Remote Sensing of Ecosystem Services:An Opportunity for Spatially Explicit Assessment

Ecosystem service is an emerging concept that grows to be a hot research area in ecology.Spatially explicit ecosystem service values are important for ecosystem service management.However,it is difficult to quantify ecosystem services.Remote sensing provides images covering Earth surface,which by nature are spatially explicit.Thus,remote sensing can be useful for quantitative assessment of ecosystem services.This paper reviews spatially explicit ecosystem service studies conducted in ecology and remote sensing in order to find out how remote sensing can be used for ecosystem service assessment.Several important areas considered include land cover,biodiversity,and carbon,water and soil related ecosystem services.We found that remote sensing can be used for ecosystem service assessment in three different ways:direct monitoring,indirect monitoring,and combined use with ecosystem models.Some plant and water related ecosystem services can be directly monitored by remote sensing.Most commonly,remote sensing can provide surrogate information on plant and soil characteristics in an ecosystem.For ecosystem process related ecosystem services,remote sensing can help measure spatially explicit parameters.We conclude that acquiring good in-situ measurements and selecting appropriate remote sensor data in terms of resolution are critical for accurate assessment of ecosystem services.

Growth and form of Quercus robur and Fraxinus excelsior respond distinctly different to initial growing space: results from 24-year-old Nelder experiments

Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to first dead and first live branch and branchiness） and stem and crown form of 24-year-old pedunculate oak （Quercus robur [L.]） and European ash （Fraxinus excelsior [L.]） were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha？1. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.

Developing nonlinear additive tree crown width models based on decomposed competition index and tree variables

Crown development is closely related to the biomass and growth rate of the tree and its width(CW)is an important covariable in growth and yield models and in forest management.To date,various CW models have been proposed.However,limited studies have explicitly focused on additive and inherent correlation of crown components and total CW as well as the influence of competition on crown radius from the corresponding direction.In this study,two model systems were used,i.e.,aggregation method system(AMS)and disaggregation method system(DMS),to develop crown width additive model systems.For calculating spatially explicit competition index(CI),four neighbor tree selection methods were evaluated.CI was decomposed into four cardinal directions and added into the model systems.Results show that the power model form was more proper for our data to fit CW growth.For each crown radius and total CW,height to the diameter at breast height(HDR)and basal area of trees larger than the subject tree(BAL)significantly contributed to the increase of prediction accuracy.The 3-m fixed radius was optimal among the four neighborhoods selection ways.After adding decomposed competition Hegyi index into model systems AMS and DMS,the prediction accuracy improved.Of the model systems evaluated,AMS based on decomposed CI provided the best performance as well as the inherent correlation and additivity properties.Our study highlighted the importance of decomposed CI in tree CW modelling for additive model systems.This study focused on methodology and could be applied to other species or stands.

Impact of anthropogenic activities on vegetation dynamics in a reservoir area: model establishment and a case study of Longkaikou Reservoir in China

Vegetation in hot and arid valleys is a crucial indicator of ecosystem health,but is vulnerable to human activities and environmental change.Using the Longkaikou Reservoir in the Jinsha River in southwestern China as a case study,we developed a spatially explicit model that combined the plant growth,fruiting,seed dispersal,and seed germination stages to reveal the potential impact of multiple human activities(reservoir construction,logging,grazing,and aerial seeding) on the vegetation dynamics of Dodonaea viscosa and Pinus yunnanensis.After reservoir construction,the grassland area of 68 km^(2) in 2003 decreased to 24 km^(2) in 2018,replaced by forest,shrubland,and bodies of water,and the precipitation increased during the dry season,which indicated the improvement of the local plant and soil environment.Our model predicted that when soil moisture decreased by more than 20% compared to current levels,the area of D.viscosa increased greatly at low elevations;however,when at higher soil moisture,P.yunnanensis would occupy more of the study area.Logging and grazing would slightly change the spatial pattern of vegetation and delay P.yunnanensis communities from achieving stability by directly reducing plant biomass.Countermeasures such as aerial seeding would increase the total area by 13.13 km^(2) and 8.09 km^(2) of two plants,respectively,and accelerate the stabilization of plant communities.The effects of multiple human activities on vegetation may counteract each other;for example,logging decreased the P.yunnanensis area whereas aerial seeding increased it,and plant biomass changed in response to this pressure.Given the complex relationships between vegetation and human impacts,our study provides a scientific basis for vegetation restoration and ecological security in this hot and arid valley.

评估全球自然对人类的贡献

自然对人类的贡献(nature’s contributions to people,NCP)是指大自然对人类生活质量的一切积极贡献和消极影响,分为10个调节型NCP、4个物质型NCP和4个非物质型NCP.但目前这些NCP的全球时空分布及其相互作用规律尚不清楚,直接制约了加强自然界多种有益贡献的生态系统管理实践.本研究构建基于指标体系的评价方法,结合生态系统演变、气候变化与人类活动全球尺度多源空间数据集,在全球范围内对1990~2018年所有18个NCPs进行空间制图,在15,204个流域单元上识别主导了NCP组合,并基于NCPs时空特征识别了全球景观变化的功能权衡关系和景观多功能性.结果表明,全球大部分NCPs的高值仅在局地出现.1992~2018年,6个调节型NCP、3个物质型NCP和2个非物质型NCP下降.29种调节型和物质型NCP组合(总共有54种组合)的主导流域占全球76%的陆地面积,而无NCP主导的流域占全球陆地面积的22%.NCPs变化的协同关系比权衡关系更为常见,但调节型和物质型NCP之间的关系普遍处于权衡状态.过渡气候地区的NCP相对少,并具有强烈的权衡关系;而低纬度地区NCPs之间的高度协同关系可能受到未来气候变化的影响.研究结果提供了对全球NCP空间变化规律的总体认知,可用于科学支撑区域景观功能的关系调控和景观多功能性提升,以增强全球人类福祉.

Elusive cats in our backyards:persistence of the North Chinese leopard(Panthera pardus japonensis)in a human-dominated landscape in central China

The North Chinese leopard(Panthera pardus japonensis),the least-known big cat,disappeared in most historical range for decades,following the development of modern civilization.Unfortunately,we have scarce knowledge about the status of this big cat so far,apart from anecdotal reports.In this study,we investigated density,distribution,and habitat use of the leopard,the apex predator,in a complex forest landscape in the Loess Plateau.We used a camera-trapping network to obtain population estimates for leopards over 2 years through spatially explicit capture-recapture models.Our results,based on maximum likelihood and Bayesian/MCMC methods,reveal that the largest wild population of the leopard was found widely distributed in remnant forests in central Loess plateau.The population is increasing in our study area,and the density of leopards(1.70(SE=0.48)−2.40(SE=0.67)/100 km^(2))is higher than other areas of China.According to the analysis of 2 seasonal occupancy models,prey species drive partially the leopard habitat use,predicting that the big cat thrives from the recovery of prey community.However,human disturbances,especially oil wells,seem to have negative impacts on the habitat use of leopards.Specifically,it is necessary to have joint efforts by the government and researchers to improve human disturbances management and prey species population density,as well as strengthen the investment in research on the North Chinese leopard,which could all further strengthen protection ability and ensure the long-term survival of this species.

Agent-based models reveal limits of mark-release-recapture estimates for the rare butterfly, Bhutanitis thaidina (Lepidoptera: Papilionidae)

Insect diversity and abundance are in drastic decline worldwide,but quantifying insect populations to better conserve them is a difficult task.Mark-release-recapture(MRR)is widely used as an ecological indicator for insect populations,but the accuracy of MRR estimates can vary with factors such as spatial scale,sampling effort and models of inference.We conducted a 3-year MRR study of B.thaidina in Yanzigou valley,Mt.Gongga but failed to obtain sufficient data for a robust population estimate.This prompted us to integrate B.thaidina life history information to parameterize agent-based models and evaluate the conditions under which successful MRR studies could be conducted.We evaluated:(1)the performance of MRR models under different landscape types,and(2)the influence of experimental design on the accuracy and variance of MRR-based estimates.Our simulations revealed systematic underestimates of true population parameters by MRR models when sampling effort was insufficient.In a total of 2772 simulations,subjective decisions in sampling protocol(e.g.,frequency,number of sampling locations,use of spatially explicit models,type of estimands)accounted for nearly half of the variation in estimates.We conclude that MRR-based estimates could be improved with the addition of more field-specific parameters.

Estimating the population density of the Asian tapir (Tapirus indicus) in a selectively logged forest in Peninsular Malaysia

The endangered Asian tapir(Tapirus indicus)is threatened by large-scale habitat loss,forest fragmentation and increased hunting pressure.Conservation planning for this species,however,is hampered by a severe paucity of information on its ecology and population status.We present the first Asian tapir population density estimate from a camera trapping study targeting tigers in a selectively logged forest within Peninsular Malaysia using a spatially explicit capture-recapture maximum likelihood based framework.With a trap effort of 2496 nights,17 individuals were identified corresponding to a density(standard error)estimate of 9.49(2.55)adult ta-pirs/100 km2.Although our results include several caveats,we believe that our density estimate still serves as an important baseline to facilitate the monitoring of tapir population trends in Peninsular Malaysia.Our study also highlights the potential of extracting vital ecological and population information for other cryptic individual-ly identifiable animals from tiger-centric studies,especially with the use of a spatially explicit capture-recapture maximum likelihood based framework.

Density and carrying capacity in the forgotten tigerland:Tigers in the understudied Nepalese Churia

While there are numerous wildlife ecology studies in lowland areas of Nepal,there are no in-depth studies of the hilly Churia habitat even though it comprises 7642 km2 of potential wildlife habitat across the Terai Arc.We investigated tiger,leopard and prey densities across this understudied habitat.Our camera trapping survey covered 536 km2 of Churia and surrounding areas within Chitwan National Park(CNP).We used 161 trapping locations and accumulated 2097 trap-nights in a 60-day survey period during the winter season of 2010-2011.In addition,we walked 136 km over 81 different line transects using distance sampling to estimate prey density.We photographed 31 individual tigers,28 individual leopards and 25 other mammalian species.Spatial capture-recapture methods resulted in lower density estimates for tigers,ranging from 2.3 to 2.9 tigers per 100 km2,than for leopards,which ranged from 3.3 to 5.1 leopards per 100 km2.In addition,leopard densities were higher in the core of the Churia compared to surrounding areas.We estimated 62.7 prey animals per 100 km2 with forest ungulate prey(sambar,chital,barking deer and wild pig),accounting for 47%of the total.Based on prey availability,Churia habitat within CNP could potentially support 5.86 tigers per 100 km2 but our density estimates were lower,perhaps indicating that the tiger population is below carrying capacity.Our results demonstrate that Churia habitat should not be ignored in conservation initiatives,but rather management efforts should focus on reducing human disturbance to support higher predator numbers.