make an introuduction and put in a hypothesis. here are a few key details This study aimed to assess the impact of human pressure and landscape structure on the populations of small mammals in Warsaw, Poland, a large urban agglomeration. The research was conducted at 17 locations along both sides of the Vistula River, which differs in urbanization levels and human influence. The study sites varied in terms of their spatial structure, distance from the city center, and exposure to human activity.
The findings revealed that species diversity was highest at the city’s borders and in rural areas. On the left bank of the Vistula, which has undergone more intensive urbanization, species diversity was lower and showed a significant negative correlation with human pressure. In contrast, the right bank, with less urban development, supported a richer diversity of small mammals, even in the city center. The striped field mouse (*Apodemus agrarius*) was the only species present on both sides of the river, while the yellow-necked mouse (*Apodemus flavicollis*) was also found on the right bank.
The study concluded that human pressure and spatial isolation are key factors influencing small mammal communities in urban environments. The less developed areas on the right bank provide better conditions for species survival, highlighting the importance of preserving green spaces and minimizing fragmentation in cities to support biodiversity.
Key terms: small mammals, species diversity, urbanization, anthropopressure.
The study was conducted in green areas (parks, gardens, and wastelands) in Warsaw, Poland, on both sides of the Vistula River. The sites varied in distance from the city center and were exposed to different levels of human pressure, which were categorized on a five-point scale. The areas ranged from highly urbanized to more rural locations, with the least human pressure found at the city borders and non-urban sites.
In total, 17 locations were studied, with small mammals trapped using live traps. A total of 933 animals from 8 species were caught, including 7 rodent species and 1 insectivore. The biodiversity of small mammal communities was assessed using the Shannon-Wiener diversity index.
Trapping occurred in September 2010 and 2011, with each location having 30 traps placed along a 600-meter line for 7 consecutive days. The relationship between species diversity, human pressure, and area size was analyzed using linear regression, Pearson correlation, and global linear models. This analysis aimed to explore how human pressure and location size influenced small mammal species composition and diversity.
### Results Summary:
1. **Species Diversity and Human Pressure:**
– A total of 933 small mammals from 8 species were trapped. Species diversity was higher on the **right side** of the Vistula River compared to the **left side**, where the number of species was lower.
– As human pressure increased, species diversity and the number of species decreased, especially on the left side of the river (GLM: F=13.58, P < 0.005). However, on the right side, urbanized areas with higher human pressure (degree 3 and 4) still had a higher species count than more natural areas.
– The **striped field mouse** was the most common species, found in all locations (52% of captures), followed by the **yellow-necked mouse** (30%) and **bank vole** (9%).
2. **Left vs. Right Bank:**
– On the **left side** (more urbanized), only three species (striped field mouse, yellow-necked mouse, and bank vole) were found, with the bank vole appearing only in low-pressure areas.
– On the **right side**, both the striped field mouse and yellow-necked mouse were found in all locations, and additional species like the wood mouse, common vole, and common shrew were also present.
– For locations with the same degree of anthropopressure and size, the **right side** showed significantly higher species numbers than the left side (GLM: F=5.05, P=0.05).
3. **Shannon-Wiener Index:**
– The **Shannon-Wiener diversity index** also decreased with increasing human pressure on the left side (GLM: F=13.58, P < 0.005) but showed no significant trend on the right side.
– On the **left side**, species diversity was positively correlated with the size of greenspaces, meaning larger areas supported more species. However, this correlation was not found on the **right side**.
4. **Size of Green Spaces:**
– For the **left side**, both species richness and the Shannon-Wiener index increased with larger greenspaces. On the **right side**, however, no such relationship was found.
– Overall, there was a significant interaction between the **size of greenspaces** and the **side of the river**, indicating that the effect of area size on species diversity differed between the two sides (GLM: F=5.04, P=0.05).
### Key Findings:
– Human pressure negatively impacted species diversity, especially on the left bank.
– Larger greenspaces supported more species on the left side but not on the right side.
– The right bank, despite urbanization, maintained a higher species diversity, possibly due to less severe human impact compared to the left bank.
### Discussion Summary:
1. **Sources of Urban Small Mammal Populations**:
– Small mammals in urban areas, such as Warsaw, often come from two sources:
– **Urban traps**: remnants of rural environments absorbed by urban development, or
– **Active colonization**: species migrating from rural areas into cities.
– The **striped field mouse**, which was present in Warsaw since the early 20th century, likely colonized the city from rural populations, rather than being an urban trap species.
– The **yellow-necked mouse** and **bank vole**, both of which have recently colonized the city, have spread further on the **right side** of the river, likely due to different urban infrastructure on that side.
2. **Urbanization and Species Distribution**:
– **Right side of the Vistula** (less urbanized) appears to provide better migration corridors and more favorable conditions for small mammal species. Greenspaces, including those close to the city center, support a higher diversity of species compared to the highly urbanized **left side**.
– The study supports the idea that areas with **greater spatial connectivity** between natural habitats allow for easier migration and colonization. **Greenspace corridors** extending from suburban areas into the city may help maintain biodiversity in urban environments.
– The results also align with the **Intermediate Disturbance Hypothesis (IDH)**, suggesting that disturbances (urbanization) can transiently increase biodiversity, especially in areas with heterogeneous environments.
3. **Impact of Urbanization on Biodiversity**:
– Increasing anthropopressure (human impact) leads to a decline in species diversity, particularly on the **left side** of the river. However, no such significant relationship was found on the **right side**, where species diversity remained higher despite urbanization.
– **Greenspaces on the left side** of Warsaw are often isolated “islands” surrounded by dense buildings and busy streets, which limit species migration and recolonization. This isolation hinders the genetic variability and long-term viability of small mammal populations.
– Conversely, the **right side** of the river, with a more connected network of greenspaces, allows for better species flow between rural and urban populations.
4. **Planning for Urban Biodiversity**:
– The study emphasizes the importance of **urban planning** in preserving biodiversity. Urban infrastructure should include **wildlife corridors** that connect local greenspaces to rural habitats to facilitate species migration and prevent isolation.
– Properly planned urban areas can serve as refuges for species, supporting their populations by allowing them to move freely and maintain genetic diversity.
– This is especially important for rare or specialized species that are less adaptable to urban environments and more vulnerable to extinction due to habitat fragmentation.
5. **Conclusions**:
– The study supports the idea that urban greenspaces, if properly connected, can serve as crucial corridors for wildlife, supporting biodiversity even in highly urbanized environments. Careful urban planning that integrates these greenspaces and corridors will help maintain healthy ecosystems in cities and contribute to the preservation of biodiversity.