Land-use History Research Articles

Evaluating the Evolution of Soil Erosion under Catchment Farmland Abandonment Using Lakeshore Sediment

Discriminating the potential sources contributing to lacustrine sediment is helpful for decision-making for catchment soils and lake management strategies within lake-catchment systems. Using a sediment fingerprinting approach from the multivariate mixing model, the spatiotemporal sources of geology and land use were identified in a small agricultural catchment in southwest China. Results showed that sediment accumulation rates (SARs) were estimated to range from 0.002 to 0.065 g cm−2 a−1 (mean 0.015 ± 0.016 g cm−2 a−1), which has a positive correlation with instrumental Indian Summer Monsoon (ISM) precipitation. Time-integrated sources were divided into four zones in combination with the changes in SARs, which were qualitatively and quantitively interpreted by particle size, and precipitation, and historical land use polies over the past ~160 years. Spatially, Quaternary granite (QG) in geology and channel bank (CB) in land use were the dominant contributors to the lakeshore sediment, respectively. Two relatively higher contributions of abandoned land (AL) to lakeshore sediment were found during the periods of 1930s–1950s and post-1990s, which originated from the dual impacts of topographical factors of slope gradient and elevation, and socioeconomic factors of the gap of farmer’s expenditure to income. The results illustrate that restricting the farmland to be abandoned would be useful for reducing the soil erosion within the lake-catchment system.

Assessment of soils and green stands in the recreational areas with different land-use history in New Moscow

Abstract. Recreational areas contribute considerably to the establishment of sustainable and comfortable urban environment. Green stands and soils of recreational areas provide important environmental functions and ecosystem services, their utilization depends on natural and anthropogenic factors distinguished by land-use history. For the case of the recreational areas of New Moscow, a comparative analysis of trees (n=1909) and soils (n=39, 0-10 cm layer) of the parks, established on former forested and fallow lands, was performed. It was shown that the species diversity was higher although the tree condition score was lower in the forest-parks, compared to the parks established on former fallow lands, which were generally characterized by a higher level of maintenance. Soils of these parks had a neutral pHH20 (7.20.8) and high content of organic matter (8.52.5 %), whereas the forest-parks soils were similar to the natural Retisols of the forest area with pHH20 6.40.2 and 5.10.2, organic matter content 5.90.2 и 3.50.2 %, respectively. Soils of the parks, established on the former fallow lands, had also a higher pollution level by particular heavy metals as well as considering the integral pollution index. Thus, a higher level of maintenance of the parks established on former fallow lands coincided with a higher anthropogenic pressure and ecosystem alteration. However, reorganization of forests into forestparks allowed partial preservation of the natural ecosystems. That is necessary to consider for planning the new urbanized areas in Moscow.

A century of anthropogenic river alterations in a highly diverse river coastal basin: Effects on fish assemblages

The global increase in human population is driving a continuous conversion of land to anthropogenic uses. This is a major threat to lotic ecosystems worldwide, as it compromises the biotic integrity and health of rivers and streams. Studies in the northern hemisphere have shown that the effects of urbanization on fish assemblages include decrease and/or loss of diversity and abundance of native species, and a proliferation of tolerant exotic species. Such effects have not been widely studied in developing countries like Chile, where urbanization has impacted several river ecosystems. Over decades, the lower zone of the Andalién River in Central Chile has gone over intense non-planned urbanization stemming from the city of Concepción, leading to several physical alterations. The native fish and lamprey fauna of this coastal river basin has been reported as very diverse, with a total of 16 native species. However, this fauna has been affected by multiple effects of different land uses and direct alterations in the riverbed. To study how these fish and lamprey assemblages have changed, this paper compiles records from 1919 to 2018 and analyzes them in relation to the direct and indirect anthropogenic alterations in the basin. The results show a significant reduction in richness and abundance of native species, with only nine species currently. The two migratory lampreys, one of them endemic (Mordacia lapicida), have been extirpated from the Andalién River basin. Conversely, the richness and distribution of introduced species has increased throughout the river basin. The invasive species Gambusia holbrooki, first registered in 1999, is currently the most abundant in the urban zone of the river. Although the more substantial direct alterations of the riverbed occurred in the lower areas, a steeper reduction in native species richness occurred in the middle areas subjected to a long history of agricultural and forestry land use. We suggest the loss of resilience of the river ecosystem, and that the collapse of biodiversity in this river system demonstrates the lack of urban planning and the inefficiency of environmental regulations in protecting native species and ecosystems with high conservation value in Chile.

Impacts of historical land use on forest soil properties in the hemiboreal forest zone, Latvia

Our study investigated soil morphology, genesis, and properties in soil profiles with different land-use history. Charcoal radiocarbon dating and digitized topographical, military and orthophoto maps from different years were used to identify land-use history. For identified land-use trajectories, soils were described, soil samples were collected, and physical and chemical analyses were performed. The history of land use, farming practices and the vegetation composition of the forest ecosystem affected soil genesis and the physical and chemical properties of soil. The abandonment and afforestation coniferous forest stands land contributed to the decrease of soil base saturation in the topsoil and soil acidification. Non-intensive agricultural practice using earthmanure and the overgrew of agricultural lands with deciduous trees increased the content of carbon and nitrogen and slowed down soil acidification.

Toward New Epidemiological Landscapes of Trypanosoma cruzi (Kinetoplastida, Trypanosomatidae) Transmission under Future Human-Modified Land Cover and Climatic Change in Mexico.

Chagas disease, caused by the protozoa Trypanosoma cruzi, is an important yet neglected disease that represents a severe public health problem in the Americas. Although the alteration of natural habitats and climate change can favor the establishment of new transmission cycles for T. cruzi, the compound effect of human-modified landscapes and current climate change on the transmission dynamics of T. cruzi has until now received little attention. A better understanding of the relationship between these factors and T. cruzi presence is an important step towards finding ways to mitigate the future impact of this disease on human communities. Here, we assess how wild and domestic cycles of T. cruzi transmission are related to human-modified landscapes and climate conditions (LUCC-CC). Using a Bayesian datamining framework, we measured the correlations among the presence of T. cruzi transmission cycles (sylvatic, rural, and urban) and historical land use, land cover, and climate for the period 1985 to 2012. We then estimated the potential range changes of T. cruzi transmission cycles under future land-use and -cover change and climate change scenarios for 2050 and 2070 time-horizons, with respect to “green” (RCP 2.6), “business-as-usual” (RCP 4.5), and “worst-case” (RCP 8.5) scenarios, and four general circulation models. Our results show how sylvatic and domestic transmission cycles could have historically interacted through the potential exchange of wild triatomines (insect vectors of T. cruzi) and mammals carrying T. cruzi, due to the proximity of human settlements (urban and rural) to natural habitats. However, T. cruzi transmission cycles in recent times (i.e., 2011) have undergone a domiciliation process where several triatomines have colonized and adapted to human dwellings and domestic species (e.g., dogs and cats) that can be the main blood sources for these triatomines. Accordingly, Chagas disease could become an emerging health problem in urban areas. Projecting potential future range shifts of T. cruzi transmission cycles under LUCC-CC scenarios we found for RCP 2.6 no expansion of favourable conditions for the presence of T. cruzi transmission cycles. However, for RCP 4.5 and 8.5, a significant range expansion of T. cruzi could be expected. We conclude that if sustainable goals are reached by appropriate changes in socio-economic and development policies we can expect no increase in suitable habitats for T. cruzi transmission cycles.

Source water vulnerability to elevated total dissolved solids within a mixed-use Appalachian River basin

The upper Monongahela River basin in West Virginia represents a watershed wherein historic land use activities, including coal mining, conventional oil and gas development, and residential and urban development have contributed to elevated total dissolved solids (TDS) concentrations within surface and source waters with widespread exceedance of the 500 mg/L secondary drinking water standard for TDS. Our research was designed to characterize spatial variability in and sources of elevated and assess vulnerability of surface and source waters to additional TDS sources and loading. We compiled 3439 unique water quality sampling records throughout the study area over a ten-year period and applied boosted regression tree (BRT) analysis to model log[x]-transformed TDS as a function of landscape attributes across the 885 sampled NHD catchments. We predicted (i.e., elevated TDS and reduced dilution capacity) and observed (i.e., increased variability in TDS and temporary exceedances of 500 mg/L) elevated vulnerability of source waters, with vulnerability being largely driven by a few dominant contributors of TDS throughout the stream network. Notably, seven 12-digit hydrologic unit code (HUC) inflows to the Monongahela River and its vulnerable tributaries were predicted to require a combined 6,664,879 m3 of water (i.e., chemical footprint) to dilute TDS concentrations below 500 mg/L from July through September. Our results provide insights into how the mixed land uses containing extractive industries can impact water quality and demonstrates the importance of both spatial and temporal processes in controlling vulnerability of source waters to water pollution.

Effects of Excess Nitrogen (N) on Fine Root Growth in Tropical Forests of Contrasting N Status

Elevated nitrogen (N) deposition may further acidify soils in tropical forests. Yet, we have limited evidence on this prediction and it remained unclear how this would affect fine root growth therein. Here, we report responses of fine root biomass, vitality, and chemistry, as well as related soil parameters to eight years of N additions in three tropical forests different in initial soil N status, with one primary forest being N-saturated, and another two younger forests (one secondary forest and one planted forest) less N-rich. Results showed that in the primary forest, fine root biomass decreased and fine root necromass increased following N addition, resulting in lower live fine root proportion (fine root vitality). Declining fine root vitality was associated with fine root Fe accumulation and soil acidification indicated by regression analysis. These alterations of fine root growth and chemistry co-occurred with soil pH decline, soil exchangeable Fe3+ mobilization, exchangeable Ca2+, and Mg2+ depletion after N treatments in the primary forest. In contrast, N addition only elevated fine root K, Al, and Fe content in the secondary forest. In the planted forest, moderate but significant decreases in soil pH, soil exchangeable K+, and Mg2+ were found after N treatment, with fine root biomass negatively correlated with soil exchangeable Al3+ and Al3+/(Ca2+ + Mg2+) ratio. Our results suggested that long-term N fertilization may negatively affect fine root growth, via severed soil acidification, Fe mobilization, and base cation depletion in highly acidified, N-saturated primary tropical forests. Initial forest N status, influenced by different land-use history, mediates N deposition effects on fine root growth.

Uncertainties of Global Historical Land Use Datasets in Pasture Reconstruction for the Tibetan Plateau

Global historical land use datasets have been widely used in global or regional environmental change studies. Historical pasture data are essential components of these spatially explicit global datasets, and their uncertainties have not been well evaluated. Using the livestock-based historical pasture dataset for the Tibetan Plateau (TP), we evaluated the uncertainties of these representative global historical land use datasets in pasture reconstruction for the TP over the past 300 years in terms of pasture area estimation and spatial pattern mapping. We found that only the Sustainability and the Global Environment (SAGE) dataset can roughly reflect the temporal and spatial characteristics of historical pasture changes on the TP. The History Database of the Global Environment (HYDE) version 3.2 and the Pongratz Julia (PJ) datasets overestimated pasture area for the TP dramatically, with a maximum area ratio of about 221% and 291%, respectively, and the Kaplan and Krumhardt 2010 (KK10) dataset underestimated pasture area for the TP dramatically, with a minimum area ratio of only 9%. As for the spatial pattern, all these global datasets overestimated the spatial scope of grazing activities obviously. The KK10 dataset unreasonably allocated pasture to forest areas in southeastern Tibet because only climate and soil factors were considered in assessing land suitability for grazing. Using population to estimate pasture area and only using natural factors to allocate pasture area into grids is unsuitable for the TP historical pasture reconstruction. In the future, more information directly related to grazing activities, e.g., the number of livestock and its spatial distribution, and social-cultural factors, including technology and diet, should be used for area estimation and spatial pattern mapping to improve the accuracy of pasture data in these global datasets.

Exclusion of plant input affects the temperature sensitivity of soil organic carbon decomposition

Plant residue input plays a vital role in cropland carbon (C) balance, which can be greatly affected by climate change. Our knowledge of the effect of plant residue on soil respiration is crucial for evaluating C exchange between the atmosphere and terrestrial ecosystems, but large uncertainties remain in the effect of plant input on the temperature sensitivity (Q10) of soil organic C (SOC) decomposition in cropland ecosystems. Here, soils were sampled from two bare fallow plots (including a Mollisol and an Alfisol with different climate and land-use history) and their adjacent old field plots, and were incubated at 10 °C and 20 °C for 815 days. The ‘equal-time’, ‘equal-C’, ‘one-pool model’ and ‘two-pool model’ methods were used to evaluate the Q10 of SOC decomposition. Results indicated that in the early stage of incubation, exclusion of plant input increased the Q10 (Alfisol) or had minor effect on the Q10 (Mollisol), which may be related to the interactions between substrate quality decrease (increase of chemical stability) and clay mineral suppression on microbial decomposition. However, in the later stage of incubation, plant residue removal decreased the Q10 values in both soils possibly due to the limitation of substrate availability on microbial decomposition. Overall, the role of plant input in the temperature sensitivity of SOC decomposition should be considered when predicting SOC stocks in a future warmer world.

A pedo-geomorphological view on land use and its potential in the surroundings of the ancient Hispano-Roman city Munigua (Seville, SW Spain)

Abstract. This study investigates the surroundings of Munigua (municipium Flavium Muniguense), a small Roman town in the ancient province of Hispania Baetica (SW Spain). The city's economy was based primarily on copper and iron mining, which brought financial prosperity to its citizens. Local production of agricultural goods is thought to have been of little importance, as the regional soil conditions do not seem to be suitable for extensive agriculture. To evaluate the recent soil agro-potential and to find evidence for prehistoric and historic land use in the surroundings of Munigua, we applied a pedo-geomorphological approach based on the physico-chemical analysis of 14 representative soil and sediment exposures. Selected samples were analyzed for bulk chemistry, texture and phytoliths. The chronostratigraphy of the sequences was based on radiocarbon dating of charcoal samples. The site evaluation of the present-day soil agro-potential was carried out according to standard procedures and included evaluation of potential rootability, available water-storage capacity and nutrient budget within the uppermost 1 m. The results show that moderate to very good soil agro-potential prevails in the granitic and floodplain areas surrounding Munigua. Clearly, recent soil agro-potential in these areas allows the production of basic agricultural goods, and similar limited agricultural use should also have been possible in ancient times. In contrast, weak to very weak present-day soil agro-potential prevails in the metamorphic landscape due to the occurrence of shallow and sandy to stony soils. In addition, the study provides pedo-geomorphological evidence for prehistoric and historic land use in pre-Roman, Roman and post-Roman times. Catenary soil mapping in the vicinity of a Roman house complex reveals multi-layered colluvial deposits. They document phases of hillslope erosion mainly triggered by human land use between 4063 ± 82 and 3796 ± 76 cal BP, around 2601 ± 115 cal BP, and between 1424 ± 96 and 421 ± 88 cal BP. Moreover, geochemical and phytolith analyses of a Roman hortic Anthrosol indicate the local cultivation of agricultural products that contributed to the food supply of Munigua. Overall, the evidence of Roman agricultural use in the Munigua area indicates that the city's economy was by no means focused solely on mining. The production of basic agricultural products was also part of Munigua's economic portfolio. Our geoarcheological study thus supports the archeological concept of economically diversified Roman cities in the province of Baetica and in Hispania.

A 16th-century biodiversity and crop inventory.

Documenting and understanding long-term biodiversity change is limited by the availability of historical data, particularly from periods preceding major anthropogenic changes associated with the Industrial Revolution. We mined the information of a standardized historical survey developed in 628 localities across Spain between 1574 and 1582 (Relaciones Topográficas de Felipe II) with the goal of producing a general characterization of Spanish settlements, including, though not limited to, natural resources. From this survey, we were able to gather 7309 records for 75 wild plant taxa, 89 wild animal taxa, and 60 crop and domestic animal taxa. These data can be used to reconstruct historical land use and habitat cover, and model historical distributions of many species, including emblematic ones such as wolf and bear, which can establish reference distributions to assess range and niche expansion, contraction, and shifts. Data are provided under a Creative Commons Attribution Non Commercial (CC-BY-NC) 4.0 License. Please cite this data paper when the data are used in publications. The authors are open to collaborate in projects based on this dataset.

Land Use Land/Cover Change Reduces Woody Plant Diversity and Carbon Stocks in a Lowland Coastal Forest Ecosystem, Tanzania

The East-African lowland coastal forest (LCF) is one of Africa’s centres of species endemism, representing an important biodiversity hotspot. However, deforestation and forest degradation due to the high demand for fuelwood has reduced forest cover and diversity, with unknown consequences for associated terrestrial carbon stocks in this LCF system. Our study assessed spatio-temporal land use and land cover changes (LULC) in 1998, 2008, 2018 in the LCF ecosystem, Tanzania. In addition, we conducted a forest inventory survey and calculated associated carbon storage for this LCF ecosystem. Using methods of land use change evaluation plug-in in QGIS based on historical land use data, we modelled carbon stock trends post-2018 in associated LULC for the future 30 years. We found that agriculture and grassland combined increased substantially by 21.5% between the year 1998 and 2018 while forest cover declined by 29%. Furthermore, forest above-ground live biomass carbon (AGC) was 2.4 times higher in forest than in the bushland, 5.8 times in the agriculture with scattered settlement and 14.8 times higher than in the grassland. The estimated average soil organic carbon (SOC) was 76.03 ± 6.26 t/ha across the entire study area. Our study helps to identify land use impacts on ecosystem services, supporting decision-makers in future land-use planning.

Conservation in conversation: People's perspectives on a woodland with high conservation value—A qualitative study

Abstract Concepts such as ecosystem services and nature's contributions to people are frameworks for articulating the value of nature and biodiversity conservation. Yet it remains difficult to argue for the conservation of species and habitats where they are inconspicuous or ‘non‐charismatic’. This paper investigates the perceptions of a woodland area in rural western Scotland, designated for its high conservation value and characterised by habitats, rare species and species assemblages with limited appreciation by non‐experts and no obvious ‘utility’ value. Based on interviews with residents and visitors as well as workshops with participants representing different types of local expertise, we show how people experience and perceive the benefits from such woodlands. Overall, our study participants emphasised values and ecosystem services that benefitted humans, strongly drawing on stories of cultural or historical land use to argue for more material opportunities to be created. For those participants without ecological expertise, the designated conservation value, albeit respected and accepted, remained vague and bland. Participants also articulated a strong underlying development logic, pushing in some way for ‘more’ to be made from the woodlands so that more people could receive benefits from the woodland either directly (e.g. mental restoration; increased use for recreation) or indirectly (e.g. through creating jobs in the local tourism industry). Our findings suggest that managing for conservation alone might cause challenges in acceptability, especially where the species and habitats conserved are of little obvious value to the non‐specialist. At the same time, participants recognised that they valued the woodland being unique in some way, and that increasing the material use of the woods might harm the very essence of what made it special. Read the free Plain Language Summary for this article on the Journal blog.

Infectividad micorrícica nativa en suelos de la Región Pampeana con cultivo de soja, diferentes historiales y características edáficas

The expansion of soybean crop in Argentina replaced other crops, extensive livestock and forest ecosystems. It’s unclear whether this has altered native microbial communities that could supply ecosystem services, such as arbuscular mycorrhizal fungi (AMF), symbionts of the roots of most higher plants and known to promote host nutrition and growth, and soil sustainability. However, the magnitude of the contribution by the AMFs depends, in part, on maintaining its abundance in the soil and their potential to form mycorrhizae with roots. Our objective was to analyze variations in mycorrhizal infectivity (IMS50) and in spontaneous arbuscular mycorrhizal colonization (AM) of soybean crops cropped at three agricultural sites from the north of the Pampean Region (Córdoba), in relation to the historical land use (Agricultural [soybeans for more than 60 years], Mixed agricultural-livestock [A-G, soybean in the last 35 years], and Sierras [soybean in the last 20 years]). An in vivo bioassay revealed that the highest IMS50 occurred at the Agricultural and Sierras sites, in relation to the Mixed A-G one, the site with the highest available soil P content. Both the IMS50 and AM negatively correlated with soil P, while IMS50 was negatively associated with sand content, and positively with water, carbon and clay content. A high degree of infective potential by native AMF was detected in soils destined for soybean crop at the Pampean Region with different historical land use. The IMS50 was a more sensitive detection method than the determination of AM colonization in the field. It is concluded that IMS 50 could be used to define agricultural management strategies to maintain/favor native AMF communities.

Planting Site Effects on Early Growth of Pecan Tree Transplants

Site selection is key to successful establishment of fruit and nut trees. The upland soils on which pecan [Carya illinoinensis (Wangenh.) K. Koch] trees are commonly planted in the southeastern United States consist of sites that have recently been in row crop cultivation or pine or hardwood timber. Anecdotal observation suggests that orchards planted to land converted from cultivated row crop fields tends to result in better tree growth and survival than those on land recently converted from timber plantations or wooded areas. The objective of this experiment was to compare growth of first- through third-leaf pecan trees planted on sites with varying land-use history [row crop cultivation or pine (Pinus spp.) tree production up to the year before planting] and to determine the effects of supplemental addition of phosphorus (P), potassium (K), and zinc (Zn) at planting on the two sites. These results suggest that the soil conditions of sites recently in pine timber production limit the growth and development of pecan trees planted to those sites. These limitations result from soil acidity and an exhaustion of soil nutrients and loss of organic matter on pine sites, making the uptake of nitrogen (N), P, K, and calcium (Ca) challenging during the establishment phase unless soils are improved before planting.

Impacts of Long‐Term Urbanization on Summer Rainfall Climatology in Yangtze River Delta Agglomeration of China

AbstractIn this study, we investigated the urbanization‐induced summer rainfall changes in the Yangtze River Delta (YRD) by analyzing long‐term observations and numerical simulations. The observation‐based analysis showed that long‐term urbanization increased the region's summer rainfall, particularly through the intensification of heavy rainfall, which is noted as the urban rain island (URI) effect. A series of numerical sensitivity experiments with three historical land use and land cover scenarios (1990, 2000, and 2010) were designed to further understand the urbanization impacts on rainfall. The observed URI effect was well reproduced by the numerical simulations, and on average, urban expansion during 1990–2010 increased summer rainfall over urban areas by 51.91 mm. The URI effect slightly weakened in the late stage of urbanization (2000–2010) compared to the early stage (1990–2000). We conclude that the strengthening of precipitation‐inhibiting effects during the late period offset the precipitation‐enhancing effects, which led to the weakening of the URI effect.

Legacy of land-cover changes on soil microbiology in Burgundy vineyards (Pernand-Vergelesses, France)

Present-day soil physicochemical characteristics, land use/land cover (LULC), and field management practices are commonly recognised as the main drivers shaping archaeal/bacterial and fungal communities in vineyard soils. Few studies have investigated the legacy of past land uses on soil microbial biodiversity, yet anthropogenic disturbances have already been proven to affect soil characteristics over decades. In this study, we explore the possibility of long-lasting impacts of forest-to-vineyard conversion on present-day soil archaeal/bacterial and fungal communities after 15 years of vine cultivation.The selected study area is in a Burgundian vineyard (Pernand-Vergelesses, Burgundy, France), where it was possible to reconstruct the history of land cover and land use for the past 40 years. Soil samples were collected from five zones managed under similar pedo-climatic conditions but with different land-use histories (a 70-year-old vineyard, a 15-year-old vineyard converted from pine forest, a 15-year-old vineyard converted from mixed forest, a pine forest and a mixed forest). For each zone, basic physicochemical parameters (organic carbon, total nitrogen, copper, C:N ratio, and soil texture) were measured, and DNA was extracted to characterise the microbial biomass, and also the richness and taxonomic composition of archaeal/bacterial and fungal communities (16S and 18S).Our results show that changes in LULC lead to differential responses in soil microbial biomass, and in archaeal/bacterial and fungal richness and taxonomic composition. After 15 years of cultivation, the present-day microbial biomass and indigenous archaeal/bacterial communities of recent vineyard soils are shown to be partly inherited from past LULC, but no evidence was found of long-term impacts of past land use on fungal communities. Past land-use history should therefore be added to the well-established set of environmental drivers, providing valuable information to explain the spatial variability of soil microbiology, observed at intra-plot, plot, and landscape scales. Integrating the history of changes in LULC is therefore recommended to evaluate and adopt the best strategies to develop sustainable management practices.

Two Millennia of Complexity and Variability in a Perialpine Socioecological System (Savoie, France): The Contribution of Palynology and sedaDNA Analysis

Over the last two millennia, European Alpine ecosystems have experienced major changes in response to the important, yet fluctuating, impact of human activities. This study aims to reconstruct the environmental history of the last 1800 years on the western edge of the Alps by analyzing sediments from Lake Aiguebelette, a large lake located in the perialpine area. We have combined analyses of pollen and other palynomorphs, such as coprophilous fungal spores, together with sedimentary DNA (from plants and mammals) in order to reconstruct both vegetation and land-use histories. A sedimentological and geochemical analysis was also conducted in order to gain an understanding of changes in erosion dynamics in response to landscape modifications that were influenced by climate and human activities. This work highlights alternating phases of anthropization and agricultural abandonment allowing forest recovery. While pollen reflects the major phases of regional deforestation and afforestation related to the dynamic of farming activities, plant DNA provides precise information on the plants cultivated in fields, orchards and vegetable gardens over the past centuries. The combination of mammal DNA and coprophilous fungal spores completes this work by documenting the history of pastoral practices.

Historic and Contemporary Land Use Shape Plant-Pollinator Networks and Community Composition

Globally, grasslands represent a critical but shrinking habitat for native plants and pollinators, with declines driven by alterations to landscape-scale habitat cover and local-scale disturbance regimes, among other factors. Specifically, as cities expand in size, an increasing proportion of regional pasture and grassland habitat is being replaced by urban development, and fewer periodic grazing and burning regimes are being supported locally, despite evidence that such regimes promote plant species richness and facilitate their interaction with native pollinators. The quantification of these plant-pollinator networks—through indices such as network connectance, specialization, nestedness, and robustness—can provide a unique opportunity to characterize key structural properties of species interactions and their response to human management and seasonal phenology. While urbanization and local disturbance regimes likely influence plant and pollinator communities and their interactions, past research in this area has primarily been conducted at limited spatial and temporal scales and has not typically quantified the impacts of both local and landscape forces on network properties. In this study, we investigate the effects of contemporary (past 10 years) and historic (prior 90 years) disturbance regimes on plant-pollinator community composition and network structure across more than 200 km of grassland in Central Texas. Our analyses indicate that for plant and pollinator communities, both contemporary and historic land management practices have led to significantly dissimilar community composition. Plant and pollinator richness and network nestedness are negatively correlated with phenological period, while pollinator richness is positively correlated with landscape-scale (2 km) urbanized land cover and is higher in historically grazed land, likely due to greater food and nesting resource availability. In contrast, we show that network connectance is positively correlated with phenological period and negatively correlated with landscape-scale urban cover. Finally, we show that pollinator robustness, a measure of resilience to plant species loss, is positively correlated with landscape-scale urbanization, likely due to greater redundancy provided by common weedy plant species. Overall, our results demonstrate that historic grazing regimes, current urbanization levels, and distinct phenological periods can simultaneously drive plant-pollinator community composition and network dynamics in shrinking but critical grassland ecosystems.

Temperature, redox, and amendments alter wetland soil inorganic phosphorus retention dynamics in a Laurentian Great Lakes priority watershed

Surface water phosphorus loading must be reduced to improve water quality and decrease harmful algal blooms. Many wetlands have a natural capacity to retain inorganic reactive PO43− via soil sorption. However, soil PO43− retention capacity is finite and may be limited by soil legacy phosphorus effects in agricultural and urban areas. This study evaluated soil PO43− retention in soils from a wetland constructed on former agricultural land in the Lake Erie, Maumee River watershed targeted for nutrient load reduction. Soil PO43− sorption isotherms were evaluated under cool (10 °C), warm (22°), aerobic, and anaerobic treatments to determine changes in PO43− retention due to environmental conditions and estimate seasonal changes in PO43− sorption. The soils displayed a strong capacity for PO43− retention by sorption. However, results indicate that cooler temperatures and anaerobic conditions decreased PO43− sorption and lowered retention rates at PO43− concentrations observed in the region. Soil amendment experiments investigated opportunities to increase PO43− retention because many soils display elevated phosphorus concentrations due to historic land use, limiting their ability to adsorb additional PO43−. Amendments increased PO43− retention capacity compared to unamended soils in the presence of high PO43− concentrations, suggesting soil PO43− retention can be improved in areas where natural storage capacity has been exhausted. Results from this study can inform natural resources managers in the Laurentian Great Lakes and elsewhere when identifying potential nutrient reduction wetland locations and assist with developing operational guidelines to optimize PO43− retention and water quality improvements using wetlands.