A new model : Herbaceous species diversity along the environmental gradient in the typical hilly areas of Henan Province

Ecological model is important. The relationship between biodiversity and disturbance gradient, however, makes it difficult to compare data from different studies and draw general conclusions. These results assessed the relationship between disturbance gradients and herbaceous species diversity in the typical hilly areas on varying spatial scales along the environmental gradient in Henan Province. Using community ecology techniques and quantitative measurements of disturbance, we detected a linear relationship between weighting values of disturbance intensity and herbaceous species diversity (Simpson), which were significantly correlated (P<0.01) in the differential ecosystem types along different disturbance gradient. Understanding a linear relationship between herbaceous species dynamics and their causes in the differential type’s landscapes is essential for further research of local ecosystem functions reaching the goal of ecosystem sustainable development in the context of biodiversity conservation. These results indicate that weighting values of disturbance are the most important environmental factors affecting the herbaceous species diversity in building a model of the ecosystem. This model may help policy makers formulate better ecological conservation and restoration plans with ecosystem.


INTRODUCTION
Ecosystems are typically filled with large numbers of plant species along environmental gradient, making species-centered studies of systemic processes and functions extremely difficult, if not outright impossible, to carry out (Liao et al., 2010;Liao et al., 2011aLiao et al., , 2011b)).The intermediate disturbance Hypothesis (IDH) suggests that species diversity will be maximal at intermediate *Corresponding author.E-mail: lbh@henu.edu.cn.Tel: 086-13839962027.
Abbreviation: IDH, Intermediate disturbance hypothesis.levels of disturbance (Connell, 1978).Moreover, many experiments have assessed the relationship between plant species biodiversity and disturbance intensity from IDH perspective along different disturbance gradients in theoretical ecology (Biswas et al., 2010;Boutin et al., 2008;Leis et al., 2005).For example, Leis et al. (2005) found that disturbance up to intermediate levels can be used to maintain biodiversity by enriching the plant species pool.Further, Biswas et al. (2010) suggested that plant species richness and diversity, functional richness and diversity reached peaks at moderate disturbance intensity in riparian and upland plant communities.
Therefore, the relationship between plant species diversity and intermediate disturbance intensity has many  real world applications in the field of ecological conservation and restoration (Table 1).Here, using plant community ecology techniques, this study analysis asked three key questions regarding the relationship between herbaceous species diversity and intermediate disturbance levels in the differential ecosystem types.First, this study asked if the IDH facilitate human understanding of the contribution of the relationship between herbaceous species diversity dynamics and disturbance gradient to different ecosystem types, and if these relationships are more useful than others.Next, this study asked if the large set of the relationship between herbaceous species diversity dynamics and disturbance gradient from IDH perspective can be compressed into a general model that is universally applicable to ecosystem studies.Finally, this study asked how the links between herbaceous species diversity and disturbance along disturbance gradient can be applied to real world scenarios in order to prevent biodiversity loss and ecosystem manage degrading or degraded ecosystems.

MATERIALS AND METHODS
The ecosystems of the typical hilly areas are results of the historical natural and anthropogenic activities in the Henan Province.Quantitative assessments mainly depended on disturbance of human-driven and season driven changes in herb biodiversity and were based on a careful choice of landscape scenarios (Table 2).
Using community ecology techniques, we examined the influences of different disturbance on dynamics of herbaceous species diversity and disturbance interactions along the different disturbance gradient along elevations gradient on the northern slope of the Fu-Niu Mountain Natural Reserve in August, 2011.Several plots (e.g.typical hilly ridge areas, typical hilly boundary areas and typical hilly center areas) were established per 1 × 1 km area.A total of 20 plots were set.Each study plot, consisted of one 20 × 20 m tree layer quadrate, five (the center and four corners of the study plot) 2 × 2 m shrub layer quadrates and five 1 × 1 m herbaceous layer quadrates.Thus, these plots include 100 herbaceous layer quadrates and 100 shrub layers in the typical hilly center areas in August, 2011 (Tables 1 to 4).

Traditional indices
This is the most widely used indices, Simpson's index (Simpson, 1949).Simpson's index of diversity is generally calculated as the complement of D: Where, pi is the proportion of the sample belonging to the ith species.

Dynamics in the dominant/companion tree species along disturbance gradient at pulsed field gradients (PFGs) levels
The results show that disturbance is an important environmental factor affecting weed species diversity in anthropogenic activities in the typical hilly areas center / the typical hilly boundary areas / the ridge of the typical hilly areas.The relationship between values of weighting disturbance and the weed species diversity investigated vary significantly in the herbaceous layer along the environmental gradient on varying disturbance scales along the different disturbance intensity gradient in the typical hilly areas (Figures 2 to 4).
The results indicate that herb diversity (e.g. Simpson indicator) is expected to increase when weighting values of disturbance is reduced along disturbance gradients in the typical hilly areas of Henan Province (Figures 2 to 4).Second, herbaceous diversity (e.g. Simpson indicator) is expected to decrease when weighting values of disturbance is increased along disturbance gradients in the typical hilly areas of Henan Province.Thus, our result implies that weak disturbance should lead to higher herbaceous species diversity in the typical hilly areas of Henan Province.
These results suggest that herb species diversity (e.g. Simpson indicator) is expected to increase when weighting values of disturbance is reduced along disturbance gradients in the farmland boundary areas and the ridge in the typical hilly areas (Figures 1 to 5).In addition, herb species diversity is expected to decrease when weighting values of disturbance is increased along disturbance gradients in the typical hilly areas boundary areas and the ridge in the typical hilly areas (Figures 3 to  4).Therefore, this result implies that weak disturbance should lead to higher herbaceous species diversity in the typical hilly areas of Henan Province.To do this, the   correlation between species biodiversity and the weighting values of disturbance was then analyzed (Table 5).This results suggest that there is a linear relationship between weighting values of disturbance and herb species diversity (Simpson),     which were significantly negative correlated (P<0.01).
The results indicate that disturbance, largely determined by weighting values of disturbance, are the most important environmental factors affecting the distribution of herb species diversity (Table 5).
The results indicate that elevation and disturbance are important environmental factors affecting the distribution of plant functional groups on southern slope of the Fu-Niu Mountain National Nature along elevation gradient, while distributions of individual species differed significantly along different elevation gradient (Figures 1 to 6, Table 6).

A general model of the links between herbaceous species diversity and disturbance gradient from IDH perspective (magnetohydrodynamics (MHD))
The IDH is used as a framework for investigating the linkages between disturbance and species diversity.
Unfortunately, the various IDH makes it difficult to compare data from different studies in order to draw general conclusions (Connell, 1978;Aronson et al., 1995).
It is therefore important to develop MHD which is  universally applicable across a range of ecosystems so that the relationship between herbaceous species diversity and disturbance gradient can be more accurately quantified with quantitative measurements of disturbance intensity.Here we proposed the use of a MHD framework that incorporates model (Figures 2 to 5) operating on varying spatio-temporal and disturbance scales for in-depth studies of the relationship between herbaceous species diversity and disturbance gradient (e.g.anthropogenic disturbance and natural disturbance).Such a MHD will facilitate ecosystem studies that apply the links between herbaceous species diversity and disturbance gradient from IDH perspective (Figures 1 to 7, Tables 1 to 6).The above MHD can help identify the relationship between herbaceous species diversity and disturbance intensity most relevant to tolerating environmental fluctuations or recovering from IDH perspective (Figure  (Liao et al., 2010;2011a, 2011b).7).Based on the fact the MHD is useful to achieving the goal of ecosystem, sustainable development in the context of biodiversity conservation is needed.For example, Bartels et al. (2010) explained that whether resource quantity or resource heterogeneity is the determinant of understory plant diversity in individual studies was dependent on stand successional stage(s), presence or absence of intermediate disturbance, and forest biome within which the studies were conducted.Carvalheiro et al. (2011) suggest that presence of weeds allowed pollinators to persist within sunflower fields, maximizing the benefits of the remaining patches of natural habitat to productivity of this large-scale crop.

Applying general model to species conservation and forest ecosystem management
The above MHD can help identify theoretical ecology (e.g.diversity dynamics, species composition, food web structure, diversifying plant-microbial system, ecosystem stability/functioning, organic agriculture, biodiversity law, watershed ecosystem management, assessment of ecosystems and biodiversity, scale dependence) (Liao et al., 2010(Liao et al., , 2011a(Liao et al., , 2011b;;Stutter et al., 2010;Shennan, 2008;Menalled et al., 2001, Bartels et al., 2010;Crowder et al., 2010;Bai et al., 2004;Davis et al., 2007;Bernez et al., 2002;Marris, 2010;Crawley et al., 2001).For instance, Menalled et al. (2001) suggest that ecosystem management systems can have both immediate and long-term effects on weed species density, abundance, and diversity.Shennan (2008) proposed that important elements for understanding biotic interactions include consideration of the effects of diversity, species composition and food web structure on ecosystem processes; the impacts of timing, frequency and intensity of disturbance; and the importance of multitrophic interactions in ecosystem.Stutter et al. (2010) proposed a mechanism whereby the establishment of vegetated buffer strips between cropland and watercourses on previous agricultural land causes a diversifying plantmicrobial system.Bartels et al. (2010) explained that whether resource quantity or resource heterogeneity is the determinant of understory plant diversity in individual studies was dependent on stand successional stage(s), presence or absence of intermediate disturbance, and forest biome within which the studies were conducted.Therefore, it will nonetheless be a substantial challenge to apply this MHD to specific real world policy problems (Gilbert 2010;James et al., 2010;Marris, 2010).

Conclusion
Progress in three key areas will substantially further efforts to gain a rigorous understanding of how the links between herbaceous species diversity and disturbance intensity, and their interactions, influence the response of ecosystem properties to changing biodiversity.First, better understanding of the relationship between herbaceous species diversity and disturbance intensity is correlated, particularly with respect to the predominant forces of human activities.Second, MHD is based on both field investigations of community ecology techniques of 100 herbaceous layer quadrates and scientific analysis, which can use more and more theoretical ecology.Finally, MHD can be useful to understand the plant species diversity and disturbance intensity from IDH perspective.Understanding MHD is essential for further research of local ecosystem functions and the goal of ecosystem sustainable development in the context of herbaceous biodiversity conservation in natural or artificial disturbance ecosystem.Therefore, MHD may help to ameliorate this situation about losses of plant species diversity (e.g.medicinal plants, honey plants, fiber plants, etc).

ACKNOWLEDGEMENT
This work was supported by the Forestry Department of Henan Province Science Foundation of China (No.201004044), the National Natural Science Foundation of China (No. 41071118) and by the many ideas of some researchers of "1st Biotechnology World Congress".

Figure 1 .
Figure 1.A digital cadastre map in the typical hilly areas of Henan Province.

Figure 4 .
Figure 4.The relationship between Simpson and disturbance in the typical hilly areas boundary areas.

Figure 5 .
Figure 5.The relationship between Simpson and disturbance in the typical hilly areas center areas.

Figure 6 .
Figure 6.The relationship between Simpson and disturbance in the typical hilly areas.

Figure 7 .
Figure7.The proposed the framework of relationship between herbaceous species diversity and disturbance gradient that incorporates herbaceous species diversity dynamic from the intermediate disturbance level, and operating on varying spatio-temporal and disturbance scales in the forest ecosystem.The model was based on the study(Liao et al., 2010;2011a, 2011b).

Table 1 .
The relationship between IDH and biodiversity from the different perspectives.

The relationship between IDH and biodiversity from the different perspectives Author Water
level fluctuations, fire and grazing are essential for maintaining plant diversity.Keddy, 2005.Increased diversity at intermediate disturbance was due primarily to increased evenness.Aronson, 1995.Diversity and soil properties were best at intermediate disturbance levels.Zhang et al., 2010.The IDH pattern was obtained for low frequency dependence and low immigration.Cordonnier et al., 2006.Generate a period-bubbling bifurcation structure and population dynamics that are most variable at intermediate disturbance frequencies.Reluga, 2004.

Table . 2
. The physical geographic conditions of Fu-Niu Mountain nature reserve.

Table 3 .
The selection of the weighting values of disturbance.

Table 4 .
Investigation Index along the elevation gradient variable.

Table 5 .
The negative correlation between Simpson and weighting values of disturbance. **P<0.01

Table 6 .
Dynamics of vegetation dominate species on the typical hill areas of the southern slope of the Fu-Niu Mountain National Nature at PFGs level along elevation gradient.