Complex causes and consequences of rangeland greening in South America -multiple interacting natural and anthropogenic drivers and simultaneous ecosystem degradation and recovery trends

Land-surface greening has been reported globally over the past decades.While often seen to represent ecosystem recovery,the impacts on biodiversity and society can also be negative.Greening has been widely reported from rangelands,where drivers and processes are complex due to its high environmental heterogeneity and societal dynamics.Here,we assess the complexity behind greening and assess its links to various drivers in an iconic,heterogeneous rangeland area,the IberáWetlands and surroundings,in Argentina.Time-series satellite imagery over the past 19 years showed overall net greening,but also substantial local browning both in protected and unprotected areas,linking to land use,temporal changes in surface water,fire,and weather.We found substantial woody expansion mainly in the unprotected land,with 37%contributed by tree plantations and the remaining 63%by spontaneous woody expansion,along with widespread transitions from terrestrial land to seasonal surface water.Fire occurrences tended to reduce greening with unprotected areas experiencing widespread and frequent fire.However,protected areas had more browning in unburnt areas than burned areas.Temporal variation in annual precipitation and temperature tended to nonlinearly influence fire occurrences with an interplay of human fire management,further shaping the vegetation greening,pointing to high complexity behind the observed rangeland greening involving interactions among local drivers.Our findings highlight that the observed overall greening is an outcome of multiple trends with clear negative impacts on biodiversity and the local livestock-oriented culture(notably expanding tree plantations)and spontaneous vegetation dynamics,partly involving spontaneous woody expansion.The latter has positive potential for biodiversity and ecosystem services in terms of woodland recovery,but can become negative in such a natural savanna region if expansions develop on a too broad scale,highlighting the importance of ensuring recovery of natural fire and herbivory regimes in protected areas along with sustainable rangeland management elsewhere.

Neglected tropical diseases risk correlates with poverty and early ecosystem destruction

Background Neglected tropical diseases affect the most vulnerable populations and cause chronic and debilitating disorders.Socioeconomic vulnerability is a well-known and important determinant of neglected tropical diseases.For example,poverty and sanitation could influence parasite transmission.Nevertheless,the quantitative impact of socioeconomic conditions on disease transmission risk remains poorly explored.Methods This study investigated the role of socioeconomic variables in the predictive capacity of risk models of neglected tropical zoonoses using a decade of epidemiological data(2007–2018)from Brazil.Vector-borne diseases investigated in this study included dengue,malaria,Chagas disease,leishmaniasis,and Brazilian spotted fever,while directly-transmitted zoonotic diseases included schistosomiasis,leptospirosis,and hantaviruses.Environmental and socioeconomic predictors were combined with infectious disease data to build environmental and socioenvironmental sets of ecological niche models and their performances were compared.Results Socioeconomic variables were found to be as important as environmental variables in influencing the estimated likelihood of disease transmission across large spatial scales.The combination of socioeconomic and environmental variables improved overall model accuracy(or predictive power)by 10%on average(P<0.01),reaching a maximum of 18%in the case of dengue fever.Gross domestic product was the most important socioeconomic variable(37%relative variable importance,all individual models exhibited P<0.00),showing a decreasing relationship with disease indicating poverty as a major factor for disease transmission.Loss of natural vegetation cover between 2008 and 2018 was the most important environmental variable(42%relative variable importance,P<0.05)among environmental models,exhibiting a decreasing relationship with disease probability,showing that these diseases are especially prevalent in areas where natural ecosystem destruction is on its initial stages and lower when ecosystem destruction is on more advanced stages.Conclusions Destruction of natural ecosystems coupled with low income explain macro-scale neglected tropical and zoonotic disease probability in Brazil.Addition of socioeconomic variables improves transmission risk forecasts on tandem with environmental variables.Our results highlight that to efficiently address neglected tropical diseases,public health strategies must target both reduction of poverty and cessation of destruction of natural forests and savannas.

Human-driven topographic effects on the distribution of forest in a flat, lowland agricultural region

Complex topography buffers forests against deforestation in mountainous regions. However, it is unknown if terrain also shapes forest distribution in lowlands where human impacts are likely to be less constrained by terrain. In such regions, if important at all, to- pographic effects will depend on cultural-historical factors and thus be human-driven （an- thropogenic） rather than natural, except in regions where the general climate or extreme soils limit the occurrence of forests. We used spatial regression modeling to assess the extent to which topographic factors explain forest distribution （presence-absence at a 48x48 m resolu- tion） in a lowland agricultural region （Denmark, 43,075 km2） at regional and landscape scales （whole study area and 10x10 km grid cells, respectively）, how landscape-scale for- est-topography relationships vary geographically, and which potential drivers （topographic heterogeneity, forest cover, clay content, coastal/inland location） determine this geographic heterogeneity. Given a moist temperate climate and non-extreme soils all landscapes in Denmark would naturally be largely forest covered, and any topographic relationships will be totally or primarily human-driven. At regional scale, topographic predictors explained only 5% of the distribution of forest. In contrast, the explanatory power of topography varied from 0%-61% at landscape scale, with clear geographic patterning. Explanatory power of topog- raphy at landscape scale was moderately dependent on the potential drivers, with topog- raphic control being strongest in areas with high topographic heterogeneity and little forest cover. However, these conditioning effects were themselves geographically variable. Our findings show that topography by shaping human land-use can affect forest distribution even in flat, lowland regions, but especially via localized, geographically variable effects.

Multi-scale phylogenetic structure in coastal dune plant communities across the globe

Aims Studies integrating phylogenetic history and large-scale community assembly are few,and many questions remain unanswered.Here,we use a global coastal dune plant data set to uncover the important factors in community assembly across scales from the local filtering processes to the global long-term diversification and dispersal dynamics.Coastal dune plant communities occur worldwide under a wide range of climatic and geologic conditions as well as in all biogeographic regions.However,global patterns in the phylogenetic composition of coastal dune plant communities have not previously been studied.Methods The data set comprised vegetation data from 18463 plots in New Zealand,South Africa,South America,North America and Europe.The phylogenetic tree comprised 2241 plant species from 149 families.We calculated phylogenetic clustering(Net Relatedness Index,NRI,and Nearest Taxon Index,NTI)of regional dune floras to estimate the amount of in situ diversification relative to the global dune species pool and evaluated the relative importance of land and climate barriers for these diversification patterns by geographic analyses of phylogenetic similarity.We then tested whether dune plant communities exhibit similar patterns of phylogenetic structure within regions.Finally,we calculated NRI for local communities relative to the regional species pool and tested for an association with functional traits(plant height and seed mass)thought to vary along sea–inland gradients.Important Findings Regional species pools were phylogenetically clustered relative to the global pool,indicating regional diversification.NTI showed stronger clustering than NRI pointing to the importance of especially recent diversifications within regions.The species pools grouped phylogenetically into two clusters on either side of the tropics suggesting greater dispersal rates within hemispheres than between hemispheres.Local NRI plot values confirmed that most communities were also phylogenetically clustered within regions.NRI values decreased with increasing plant height and seed mass,indicating greater phylogenetic clustering in communities with short maximum height and good dispersers prone to wind and tidal disturbance as well as salt spray,consistent with environmental filtering along sea–inland gradients.Height and seed mass both showed significant phylogenetic signal,and NRI tended to correlate negatively with both at the plot level.Low NRI plots tended to represent coastal scrub and forest,whereas high NRI plots tended to represent herb-dominated vegetation.We conclude that regional diversification processes play a role in dune plant community assembly,with convergence in local phylogenetic community structure and local variation in community structure probably reflecting consistent coastal-inland gradients.Our study contributes to a better understanding of the globally distributed dynamic coastal ecosystems and the structuring factors working on dune plant communities across spatial scales and regions.

CForBio : 监视中国森林生物多样性的一个网络

中国怀有森林类型和联系森林的生物多样性的一个富有的变化，连接了到历史、当代的环境因素。然而，是有一张大人口和快速的经济开发的一个国家，它的多样的森林正在面对 unprecedent 挑战。中国福雷斯特生物多样性网络(CForBio ) 被开始 12 ? 年以前在瓷器森林生态系统学习生物多样性的维护。在这评论，我们首先在 CForBio 总结研究进步，然后为未来研究给建议。在过去 12 ? 年，研究主要基于 CForBio 集中了于本地生态的因素例如过滤的环境，关於生命的相互作用和小规模的疏开限制。我们建议(1 ) 在 CForBio 的未来研究应该在树上继续研究，但是更阐述昆虫，鸟，哺乳动物，微生物和另外的有机体组；(2 ) 在森林生物多样性上调查普遍 defaunation 的效果，结构并且工作；(3 ) 在森林作文上评估气候变化的多样的效果，结构并且工作；(4 ) 包括新技术，例如遥感，到更好的监视器和学习森林生物多样性变化和维护。

Early dynamics in plant community trait responses to a novel, more extreme hydrological gradient

Aims For temperate regions such as Northern Europe,predicted climate change patterns include an increase in winter precipitation causing increased risk of flooding,whereas periods of droughts will become more frequent in summer.The aim of this study is to explore vari-ations in plant functional trait distributions along a hydrological gradient spanning from recurrent drought events to recurrent flood-ing-mimicking future precipitation patterns.Methods The experiment was conducted in a controlled grassland experi-ment over a period of 3 years.A novel and more extreme hydro-logical regime was achieved by manipulating the flow of a nearby stream thereby creating a continuous hydrological gradient from flooding during winter to drought during summer.Plant commu-nity responses were recorded along this hydrological gradient.Community-weighted trait distribution changes along the gradient were described using null models.Six functional traits were con-sidered:seed mass,leaf dry matter content(LDMC),leaf area,leaf thickness,specific leaf area(SLA)and height.Important findings Over time,responses in plant functional traits changed at the community level.Over the study period consistent changes occurred in the mean trait value of several traits.Communities in relatively dry plots became dominated by species with water-conserving life strategies,represented by high seed mass and thick leaves.In contrast,disturbance-resistant species(high leaf dry matter content)became dominant in flooded plots,indicating that persistence to flooding was the most important factor control-ling the functional structure in those communities.Furthermore,a high abundance of small-seeded species in flooded plots likely indicates higher frequency of species with higher dispersal ability through hydrochory.In conclusion,plant traits are useful for predicting responses to climate change,but abrupt and extreme climate event may cause unexpected responses because they have no analog to previously more stable conditions.We suggest that traits related to dispersal and resistance to disturbance are useful in describing responses to flooding and that these traits should be included in future inves-tigations of plant community responses to extreme hydrological events.

From unusual suspect to serial killer: Cyanotoxins boosted by climate change may jeopardize megafauna

The recent mass mortality event of more than 330 African elephants in Botswana has been attributed to biotoxins produced by cyanobacteria;however,scientific evidence for this is lacking.Here,by synthesizing multiple sources of data,we show that,during the past decades,the widespread hypertrophic waters in Southern Africa have entailed an extremely high risk and frequent exposure of cyanotoxins to the wildlife within this area,which functions as a hotspot of mammal species richness.The hot and dry climatic extremes have most likely acted as the primary trigger of the recent and perhaps also of prehistoric mass mortality events.As such climate extremes are projected to become more frequent in Southern Africa in the near future,there is a risk that similar tragedies may take place,rendering African megafauna species,especially those that are already endangered,in risk of extinction.Moreover,cyanotoxin poisoning amplified by climate change may have unexpected cascading effects on human societies.Seen within this perspective,the tragic mass death of the world's largest terrestrial mammal species serves as an alarming early warning signal of future environmental catastrophes in Southern Africa.We suggest that systematic,quantitative cyanotoxin risk assessments are made and precautionary actions to mitigate the risks are taken without hesitation to ensure the health and sustainability of the megafauna and human societies within the region.