Microclimatic Gradients Research Articles

Microclimatic Gradient as a Source of Variations in Cultivable soil Microfungal Communities at the Negev Desert, Israel

We studied the effect of microclimatic gradient on the spatial (8 habitats) and seasonal (autumn, winter, and summer) variations of culturable soil microfungal communities at the north-facing slope (NFS) and the south-facing slope (SFS) of Nahal Boker, the Central Negev Desert, Israel. Using the soil dilution plate method, a total of 122 species from 56 genera was isolated. The communities' composition was subjected to pronounced interslope variations in each season. While xerotolerant melanin-containing species (mainly with the protective multicellular spore morphology) predominated in the soil of NFS, peaking up in the summer, thermotolerant and thermophilic Aspergillus spp. were especially abundant at the SFS. Aspergilli also dominated the thermotolerant communities isolated at 37 °C from both slopes. The more severe microclimatic regime at the SFS resulted in the least pronounced spatial and seasonal intraslope variability of the community composition as compared to the more benign and heterogeneous NFS. The quantitative parameter—the density of microfungal isolates, exhibited significant and positive relationship with organic matter and moisture content. In seasonal dynamics, the severe summer conditions significantly reduced the differences in isolate density at the NFS, which were markedly expressed in the autumn and winter between habitats receiving additional water by runoff and the adjacent habitats that did not benefit from runoff water.

Dynamic Microclimate Boundaries across a Sharp Tropical Rainforest–Clearing Edge

As landscapes become increasingly fragmented, research into impacts from disturbance and how edges affect vegetation and community structure has become more important. Descriptive studies on how microclimate changes across sharp transition zones have long existed in the literature and recently more attention has been focused on understanding the dynamic patterns of microclimate associated with forest edges. Increasing concern about forest fragmentation has led to new technologies for modeling forest microclimates. However, forest boundaries pose important challenges to not only microclimate modeling but also sampling regimes in order to capture the diurnal and seasonal dynamic aspects of microclimate along forest edges. We measured microclimatic variables across a sharp boundary from a clearing into primary lowland tropical rainforest at La Selva Biological Station in Costa Rica. Dynamic changes in diurnal microclimate were measured along three replicated transects, approximately 30 m in length with data collected every 1 m continuously at 30 min intervals for 24 h with a mobile sensor platform supported by a cable infrastructure. We found that a first-order polynomial fit using piece-wise regression provided the most consistent estimation of the forest edge, relative to the visual edge, although we found no “best” sensing parameter as all measurements varied. Edge location estimates based on daytime net shortwave radiation had less difference from the visual edge than other shortwave measurements, but estimates made throughout the day with downward-facing or net infrared radiation sensors were more consistent and closer to the visual edge than any other measurement. This research contributes to the relatively small number of studies that have directly measured diurnal temporal and spatial patterns of microclimate variation across forest edges and demonstrates the use of a flexible mobile platform that enables repeated, high-resolution measurements of gradients of microclimate.

Microclimate and habitat heterogeneity as important drivers of soil Collembola in a karst collapse doline in the temperate zone

AbstractChanges in well‐delimited Collembola communities along a steep microclimatic gradient at the entrance of Silická ľadnica Ice Cave, Slovakia, were investigated after 10 years (2007, 2017). We focused on the occurrence of psychrophilic and endemic species occupying this unique karst collapse doline and their response to climatic singularities in the given years as well as the increasing trend in regional air temperature. The soil temperature means at sites across the doline slope corresponded with climatic trends in the periods 2006–2007 and 2016–2017. Significantly lower average soil temperatures but significantly higher mean abundances, species richness, and diversity indices of the collembolan communities were recorded at sites during the second study period, which was characterized by more favorable soil microclimatic conditions (temperature and moisture content) compared to the first period. The dominance structure and community composition of the studied assemblages appeared to be relatively constant after 10 years, indicating stable collembolan communities, especially at cold sites at the bottom of the doline. Redundancy ordination analysis documented a clear delimitation of the communities in relation to the soil temperature, pH, and C:N ratio in both periods. Long‐term (30‐year) regional climatic data showed an increasing trend of annual air temperature means and precipitation. However, an increase in the number and abundance of xerothermophilous species and a decline in psychrophilic species (mostly endemic) along the gradient as a potential response of the increasing regional temperature were not observed, suggesting the high resilience of these communities. Microclimate and habitat heterogeneity are probably major drivers of soil Collembola communities along the steep microclimatic gradient of a karst collapse doline, which was observed by the repeated sampling after 10 years. Karst dolines as potentially important local sources of ɑ‐diversity will likely become increasingly indispensable refugia for local biodiversity under ongoing global warming, thus deserving reliable conservation.

Microclimate structures communities, predation and herbivory in the High Arctic.

In a warming world, changes in climate may result in species‐level responses as well as changes in community structure through knock‐on effects on ecological interactions such as predation and herbivory. Yet, the links between these responses at different levels are still inadequately understood. Assessing how microclimatic conditions affect each of them at local scales provides information essential for understanding the consequences of macroclimatic changes projected in the future.Focusing on the rapidly changing High Arctic, we examine how a community based on a common resource species (avens, Dryas spp.), a specialist insect herbivore (Sympistis zetterstedtii) and natural enemies of lepidopteran herbivores (parasitoids) varies along a multidimensional microclimatic gradient. We ask (a) how parasitoid community composition varies with local abiotic conditions, (b) how the community‐level response of parasitoids is linked to species‐specific traits (koino‐ or idiobiont life cycle strategy and phenology) and (c) whether the effects of varying abiotic conditions extend to interaction outcomes (parasitism rates on the focal herbivore and realized herbivory rates).We recorded the local communities of parasitoids, herbivory rates on Dryas flowers and parasitism rates in Sympistis larvae at 20 sites along a mountain slope. For linking community‐level responses to microclimatic conditions with parasitoid traits, we used joint species distribution modelling. We then assessed whether the same abiotic variables also affect parasitism and herbivory rates, by applying generalized linear and additive mixed models.We find that parasitism strategy and phenology explain local variation in parasitoid community structure. Parasitoids with a koinobiont strategy preferred high‐elevation sites with higher summer temperatures or sites with earlier snowmelt and lower humidity. Species of earlier phenology occurred with higher incidence at sites with cooler summer temperatures or later snowmelt. Microclimatic effects also extend to parasitism and herbivory, with an increase in the parasitism rates of the main herbivore S. zetterstedtii with higher temperature and lower humidity, and a matching increase in herbivory rates.Our results show that microclimatic variation is a strong driver of local community structure, species interactions and interaction outcomes in Arctic ecosystems. In view of ongoing climate change, these results predict that macroclimatic changes will profoundly affect arctic communities.

Are wide but selectively logged buffer strips better than narrow ones?

ABSTRACT The microclimate of streamside habitats are protected from the effects of logging with buffer strips of retained trees. However, these buffer strips are often narrow due to their financial loss. Wider, selectively logged buffers might protect the microclimate while providing the same economic return. This study investigates the effects of logging on the microclimate and the growth of the bryophyte Hylocomium splendens on two streamside buffers: a standard unlogged narrow buffer (∼15 m) and a wider buffer (∼30 m) selectively logged with decreasing intensity towards the stream. The study was conducted in Central Finland on eight sites where the two buffers were logged next to each other. The near-stream change in air temperature and relative humidity was measured from pre-logging to post-logging. Additionally, post-logging microclimate gradients and the growth of H. splendens was measured on a 30 m transect away from the stream. The results showed no significant differences in the ability of the two kinds of buffers in maintaining streamside microclimate, and neither buffer seems to protect the microclimate from the negative effects of logging. The growth of H. splendens also decreased in both buffers. We conclude that wider, unlogged buffer strips are required to protect riparian forest microclimate.

Microclimatic Tipping Points at the Beech–Oak Ecotone in the Western Romanian Carpathians

European beech (Fagus sylvatica) is a drought-sensitive species that likely will retreat from its xeric distribution edges in the course of climate warming. Physiological measurements indicate that the species may not only be sensitive to soil water deficits, but also to high temperatures and elevated atmospheric vapor pressure deficits (vpd). Through microclimatological measurements in the stand interior across near-natural beech forest–oak forest ecotones, we searched for microclimatic tipping points in the contact zone with the aim to define the thermic and hydrometeorological limits of beech more precisely. In three transects in the foothills of the Romanian western Carpathians, we measured in mid-summer 2019 air temperature, relative air humidity, and vpd at 2 m height in the stand interior across the ecotone from pure oak to pure beech forests, and compared the readings to the microclimate in forest gaps. Mean daytime temperature (T) and vpd were by 2 K and 2 hPa, respectively, higher in the oak forests than the beech forests; the extremes differed even more. Especially in the second half of the day, the oak forests heated up and were more xeric than the beech forests. Part of the differences is explained by the elevation difference between oak and beech forests (200–300 m), but species differences in canopy structure, leaf area, and canopy transmissivity enhance the microclimatic contrast. Our T and vpd data point to thresholds at about 30 °C and 25 hPa as maxima tolerated by beech in the lowermost shade canopy for extended periods. In conclusion, the rather sharp stand microclimatic gradient demonstrated here for the xeric distribution limit of beech may well be the decisive factor that hinders the spread of beech into the warmer oak forests.

The relationship between epixylic bryophyte communities and microclimate

AbstractAimDead wood‐inhabiting bryophyte communities are formed by several important factors. Besides the amount, quality and continuity of the substrate, there are also external factors indirectly influencing their structure. One of the most important is local microclimate. This fact has been recognized by many previous authors, yet studies exploring the direct effect of the microclimate on epixylic bryophytes are still sparse. Based on directly measured values of local temperature, air humidity and canopy openness (CO), we explored the associations between microclimate and epixylic bryophyte communities.LocationOld‐growth mixed Fagus sylvatica‐Abies alba montane forest in the Czech Republic (West Carpathians).MethodsThe associations between microclimate and bryophyte communities were studied on 61 large logs of Abies alba in advanced decay stage. Air temperature and humidity were measured in three periods of the year 2017, CO was measured in leafless and leaf‐on periods. Water potential (Ψ) values were calculated from the data. The importance of the seasons was compared, the effect of microclimate variables on the species composition of logs was explored by canonical correspondence analysis. The effect on total cover and species richness was analyzed by linear models.ResultsOur analysis revealed a clear relationship between the communities and the microclimatic gradient. The most important factors for bryophyte composition were the spring and summer water potential and CO in the leaf‐on period. Total species richness and cover increased with increasing water potential (relatively cool and humid conditions). Also, the appearance of sensitive epixylic specialists (mainly liverworts) was positively correlated with these microclimatic conditions. On the other hand, species more tolerant to desiccation preferred logs with a drier and warmer microclimate.ConclusionsComparing logs with similar physical properties but different microclimates, we confirmed that epixylic bryophyte communities are significantly associated to microclimatic conditions in natural temperate forest.

Maintaining mechanisms of riparian invertebrate biodiversity: A review

Riparian zones, the critical ecological interfaces between terrestrial and aquatic ecosystems, are species rich habitats. However, riparian zones are seriously threatened by human activities in the world. Riparian invertebrates represent a large proportion of riparian biodiversity, perform various ecological functions, and provide an essential link between aquatic and terrestrial ecosystems. Although many studies have investigated the riparian invertebrate communities, there is lacking a comprehensive summary of maintaining mechanisms underlying riparian invertebrate diversity. This review discussed seven characteristics of riparian zones that might support high riparian invertebrate diversity: flood and drought, nutrient, microhabitat diversity, riparian vegetation, microclimate gradients, food resources and river spatial gradients. Further, we summarized the maintaining mechanisms of riparian invertebrate diversity. Disturbances of periodic flood and drought trigger the reproduction and migration of invertebrates, increase the turnover of invertebrate communities, and create suitable conditions for riparian invertebrates. Adequate nutrients support a high invertebrate diversity by increasing primary productivity of riparian habitats. Elevated microhabitat diversity provides a variety of niche space for specialist riparian invertebrates. Strong microclimate gradients provide complex and diverse habitats and thus facilitate the coexistence of aquatic and terrestrial invertebrates in riparian zones. Cross-ecosystem resource subsidies increase food availability and contribute unique food sources to riparian invertebrates. The differentiation of these factors along river longitudinal and lateral gradients provides conditions for the diversification of riparian invertebrates at a larger scale. Understanding the maintaining mechanisms of riparian invertebrate diversity is important for conservation of riparian biodiversity and integrated management of river ecosystems.

Intraspecific variation influences performance of moss transplants along microclimate gradients.

Identifying the environmental drivers of population dynamics is crucial to predict changes in species abundances and distributions under climate change. Populations of the same species might differ in their responses as a result of intraspecific variation. Yet the importance of such differences remains largely unexplored. We examined the responses of latitudinally distant populations of the forest moss Hylocomiastrum umbratum along microclimate gradients in Sweden. We transplanted moss mats from southern and northern populations to 30 sites with contrasting microclimates (i.e., replicated field common gardens) within a forest landscape, and recorded growth and survival of individual shoots over 3 yr. To evaluate the importance of intraspecific variation in responses to environmental factors, we assessed effects of the interactions between population origin and microclimate drivers on growth and survival. Effects on overall performance of transplanted populations were estimated using the product of survival and growth. We found differences between southern and northern populations in the response to summer temperature and snowmelt date in one of three yearly transitions. In this year, southern populations performed better in warm, southern‐like conditions than in cold, northern‐like conditions; and the reverse pattern was true for northern populations. Survival of all populations decreased with evaporation, consistent with the high hydric demands and poikilohydric nature of mosses. Our results are consistent with population adaptation to local climate, and suggest that intraspecific variation among populations can have important effects on the response of species to microclimate drivers. These findings highlight the need to account for differential responses in predictions of species abundance and distribution under climate change.

Substrate quality and not dominant plant community determines the vertical distribution and C assimilation of enchytraeids in peatlands

AbstractPeatlands are important carbon (C) stores as a result of acidity, waterlogging conditions and low temperatures slowing decomposition rates. However, climate change is predicted to bring not only changes in abiotic conditions but also the replacement of peat‐forming vegetation, such asSphagnummosses, with vascular plants. In these systems, enchytraeid worms represent the dominant mesofaunal group, and previous climate change manipulations have shown that their abundances and vertical distribution are strongly influenced by temperature and moisture gradients, with important implications for C cycling. Therefore, determining their behavioural responses to changes in both abiotic and biotic factors is crucial to quantify their contribution to decomposition processes.We investigated the importance of vertical edaphic gradients (soil moisture and labile C) on enchytraeids total numbers, vertical distribution and feeding activities by inverting intact soil cores and hence, reversing both substrate quality but leaving the microclimatic gradients intact. This manipulative experiment was set up in two different peatland areas, one dominated by heather (Erica mackaiana) and another by mosses (Sphagnumsp.) to determine the influence of different plant functional growth forms on these responses.Our results showed that most enchytraeid species were ‘stayers’ (i.e. in the ‘Upturned cores’, they remained in the same layer where they are ‘Normally’ located), and hence, their vertical distribution was more dependent on substrate quality than a change in microclimate. This response was more evident under drier conditions (i.e. the highest locations of the height gradient at the heather site) than at the wettest locations (i.e. the bottom of the slope and under mosses) due to more pronounced vertical gradients in substrate quality. Furthermore, radiocarbon measurements on enchytraeid tissues showed that to avoid competition among the growing populations for the limited labile resources present in the top layers, enchytraeids selected older C sources.These findings indicate that future climate change scenarios will not only bring important changes in the abiotic conditions (temperature and moisture) and biotic properties of peatlands (both vegetation composition and below‐ground soil biota community structure and vertical distribution) but also alterations in the feeding preferences of key decomposers that could result in the mobilization of previously unavailable C pools.A freePlain Language Summarycan be found within the Supporting Information of this article.

基于改进的双作物系数法估算辽河三角洲芦苇湿地蒸散量

PDF HTML阅读 XML下载 导出引用 引用提醒 基于改进的双作物系数法估算辽河三角洲芦苇湿地蒸散量 DOI: 10.5846/stxb201810272317 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学青年基金项目（41405109）；辽宁省科技厅重点研发计划指导计划项目（2018108004）；中国气象局气候变化专项（CCSF201819） Evapotranspiration estimation of Phragmites australis wetland in the Liaohe River Delta based on the improved dual crop coefficient method Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以辽河三角洲湿地芦苇群落为研究对象，利用涡动相关通量、小气候梯度要素、群落内水面蒸发量以及芦苇群落生长参数等数据，基于FAO-56模型的双作物系数法，分别计算作物系数Kc、基础作物系数Kcb和水面蒸发系数Kw，分析其日变化动态及主导影响因子，建立基于生物因子和环境因子的小时尺度双作物系数模型。结果如下：（1）芦苇生长初期，Kc和Kcb的日变化呈现早晚高、中午略低的多峰波动曲线；在快速生长期和稳定生长期，Kc和Kcb白天波动幅度较小，早晚波动幅度较大；生长末期，Kc和Kcb夜晚波动幅度较大，白天呈现多峰波动曲线；Kw白天较小、夜晚较高，生长初期白天的数值显著高于其他时期。（2）相关分析表明，气温、相对湿度、风速、株高和叶面积指数是Kc、Kcb和Kw的影响因子；基于生物因子和环境因子重新构建双作物系数模型，基于改进的双作物系数法模拟芦苇群落蒸散，决定系数R2达0.894。（3）利用改进的双作物系数模型和FAO-56模型，对辽河三角洲芦苇群落的蒸发与蒸腾过程进行模拟，实现芦苇群落蒸发过程与蒸腾过程的分离，解决了实际观测无法直接获取芦苇群落蒸腾量的问题，同时提高了芦苇群落蒸散的模拟精度。（4）调整了FAO推荐的芦苇单作物系数常数值，调整后的作物系数更适用于辽河三角洲芦苇湿地。 Abstract:Phragmites australis wetland in the Liaohe River Delta of Northeastern China was selected as a research object. Based on the dual crop coefficient of FAO-56 model and the observed data (including flux data, microclimate gradient data, water evaporation, growth parameters of P. australis, etc.) in Panjin Wetland Ecosystem Research Station, the crop coefficient (Kc), the basal crop coefficient (Kcb), and the water evaporation coefficient (Kw) were calculated. The diurnal dynamics of three coefficients and their influencing factors were analyzed. Dual crop coefficient model at hour scale was established using the biological factors and environmental factors. The results are as follows:(1) In the initial growth stage, the diurnal variation of Kc and Kcb showed multi-peak fluctuation with higher values in the morning and evening and lower values at noon; during the rapid development and stable stage, the fluctuation ranges of Kc and Kcb were smaller in the daytime and larger at night; at the end of growth season, Kc and Kcb fluctuated greatly at night and presented multi-peak curves in the daytime. Kw was smaller in the daytime and higher at night, with the daytime values in the initial stage higher than those of the other stages. (2) The correlation analysis showed that the influencing factors of Kc, Kcb, and Kw were air temperature, relative humidity, wind speed, plant height, and leaf area index. The dual coefficient model was reconstructed with the biological and environmental factors. Thus, the simulation of the evapotranspiration in P. australis wetland was improved with the determination coefficient R2 reaching 0.894. (3) Using the improved dual crop coefficient model and FAO-56 model, the evaporation and transpiration of P. australis wetland in the Liaohe River Delta were simulated. This could solve the problem that transpiration is unobtainable from direct observation and improve the accuracy of evapotranspiration simulation. (4) We adjusted the constant value of P. australis crop coefficient recommended by FAO which was more suitable for the Liaohe River Delta wetland. 参考文献 相似文献 引证文献

Darker ants dominate the canopy: Testing macroecological hypotheses for patterns in colour along a microclimatic gradient.

Gradients in cuticle lightness of ectotherms have been demonstrated across latitudes and elevations. Three key hypotheses have been used to explain these macroecological patterns: the thermal melanism hypothesis (TMH), the melanism‐desiccation hypothesis (MDH) and the photo‐protection hypothesis (PPH). Yet the broad abiotic measures, such as temperature, humidity and UV‐B radiation, typically used to detect these ecogeographical patterns, are a poor indication of the microenvironment experienced by small, cursorial ectotherms like ants.We tested whether these macroecological hypotheses explaining cuticle lightness held at habitat and microclimatic level by using a vertical gradient within a tropical rainforest.We sampled 222 ant species in lowland, tropical rainforest across four vertical strata: subterranean, ground, understory and canopy. We recorded cuticle lightness, abundance and estimated body size for each species and calculated an assemblage‐weighted mean for cuticle lightness and body size for each vertical stratum. Abiotic variables (air temperature, vapour pressure deficit and UV‐B radiation) were recorded for each vertical stratum.We found that cuticle lightness of ant assemblages was vertically stratified: ant assemblages in the canopy and understory were twice as dark as assemblages in ground and subterranean strata. Cuticle lightness was not correlated with body size, and there was no support for the TMH. Rather, we attribute this cline in cuticle lightness to a combination of the MDH and the PPH.Our findings indicate that broad macroecological patterns can be detected at much smaller spatial scales and that microclimatic gradients can shape trait variation, specifically the cuticle lightness of ants. These results suggest that any changes to microclimate that occur due to land‐use change or climate warming could drive selection of ants based on cuticle colour, altering assemblage structure and potentially ecosystem functioning.

Trails‐as‐transects: phenology monitoring across heterogeneous microclimates in Acadia National Park, Maine

AbstractClimate‐driven shifts in phenology, which are being observed worldwide, affect ecosystem services, trophic interactions, and community composition, presenting challenges to managers in protected areas. Resource management benefits from local, species‐specific phenology information. However, phenology monitoring programs in heterogeneous landscapes typically require serendipitous historical records or many years of contemporary data before trends in phenological responses to changes in climate can be analyzed. Here, we used a trails‐as‐transects approach to rapidly accumulate monitoring data across environmental gradients on three mountains in Acadia National Park, Maine, USA, and compared our results to phenological changes observed in Concord, Massachusetts, USA. In four years of intensive monitoring of transects on three mountains, we found large variability in spring temperatures across the mountains, but consistent patterns of advancing flower and leaf phenology in warmer microclimates. Reduced sampling intensity would have yielded similar results, but a shorter duration would not have revealed these patterns. The plants in Acadia responded to warming spring temperatures by shifting leaf and flower phenology in the same direction (earlier), but at a reduced rate (as measured in d/°C), in comparison with plants in southern New England (e.g., Concord, Massachusetts, USA). Our approach takes advantage of topographical complexity and associated microclimate gradients to substitute for long time series, allowing for rapid assessment of phenological response to climate. Other climate gradients (e.g., urban‐to‐rural, latitudinal, or coastal‐to‐inland) could work similarly. This intensive monitoring over a short time period quickly builds a robust dataset and can inform management decisions regarding future monitoring strategies, including sampling designs for citizen science‐based phenology monitoring programs.

Microclimate Influences Mangrove Freeze Damage: Implications for Range Expansion in Response to Changing Macroclimate

In response to warming winter air temperatures, freeze-sensitive mangrove forests are expected to expand at the expense of freeze-tolerant salt marshes. To better anticipate and prepare for mangrove range expansion, there is a need to advance understanding of the modulating role of microclimate. Here, we synthesized hypotheses regarding the effects of microclimatic variation on temperature gradients and mangrove freeze damage. Temperature data from the literature and from temperature loggers were used to quantify ecologically relevant temperature gradients. Then, literature-derived mangrove freeze damage data were used to quantify the ecological effects of these temperature gradients. Six microclimatic factors are described that produce air temperature gradients that modulate mangrove responses to winter temperature extremes: (1) distance from the ocean; (2) distance from wind buffers; (3) mangrove canopy cover; (4) height above the soil surface; (5) local slope concavity; and (6) tidal inundation. Variation in these factors produces local temperature differences that range from 2 to 14 °C, with concomitant effects on horizontal and vertical patterns of biological damage from freezing. Collectively, our results elucidate the influence of microclimate on spatial patterns of biological damage and mortality due to winter temperature extremes. As mangrove ranges expand in response to climate change, we anticipate that microclimatic variation will produce adverse environments where mangrove expansion is prohibited as well as expansion hot spots where mangroves are protected. Subsequent expansion into newly available habitat will occur from protection zones, and microclimatic gradients may even produce positive feedback cycles that ultimately accelerate the rate of range expansion in response to warming.

Microclimate and matter dynamics in transition zones of forest to arable land

Human-driven fragmentation of landscapes leads to the formation of transition zones between ecosystems that are characterised by fluxes of matter, energy and information. These transition zones may offer rather inhospitable habitats that could jeopardise biodiversity. On the other hand, transition zones are also reported to be hotspots for biodiversity and even evolutionary processes.The general mechanisms and influence of processes in transition zones are poorly understood. Although heterogeneity and diversity of land use of fragments and the transition zones between them play an important role, most studies only refer to forested transition zones. Often, only an extrapolation of measurements in the different fragments themselves is reported to determine gradients in transition zones.In this article, we analyse environmental gradients and their effects on biota and matter dynamics along transects between managed continental temperate forests and agricultural land for one year. Accordingly, we found S-shaped microclimatic gradients in transition zones of 50–80 m between arable lands and forests. Aboveground biomass was lower within 65 m of the transition zone, 30 m in the arable land and 35 m in the forest. Soil carbon and nitrogen contents were elevated close to the transition zone’s zero line.This paper contributes to a quantitative understanding of agricultural landscapes beyond individual ecotopes, and towards connected ecosystem mosaics that may be beneficial for the provision of ecosystem services.

The Plane Area of Daily Dynamics of Microclimate Gradient Concepts, Methods and Application Results

The Plane Area of Daily Dynamics of Microclimate Gradient Concepts, Methods and Application Results

Microclimate and demography interact to shape stable population dynamics across the range of an alpine plant

Heterogeneous terrain in montane systems results in a decoupling of climatic gradients. Population dynamics across species' ranges in these heterogeneous landscapes are shaped by relationships between demographic rates and these interwoven climate gradients. Linking demography and climate variables across species' ranges refines our understanding of the underlying mechanisms of species' current and future ranges. We explored the importance of multiple microclimatic gradients in shaping individual demographic rates and population growth rates in 16 populations across the elevational distribution of an alpine plant (Ivesia lycopodioides var. scandularis). Using integral projection modeling, we ask how each rate varies across three microclimate gradients: accumulated degree-days, growing-season soil moisture, and days of snow cover. Range-wide variation in demographic rates was best explained by the combined influence of multiple microclimatic variables. Different pairs of demographic rates exhibited both similar and inverse responses to the same microclimatic gradient, and the microclimatic effects often varied with plant size. These responses resulted in range-wide projected population persistence, with no declining populations at either elevational range edge or at the extremes of the microclimate gradients. The complex relationships between topography, microclimate and demography suggest that populations across a species' range may have unique demographic pathways to stable population dynamics.

Intracanopy adjustment of leaf-level thermal tolerance is associated with microclimatic variation across the canopy of a desert tree (Acacia papyrocarpa).

Tree crowns are spatially heterogeneous, sometimes resulting in significant variation in microclimate across the canopy, particularly with respect to temperature. Yet it is not known whether such localised temperature variation equates to intracanopy variation in leaf-level physiological thermal tolerance. Here, we studied whether microclimate variation across the canopy of a dominant desert tree equated to localised variation in leaf thermal thresholds (T50) among four canopy positions: upper south, upper north, lower south, lower north. Principal component analysis was used to generate a composite climatic stress variable (CSTRESS) from canopy temperature, vapour pressure deficit, and relative humidity. We also determined the average number of days that maximum temperatures exceeded the air temperature equating to this species' critical threshold of 49°C (AT49). To estimate how closely leaf temperatures track ambient temperature, we predicted the thermal time constant (τ) for leaves at each canopy position. We found that CSTRESS and AT49 were significantly greater in lower and north-facing positions in the canopy. Differences in wind speed with height resulted in significantly longer predicted τ for leaves positioned at lower, north-facing positions. Variation in these drivers was correlated with significantly higher T50 for leaves in these more environmentally stressful canopy positions. Our findings suggest that this species may optimise resources to protect against thermal damage at a whole-plant level. They also indicate that, particularly in desert environments with steep intracanopy microclimatic gradients, whole-plant carbon models could substantially under- or overestimate productivity under heat stress, depending on where in the canopy T50 is measured.

Microtopography determines the habitat quality of a threatened peatland butterfly at its southern range margin

Knowledge of the ecology of pre-adult stages of an organism at its species’ range margins is a prerequisite for conserving species, especially for understanding its responses to future climate changes. Largely sedentary premature life stages require specific living conditions within a relatively small area. Such conditions are created by vegetation structure heterogeneity and a microclimate gradient, generated by varying microtopography. We investigated the microhabitat selection patterns of egg-laying females and overwintering caterpillars of peatland butterfly Coenonympha tullia relative to vegetation composition, water quantity and microclimatic conditions across microtopographic zones of transition mire at the species’ southern range margin. We showed that (1) small-scale variability in mire microtopography determines oviposition site selection and larval presence; (2) microhabitats of pre-adult stages were largely confined to the intermediate microtopographic zone of the transition mire (flats); (3) egg-laying females and overwintered larvae preferred microsites with high coverage of main hostplants (Trichophorum alpinum, Carex lasiocarpa, C. limosa, C. panicea), and those with more humid and cooler summertime conditions than on hummocks; (4) females and larvae avoided shallow hollows permanently filled with water. The vegetation structure of flats enables the females to select spots with sufficient humidity for egg development, and allows the larvae to change their location according to suitable thermal and moisture conditions. We also discuss poor prospects for species in view of impacts of future climate changes on mire ecosystems.

Microclimatic gradients provide evidence for a glacial refugium for temperate trees in a sheltered hilly landscape of Northern Italy

ABSTRACTAimRefugia play a key role in conserving biodiversity during periods of unfavourable and highly variable regional climate. However, refugial populations are often small and fragmented, which makes their identification difficult. In this study, we investigate whether an area of complex topography in the southern foreland of the Alps could have provided a suitable microclimate to serve as a glacial refugium for temperate trees during the last glacial.LocationThe Euganean Hills in Northern Italy (Veneto).MethodsWe assessed the current microclimatic variability in the ecologically diverse region on a fine scale by recording half‐hourly near‐surface temperatures over a period of 11 months. After comparing our measurements with today's vegetation distribution, broad‐scale synoptic patterns, and topoclimatic factors, we estimated refugial suitability based on extreme temperatures, climatic stability, and difference from the regional average.ResultsPresent‐day temperature gradients within the Euganean Hills are large enough to explain the presence of the temperate tree species Fagus sylvatica as well as Mediterranean Quercus ilex, two species that are absent elsewhere in the adjacent Po Plain. During winter, anticyclonic weather patterns resulted in strong atmospheric inversions, with temperatures increasing by +1°C/100 m in the hills relative to the surrounding Po Plain.Main conclusionsOur high‐resolution climate data support multi‐proxy palaeoecological records identifying the Euganean Hills as a refugium for temperate trees. Temperature anomalies of 2–4°C relative to the surrounding Po Plain are sufficient to allow several temperate tree species to survive the Last Glacial Maximum (LGM) in the Euganean Hills under a harsh continental climate. Specifically, elevations >200 m a.s.l. in the central parts of the hills may have provided suitable conditions for local LGM refugia. Regions of complex topography such as the Euganean Hills conserved past and present biodiversity and provide high‐priority areas for conservation under future climate warming.