Herb Species Richness Research Articles

Differential responses of forest strata species richness to paleoclimate and forest structure

Regional factors, such as historical and contemporary climate conditions, and local factors, such as vegetation structural attributes, can influence current patterns of plant species richness but their relative roles remain unknown, particularly across forest strata. Here, we used a multi-scale survey of temperate forest plots across a large region of Northeast China to explore the relative importance of environmental factors (paleoclimate, contemporary climate, topography and anthropogenic disturbance) and forest structural attributes (stem abundance, stand basal area and tree size variation) on tree, shrub, and herb species richness. Although environmental and forest structural factors all played a role in explaining plant species richness patterns, their relative roles varied in direction and magnitude depending on forest stratum. Tree species richness increased with the magnitude of change in temperature since the Last Glacial Maximum (AnomalyMAT) but declined with increasing magnitude of change in precipitation (AnomalyMAP). By contrast, herb species richness declined with increasing AnomalyMAT but increased with AnomalyMAP, highlighting contrasting processes for tree and herb species richness driven by paleoclimate. Contemporary climate played a lesser role in explaining species richness, but tree species richness increased with diurnal temperature range, shrub species richness increased with the climatic moisture index, and herb species richness increased with both climatic variables. Herb species richness also increased with disturbance intensity, whereas tree and shrub richness declined. Overall, plant species richness increased significantly with all forest structural attributes, except for stem abundance, which had a negative effect on herb species richness, and forest structure mediated the linkages between plant species richness and disturbance or climate. The pronounced influence of paleoclimate on forest plant species richness highlights the potential threat of current climate change for forest diversity. Together, simultaneous consideration of past and current climate as well as forest structural attributes could improve our understanding of the complex mechanisms shaping patterns of plant species richness across forest strata.

Temperature and productivity distinctly affect the species richness of ectothermic and endothermic multitrophic guilds along a tropical elevational gradient.

The diversity of endotherms and ectotherms may be differently affected by ambient temperature and net primary productivity (NPP). Additionally, little is known about how these drivers affect the diversity of guilds of different trophic levels. We assessed the relative role of temperature and NPP in multitrophic guilds of ectothermic (arthropods: ants, ground beetles, spiders, and harvestmen) and endothermic (large mammals) animals along a tropical elevational gradient. We sampled arthropods at eight elevation belts and large mammals at 14 elevation belts in Atlantic rainforest (ranging from 600 to 2450m.a.s.l.) of Itatiaia National Park, Southeast Brazil. Overall arthropod species richness was more associated with temperature than overall large-mammal species richness, while the latter was more associated with NPP. When separated into trophic guilds, we found that the species richness associated with NPP increased across arthropod trophic levels from herbivores to predators. Conversely, although NPP influenced large-mammal herbivore species richness, its effects did not seem to accumulate across large-mammal trophic levels since the species richness of large-mammal omnivores was more associated with temperature and none of the variables we studied influenced large-mammal predators. We suggest that thermal physiological differences between ectotherms and endotherms are responsible for the way in which arthropods and large mammals interact with or are constrained by the environment. Furthermore, the inconsistency regarding the role of temperature and NPP on species richness across multitrophic guilds of ectotherms and endotherms could indicate that thermal physiological differences might also interfere with energy use and flux in the food web.

Local habitat factors and spatial connectivity jointly shape an urban insect community

As the world becomes more and more urbanized, it is increasingly important to understand the impacts of urban landscapes on biodiversity. Urbanization can change local habitat factors and decrease connectivity among local habitats, with major impacts on the structure of natural food webs. However, most studies have focused on single species, or compared rural to urban habitats, which do not inform us on how to design and manage cities to optimize biodiversity. To understand the local and spatial drivers of ecological communities within urban landscapes, we assessed the relative impact of local habitat factors (sunlight exposure and leaf litter) and spatial connectivity on an oak-associated herbivore community within an urban landscape. From the local habitat factors, leaf litter but not sunlight exposure was related to herbivore species richness, with leaf litter contributing to the maintenance of high species richness on isolated trees. Guilds and species differed strongly in their response to local habitat factors and connectivity, resulting in predictable variation in insect community composition among urban oaks. Taken together, our study shows an interactive effect of local and spatial factors on species richness and species composition within an urban context, with guild- and species-specific life histories determining the response of insects to urban landscapes. To maintain biodiversity in the urban landscape, preserving a dense network of local habitats is essential. Moreover, allowing leaf litter to accumulate can be a simple, cost-effective conservation management practice.

Small-scale traditional maize farming fosters greater arthropod diversity value than conventional maize farming

Globally insects are in decline, with the transformation of natural areas for agriculture one of the most important drivers of this decline. Yet, insects play an important role in regulating ecosystem services such as pollination, soil fertility and pest suppression, so their conservation within agricultural areas is critical. We examined comparative impacts of traditional small-scale low input farming versus large-scale conventional farming systems, and mono-cropped versus inter-cropped systems in Kenyan maize fields on predator, ant and herbivore arthropod species richness and composition. We also considered the value of hedgerows and percentage of surrounding maize cover for arthropod conservation. As expected, traditional farming retained higher herbivore species richness, evenness and abundance, as well as higher predator abundance compared to conventional farming. Percentage maize cover was positively correlated to ant species richness, predator and herbivore abundance, as well as determining species assemblage composition for ants and herbivores. Hedgerow volume and the comparison of mono- vs inter-cropping were important predictors for predator evenness. These results suggest that the low input farming systems retain far higher arthropod numbers, although this does not seem to be due to the use of intercropping on the farms. Rather it seems that hedgerows play an important role in maintaining arthropods. While higher maize coverage surrounding the farm increases the species and abundance of arthropods in the fields, this is most likely due to the high biotope fidelity of arthropods that specialize in open cropping systems such as maize fields.Implications for insect conservationThe results here are encouraging as the retention of culturally important farming techniques (i.e., the traditional Kenyan farmers) and small improvements, such as the retention of hedgerows, greatly promotes biodiversity in the farmlands.

The diversity of soil mesofauna declines after bamboo invasion in subtropical China

Plant invasions often act as ecosystem ‘simplifiers’ to simplify diversity and community structure of soil biota. However, inconsistent relationships between plant invasion and soil fauna have been found and few studies have addressed how soil fauna communities change upon plant invasions across taxa and feeding guilds. Here, we investigated the effects of moso bamboo (Phyllostachys edulis) invasion in subtropical China on soil mesofauna communities using novel high-throughput sequencing (HTS). Specifically, we analyzed the spatio-temporal dynamics of fauna diversity and feeding guilds in the litter and soil layers for three stages of moso bamboo invasion, i.e., uninvaded (secondary broadleaved forest), moderately invaded (mixed bamboo forest) and completely invaded (P. edulis forest). Overall, we found that the completely invaded bamboo forest decreased species richness and diversity of total fauna, herbivores, and microbivores consistently across different soil layers, but less so detritivores and predators. Although we did not find any interaction effects of bamboo invasion and soil layers on soil fauna diversity indices, significant interaction effects were found on the community composition, for total fauna and their feeding guilds. Specifically, the detrimental effects of bamboo invasion on the trophic structure of soil fauna communities were more profound in the litter layer than in the soil layer, suggesting that a litter layer with more diverse taxa does not mean higher resistance to plant invasion in maintaining the soil food web structure. Taken together, our findings suggest that different responses within fauna feeding guilds to plant invasion were pervasive, and a deeper soil layer may better alleviate the negative effects of pant invasion on fauna community structure. These shifts in soil biodiversity may further degrade ecosystem functioning.

Pattern of species richness and floristic spectrum along the elevation gradient: A case study from western Himalaya, India

The floristic life-form spectrum of any area unveils the prevailing phytoclimatic conditions, helps in understanding the species-environment relationship and can be applied to compare the vegetation pattern of one eco-zone to another. We scrutinized the pattern of species richness (SR) and floristic spectrum along the elevation gradient in a biodiversity-rich eco-zone of western Himalaya (western Ramganga valley, Uttarakhand, India) between 1200 m (river bank) to 3100 m a.s.l. (summit). The elevation range was classified into six elevation bands (i.e. <1500 m, 1500–1800 m, 1801–2100 m, 2101–2400 m, 2401–2700 m, >2700 m), to prepare the presence (1)/ absence (0) species data matrix using local distribution (elevation range) of each species to estimate the SR of various growth-forms and life-forms for the particular elevational band. The findings suggest that the correlation of SR with elevation is not linear as the species richness peaks at the middle elevation (humped-back shape relationship). The forest cover is large and continues up to the summit; thus, the correlation of tree and shrub SR with elevation is not clear; though, a partly positive correlation was observed between elevation and herb SR while negative correlation between climber SR and elevation. The percentage of phanerophytes and therophytes in total life-forms decreased significantly with increase in elevation while inverse trend was shown by hemicryptophytes and cryptophytes. The pattern of phytoclimate in the area varied from phanero-therophytic at the lower elevation to phanero-hemicryptophytic at the middle and hemicrypto-phanerophytic at the upper elevation. The present contribution is an attempt to fill the knowledge gap in pattern of growth-form, life-form and phytoclimate within the forest-covered montane zone of western Himalaya. It will be helpful in understanding the vegetation dynamics in mountain ecosystems and serve as a ready reference to planners in any future conservation strategy for the area.

Tree species diversity enhances plant-soil interactions in a temperate forest in northeast China

The plant-soil interactions may drive the diversity and functioning of forests, but we do not fully understand how interrelationships between plant and soil compartments are underlined by multiple ecological mechanisms. Here, we hypothesize that positive plant-soil interactions enhance biodiversity and functioning in a temperate forest. To do so, we tested the relationships between plant diversity (i.e., tree and herb species richness) and functions (i.e., coarse woody productivity and litterfall productivity), and soil diversity (i.e. bacterial, fungal and nematode) and functions (i.e. soil nutrient and carbon stock), and their interrelationships in a temperate forest in northeast China. The positive relationship between diversity and functioning was predominant within plant and soil compartments, and hence, provide support to the niche complementarity effect. As such, the positive interrelationships between the diversity of soil and plant compartments provide support to the positive plant-soil interactions. Tree species diversity was positively related with herb species diversity and coarse-woody productivity. Importantly, tree species diversity had pronounced positive effect on soil biodiversity resulting in increased soil carbon stocks, indicating that tree species diversity effect matters for linking positive interrelationships between plant and soil compartments of a temperate forest. This study shows that tree diversity effect is the main regulating biotic mechanism for linking the positive connections between plant and soil compartments of a temperate forest, and hence, the niche complementarity effect can enhance forest functioning through positive interactions on resource supply. We argue that linking the multiple key functions and diversity indices of forests can enhance our knowledge on the main influential factors and underlying ecological mechanisms.

Factors that shape the elevational patterns of plant diversity in the Yatsugatake Mountains, Japan.

Elevation is involved in determining plant diversity in montane ecosystems. This study examined whether the distribution of plants in the Yatsugatake Mountains, central Japan, substantiated hypotheses associated with an elevational diversity gradient. Species richness of trees, shrubs, herbs, ferns, and bryophytes was investigated in study plots established at 200‐m elevational intervals from 1,800 to 2,800 m. The changes in plant diversity (alpha and beta diversities, plant functional types, and elevational ranges) with elevation were analyzed in relation to climatic factors and elevational diversity gradient hypotheses, that is, mass effect, mid‐domain effect, and Rapoport's elevational rule. In addition, the elevational patterns of dominance of plant functional types were also analyzed. A comparison of alpha and beta diversities revealed that different plant groups responded variably to elevation; the alpha diversity of trees and ferns decreased, that of herbs increased, whereas the alpha diversity of shrubs and bryophytes showed a U‐shaped relationship and a hump‐shaped pattern. The beta diversity of shrubs, herbs, and bryophytes increased above the subalpine–alpine ecotone. In accordance with these changes, the dominance of evergreen shrubs and graminoids increased above this ecotone, whereas that of evergreen trees and liverworts decreased. None of the plant groups showed a wide elevational range at higher elevations. These elevational patterns of plant groups were explained by climatic factors, and not by elevational diversity gradient hypotheses. Of note, the changes in the dominance of plant groups with elevation can be attributed to plant–plant interactions via competition for light and the changes in physical habitat. These interactions could alter the elevational diversity gradient shaped by climatic factors.

Moving through the mosaic: identifying critical linkage zones for large herbivores across a multiple‐use African landscape

Reduced connectivity across grassland ecosystems can impair their functional heterogeneity and negatively impact large herbivore populations. Maintaining landscape connectivity across human-dominated rangelands is therefore a key conservation priority. Integrate data on large herbivore occurrence and species richness with analyses of functional landscape connectivity to identify important areas for maintaining or restoring connectivity for large herbivores. The study was conducted on a landscape with a mosaic of multiple land uses in Laikipia County, Kenya. We used occupancy estimates for four herbivore species [African elephant (Loxodonta africana), reticulated giraffe (Giraffa reticulata), plains zebra (Equus quagga), and Grevy’s zebra (Equus grevyi)] and species richness estimates derived from aerial surveys to create resistance surfaces to movement for single species and a multi-species assemblage, respectively. We validated single-species resistance surfaces using telemetry data. We used circuit theory and least cost-path analyses to model linkage zones across the landscape and prioritize areas for connectivity restoration. Resistance layers approximated the movements of our focal species. Results for single-species and multi-species connectivity models were highly correlated (rp > 0.9), indicating similar spatial patterns of functional connectivity between individual species and the larger herbivore assemblage. We identified critical linkage zones that may improve permeability to large-herbivore movements. Our analysis highlights the utility of aerial surveys in modeling landscape connectivity and informing conservation management when animal movement data are scarce. Our results can guide management decisions, providing valuable information to evaluate the trade-offs between improving landscape connectivity and safeguarding livelihoods with electrified fences across rangelands.

Biodiversity of Lepidoptera fauna in horticultural ecosystem in RVSAC-Usilampatti, Thanjavur

Biodiversity is a function of the number of the any taxon present, the evenness with which the taxons are distributed (species evenness or family evenness) and the interaction component of richness and evenness. The present investigation was carried out to study the arthropod biodiversity in Horticulture ecosystem at RVS Agricultural College, Thanjavur, India. The farm lies between 10.6796° N latitude and 78.9194° E longitude with an altitude of 426.7M above MSL. The insect collections were done in both Agri-Horticultural crops (Maize, Castor, Thenai, Cotton, Mango, Sapota, Coconut, Guava and some weeds). In the study, a total of 39 fauna species (butterflies) were recorded in horticultural ecosystem under 39 genera, 14 families and 1 order were observed in the horticultural ecosystem. Among the insect families, the family Nymphalidae consists of many species followed by Noctuidae. It was also recorded a total of 11 species under the family Nymphalidae followed by Noctuidae (10 species). Among the different functional groups, a diversity of a herbivores and tourist was maximum and comprised of 27 species under herbivores and 13 species under tourists. Species richness and diversity index were calculated for comparison within weekly collection and to know the variance between lepidopteron species. It was concluded that the species richness of herbivores and tourist were found to be abundant during winter 2018 and summer 2019.

Ground-dwelling spiders in agroecosystems of the Dry Chaco: a rapid assessment of community shifts in response to land use changes

ABSTRACT Deforestation and land-cover changes have transformed the Argentinian Dry Chaco into a mosaic dominated by crops and ranch fields. Although land-use activities are seen as one of the major driving forces of biodiversity loss, the specific impacts in this ecoregion are poorly understood. In this study, we analyse the effects of land uses and management on ground-dwelling spiders in agroecosystems of the Dry Chaco, in the North of Argentina. We identified four land-use classes: secondary forests, pastures, orchards, and crops. Additionally, 15 environmental variables were recorded within these land-use classes. Management, tree cover and species richness of trees, shrubs and herbs were the most important variables determining spider community composition. Three families, lycosids (Lycosidae), thomisids (Thomisidae), and zodariids (Zodariidae), were associated as taxonomic indicators as well as functional indicators of the different groups of land uses; thus suggesting that functional traits of ground-dwelling spiders reflect habitat changes within the agricultural landscape they inhabit.

Strong influences of stand age and topography on post-fire understory recovery in a Chinese boreal forest

Soil resource quantity and heterogeneity as well as overstory characteristics change along with stand age after fire disturbance, imposing strong influences on post-fire understory recovery. In this study, we aimed to assess how soil resource (nitrogen quantity and heterogeneity), topographic position (aspect), overstory characteristics (basal area), and stand age affected understory characteristics (cover, richness, evenness, and composition) during boreal forest succession after fire disturbance. We collected plant community and environmental data from 76 stands aged at 4 to 203 years post-fire in the boreal forest of Northeast China. We separately tested the effects of the considered factors on the characteristics of total understory, shrubs, and herbs. Total understory cover was higher at the south-facing slopes and flat locations than at north-facing slopes. Species richness of total understory, shrubs, and herbs was higher at the flat locations and south-facing slopes than at the north-facing slopes. The cover of total understory and shrubs showed increasing trends along with stand age, soil nitrogen quantity, and overstory basal area as well as decreasing trends along with soil nitrogen heterogeneity, while the cover of herbs showed reversed trends across all the three topographic positions. Understory richness showed decreasing trends along with soil nitrogen quantity as well as increasing trends along with soil nitrogen heterogeneity and overstory basal area. Total understory evenness showed flat trends along with soil nitrogen quantity, heterogeneity, and stand age as well as decreasing trends along with overstory basal area. Understory community composition was mainly affected by topographic position, stand age, and overstory basal area. During understory recovery, community composition shifted from shade-intolerant species to shade-tolerant species. Our results highlight the importance of topography and stand age in post-fire understory recovery in boreal forests of China, mediated through availability of light and soil nutrients.

Vegetation and ecosystem carbon recovery following shifting cultivation in Mizoram-Manipur-Kachin rainforest eco-region, Southern Asia

BackgroundShifting cultivation (locally known as “jhum”) is a major driver of deforestation and loss of ecosystem services in rainforests. For developing any effective conservation of biodiversity and carbon service program, an in-depth understanding to the recovery of vegetation and carbon after abandonment of jhum is essential. We estimated species richness, abundance and composition of trees, shrubs and herbs, carbon distribution in aboveground and belowground components along a chronosequence of jhum fallow in northeast India, and elucidated the factors affecting the recovery processes of jhum fallows.MethodsSpecies composition and other plant community attributes, carbon storage in different pools were studied in 5 jhum fallows (< 5, 5–10, 11–15, 16–20, 21–25 years old) and an old-growth forest. The data were subjected to linear mixed effect modeling using R-package “nlme” for identifying the important factors contributing to the recovery of vegetation and carbon.ResultsSpecies composition varied significantly (P < 0.05) between jhum fallows and old-growth forest. Tree density varied from 28 stems ha−1 in 5 years old jhum fallow to 163 stems ha−1 in old-growth forest. Both biomass carbon in all components and soil organic carbon were significantly (P = 0.01) lower in jhum fallows than in the old-growth forest except living non-woody biomass component. The recovery of aboveground biomass carbon was faster during early successive years than the mid-successive jhum fallows. Total ecosystem carbon and soil organic carbon stock in the oldest jhum fallow was 33% and 62% of those in the old-growth forest, respectively. The fallow age was found to be the most important explanatory factor in the recovery process of vegetation and carbon stock in re-growing fallows.ConclusionThe shifting cultivation fallows gradually recovered both vegetation and carbon and are potential repository sites for biodiversity conservation, which may take much longer time to reach up to old-growth forest in northeast India.

Community structure and carbon and nitrogen storage of sagebrush desert under grazing exclusion in Northwest China

Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China. Grazing exclusion (GE) is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services. Nevertheless, there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon (C) and nitrogen (N) storage. It remains poorly understood in the arid desert regions, whilst being essential for the sustainable use of grassland resources. To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions, we investigated the community structure and plant biomass, as well as C and N storage of plants and soil (0–100 cm depth) in short-term GE (three years) plots and adjacent long-term freely grazing (FG) plots in the areas of sagebrush desert in Northwest China, which are important both for spring-autumn seasonal pasture and for ecological conservation. Our findings indicated that GE was beneficial to the average height, coverage and aboveground biomass (including stems, leaves and inflorescences, and litter) of desert plant community, to the species richness and importance values of subshrubs and perennial herbs, and to the biomass C and N storage of aboveground parts (P<0.05). However, GE was not beneficial to the importance values of annual herbs, root/shoot ratio and total N concentration in the 0–5 and 5–10 cm soil layers (P<0.05). Additionally, the plant density, belowground biomass, and soil organic C concentration and C storage in the 0–100 cm soil layer could not be significantly changed by short-term GE (three years). The results suggest that, although GE was not beneficial for C sequestration in the sagebrush desert ecosystem, it is an effective strategy for improving productivity, diversity, and C and N storage of plants. As a result, GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.

Species–area relationships on small islands differ among plant growth forms

AbstractAimWe tested whether species–area relationships of small islands differ among plant growth forms and whether this influences the prevalence of the small‐island effect (SIE). The SIE states that species richness on small islands is independent of island area or relates to area in a different way compared with larger islands. We investigated whether island isolation affects the limits of the SIE and which environmental factors drive species richness on small islands.LocationSeven hundred islands (&lt; 100 km2) worldwide belonging to 17 archipelagos.Major taxa studiedAngiosperms.MethodsWe applied linear and breakpoint species–area models for angiosperm species richness and for herb, shrub and tree species richness per archipelago separately, to test for the existence of SIEs. For archipelagos featuring the SIE, we calculated the island area at which the breakpoints occurred (breakpoint area) and used linear models to test whether the breakpoint areas varied with isolation. We used linear mixed‐effect models to discern the effects of seven environmental variables related to island area, isolation and other environmental factors on the species richness of each growth form for islands smaller than the breakpoint area.ResultsFor 71% of all archipelagos, we found an SIE for total and herb species richness, and for 59% for shrub species richness and 53% for tree species richness. Shrub and tree species richness showed larger breakpoint areas than total and herb species richness. The breakpoint area was significantly positively affected by the isolation of islands within an archipelago for total and shrub species richness. Species richness on islands within the range of the SIE was differentially affected by environmental factors across growth forms.Main conclusionThe SIE is a widespread phenomenon that is more complex than generally described. Different functional groups have different environmental requirements that shape their biogeographical patterns and affect species–area and, more generally, richness–environment relationships. The complexity of these patterns cannot be revealed when measuring overall plant species richness.

Spatiotemporal dynamics of wild herbivore species richness and occupancy across a savannah rangeland: Implications for conservation

Private lands are critical for maintaining biodiversity beyond protected areas. Across Kenyan rangelands, wild herbivores frequently coexist with people and their livestock. Human population and livestock numbers are projected to increase dramatically over the coming decades. Therefore, a better understanding of wildlife-livestock interactions and their consequences for biodiversity conservation on private lands is needed. We used a Bayesian hierarchical, multi-species and multi-year occupancy model on aerial survey data of 15 wild-herbivore species, spanning 15 years (2001–2016) to investigate a) spatiotemporal trends in species occurrence and richness across a mosaic of properties with different land uses in Laikipia County, central Kenya; and b) the effects of distance to water, vegetation and livestock relative abundance on species occurrence and richness. Although mean herbivore species richness varied little over time, we observed high spatial variation in species occurrence across Laikipia, mainly driven by negative effects of high livestock relative abundance. As expected, ‘wildlife friendly’ properties had higher herbivore species richness than other areas. However, high variability suggests that some pastoral properties support rich herbivore communities. The area occupied by five species with global conservation concerns (reticulated giraffe, Grevy's zebra, Beisa Oryx, Defassa waterbuck and gerenuk) and for which Laikipia County is one of the last refuges was <50% across years. We conclude that ‘wildlife friendly’ properties remain crucial for conservation, although some pastoralist areas offer suitable habitats for wild herbivores. Effective management of stocking rates is critical for maintaining ecosystems able to sustain livestock and wildlife on private lands, ensuring protection for endangered species.

Long-term effects of thinning and woody control on longleaf pine plantation development, understory abundance, and tree damage from an ice storm

Longleaf pine (Pinus palustris) plantations have been established across the southeastern United States as the first step in restoring the declining savanna ecosystem, yet their long-term stability and development to open canopied woodlands may depend on early density and vegetation management treatments. Commercial thinning (CT) was applied in 2012 (year 18) to a long-term study of longleaf pine community restoration at the Savannah River Site near Aiken, SC to increase abundance of herb species. Although precommercial thinning (PCT) and woody vegetation control increased herb species cover during the first five years of the study, measurements from years 17 to 22 indicated a continuing decline in their cover since year 9 despite application of CT in year 18. Herb species richness, however, increased from 21 to 43 species per 100 m2 area during the last six years of the study, likely a result of disturbances associated with CT and an ice storm in year 20. Application of PCT in 1994, when the plantations were 8–11 years old, reduced their susceptibility to stem bending and breakage from the ice storm, which occurred 20 years later in 2014. Measured 5 months before the storm, pine height: dbh ratio (HD) averaged 78 and 90 for trees growing with and without PCT, respectively, and stem breakage (% of trees) from the ice storm increased linearly (r2 = 0.53) with HD. Pine mortality from the combined effects of glaze ice and wind differed with (28%) versus without (45%) PCT, indicating that long-term stability of longleaf pine plantations depends on early density management.

Flora of Baturité, Ceará: a Wet Island in the Brazilian Semiarid

Abstract The biota of the humid mountain ranges of the Brazilian semiarid is still poorly understood. In order to fill this scientific gap, we carried out an extensive survey along altitudinal ranges (400m - 1,000 m) on both the windward and the leeward slopes of the Baturite Mountain Range, in the state of Ceara state. We registered 400 plant species and 92 families. The Myrtaceae (36 spp.), Fabaceae (25 spp.), Rubiaceae (20 spp.) and Bromeliaceae (15 spp.) families predominated on the windward slope; while Fabaceae (19 spp.), Myrtaceae (14 spp.) and Euphorbiaceae (11 spp.) were the most abundant on the leeward slope. As we expected, the species richness of trees, shrubs, subshrubs, epiphytes and terrestrial herbs was positively correlated with the altitude (R2 > 0.60). Above 800 m, we registered 273 species exclusive to the windward slope, 81 exclusive to the leeward slope, and 46 shared species. Therefore, management actions must consider the spatial heterogeneity, distribution and taxa richness.

Host plant phenology, insect outbreaks and herbivore communities - The importance of timing.

Climate change may alter the dynamics of outbreak species by changing the phenological synchrony between herbivores and their host plants. As host plant phenology has a genotypic component that may interact with climate, infestation levels among genotypes might change accordingly. When the outbreaking herbivore is active early in the season, its infestation levels may also leave a detectable imprint on herbivores colonizing the plant later in the season. In this study, we first investigated how the spring phenology and genotype of Quercus robur influenced the density of the spring-active, outbreaking leaf miner Acrocercops brongniardellus. We then assessed how intraspecific density affected the performance of A. brongniardellus and how oak genotype and density of A. brongniardellus affected the insect herbivore community. We found that Q. robur individuals of late spring phenology were more strongly infested by A. brongniardellus. Conspecific pupae on heavily infested oaks tended to be lighter, and fewer heterospecific insect herbivores colonized the oak later in the season. Beyond its effects through phenology, plant genotype left an imprint on herbivore species richness and on two insect herbivores. Our results suggest a chain of knock-on effects from plant phenology, through the outbreaking species to the insect herbivore community. Given the finding of how phenological synchrony between the outbreak species and its host plant influences infestation levels, a shift in synchrony may then change outbreak dynamics and cause cascading effects on the insect community.

Linkages between Phosphorus and Plant Diversity in Central European Forest Ecosystems—Complementarity or Competition?

The phosphorus nutrition status of European forests has decreased significantly in recent decades. For a deeper understanding of complementarity and competition in terms of P acquisition in temperate forests, we have analyzed α-diversity, organic layer and mineral soil P, P nutrition status, and different concepts of P use efficiency (PUE) in Fagus sylvatica L. (European beech) and Picea abies (L.) H. Karst. (Norway spruce). Using a subset of the Second National Soil Survey in Germany, we correlated available data on P in the organic layer and soil with α-diversity indices for beech and spruce forests overall and for individual vegetation layers (tree, shrub, herb, and moss layers). Moreover, we investigated α-diversity feedbacks on P nutrition status and PUE of both tree species. The overall diversity of both forest ecosystems was largely positively related to P content in the organic layer and soil, but there were differences among the vegetation layers. Diversity in the tree layer of both forest ecosystems was negatively related to the organic layer and soil P. By contrast, shrub diversity showed no correlation to P, while herb layer diversity was negatively related to P in the organic layer but positively to P in soil. A higher tree layer diversity was slightly related to increased P recycling efficiency (PPlant/Porganic layer) in European beech and P uptake efficiency (PPlant/Psoil) in Norway spruce. The diversity in the herb layer was negatively related to P recycling and uptake efficiency in European beech and slightly related to P uptake efficiency in Norway spruce. In spruce forests, overall and herb species richness led to significantly improved tree nutrition status. Our results confirm significant, non-universal relationships between P and diversity in temperate forests with variations among forest ecosystems, vegetation layers, and P in the organic layer or soil. In particular, tree species diversity may enhance complementarity and hence also P nutrition of dominant forest trees through higher PUE, whereas moss and herb layers seemed to show competitive relationships among each other in nutrient cycling.