. This finding emphasizes the need to balance short-term increases in disturbance susceptibility with long-term benefits in forest resilience when planning management interventions in mountain forests. Our findings highlight the importance of considering multiple interactive drivers, including management and land-use history, for understanding forest disturbance regimes.

Conservation challenges for Victorian Banksias: Workshop May 2020

Banksias are iconic Australian plants, with a Gondwanan origin. Their specialised roots help survival on low‐phosphorus soils, and many species have reproductive cycles adapted to fire. They are trophically important in many of Australia’s native forests, woodlands and heathlands, providing nectar, pollen and seeds for many species of birds, mammals and invertebrates. While legacies of land use have reduced the historic extent of some Banksia species, more recent declines have raised additional concerns about their persistence in some landscapes. A range of factors are considered to be impacting Banksia persistence (Lamont et al. 2007), including habitat loss and fragmentation (e.g. Miller et al. 2020), increased fire frequency (e.g. Bradstock et al. 1997) and climate change (e.g. Steel et al. 2019), but there is no consensus about how these interacting factors may be driving declines, and how widespread these declines may be. The challenges facing Banksia species conservation in the south‐eastern state of Victoria were the focus of an online workshop in May 2020. The workshop brought together researchers and land managers from Victorian and interstate universities, Victorian government agencies and volunteer land management groups to share their knowledge of the threats facing banksias, and document ideas to reverse declines. It was organised by Arthur Rylah Institute for Environmental Research (Department Environment, Land, Water and Planning), La Trobe University (Department of Ecology, Environment and Evolution) and Federation University (Centre for eResearch and Digital Innovation).

Post-Fire Vegetation Response in a Repeatedly Burned Low-Elevation Sagebrush Steppe Protected Area Provides Insights About Resilience and Invasion Resistance

Sagebrush steppe ecosystems are threatened by human land-use legacies, biological invasions, and altered fire and climate dynamics. Steppe protected areas are therefore of heightened conservation importance but are few and vulnerable to the same impacts broadly affecting sagebrush steppe. To address this problem, sagebrush steppe conservation science is increasingly emphasizing a focus on resilience to fire and resistance to non-native annual grass invasion as a decision framework. It is well-established that the positive feedback loop between fire and annual grass invasion is the driving process of most contemporary steppe degradation. We use a newly developed ordinal zero-augmented beta regression model fit to large-sample vegetation monitoring data from John Day Fossil Beds National Monument, USA, spanning 7 years to evaluate fire responses of two native perennial foundation bunchgrasses and two non-native invasive annual grasses in a repeatedly burned, historically grazed, and inherently low-resilient protected area. We structured our model hierarchically to support inferences about variation among ecological site types and over time after also accounting for growing-season water deficit, fine-scale topographic variation, and burn severity. We use a state-and-transition conceptual diagram and abundances of plants listed in ecological site reference conditions to formalize our hypothesis of fire-accelerated transition to ecologically novel annual grassland. Notably, big sagebrush (Artemisia tridentata) and other woody species were entirely removed by fire. The two perennial grasses, bluebunch wheatgrass (Pseudoroegneria spicata) and Thurber's needlegrass (Achnatherum thurberianum) exhibited fire resiliency, with no apparent trend after fire. The two annual grasses, cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae), increased in response to burn severity, most notably medusahead. Surprisingly, we found no variation in grass cover among ecological sites, suggesting fire-driven homogenization as shrubs were removed and annual grasses became dominant. We found contrasting responses among all four grass species along gradients of topography and water deficit, informative to protected-area conservation strategies. The fine-grained influence of topography was particularly important to variation in cover among species and provides a foothold for conservation in low-resilient, aridic steppe. Broadly, our study demonstrates how to operationalize resilience and resistance concepts for protected areas by integrating empirical data with conceptual and statistical models.

Land-use legacies and forest change

Land-use legacies and forest change

Site preparation impacts on soil biotic and abiotic properties, weed control, and native grass establishment

In severely degraded systems active restoration is required to overcome legacies of past land use and to create conditions that promote the establishment of target plant communities. While our understanding of the importance of soil microbial communities in ecological restoration is growing, few studies have looked at the impacts different site preparation techniques have on these communities. We trialed four methods of site preparation: fire, top‐soil removal (TSR; removal of top 50 mm of soil), slashing (vegetation cut to 30 mm, biomass removed), and carbon (C; as sugar and saw‐dust) addition, and quantified resulting soil bacterial communities using DNA metabarcoding. We compared the effectiveness of these techniques to reduce weed biomass, improve native grass establishment, and induce changes in soil nutrient availability. TSR was the most effective technique, leading to a reduction in both available nutrients and competition from weeds. In comparison, the remaining methods had little or no effect on weed biomass, native grass establishment, or soil nutrient availability. Both TSR and C addition resulted in changes in the soil bacterial community. These changes have the potential to alter plant community assembly in many ways, such as via nutrient acquisition, pathogenic effects, nutrient cycling, and decomposition. We recommend TSR for ecological restoration of old‐fields and suggest it is a much more effective technique than burning, slashing, or C addition. Restoration practitioners should consider how their management techniques may influence the soil biota and, in turn, affect restoration outcomes.

Andes, Bofedales, and the Communities of Huascarán National Park, Peru

Mountain wetlands are abundant in the high elevations of the tropical Andes. Wetlands occupy ~11% of the total park area and are mostly found in the large mountain valleys. Wetlands occur up to 5000 m asl, but most occur between 4,000–4,700 m asl. The highest elevation wetlands are typically dominated by cushion plants, while lower elevation wetlands are more commonly occupied by graminoids. About 60% of all wetlands are peatlands and the remainder are mineral soil wet meadows. The peatlands are up to 11 m deep and 12,000 years old, storing an average of 2,101 Mg C ha-1, which is comparable to lowland tropical peatlands. Our work in Huascarán National Park in Peru is also showing the importance of wetlands in a coupled natural-human system. These wetlands and alpine landscapes are shaped in part by legacies of past human land use, including ancient pastoralism and farming, and are also affected by millions of downstream users dependent upon wetlands and glacier-fed streams for water and energy production. Biodiversity and endemism is high among taxonomic groups such as plants, birds, fish, amphibians and insects. Currently the tropical Andes are in ecological flux due to rapid land cover changes caused by both biophysical and socioeconomic drivers. In addition, the high Andes are experiencing warming and rapid glacial retreat that is resulting in hydroecological changes and socioeconomic changes to the traditional Andean societies that feed back to changes in wetland sustainability.

Land-use legacies affect Norway spruce Picea abies colonization on abandoned marginal agricultural land in Eastern Baltics

Understanding forest regeneration in relation to land-use legacies is an important goal of research on global environmental changes and future ecosystem patterns. Recent findings on spruce regeneration on abandoned agricultural land showed it to be linked to land-use legacies involving increased soil fertility by fertilization. We argue that indirect drivers like land-use changes from arable land to grassland, which affect soil fertility and vegetation density, could also be involved. We selected a study area where changes in land-use involved gradual abandonment of agricultural intervention and created substantial heterogeneity in forest stand age and species composition. Over a 60-year period, the tree colonization pattern changed from deciduous tree species in 1950–1970 to Norway spruce in the later period. Generalized linear logistic regression models were generated to explain the presence of deciduous tree and spruce colonization in relation to soil and land-use factors. The importance of plant community composition on establishment of tree species was studied by Cluster analysis and unconstrained ordination. Deciduous forest development was negatively related to past agricultural use as arable land and positively related to extensively used grasslands (meadows and pastures) and no soil factors entered the explanatory model. Ecological amplitude of deciduous tree species and differing patterns of agricultural land management at landscape and farm scales are discussed as possible explanations. Spruce regeneration was significantly explained by soil moisture and agricultural use as arable land followed by conversion to grassland. We conclude that spruce regeneration is a phenomenon characteristic not only for previously fertilized agricultural land but also for marginal agricultural land if the management ensures development of dense herbaceous layer.